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CaptainSlug

Member Since 17 Feb 2006
Offline Last Active Today, 08:25 PM

#360279 Caliburn: Mag-fed Pump-action Springer

Posted by CaptainSlug on 02 June 2017 - 10:36 AM

Okay, this is what I hate the most about 3D printing. I have 7 parts, all printed from the same file. Five of them from the same printer. But each one has slightly different inside dimensions. Some of the people I'm working with clearly weren't scaling the models consistently when sending the files to the printer.
rs3_79.jpg
1. Printed by Jacob. Inside Dimensions: 3.208" x .870"
2. Printed by gangasaur's coworker (scaled to metric): 3.188" x .874"
3. Printed by Shahram: 3.185" x .862"
4. Printed by Shahram: 3.186" x .862"
5. Printed by Shahram: 3.164" x .868"
6. Printed by Shahram: 3.162" x .868"
7. Printed by Shahram: 3.165" x .867"
 
Part 1 fits mags so easily that they drop free. It required no sanding. The only issue I had with it was support material inside the through-holes.
Parts 2 through 4 fit a mag and only needed a little filing to smooth out print scraggles.
Parts 5 through 7 will not fit a mag and are going to almost need machining to be usable.
 
Print inconsistency issues are really slowing me down at the moment. This part specifically is going to have to be cast if I don't want to have to deal with having to post-machine these parts.
 
And with all of that whining aside...
 
rs3_80.jpg
Here's a photo of 10 individually-wrapped and pre-lubricated fleshlights aluminum plunger tubes with SCH40 adapter rings for each end.
rs3_81.jpg
15 padded buttplates
rs3_82.jpg
14 Clear Stock Spacers, 14 Spring Posts, 12 aluminum barrels, 10 sets of threaded rods and spacers, 10 pairs of Bolt Arms
rs3_83.jpg
And lots of hardware. I need to punch out more silicone rings this afternoon.
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#360211 Caliburn: Mag-fed Pump-action Springer

Posted by CaptainSlug on 30 May 2017 - 01:33 PM

And here's how I'm casting part sets. Pour a mold, cover with a polypropylene sheet to squeeze off the excess, cover with another mold, then repeat. I can do 3 or 4 tiers before running out of room in either pressure pot.
rs3_77.jpg
The parts then cure inside the pressure pot at 50psi for a minimum of 30 minutes. They can be removed from the molds safely and predictably after 6 hours.

It's advisable to remove as much of the flashing from the mold prior to trying to pull the parts, and this step should be done with a tool and not with your finger nails. The broken edges of the urethane are very sharp and I cut the underside of my nails twice this weekend before deciding that is really painful. So now I use a plastic tool or a scrap of polypropylene instead.

 

If any of the parts get distorted they can be flattened back out by the hotplate I have set on low. I have a sheet of aluminum on the burner which helps spread out the heat and provides a flat surface for parts or molds to rest on.
 

Name	        Qty	Color	Process
GripLeft	4	White	Cast
GripRight	4	White	Cast
GripSpacerLeft	4	White	Cast
GripSpacerRight	4	White	Cast
Spreader	4	White	Cast
StockAlt2       0	White	Cast
Butt	        4	White	Cast
Foregrip	6	White	3D Print
Magwell 	6	White	3D Print
Ram2    	6	White	3D Print
Rail_Top	4	Black	Cast
GripMiddle	6	Black	Cast
MagRelease	4	Black	Cast
Jam      	6	Black	Cast
DartGuide	6	Black	Cast
P1      	4	Black	Cast
P2      	5	Orange	Cast
P3b      	5	White	3D Print
Trigger  	6	Orange	Cast
Muzzle  	6	Orange	Cast
Sear    	6	Orange	Cast
Bolt1   	6	Orange	Cast
			
Buttplate 	0	Clear	Machined
Buttplate Foam	0	Grey?	Cut

Now that I have my minimum quantities for the primary cast parts I need to finish the StockAlt2 mold and get the hardware kits put together.

 

EDIT: StockAlt2 Mold is fixed and in the pressure pot now.


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#360102 Caliburn: Mag-fed Pump-action Springer

Posted by CaptainSlug on 25 May 2017 - 09:26 AM

Phew. This has a hell of a learning curve. I'm still having some issues producing the orange parts at the right shade, and I may just have to give up on trying to cast them as opaque. That pigment only seems to produce clear parts with this urethane, so that may have to be how they end up since adding opaque white just weakens the orange too much.

rs3_73.jpg

The "demold time" listed for this material is completely wrong for the kinds of parts I am making. If I want a 30 to 60 minute demold time I will have to pour into the mold, then stick the mold into a proofing oven at 150F. This urethane requires heat to cure, so if you just leave the mold to sit at ambient temperature you won't be able to demold for at least 6 hours. Doing it any earlier than that without heating and you will risk distorting your parts as you pull them out of the mold.

