Naturalman7

Started July 17, 2014

Updated August 3, 2014. Updated photos and added info regarding the real and not CAD blaster.


Disclaimer:

Although I could build and document a Pumpbow in a day or two, there was no chance McMaster would deliver the necessary parts in time so I decided to make this a virtual write-up and retake all the pictures with real materials when they arrive. However, this is not just a virtual blaster as well; it’s tried and proven.

This write-up uses Captain Slug's original 'format' of a guide with the process broken up into steps and not sections.



 

Pumpbow Write-up

Intro


Captain Slug’s original write-up is excellent and easy to follow. Reading that first will give the reader a solid basis. In fact, one can simply follow the original guide and make simple modifications to convert it to pump action. But for the unexperienced, it would be difficult. Ryan201821’s Pumpbow overview is the only thing close to a Pumpbow write-up I’ve seen, and it isn’t much. So, naturally, a new official write-up is necessary. This write-up includes step-by-step instructions, photos, printable stick-on templates, and a McMaster parts-list. It also does not require any tools beyond what is required for the original plusbow (+bow). This write-up is essentially a replication of Ryan’s and Slug’s work and some sections are repeated word for word. The conversion to single piece side plates and pump action is simply reducing the width of the frame pieces and aluminum spacers.

Several screw lengths have been increased to give them more strength when attached. I recommend using screws with lock washers wherever possible to prevent any screws from loosening over time due to vibration – an issue I’ve come across. You can honestly use whatever length of screw you want. I think specifying 5/16” screws is kind of weird when any other more common length would work.

Slug’s original guide skips steps sometimes. If you attempt to follow the original exactly, you’ll likely be confused as to how some screws magically appear, or disappear, as I was.

You can cut the parts from sheet from thicker material for increased strength if desired, but you would have to adjust the design accordingly. If the handle trigger guard pieces are made with 3/8" thick polycarbonate, the aluminum threaded spacers can be omitted, but the handle pieces would need to be sanded heavily to be comfortable.





Overview and Cost

Performance is the same as a regular +bow – dependent on the spring the user wishes to use and desired draw. The blaster in this write-up has a lot of options that can be added or removed. The stock, handle, priming handle and methods can all be done differently based on personal preference.

The blaster seen in this write up cost ~$40.00. Keep in mind that these calculations use an exact value for the area of the machined pieces and the actual cost is likely much higher. I will update these values when I can determine a more accurate number for the amount of material used. The handle can be replaced with either wood or polyethylene, which would affect cost. Changing the front seal piece could reduce the price an additional $4.00.

The cost of materials to build one of these blasters is ~$139.53, omitting shipping costs and tax. This is not the cheapest possible, but it is likely the best raw materials cost to produce the cheapest per blaster cost.

The most time consuming part of this blaster is sanding the wood pieces to fit your comfort.





Templates

PDF:

https://drive.google...it?usp=sharing' class='bbc_url' title='External link' rel='nofollow external'>PumpBow Templates.idw

The side plate templates are too long to fit on one page. There are duplicates of the side plates so the two halves of each can be stuck together.

JPG previews of templates – not 1:1 scale (unless someone can tell me how).





Tools




Part List/McMaster Parts List/Materials List


Download: Pumpbow BOM.xlsx

Text version:
All items available through http://www.mcmaster.com/

The UHMW rectangle pieces are missing from the parts list because they are literally just scrap rectangles cut from the angled bars. Just make sure you order a length of UHMW that is at least 1' length, which shouldn't be a problem because 1' is the shortest length available.





Diagrams








Procedure


Step 1: Templates



If you have large fingers and find the trigger guard uncomfortable, you can remove the trigger guard and overhaul the handle. A simple cutting off of the trigger guard can solve this problem.


Download the template sheets from the Templates section.

Print them on full sheet label paper. If you run out of color ink (like Slug did), you won’t have any problems because all the hole sizes are printed on the templates and not in color.

Cut all of the individual templates apart using scissors.

Arrange the cutting templates on the thicknesses of polycarbonate sheet indicated on each template. You’ll have to buy polycarbonate sheets for the side plates larger than the typical 12”x12”.

Keep enough of a gap between the templates to allow the blade of the scroll saw to cut in between the parts. Once you have them arranged, remove their backing paper and apply them to the protective film on the sheets.

If you want super precise cuts and holes, also use the templates for the UHMW pieces.




Step 2: Drill Holes




Using a drill press or power drill follow the hole sizes you printed to drill out all of the holes to the required sizes. I highly recommend a drill press to keep the holes as precise and straight as possible. It goes a long way in ensuring easy assembly.

Also make sure to drill 5/32" diameter pilot holes in the center of the areas you will have cut out. Such as the pass through holes in the frame pieces and catch plate, the slide tracks in the trigger and catch plate, the trigger wells in the sides of the grip and the center of the priming handle.

Use a 1/2" bit and a 9/16" bit on the indicated holes.

The wooden butt stock's 7/64" holes are thru holes - to be drilled all the way through. The 1/4" holes on top of the 7/64" are only for counterboring the holes. Drill them half way through on the backside of the piece. The rest of the holes in the butt stock (the three other 1/4" holes in the middle of the template are to be drilled on the template and to a depth of around half way through. If that sounds confusing, click the spoiler for some pictures.




Step 3: Internal Cuts




Use a scroll saw or jig saw to make the internal cut outs in the trigger catch and grip pieces before cutting them off of the rest of the sheet. Start by feeding the blade through the pilot holes drilled in Step Two then re-tensioning the blade. If the sheets are too large to fit in your saw, free some of the pieces off of each other. I would go against Slug’s original words and not suggest a jig saw. I find them too imprecise, but perhaps it’s just my lack of skill with jig saws.




Step 4: External Cuts




If any of the pieces are safely cut-able with a table saw, use a band saw to make all of the external cuts needed to free and shape the parts out of the sheet. Use a scroll saw cut any of the small, more difficult pieces. The square-er and larger pieces I cut with a table saw. I find it’s also easier to make straight cuts with a table saw than a scroll saw if inexperienced, but also more dangerous, so be aware.

It’s worth noting that the larger polycarbonate disk is for the front of the skirt seal. It squishes the skirt seal which seals the two holes in the top of the skirt and compresses the skirt which flares it outward, which helps the seal. I’ve found that making this piece as perfect as possible goes a long way to making the seal perfect. The front polycarbonate disk flares the seal outward and presses it into the walls of the PVC body. I’ve found it easiest to machine this piece with a hole saw, then lathe it down to fit if you’re not good with a scroll saw.

Also cut the two sections of the UHMW angle for the pump grip and two 1/2”x6” pieces of UHMW.




Step 5: Aluminum Priming Bars




Cut two 13” length sections of ¼”x1/2” aluminum bar. Measure, mark, and drill 7/64” and 5/32” holes where indicated. Then tap the 7/64” holes #6-32.




Step 6: Trigger Catch




Use a scroll saw or band saw or hobby knife to round the corners on the trigger catch as shown. This will allow the trigger spring to fit over this peg.




Step 7: Side Drilling




Either use a steady hand, or a drill press vice (or even better a good mill) and drill the holes in the sides of the pieces as marked. Drill each hole to a depth of around 1/2 of an inch.




Step 8: Tapping




Tap every 7/64” hole in polycarbonate with a UNC #6-32 tapping bit. Also tap the one hole in the thumb hole stock and the 7/64” holes in the UHMW and aluminum. The rest can be left 7/64”.




Step 9: Nylon Rods




Using a mitre saw with box, table saw, band saw, scroll saw or circular saw cut two 8-1/4" length sections, one 7" length section, one 9” length section, and one 5" length section off of the 1/2" diameter plastic rod.

Mark the center of both ends of all of the rods.