 

One-sided molds are also trickier than I anticipated. Half of the above parts have a bubble or two in their flat side. If I want to cast parts without bubbles they have to be poured, placed in the pressure pot for 30 minutes, then placed in the proofing oven for 30 minutes. But for the majority of these parts, some surface bubbles don't impact part performance, and are only cosmetic defects. And with the number of parts I need to produce per blaster, having to load all of them into a pressure pot would require having multiple pressure pots.

 

This product also has far too little pot life for vacuum to be used to de-air the poured mix. Supposedly you can de-air or just dry Part A in vacuum prior to mixing and that supposedly reduces the quantity of bubbles. I might consider just storing it in a vacuum chamber in the future, but that would require pouring it into a much larger container.

 

Edit: I'm going to do one further attempt at spincasting. Some of the spincasting molds may not be worth doing that way and as a result might get cut up into individual molds. This would make a set of molds much easier to fit inside of a pressure pot for curing.


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#359549 Caliburn: Mag-fed Pump-action Springer

Posted by CaptainSlug on 28 April 2017 - 10:00 PM

Sure, you can be my huckleberry. I already sent the long-form reply to you on Reddit.
 
In other news, my spin-casting equipment is done.
 
 

Yay!
CaptainSlug would this be okay as my first homemade. I have a smaller end 3d printer. How big is the largest peice.
A little backloged ATM but by the end of summer I should be able to have my very own homemade. So happy!

The largest parts are the mag well (5.023 x 4.281 x 1.75 inches) and foregrip (4.22 x 3.19 x 1.875 inches). The mag well is the only part that needs any support material, and it only needs a little bit on one side. I couldn't put a 45-degree angle on the part near the trigger guard without making the part either uglier, or potentially more difficult to make a mold for.
The "construction" process will involve drilling a few holes, pulling out some support material, cutting some tubes, threaded rods, and 16ga nails to length, then just general assembly. It's really easy to put together once you have all the parts. This is the first homemade blaster that I will feel comfortable shipping as a loose set of parts for the end-user to assemble themselves.
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#359541 Caliburn: Mag-fed Pump-action Springer

Posted by CaptainSlug on 28 April 2017 - 06:16 PM

Has it exploded from the plunger firing? Does it show signs of exploding?

Doesn't seem to be showing any signs of wanting to explode after a dozen dry fires. Making the bolt and the front of the plunger tube EXTRA THICK and printing both at 100% infill seems to have fixed the structural issues. It also made assembly a bit easier.


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#359504 High Cap Magazine Collective Brain-Spew

Posted by CaptainSlug on 27 April 2017 - 11:42 AM

I have no idea. But I suspect 22 darts is likely to be the ceiling of being reasonable in terms of mag dimensions and spring load.
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#359483 Caliburn: Mag-fed Pump-action Springer

Posted by CaptainSlug on 26 April 2017 - 02:27 PM

Image dump. No big issues with assembly so far. A few spots that I had to file down will be modified in the STLs before I make them available. I'll do final assembly and test the catch tomorrow.
rs3_39.jpg
rs3_40.jpg
rs3_41.jpg
rs3_42.jpg
rs3_43.jpg
rs3_44.jpg
rs3_45.jpg
rs3_46.jpg


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#359341 What was the first known homemade?

Posted by CaptainSlug on 20 April 2017 - 12:02 PM

All the early homemade discussion was at NerfHQ, not here. So all of that information is largely lost.

 

Zero made some of the first war-usable homemades, but everything at that time was typically air-powered and it was pretty rare that their use was allowed. The SNAP series is pretty much the genesis of allowing homemades at Nerf Wars.


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#359260 THIS one simple design will have you in TEARS...

Posted by CaptainSlug on 15 April 2017 - 09:40 AM

I have one designed but will do the initial prototype through machining.

 

AND I'm going to break my usual habits a bit and make it entirely out of PVC. So screws will be used sparingly and some of the assemblies will just get glued together.


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#359231 THIS one simple design will have you in TEARS...

Posted by CaptainSlug on 14 April 2017 - 09:31 AM

Double-post of mechanical sexiness.

sp_09.jpg

The trigger and magazine release share the same spring, and the same pivot point.

sp_10.jpg

This means that the trigger guard itself is the magazine release. To drop the mag you just push your trigger finger forward inside the trigger well.

This is exceptionally novel and the only thing I can think of that's similar is the ring trigger on early revolvers that were used to index the cylinder.


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#359152 Caliburn: Mag-fed Pump-action Springer

Posted by CaptainSlug on 10 April 2017 - 07:05 PM

No progress today. Didn't have time or opportunity at work to use the oven, which shares an outlet with a chiller that is tied to a vacuum weld chamber.

 

Do you think you could put a k14 in this?

No. You would have to make almost all of the blaster pats out of much higher grade materials. I'm not interested in entertaining springs that nobody can actually prime. Especially when this blaster already hits 210 fps.

 

Although, on a related note I did just find a casting epoxy that's 90% of the strength of polycarbonate when cured.


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#359056 Replacing broken/ripped O-Rings

Posted by CaptainSlug on 06 April 2017 - 08:27 AM

I wrote this out to answer this question elsewhere and thought it might be good to store it here.

 

IF you break/rip/tear and O-Ring and you need to find a replacement for it, here's how you can do so.

 

1. Use a ruler to measure the length of the broken o-ring piece inside of the curve.

2. Use that length with this calculator set to "Given C"  http://www.calculato...lane/circle.php

3. Write that number down as you now have the actual ID of the O-Ring (or close to it).

4. Measure the thickness of the O-Ring as best you can. This number will be close to either a fractional size, or a millimeter size. It's best if you can use a caliper to get this number, but a ruler with both inches and millimeters will do. Always make sure to round DOWN to the nearest fraction or millimeter since o-rings are oversized. For example a "3/16" cord width O-Ring is going to have a NOMINAL width of .210".

5. Write that number down.

6. Take both numbers and poke through the McMaster catalog in the o-ring section. You can find the nearest ACTUAL SIZE for Inner Diameter from their list as well as the ACTUAL (or fractional) cord width.

https://www.mcmaster...-rings/=172uud9

 

Just pick BUNA-N as your material for now. The majority of the o-rings used for Nerf are that material.

 

dash.jpg

Now you have the DASH NUMBER of the o-ring you need. You can order the o-ring you need from McMaster, Amazon, Fastenal, or buy it from a hardware store. If you want to buy the o-ring from Home Depot you may need this chart to convert from DASH NUMBER sizes to the Danco brand o-ring part numbers.

http://captainslug.c..._reference.xlsx

 

Other brands may have different part numbers so check your nearest hardware store's online catalog before going to see what brand of o-rings they sell. If they don't list the products in DASH number sizes just e-mail the manufacturer and ask them for a similar conversion chart.


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#359017 Caliburn: Mag-fed Pump-action Springer

Posted by CaptainSlug on 04 April 2017 - 10:32 AM

rs3_29.jpg

rs3_30.jpg

 

Also, another video.

 


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#358767 THIS one simple design will have you in TEARS...

Posted by CaptainSlug on 24 March 2017 - 04:05 PM

This is a pretty rough draft at the moment. I won't get any further on this for a while until I have time to try making a magazine. And given how many other things I SHOULD be working on, who knows when that will be.

I just wanted to see what the layout would have to be for a miniaturized mag-fed Piranha. And Chanclas was correct, it could totally work. There's just enough room to get 3-1/8 inch of plunger stroke out of a 1-1/4 SCH40 pipe.

sp_00.jpg

The cut in the front of the slide lets the cable feed through, but will pull on the eyelet of it to prime the plunger. I haven't decided on a return spring for the slide yet. One I have in mind might just barely fit over the barrel but may have to be stretched to get the right collapse length to extended length measurements. If I run out of room I'll probably just have to make the barrel a little bit further away from the plunger tube.

sp_01.jpg

sp_02.jpg

sp_03.jpg


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#358698 Caliburn: Mag-fed Pump-action Springer

Posted by CaptainSlug on 22 March 2017 - 03:10 PM

Raise your hand if you like RAILS.

rs3_22.jpg

Work apparently has some leftover Platinum molding silicone so I'm going to make a mold or two this week for some of the simpler parts I haven't had to revise.

 

I figured out how to make a 2-part mold for the mag well and that necessitated some changes that mushed up the styling so I had to reprofile it and the grip in a new pattern. So the lettering has been moved to the mag well.

 

The test print of the foregrip also lacked some vertical girth and was promoting weird hand-hold positions. So it gets a 5-point underside rail and a slight profile adjustment.

 

The grip has been split into 3-parts so that it will print much easier and subsequently be much MUCH easier to cast. The print orientation means that even a low infill percentage print of these parts should be more than strong enough.

rs3_23.jpg

 

It seems that the only part left to annoy me is the stock reducer. The cast part is going to have to be FAT if I want to make it from a one-sided mold and it really can't be avoided. So the printed version of that part will be slightly cooler looking as a result.

 

Time to order some supplies. Then I get to make 16 molds


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