Using a 7/64" bit in a drillpress or power drill drill to a depth of around 1/2 of an inch. Then tap the holes with a UNC #6-32 tapping bit.

It’s easiest to make these holes as centered as possible on a lathe.




Step 10


Unsanded handle. Just imagine how painful it would be to try to use this.


Remove the cutting templates and protective film from the plastic sheet parts.

Deburr the edges of all of the sheets using a hobby knife To quickly remove the burrs simply orient the blade perpendicular against the edges of the sheet and run it along them. Any trouble spots can be cleaned with the hobby knife by manually cutting away the burrs.
Further smoothing can be done with sandpaper if desired. I would recommend doing so on all the pieces, especially around the handle trigger guard. Use either a lot of elbow grease and sand paper to round the grip/stock or use a power sander of some sort.




Step 11




Assemble the center frame piece and catch plate together as shown using washers and 3/4" length screws.

Attach the 9" length section of 1/2" diameter rod to the center frame piece using a 3/4" length screw. Mark on it where the centerline of the catch plate is.

Remove the 9" rod and using a 7/64" bit in a drillpress or power drill drill through where marked. Then tap the hole with a UNC #6-32 tapping bit.

Attach the 9" length rod to the rear frame piece again using a 3/4" length screw. Install a set screw into the newly tapped hole by hand.

Install a 1" length spring (one with a load between one and five pounds) onto the catch plate and the set screw.




Step 12




Attach the 8-1/4" length sections of 1/2" diameter rod to the rear frame piece with 3/4” screws. Slide the rear frame piece onto the 9" length rod.




Step 13




Attach the side panels using 1/2" length screws.




Step 14




Attach the ¼” length threaded spacers to each trigger guard handle pieces with 1/4” length screws.




Step 15




Attach the thumb hole stock to the two trigger guard handle pieces with six 3/8” length screws and two 3/8” length set screws. I use the set screws instead of regular screws because the screw head was right on the joint of my thumb and was quite uncomfortable. The handle is attached with plenty of screws and it would likely be possible to omit a screw here all together.




Step 16




Attach the rest of the handle and trigger hardware to the grip pieces. Attach the last aluminum spacer with 3/8” screws and assemble the trigger with a 1-1/4” L screw, the two ¼” L spacers, and trigger.




Step 17




Put a lock nut on the end of the 1-1/4" length screw, but only tighten it enough for it to lock or the trigger won't slide.




Step 18




Now use ¼” and two 3/8" length screws to attach the grip assembly to the catch and stock assembly.




Step 19




Attach the polycarbonate stock plate with three ½” screws.




Step 20




Then attach the wood stock plate with two ¾” screws. You can use any material you like for the stock, but I like NoM’s +bow style. The holes in the back of the butt plate should fit nicely over the screws.

NoM’s +bow




Step 21




Attach the forward bottom plate as shown. I choose to use this piece instead of two 1-1/2” aluminum threaded spacers because it prevents the front from turning and torqueing better. It’s also what Ryan did on his Pumpbow thread (probably to integrate some sort of pump-auto-return feature).




Step 22




Attach the two UHMW rectangle pieces to the side plates with set screws. Four screws may be excessive and fewer could be used.




Step 23




To stop any possible spring binding (where the spring gets stuck in the catch), chamfer the front, shorter, section of the plunger rod. I find this is easiest to do on a table sander, but it can also just be cut and smoothed with a knife.




Step 24




Take a 1-1/4” length screw, cut off the head with a hacksaw or horizontal bandsaw, ‘debur’ the end if it’s sharp and unclean, then screw it into the other plunger rod.




Step 25




Then, assemble the plunger head as pictured. A 1.25” x .25” metal fender washer acts as the spring rest and supports the skirt seal, the rotary shaft ring seal creates the air seal, the small section (11/64”) of 1” OD 7/8” ID tubing keeps the skirt seal from buckling inward on itself and ruining the air seal, and the polycarbonate disks in front squishes the skirt seal which seals the two holes in the top of the skirt and compresses the skirt which flares it outward, which helps the seal. I’ve found that making this piece as perfect as possible goes a long way to making the seal perfect. The front polycarbonate disk flares the seal outward and presses it into the walls of the PVC body. Without the tubing piece, the skirt seal sometimes buckles inwards and causes one side of the skirt to not seal probably. With a proper polycarb disk on top combined with a tubing piece of the right height, the seal is perfect and low friction. If the plunger head when lubricated has too much friction in the PVC, take down the OD of the polycarb disk slightly and retest fit it. This method seems to create a 100% seal perfectly, every time.




Step 26




Install the plunger cross and slide the plunger tube over it.




Step 27




Lube up the seal with a silicone based lube, add a spring, and insert the plunger rod into the plunger tube, from the front. It should be a fairly tight fit, but should slide.




Step 28




Mark where shown on both sides of the plunger tube. Using a 1/8" bit in a drillpress or power drill drill where marked on both sides.




Step 29




Insert the bushing adapter into the end of the plunger tube temporarily and mark it as shown on both sides.

You don't want to drill the holes in the bushing too far forward or it will prevent you from installing a barrel.

Here are three slightly different ways of attaching the front bushing.

My method:

Slug's original tried-and-true (but difficult and archaic) method:

Xellah's thoughts:

No matter the method, DO NOT OVERTIGHTEN THE HEX NUT AND SCREW.





Step 30




Either use the templates to drill the bottom of each UHMW angle, or use the bottom plate to measure and mark the angles. Either way, attach the angles to the bottom plate with four 3/8” screws.




Step 31




Attach the grip to the two aluminum bars with ½” screws.




Step 32




Add the rectangle piece with the hole (Priming Plate) to the back of the plunger rod and slide the grip onto the body.

Langley has experienced an issue with the priming system.





Step 33




Attach the aluminum to the priming plate with two ¾” screws. Add the small priming disk to the end of the plunger rod and attach it with a ¾” screw.




Step 34


New screws are pink.


Drill one last 7/64” hole in the bottom of the front plate and tap it. Add a 3/8” screw in this new hole and add another one to the trigger. Attach a rubber band to the screw and the trigger screw.




Will add these last two sections, later.

Modifications

A vertical foregrip can be attached to the square plate under the pump handle, but this could cause the plate to crack and the angle brackets to warp. It's better to use a horizontal foregrip, like on the pump-action blasters in my previous write-ups as seen here:




Problems

Priming Plate

I'm not entirely sure what Langley was talking about here:


If you notice excessive friction on the side plates, you can add some adhesive backed Teflon film under the aluminum bars.

Problem with friction with real blaster:





[url=https://flic.kr/p/ogWxcp]





Pumpbow Prototype Firing Video






But feel free to post anyway, I shouldn't need a lot more photos. Comments, questions, concerns?

 

Begun January 24, 2014

Disclaimer: I did not want to anger any admins so instead of creating a new post for each section and making an interactive table of contents, I just broke it up into a few different sections due to image posting limits.


Is there a limit to the number of links allowed in a post? I'm not unfamiliar with post formatting, but for some reason, some things don't like to work right.


Read photos from left to right, top to bottom. Thank you Zorns Lemma for helping me with regex.

 

Rainbow

This writeup for a Rainbow Pump will address common points of failure and pitfalls, include a McMaster parts list, extensive photos and instructions, diagrams and cutting templates. This is an 'Open Source' homemade design based on Ryan's original Rainbow Pump. However, this one requires slightly fewer steps and is also slightly cheaper. I would have focused on a pump-action plusbow writeup instead, but I feel like due to their greater cost, difficulty to make, and similar performance, a pump-action Rainbow is better. I saw numerous +bows used during 'geddon, and they all seemed similar in most ways to a pump-action Rainbow. Because there is already a very good write-up (although old), this writeup will not go super in depth on the things that are similar, but will focus on the things that are different. Much of this information is repeated from my other write ups. If you’ve read those, you’ll encounter repeat information. If you haven’t read them, I’d recommend you do. They have some information that isn’t repeated. Without further delay, here it is:




 

Pump-action Rainbow Blaster

Table of Contents

-Overview and Cost
-Templates
-Tools
-Diagrams
-Procedure - Linked
--Machining Pieces
---Side Plates
---Handle Pieces
---Catch Circles
--Handle
---Handle Assembly
--Catch
---Cut
---Drill and Tap
---Assemble
--Plunger Rod
--Main Body - Linked
---Measuring
---Cutting, drilling, and Milling
---Tapping
---Catch
---Reattach Handle
---Back to Plunger Rod - Linked
--Priming Slide
---Slot in Priming Slide
---Access Hole
---Half Pipe
--Back to the Blaster
--Sheath and Stock
--Front Bushing - Linked
--Modified Stock
-Errors
-Plunger Rod Breakage




Overview and Cost
Ryan’s original blaster used a PVC inter coupler piece that I didn’t think was the most efficient thing. That’s the main difference and is what this blaster is based upon.

The blaster seen in this write up cost $44.55. Omitting the optional nylon washers would reduce the cost ~$0.38. An opaque blaster would bring the cost down a further $25.00, but would make assembly difficult. Changing the seal piece would reduce the price an additional $4.00. I anticipate the cheapest this blaster could be produced is ~$15.00.

The cost of materials to build one of these blasters is $180.00. This is not the cheapest possible. This is likely the best raw materials cost to produce the cheapest per blaster cost.




Templates

Rainbow Catch Templates.jpg
Rainbow Catch Templates.pdf
Rainbow Catch Templates.idw





Tools
• Drill
• Scroll saw
• Screw drivers – ph2 for #6 and #8 screws
• Tapping sets (#6-32, #8-32)
• Dremel disks for cutting (diamond cutting wheels are best) and/or a jigsaw or mill
• Hacksaw or other tool for cutting sections of PVC such as pipe cutters or rotational cutters
• 7/64” drill bit for #6-32 tapping
• Drill bit for string pass-through (7/32” works for a 3/16” string, if the ends are whipped well)
• 5/32” for #6 pass-through holes
• Drill bit for screw driver to fit through (7/16” fits my drill/driver ¼” adaptor)
• 3/8” bit for slots (or anything around ¼” should work.
• 3/16” bit for metal rod (or whatever sized rod you want to use)
Recommended
• Drill press
• Hole-saw – 1-3/8”
• Sanding belt
• Dremel sanding wheel, sand paper, files
• Hammer
• Pliers
• Something long and skinny to move the plunger rod. Also something to place behind the plunger rod to hold it in place.
• A screwdriver that fits in the hole for the priming rod can be used as a temporary priming handle




McMaster Parts List/Materials List

Clicking the image will take you to the google drive shared excel sheet. The photo file can be found on flickr.



• 2x Small Washers for catch (#6 x 3/8" Washers)
• 9x #6-32 x 1/2” Machine Screws
• #6-32 x 1-1/4" Machine Screw
• 7x #6-32 x 3/4" Machine Screws
• #6-32 Nylon Insert Lock Nut
• #8-32 x 1.25” Machine Screw
• 1-¼” PVC Tee
• 1”- ½” PVC Bushing
• ~19.5 sq in of 1x8x2 Poplar Board
• ~20” of 3/16” Braided Polyester Cord
• 3/16” x 1-1/4” Fender Washer Metal washer for base of plunger head (or Ryan Mc#’s plunger head assembly)
• 2” of 3/16” Diameter Steel Rod for priming rod
• 15” of 8663K15 Black Delrin® Acetal Resin Rectangular Bar, 3/8" Thick x 3/8" Width or 3/8” Square Nylon Rod
• Catch spring (I’ve got no part numbers for you. I’ve collected all sorts pen springs and such that I use. Just find something that looks like it’ll work, and it should.)
• 17.75” of 9245K51 Clear PETG Tube, 2" OD, 1-3/4" ID or 1.5” Thinwall PVC (the higher the PSI, the better)
• Main Power Spring. I use [k26]’s (McM #9637K26) Compression Spring Spring-Tempered Steel, 11" L, .844" OD, .08" Wire
• 11/64” of 8585K14 Impact-Resistant Polycarbonate Round Tube, 1" OD, 7/8" ID, Clear
• ~14 sq in of 8574K43 Impact-Resistant Polycarbonate Sheet, 1/4" Thick, 12" x 24", Clear (catch) – clear is cheaper than tinted
• ~6.75 sq in of 8574K41 Impact-Resistant Polycarbonate Sheet, 1/8" Thick, 12" x 24", Clear (side plates)
• 24” x 49035K86 Std-Wall (Schedule 40) Clear PVC Unthrd Pipe 1-1/4" Pipe Size or standard opaque PVC. The thicker walled, the better.
• 9” of 49035K28 Std-Wall (Schedule 40) Clear PVC Unthrd Pipe 2" Pipe Size or opaque 2” PVC
• Skirt seal – McMaster part #9562K46 Stretch-Fit Rotary-Shaft Ring Seal 1" Shaft Diameter, 0.95" to 1.07" Shaft Diameter
• 6x 92311A146 Type 18-8 SS Cup Point Socket Set Screw 6-32 Thread, 3/8" Length
Optional
• 1-1/4" PVC Endcap or 45 elbow and 2” of 1-1/4” PVC
• 9x 90295A075 Nylon 6/6 Flat Washer #6 Screw Size, .140" ID, .313" OD, .057"-.067" Thk




Diagrams

If someone knows how to share flickr photos without having the photo name or name of photographer appear so I can save room, that'd be great.

Intro
The first experiment I did with making a Rainbow type blaster was incredibly successful. Since then, I've made numerous Rainbow style blasters and I still haven't shared any of my experiences – now here they are. The rainbow refers to the unique catch mechanism. It was so named because it was originally designed by the ‘Rainbow Clan’. It utilizes two polycarbonate disks sandwiching a moving catch plate that catches in a notch cut into the plunger rod. The catch, like most of the work done on this blaster, requires use of tools not typically available to the average Nerfer. Cutting of the polycarbonate circles, the square holes in the centers of the disks, and drilling precise holes are all necessary in this build. A hole-saw, scroll saw, drill press, sanding tools, and skill with the aforementioned are all highly recommended and completing this build without these is extremely difficult, if not impossible – if you want to try some other techniques than the ones in this guide that builds the machined catch pieces that accomplishes similar goals with less tools, then try here: Handmade Rainbowpump Variant. It just takes more time and effort if you don’t have tools.



I'll add/edit/optimize the photos and provide links to references and other sources later. There should be enough info...for now.


Overview and Cost
This is a simple and basic blaster that has been commissioned in the past, but I haven’t seen any sort of write up for it. I’ve seen a lot of NoM’s commissioned Rainbow Pistols, and they all look super nice. This write up won’t address counter sunk black oxide screws, staining wood or fancy engravings, but will just be the basics. Perhaps, I’ll add a section later on customization if I do any fancy experiments.

This write up places the handle half an inch from the rear of the PVC main body of the blaster. I personally liked this look better, but relocating the handle further back on the blaster can reduce cost and size of the blaster.


The blaster seen in this write up cost $16.82. Omitting the optional nylon washers would reduce the cost ~$0.38. An opaque blaster would bring the cost down a further $3.00. Changing the seal piece would reduce the price an additional $4.00. I anticipate the cheapest this blaster could be produced is $9.50.

The cost of materials to build one of these blasters is $138.11. This is not the cheapest possible. This is likely the best raw materials cost to produce the cheapest per blaster cost.


Tools
Required
• Drill
• Scroll-saw
• Screw drivers – ph2
• Tapping sets (#6-32, #8-32 optional)
• Sand paper
• Hacksaw
• 7/64” drill bit for #6-32 pilot hole
• 5/32” hole for #6 pass through screw holes
• Drill bit that your screw driver can fit through (5/16”)
• 9/64” drill bit for #8 pass through
Recommended
• Drill press
• Table saw
• Table Belt Sanding
• Hole saw – 1-3/8” or 1.5”


Materials
• 2x #6 x 3/8" Washers
• #6-32 Nylon Insert Lock Nut
• 12x #6-32 x 1/2" Machine Screws
• #6-32 x 1-1/4" Machine Screw
• 3x #6-32 x 3/4" Machine Screws
• 2x #6-32 x 3/8" Machine Screws
• #8-32 Nylon Insert Lock Nut
• #8-32 x 1.25" Machine Screw
• #8-32 x 3" Machine Screw or a 2.5” screw if you can find one
• 14 sq in 1 x 8 x 2 Poplar Board
• 1”- ½” PVC bushing
• 3/16" x 1-1/4" Fender Washer
• 2x 3/8" x 3/16" x 1" Nylon Spacers
• 8.5”x Black Delrin® Acetal Resin Rectangular Bar, 3/8" Thick x 3/8" Width
• Catch spring
• 5”x [k25] Compression Spring, Spring-Tempered Steel, 11.0" Long,.968" OD, .08" Wire
• 6.75 sq in Impact-Resistant Polycarbonate Sheet, 1/8" Thick, Clear
• 6 sq in Polycarbonate Sheet 1/4" Thick, Clear
• 9”x Std-Wall (Schedule 40) Clear PVC Unthrd Pipe 1-1/4" Pipe Size
• Stretch-Fit Rotary-Shaft Ring Seal 1" Shaft Diameter
Optional
• 8x Nylon General Purpose Flat Washer, NO. 6 Screw Sz, .32" OD, .05"-.07" Thk


Important note: The reason I did not include a part number or anything for the catch spring was because you can use any spring you want. I used a small spring that I took from a different Nerf blaster. If you don't have any springs just lying around, you can use a spring from a pen if you can cut it down. It should be pretty easy. I've never purchased springs from McMaster for this purpose before, but I imagine you can find them.

 

 

Templates
Here are some different versions of the handle and the catch pieces. idw wasn't playing nice and wouldn't let me annotate the threads properly.
PDF Version
IDW Version



Procedure

Machined Pieces
You can either machine each piece before starting, or machine each as you go. I prefer to machine each as I go, unless mass producing any piece. But for clarity’s sake, I’ll just have you do it now until you’re more familiar with how to make each piece.

Apply the sticker templates to the polycarbonate on the indicated thicknesses. There are protective sheets on the polycarbonate. Glue or, if printed on adhesive backed paper, stick the templates on the polycarbonate. The rectangle side plates are the only pieces that need to be 1/8” thick. I’ve theorized using the 1/8” thick polycarbonate for the rear catch circle which may be possible. All other pieces are ¼” thick polycarbonate. The rectangle handle piece, trigger, and main handle piece are all for 1” wood – with a ¾” nominal thickness. You could look into what NoM has done with his handles and use polycarbonate for the trigger, but I’ll keep this guide basic.

The easiest way to machine the pieces is to first drill all the holes on the faces of the pieces. Drill the holes as marked. Then, use a table saw to cut the square rectangles, cut the front wood handle piece, and cut the wood main handle piece. The wood trigger is easiest to cut on a scroll saw. The catch pieces, circles and catch plate, are also easiest to do on a scroll saw. However, I’ve recently found using a hole-saw and turning it down on a lathe is easiest for the circles.

Each piece has little quarks that I’ve come across.

Side Plates
Drill and cut the side plates out of 1/8” polycarbonate. ¼” thick polycarbonate is useable and would be an easy option due to ¼” polycarbonate being also required for other parts of the blaster. The easiest way to machine these pieces is to cut them on a table saw and drill the holes with a drill press. Either drill all holes on the handle side plates 5/32”, or drill the middle hole 7/64” and tap for #6-32. If tapped, this allows the trigger screw to tighten or loosen on the trigger. I find that, depending on how the handle wood pieces are sanded, the side plates could end up being too tight on the trigger to allow it to rotate freely. This can be resolved by sanding the trigger smaller or increasing the gap between the side plates by adjusting the trigger screw. You’ll want to sand all the edges and corners down so that it’s comfortable – more on this later.


Handle Pieces
Drill and cut the forward handle piece, trigger, and handle. It is often easier to drill the pieces before cutting, because there’s more material to hold onto while drilling. However, the order isn’t important. All the holes are 7/64” except for the trigger which is a pass through for a #6 screw - 5/32”. The forward piece and handle are easiest done on a table saw and the trigger is easiest to cut out on a scroll saw. When the main handle is cut, drill the two holes on top. The holes in top of the main handle are easiest done in a drill press vise where the holes will be straight and the base of the handle will be flush. These, as well as all the holes drilled, should be centered and straight. Otherwise, your handle or other pieces could be ridiculously crooked and may cause friction, the screws to not align, or other problems. When the pieces are drilled and cut, sand them down. Smooth down edges and sand the trigger and handle so they are comfortable to use. I use Ryan’s original templates, but I remade them with more detailed markings - like center lines for example.


Only one of the top 7/64” holes in the forward wood handle piece is needed. The other hole, if used, interferes with the function of the blaster. Modification of some of the pieces may remove redundancy, but the templates were borrowed from Ryan and the parts I’ve mass produced are also interchangeable with my Rainbow Pump blasters. I will add this to the customization section.

The trigger’s flat top prevents the trigger from over traveling forwards. If the hole is drilled too high or the top cut is too low, than the trigger will be allowed to move forwards, which may be a minor undesired feature.

Catch Circles

The catch circles are easiest to first drill the two 7/64” holes in each circle, then to cut them out with a hole-saw, and then to finally lathe them down so they fit in 1.25” PVC. However, if you’d like the practice or are good with a scroll saw, than it would be faster to simply attempt to cut the circles with it. If done with a scroll saw, it’s easier to drill a pass through hole for the scroll saw blade in the center of circles to cut out the square holes. I like the perfect roundness of lathes, but a scroll saw is faster and, with skill, is just as easy to make round. However, if cut with a scroll saw, it may be necessary to sand the edges down so that it fits smoothly into PVC.


The catch plate is easiest to just cut out on a scroll saw after drilling a center hole. After all the pieces are drilled and cut, thread a scroll saw blade through the pieces and cut the square holes. I find it’s easiest to start the cuts diagonal first, and then square out the holes. Here are some pictures to clarify.

Drill the center hole.


Cut diagonally.


Shave out the inside of the squares.


Then clean it up.


You’ll want to make sure that all the pieces are smooth and sanded well. They need to be able to slide across each other freely.

Also, while making each piece of the catch, you’ll want to make sure that the square holes fit the Delrin rod and that at each step, the catch fits in the PVC body or you’ll have to sand it down again.


Plunger Head Circle
The easiest piece to machine is the circle of polycarbonate for the front of the plunger head. I find that this piece should be as wide as possible, but still allow the plunger head to fit into the PVC plunger tube. More on this later.




Handle

Handle Assembly
After the pieces are cut and all the holes are drilled, assemble the handle. Assemble the handle with eight #6-32 x ½” screws. Tighten well – I like my handles to not have any wiggle. I use nylon washers because I think they look nice and you wind up with a lot of extra washers from making a +bow. Omitting these washers reduces the cost of the blaster by ~$0.38. However, I’ve also noticed that the handle may be thinner than the 1” that these two screws would require and that the washers give a larger margin of error in the thickness of the wood or length of the screws. This is also another reason one may want to use ¼” thick side plates instead of 1/8”.


Catch

Cut
I know I’ve said some of this before, but here’s where it’s important.

Cut, drill and tap all the catch pieces. It’s easier to drill the two 7/64” holes in the catch circles before cutting anything out. Cutting the pieces out is pretty self-explanatory, but it took me a few tries to cut circles and such perfectly on a scroll saw. I’ve found that the easiest way to make the catch circles was to find a hole-saw and cut the templates out, then widdle it down on a lathe until it fit easily in the main body. The catch assembly and pieces should fit in the 1.25” PVC freely. One of the common pitfalls is machining the catch pieces. There’s quite a bit of margin of error, but the process can be made easier through a little bit of practice and technique. Just go slow and steady is the key. I find the easiest way to cut the square holes are to thread the blade through the center hole of the hole saw, cut diagonally across the squares, then ‘carve’ out the rest of the hole. Continuously test fit the 3/8” square Delrin rod into the catch pieces. For the catch plate, drill a pass through hole for the scroll saw blade, then cut the square hole.


Drill and Tap
Drill a 7/64” hole centered through the bottom of the catch plate and tap it for #6-32. Also tap the holes in the catch circles #6-32. Make sure the holes in the catch circles are straight, otherwise, if you’ve originally made the circles perfectly sized, the misaligned holes could cause the circles to no longer fit. With all the work done on the catch, debur and sand all the edges and holes in the catch pieces so they are smooth.


When I had originally printed out templates, they included diagonal holes for the screws to attach the catch to the main body. You can either drill and tap these in one of the catch circles, or simply wait to drill and tap them later – which would likely be easier, but I’ve done it successfully with either way.


Assemble
With the catch plate as a guide, assemble the catch with two #6-32 x ¾” screws with a .25" gap between the circles. The catch plate should slide freely in between the circles.


On the first Rainbow’s I made, I simply drilled the templates, cut the circles, and rounded them out on a table belt sander instead of a lathe. Using a table sander gave the advantage of being able to easily sand the catch circles as a whole assembled piece, if needed.

When the catch is assembled, it should still slide into the PVC easily. If the holes are misaligned and the catch is lopsided at all, hitting it with a touch of the sander can straighten it out to fit in the PVC again.



Main Body

Measuring and Marking
Figure out what spring you want to use. You’ll need to adjust the design to whatever it is you’re using. Take into account the length and pre-compression. The spring will change the length of PVC, the length of plunger rod, position of catch and subsequently the handle. I was thinking about creating some sort of program to calculate all the recommended dimensions based on inputting different spring and draw preferences.

I’ll be using 5” of [k25] with 0.5” of pre-compression.

I like any words on the PVC to be on the bottom of the blaster. Use a three sided ruler to mark the bottom. Then, use a marking rig to measure the body in eighths and extend these marks.


This write up places the handle half an inch from the rear of the PVC main body of the blaster. Make a mark there on the bottom of the blaster.

Place the handle on the mark and mark on the PVC where the holes in the wooden handle pieces are and where the trigger lines up.


With the marking jig rig again, extend/copy the marks of the three holes to the top of the handle.

Drilling
Drill the marks for the handle on the bottom 7/64” and make sure the handle still lines up with those holes. These holes are the two closest to the back and the one closest to the front. Tap each of the 7/64” holes in the bottom of the blaster #6-32.


Then, drill the mark for the trigger 5/32”.

Flip the body over and drill the three holes on the top of the blaster to fit a screwdriver through. The position of these holes should be marked on the blaster and should be mirrored from where the holes for the handle are. These wider holes are for attaching the handle. I used a 7/16” bit, but a smaller hole would work if your screw driver is smaller.



Catch
Take the catch, which should fit into the body, insert it with the threaded side of the screws to the front. If you’re wondering, the flat side of the catch will act as the rear spring rest.

Align the catch plate over the 5/32” pass through hole in the bottom.

Assemble the catch spring into the blaster and tighten it down so the catch stays in position.


Then, with a 7/64” bit, drill all the way through the body and catch circle on the diagonal sides. In order to keep the catch centered properly when drilling the holes, I like to hold the position of the catch with small drill bits.


With the holes drilled, now here there are a few choices. Remove the catch and tap the PVC and polycarbonate. If you did not drill and tap the catch circle before, you can remove the catch from the body and tap the holes. Or, simply tap the holes through the catch. Either way, put threads into the PVC and catch. You will need to push the catch out of the PVC with something long and skinny.


Attach the catch with four #6 x 1/2” machine screws.

Make sure that the affixed catch can fit the 3/8” Delrin rod freely and without friction. This shouldn’t be an issue if you test fit as you go and make sure you drill and tap all the holes properly.

At this point, you can remove any sharpie marks with alcohol.



Attaching Handle
Attach the handle with three #6 x ¾” machine screws.

It’s easiest to do this by holding the blaster upside down and starting the screws partially into the body.


When the screws are held into the body, I like to press the handle against the body and tighten the front most screw first, then the rear most, and finally the middle.


Make sure that the trigger is oriented properly, and not angled when you attach the handle.



Plunger Rod
At this point, I like to make the plunger rod next. This will determine the draw length and placement of catch.

Cut the section of 3/8” square Delrin to length – 8.5” is what I used. The length mostly effects how much finger room you have to grip the nylon pull back handles.

Then, mark the center of one end of the Delrin – which will be called the plunger rod (PR) from now on.


Drill two holes into the plunger rod. One in the center of the end of the rod for the plunger head, and one for the pullback handles.


I like to use a #8 sized screw for the front of the plunger (or plunger head/PH) because its wider diameter helps keep the PH centered. Drill a 9/64” pilot hole approximately one inch deep into the Delrin and tap it #8-32. Keeping the hole drilled and tapped centered will assist in making the air seal as perfect as possible.


Drill the second hole 11/64” pass through hole for a #8 screw centered on the rear end of the Delrin rod.

Plunger Head & Catch Notch

Create another ¼” polycarbonate disk that fits onto the top of the rotary shaft ring seal.

Then, assemble the plunger head as pictured. A 1.25” x .25” metal fender washer acts as the spring rest and supports the skirt seal, the rotary shaft ring seal creates the air seal, the small section (11/64”) of 1” OD 7/8” ID tubing keeps the skirt seal from buckling inward on itself and ruining the air seal, and the polycarbonate disks in front squishes the skirt seal which seals the two holes in the top of the skirt and compresses the skirt which flares it outward, which helps the seal. I’ve found that making this piece as perfect as possible goes a long way to making the seal perfect. The front polycarbonate disk flares the seal outward and presses it into the walls of the PVC body. Without the tubing piece, the skirt seal sometimes buckles inwards and causes one side of the skirt to not seal probably. With a proper polycarb disk on top combined with a tubing piece of the right height, the seal is perfect and low friction. If the plunger head when lubricated has too much friction in the PVC, take down the OD of the polycarb disk slightly and retest fit it. This method seems to create a 100% seal perfectly, every time.


Test fit this whole thing by lubing up the seal and inserting this plunger rod into the plunger tube, from the front. It should be a fairly tight fit, but should slide.


Test the compression of your spring and gauge where the catch notch in the rod needs to be.

I cut my notch for a 5” long [k26] with ½” pre-compression 1.75” from the plunger head. Keep in mind the thickness of the catch plate and catch circles. You’ll have to account for the added ½” in your measurements.

This notch is cut too deep.

With the spring and plunger rod properly fit in the body. Place the nylon spacers, #8-32 x 3” machine screw, and #8-32 locknut into the hole of the plunger rod. The machine screw will be too long, so hacksaw it down to a better size. Unless you can find a #8-32 x 2.5” screw, but I’ve been unsuccessful.


Front Bushing
The last, and arguably the most important step of a Nerf blaster is the front seal. There are a few different ways to create this seal. One involves plumber’s goop and tape of some sort.

Either sand down the lip of the bushing or have it stick out.


Wrap the base of the bushing in packing tape (or electrical tape, but I’ve found packing tape to be better).


Apply goop around the bushing and insert it into the front of the PVC. Apply any excess goop that leaks out around the seam of the front to ensure it seals properly


On the top and the bottom, measure ½” from the front of the bushing and drill two holes into the bushing 3/8” deep. I like to put the two screws for the front bushing on the top and bottom because if the screws were placed on the sides and the blaster down, the heads of the screws can scratch a smooth surface if the screw heads are not smooth.



Screw in two #6-32 x 3/8” machine screws to attach the front bushing. I find two to be enough. One would be too little, and I haven’t noticed that three provides any benefits.

By drilling the holes exactly to depth and not tapping them, it allows the fit of the screw in the hole to be tight enough that it helps the bushing to seal around the screw and it also creates slight ‘squishing’ of the bushing that increases friction in the bushing which can keep ½” PVC in the bushing better.

The second method, and the method I am still not sure how to perfect, involves just sealing and attaching the bushing with friction. Basically, it’s just hammering the bushing into the front of the PVC. Wrapping the bushing in tape can help keep it centered. The friction of the lip on the bushing creates a perfect seal with the PVC and the lip is wide enough to keep the bushing centered. However, I’ve found that, depending on the exact dimensions of the PVC and bushing, the force caused by the difference in size can actually cause the PVC to crack and ruin the blaster. The ID of the PVC is 1.335” and the OD of the bushing is 1.375”. I’ve lathed down the bushing to 1.365”, but there wasn’t enough friction to keep the bushing in place when pushing on a wye or barrel. However, it didn’t crack after several days, so there is room for a wider bushing that could work. The bushing sealed, but did not stay in place. Opaque PVC has a wider ID than clear, so that also causes a difference. Some pictures of the process:


After the bushing is dry and sealed, the blaster is done.



Maintenance
If excess dirt gets in the plunger tube/pressure chamber/main body/PVC, the front bushing can be unscrewed and removed by hammering or banging the rear of the plunger rod. I’ve done this several times without breaking the plunger rod and having seen any adverse effects. With the bushing removed, you can unscrew the pullback handles then remove the plunger and do whatever cleaning or replacement/repair you need.


Performance
I’ve found that my Rainbow Pistol shoots amazingly well. Much better than I originally thought it would. I used it at ‘geddon and loved it and have used it in local wars to great effect. It’s a great loaner blaster - powerful, accurate, easy to prime, small, and, coupled with a loading mechanism, decent rate of fire. It’s comparable to a panther, but slightly bigger, less range, and is easier to prime which gives it a greater RoF.

Barrel
I found the optimal barrel length (at least with my darts and a fairly tight batch of CPVC) is ~8.5” and can achieve ranges in the 80s consistently. In my ventures, I’ve found three different fits of CPVC. All three have different ID’s and I’ve find the tighter the fit, the better. I hammer the CPVC barrels into sections of ½” PVC. The fit, in the right brands of ½” PVC, is such that it stays together and seals with no further effort. One batch of the CPVC had an OD of less than 5/8” and required finding a batch of SCH40 ½” PVC that had a slightly smaller ID than regular and I had to CPVC/PVC cement the two together. If glued well, the two brands seal despite a large clearance.


Speed Loader
I like old fashioned speed loaders. It reminds me of the time when most people used simple speed loaders all the time. It’s my favorite method of loading pistols and I’ve used them a lot on CPVC couplered Nitefinder pistols.

The easiest way is simply taking 1.5” sections of SCH40 PVC and mallet-ing 8.5” sections of CPVC into them. The fit of these brands is such that they stay together. I then PVC/CPVC cemented them together and held them in a vise until they dried. The bond was quite strong, but to be sure, I then wrapped it in stylish tape.

RSCB
These are a fairly dated technology, but this was the first real RSCB I’ve made so I thought I’d share. Instead of just sticking ½” PVC fittings and pipes into each other, I stuck a variety of different pipes into each other to decrease overall size and dead space. I took a ¾” length of ½” SCH40 PVC, hammered it in a 1.25” length of ½” CPVC, added a CPVC tee, glued it into a ½” PVC tee, added a barrel and loading tube. I cemented in all the fittings and CPVC sections.

To adapt the barrel to load from the RSCB, I took a ¾” countersink and reamed the CPVC/PVC. I then took a large step less drill bit to create a smoother loading for the dart. I’ve found this is necessary because the dart seals better and loads much more reliably.


You may need to modify the design to stop darts from getting stuck in the tee, but I've found that it happens rarely enough that it's acceptable - but it does happen.


Slide Breech
Drill the ID of a section of ½” PVC out to 5/8”. The easiest way I’ve found is with a lathe and drill bit. I’ve used a steady hand and a 5/8” spade bit effectively as well. Cut a rectangle in the PVC. The size of this cutout section depends on the size of darts you intend to use. I start the cut by, obviously, marking and measuring it out first. I put the rectangle ~1” from the end of the PVC. This gives room to insert the breech into the bushing and a little extra so that it doesn’t feel too crowded. You’ll have to account for this extra distance when cutting the slot.

Cut the rectangle to the shape and size you want. I use a Dremel for breeches. There’s not another way I can think of to cut the slot.

I add a locking lug to keep the breech from opening due to air pressure from a tight dart fit.

I add this by cutting a semicircular in the bottom of the slot in the ½” PVC with a Dremel or drilling it with a bit.

I then drill a small hole for a small screw in the CPVC barrel. I close the breech and mark where the lug hole is. I then take a small nylon spacer and attach it with a small screw. It’s hard to find a perfect spacer and a perfect length and size of screw, just make sure the screw doesn’t stick too far into the CPVC and a dart can slide in. A breech can be considered either complex enough to need a write up of its own, and I’m sure there may be one, or several, write ups already. Or it can be simple enough to not need one and I’ll assume the latter.

One thing you should do is ream the CPVC to make it much easier to load and it makes a big difference. The darts will slip into the CPVC and angle right into the breech instead of potentially getting caught on a square edge.

Hopper
I’ve never tried to hoppered a RBPistol before. I imagine it would be possible with a low capacity hopper and will update this section when I try.

My aim here is to elaborate on the design by KaneTheMediocre. The original Aabow write-up was not very in-depth and the pictures, as of recently, are all broken. I've seen several different ways people make their bows, but this way is still relatively simple, takes a short amount of time, and is entirely mechanically fastened which means you can swap out parts and can have more customization such as changing out different bow arm lengths, adding a stabilizer, or re-tensioning the string.

End product is a 4' bow powered blaster with ~10" of draw.

AAbow (1) by Naturalman_7, on Flickr


Materials:

• 4x #6-32 x 3/8-in Machine Screws
• #8- 32 x 1/2-in Machine Screw
• #8 Finishing Washer
• 1" x 1/2" PVC Bushing
• 6" of 1" x 10-ft PVC
• 12"+5.5" of 1/2" CPVC
• 1/2" CPVC Endcap
• 1/2" CPVC Tee
• 2x .75" of 1/2" PVC
• 13" of 1-1/4" PVC
• 1-1/4-in PVC Tee
• 2x 1-1/4-in x 1-in PVC Bushings
• 3/16-in x 1-1/2-in Rubber Washer
• 3/16-in x 1-1/4-in Fender Washer
• 3.5' of 3/16-in x 75-ft Braided Polypropylene Rope
• 4' of 3/4" CPVC
• 3/4" PVC Endcap
• Duct Tape

Cost:
Total cost is just over $10. I've sold several of these to people locally for $20 ea.



Tools:
The only tools I use for these bows are a hacksaw, drill, and dremel sanding wheel - sand paper may also work. I used 1/8", 3/16", and 1/4" drill bits and a 5/8" spade bit. I also use a mallet for fittings that are unusually tight.



Procedure:

After cutting the necessary sections of pipe, I like to make the cross for the arms first.

Take the two 1-1/4-in x 1-in PVC Bushings and sand down the inside so the 1" PVC can fit. I use a dremel sanding wheel, but sand paper could also work.

AAbow (2) by Naturalman_7, on Flickr



It should fit fairly easily on 1" PVC.

AAbow (3) by Naturalman_7, on Flickr


Push these fittings into the ends of the PVC tee and add the 1" section of PVC.

AAbow (4) by Naturalman_7, on Flickr



Drill a 5/8" hole through the center of this tee assembly.

I use this series of reducer bushings and PVC to make a centered hole.

AAbow (10) by Naturalman_7, on Flickr



Once I'm through most of the way, I remove the centering rig and continue drilling the hole because the rig stops the bit from drilling all the way through. Just take a pair a pliers and pull out the bushings, then continue the hole.

AAbow (11) by Naturalman_7, on Flickr

AAbow (12) by Naturalman_7, on Flickr



At this point, make sure that 1/2" CPVC can fit through the hole centered and with relatively little friction. If not, take a dremel or a file and sand the inside of the hole and check fit again.

AAbow (13) by Naturalman_7, on Flickr



Take the bow arms, measure the middle, then wrap duct tape around 3.5 inches on either side of the middle. The arms should fit inside of the 1" PVC. The measuring should put the marks where pictured.

AAbow (5) by Naturalman_7, on Flickr

AAbow (6) by Naturalman_7, on Flickr

AAbow (7) by Naturalman_7, on Flickr



Drill another 5/8" hole in the arms. It's okay if the hole isn't clean.

AAbow (8) by Naturalman_7, on Flickr

AAbow (9) by Naturalman_7, on Flickr



Take the CPVC endcap and drill a 1/8" hole as centered in it as possible. I try to make a center mark by putting a sharpie through a section of CPVC to mark the center.

AAbow (16) by Naturalman_7, on Flickr

AAbow (17) by Naturalman_7, on Flickr



After drilling a hole in the CPVC endcap, attach it to the end of the CPVC pipe and drill 1/8" pilot holes for a #6 machine screw or two. Then add the screws.

AAbow (14) by Naturalman_7, on Flickr

AAbow (15) by Naturalman_7, on Flickr

AAbow (18) by Naturalman_7, on Flickr



Place the metal fender washer, rubber washer, and finishing washer (or in this photo, #8 fender washer) on the plunger head in this order. Secure this assembly with the #8 machine screw. The rubber washer will form a slight cup shape when tightened properly.

AAbow (19) by Naturalman_7, on Flickr



Lubricate this assembly and slide it into the 1-1/4" PVC so that the cup shape is maintained. The 1-1/4" PVC may have debris in it from sanding and/or cutting. You'll want to make sure everything is clean when you assemble it.

AAbow (20) by Naturalman_7, on Flickr



At this point, take the last reducer bushing, a section of PVC and the section of CPVC and assembly them together as shown.

AAbow (21) by Naturalman_7, on Flickr

AAbow (22) by Naturalman_7, on Flickr



Place this assembly onto the front of the 1-1/4" PVC. Do this by taking a section of 3/4" PVC or another similarly sized pipe and pushing it so that it is flush with the end of the pipe. The lip of the reducer bushing will create a seal with the 1-1/4" PVC. This piece should sit flush with the PVC.

AAbow (23) by Naturalman_7, on Flickr

AAbow (24) by Naturalman_7, on Flickr



Take the 3/4" PVC endcap, sand the edges down so that it fits inside the 1-1/4" PVC, and drill a 5/8" hole centered in it. Sand and/or drill out the hole so that it fits loosely around the 1/2" CPVC. You can use a similar method for drilling the 5/8" hole for marking the center of the endcap.

AAbow (25) by Naturalman_7, on Flickr



Drill a 1/8" pilot hole through the 1-1/4" PVC and endcap and secure it with a #6 machine screw.

AAbow (26) by Naturalman_7, on Flickr



Place the CPVC tee on the other end of the CPVC, drill a 1/8" pilot hole, and attach the tee with a #6 screw.

AAbow (27) by Naturalman_7, on Flickr



With the arms and mainbody assemblies done, attach the two together by pushing/hammering the arms onto the top of the 1-1/4" PVC.

AAbow (28) by Naturalman_7, on Flickr

AAbow (29) by Naturalman_7, on Flickr



After these two parts are attached, take the last little stub of PVC, measure where the excess CPVC is, cut it, and hammer it onto the end of the CPVC by the arms. This step isn't necessary if you use an exact sized piece of CPVC, but I find that it works pretty much just as well this way and saves me the hassle of finding or cutting an exact piece of CPVC and makes it so I can just use a scrap piece of CPVC and not worry about the length.

AAbow (30) by Naturalman_7, on Flickr

AAbow (31) by Naturalman_7, on Flickr



Drill 3/16" holes on both ends of the arms and cut wide notches for the bow string. The string will be pushed through the notches and the knots in the string will sit on the holes. You can optionally only cut notches on one end of the arms and just thread the string through the holes on the side without notches. I've done both ways, and I prefer to be able to completely un-string both ends if desired.

AAbow (32) by Naturalman_7, on Flickr

AAbow (33) by Naturalman_7, on Flickr



Next, string the bow. Tie a knot in one end of the string and place it in one of the ends of the arms. Thread the other end of the string through the hole by the tee, tie a knot in the other end of the string and place it on the end of the arm. Place the second knot so that when strung, the bow arms are a little before the end of the 1-1/4" PVC. With the plunger assembly pushed all the way to the front, mark and drill a 1/4" hole in the end of the plunger rod. The hole should be parallel with to the tee and perpendicular to the CPVC. Place the hole just in front of the endcap so that the bow string stops the plunger before the front of the plunger impacts the front of the bow.

AAbow (34) by Naturalman_7, on Flickr

AAbow (35) by Naturalman_7, on Flickr



One optional step at this point, is to add something to protect the string from wearing out from impact. I found this vinyl tubing works well.

AAbow (36) by Naturalman_7, on Flickr



Cut a section of the tubing, and push the rope through. I use a drill bit because it's small and pointy.

AAbow (37) by Naturalman_7, on Flickr



String the bow like normal but drill the hole in the CPVC slightly larger. If you drill a perfectly sized hole, the tubing will be able to sit snug and stay there.

AAbow (38) by Naturalman_7, on Flickr



If you don't have a perfect sized drill bit, applying a little bit of glue like hot glue will keep it in place.

AAbow (39) by Naturalman_7, on Flickr



Finished.


There it is, A completed AABow writeup that can be found on Nerfhaven.

AAbow (40) by Naturalman_7, on Flickr





I apologize for the brevity of this write-up; time does not allow me to create as lengthy write-ups as I would like. I will, of course, continue to lengthen and edit my write-ups continually in the future. Expect at least 3 more write-ups soon (a twist on the original Rainbow Pump, a competitive war-worthy sidearm, and a non-expensive Pump-action Crossbow).

Derrikk J. Sun
January 17, 2014
 

Pump-action SNAP 3.0 Write-up
I hope I don’t offend anyone by making this write-up
All pictures are mine unless otherwise stated

This is an extremely long, fully detailed, picture-heavy write-up. The sheer length of it may discourage anyone thinking about following it and it might be confusing at first, so try to read it more than once before undertaking. While it’s a fairly simple, step-by-step guide, it’s also fully comprehensive. This guide assumes the reader has at least an elementary knowledge of basic reasoning and understanding. Any terms or phrases not defined in the write-up itself can be found in the glossary. This write-up uses the term ‘gun’ and ‘blaster’ interchangeably. Apologies if this write-up is too long.


This write-up is broken into a number of sections. If there's a way to link to a certain line of text in a single post, someone please do let me know.


Each section is bolded in title and ends with a horizontal line. First tier writing is bolded and italicized. Steps are underlined. Substeps (#.# steps) are just italicized.



 

Table of Contents

 

Intro

There is definitely a plethora of different, all effective, pump-action, war-worthy blasters out there, but few are simple to understand and have easy to follow guides on how to build them. This blaster is not new or original, but searches for “SNAP 3.0” have yielded no results when looking for a good write-up. This design’s credit goes to TheNerfOmania. When searching for a guide I could follow, I did not find one, but I saw his design on YouTube and liked its simplicity, so I used it as a basis for the design in this write-up (TheNerfOmania). Props to you NoM for sharing your work.

 

Purpose

To create a step-by-step guide to building a pump-action SNAP 3.0 that not only explains what to do, but teaches the reason behind why each step is taken and is done the way described so that those fairly new to building homemade Nerf guns or those with less experience can construct a reliable blaster and understand the ideas behind some practices and techniques. As such, terms and definitions will be explained throughout this guide.

 

Overview

The final product will be a full length (11” long) [k26] spring powered pump-action homemade blaster. [k26] refers to the part number of the spring (which is 9637K26) as available through McMaster.com, an industrial and commercial supply company. The draw length (amount of length of the prime) is 6” with .5” pre-compression of the spring at rest. The blaster is not dry-fire safe (fire-able without a dart in the barrel), but sturdy and easy to disassemble and repair when necessary. The overall length is ~19”. Performance is on-par with similarly powered blasters, achieving a range of ~100-120’ with the ideal barrel length with a 10 dart/1’ hopper of ~16” (see the barrel subsection for an explanation).

 

Cost

The cost of a PumpSNAP 3.0 can vary greatly depending on what is used as handles. If the cost of the handle is excluded, the total price per blaster is ~$18.65. This value also excludes the cost of a roofing nail and clothespin which were obtained for free in this write-up. The total cost for all raw materials is $63.24. A Maverick’s cost would need to be added to these costs if one is to be used. The price if using wood for handles instead of a Maverick would be much less, but would also be necessary to take into account if used.

The figures used in these calculations can be found from this spreadsheet: PumpSNAP 3.0 cost sheet (Sun). The table is also included below. Usage of each part is explained in the write-up.



 

Materials



 

Tools



 

Procedure

The main event.

The order that the steps appear in is the order that I’ve found to be the easiest. But I’m no professional. As long as you have a bowl before you pour the milk or the cereal, it doesn’t really matter which is poured first. With that being said, let’s begin.



[b]Main Body


Step #1: Measuring and marking the main body

If you’ve gathered all the parts and cut all the sections of pipe before starting, as I’d assume one would do, then the first step is simply to figure out where the heck everything is supposed to go. When designing or building a homemade, before I do anything, I would draw a picture. Pictorial representations are always easier to understand than mental images or long blocky segments of text. Click “show spoiler” to view.



The picture really only helps if you care to understand what is happening as you build it, as I hope you do. Basically, we know the [k26] spring is going to be the ‘powerhouse’ of the blaster, and given the amount of draw we chose, we we’ll build off of and around that. Why a 6” draw? Because too much is difficult and annoying to use, and too little is both a waste of spring, another step if you choose to cut the spring, and isn’t as powerful competitively. Further explanation explained below.





This is the ~22” of thickwall 1-1/4” PVC.



A note about PVC, get the right PSI rating. A higher rating means thicker walls. The correct pipe would be 480 PSI. Don’t use anything with thinner walls. The inner diameter of lower PSI-rated pipe is too large to form a seal with the rubber washers and is also not strong enough to handle repeated impacts. On the first homemades I built, I used 160 PSI pipe and the front ends cracked and blew off when I fired it.



If you have the right pipe, make a mark at every critical point where a hole needs to be drilled, you should mark after measuring at least twice. These points would be ~5/8” from the very front, 7.75” from the front, 12.5” from the front, 13.5”, and 19.5”.



The first mark is for two set screws that will be used to secure the front bushing, the second for the hole in the main body for the catch nail, the third for two more set screws to hold the ¾ PVC end cap in place to act as a spring stop, and the last two for drilling, cutting, grinding and filing the slots for the priming slide. I’ll explain each part more in-depth as they appear later.



Using this fancy tool made out of a 1-1/4” PVC fitting (credit to Daniel Beaver from his Quixote guide), the sides of the pipe can be accurately marked (Beaver). I also use this to make my marks around the circumference of the pipe in the previous step. I’ll borrow some pictures from him to get the point across better (it’s also a really great write-up, btw).

 

...

In order to mark the other side accurately, I made a little guide tool. I cut off an edge of a 1-1/4” coupler, and then made marks on all the compass points. This slips snuggly onto the plunger tube, and allows me to accurately mark the opposite edge.

And one poor quality one of mine:




You could also take it a step further and make one of these: a perfect PVC quarter marking jig that was also used by NoM (Phoenix66).




Step #2: Orientating the blaster and nail hole


At this point, decide where the top and bottom of the blaster will be. I like to put any text on the pipe on the bottom side of the blaster. Drill a 9/64” hole for the roofing nail perpendicular (straight) into body.




Hopefully you’ve read a little bit about how clothespin triggers work. If not, here’s a brief explanation. The nail will sit against the PVC in this hole until the clothespin is opened and the nail retracted. The nail, when pulled down, releases the firing mechanism. This process will be further explained later.



After the bottom of the blaster is marked by the hole, I find it best to mark this bottom with a line along the length of the pipe. I use this engineer’s ruler (credit to Beaver again for this) to draw a line perfectly parallel to the body of the blaster (Beaver).

 

...I highly suggest using a three-sided ruler for these, since you can lay it flat against the curve of the tube and make very straight lines. First, draw a centerline all the way down the side of the tube.


 

And another one of mine:






Then, mark the sides perpendicular to the bottom using the same measuring tool and align it so the bottom stays on bottom.


Mark the front…





Second to last…





…and last line on either side.




The first is for the front bushing and the last are for the priming slide slots.




Then measure ¼” wide (or 1/8” from either side of the last two marks) and draw straight lines to form rectangles on either side of the body. These will be the priming slide slots on the back end of the blaster.








Step #3: Making priming slide slots

Doing this step right reduces a lot of friction on the priming slide. Doing it properly makes the blaster look very clean, and neat and ensures that the priming bolts slide evenly and smoothly.



Take a ¼” drill bit and drill where the ends of the slots are as pictured:





Drill all the way through and the two sides should line up. If they’re a little crooked, wiggle the bit around so the holes align perpendicularly to the body.





Next, using whatever method you choose, cut out those slots. I use a rotary tool.





To quote a better man than myself:
 

.... I recommend a diamond cutting wheel for this job, as it works a lot better than other cutting wheels.

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I happen to come across a diamond cutting wheel when borrowing a Dremel from a friend. They do work very well.






A quick side note about this step: it’s pretty common for pump-action blasters to require cutting long slots like these. The easiest way is to just invest in a quality rotary tool. However, if you choose not to buy a Dremel, there’s still plenty of hope and I won’t expressly require a Dremel or rotary tool. Carbon shared an innovative way to make these slots using a drill and some sanding/filing/cleaning up (Carbon).

...

I used a new slot making method this time: I drilled out holes, and then connected them with a sanding drum. it works, and works well.

 

After having drilled and cut these slots, you’ll probably end up with (especially if you used a Dremel) a lot of PVC dust and other debris inside your blaster. This is bad. If left alone, it will literally clog up your blaster and ruin your seal and washers. This would be an ideal time to rinse out your blaster. This will be the last heavy tooling step on the main body and it can also be set aside at this time.