13 replies to this topic

[Zorns Lemma]

I rebuilt this design http://nerfhaven.com...showtopic=21567to not be completely awful. snakerbot gets at least 50% of the credit.

Materials:
-1-1/4" PVC (clear makes construction easier)
-1" thinwall PVC (critical to fit around 1/2" fittings, not critical if using a breech)
-7/8" ID x 1-3/8" OD U Cups 9691K56
-1/4" aluminum rod (substitutable)
-1/2" Delrin rod (substitutable)
-9/16" ID x 5/8" OD nylon tube 8628K57 (substitutable)

The priming pump is now constructed out of 1" thinwall PVC. The seal is created by sandwiching a u-cup between 1/2" PVC and 1/2" PVC couplers. The couplers then fit inside the 1" thinwall.


Channels are cut into the priming pump to fit around a wye. The stub of 1/2" PVC that extends through the u-cup seats with the wye.


The plunger rod consists of a length of 1/4" aluminum rod. The catch notch is created by turning 1/2" rod on a lathe to create the sloped omnidirectional ramp. A 1/4" hole is bored for the rod and secured with a set screw.


The plunger head is created by the same mechanism of 1/2" PVC and u-cup. It is seated between a section of 1/2" coupler and a 1/2" x 1" bushing. The plunger head is attached to the plunger rod via reducing the 1/2" PVC to 1/4" ID through tubes and 1/2" rod and then fastened to the plunger rod.


The plunger rod is cut to length so that the catch face meets with the catch at draw, thus it must be shorter than that length at rest


The catch is a standard rainbow catch, except with a 5/8" hole at the spring rest. This houses the 5/8" OD tube which fits inside the spring and yet is wide enough to allow unrestricted travel of the plunger rod and catch nub. This prevents spring buckling during compression which would cause tons of issues. I used a [k26] spring; use of a [k25] spring would enable 1/2" PVC to be used to center the spring (or some other tube of choice).


The trigger this time is mechanically linked from a rear trigger to front trigger via metal rod. This method is far superior than cutting a single large trigger. With better crafting of the rear trigger, you can use the physics of lever arms so that the trigger pull is much smoother (I was not paying attention and have a 1:1 ratio of horizontal to vertical movement. A 3:1 ratio would alleviate some of the stress on the stock trigger).


Functionally, this blaster is identical to the FAL-1. It is pump action except the pump runs coaxial and interior of the plunger tube, alleviating the need for linkages that would increase the length of the blaster.


The blaster is attached to the lower trigger housing (appropriated firefly shell) via polyethylene blocks. The blaster can be considered "unibody" except the 1-1/4" PVC body is segmented by couplers to allow for attachment points to the lower trigger housing and also to greatly ease construction and disassembly.


The barrel is held in place by a bushing at the front.


The blaster including barrel is approximately 30" long to the front bushing (the barrel in place is not the correct length). Here is a comparison shot with Ryan's newly shortened tubing blaster with vertical pump grip. Around 4" of the blaster can be cut down by rebuilding the front of the blaster more efficiently.


(Rebuilt to cut off 4" from the front)

Edited by CaptainSlug, 01 November 2017 - 07:44 AM.

[andtheherois]

This looks great. I had a similar idea a while back though I wanted to try to get around using the barrel length for the pump grip. I love that the firefly shell works as the "lower receiver" for this. How comfortable is it having the pump all the way at the front? What's the draw length? How good is the pump seal with the U-cup?

It seems that if we're going to move towards shorter blasters without a bullpup design we'll have to start putting the plunger tube in the stock portion of a traditional blaster.

Edited by andtheherois, 21 December 2012 - 08:57 PM.

[spencerak]

Ive always been a fan of your Fals, this one as well looks great.

[Zorns Lemma]

1. How comfortable is it having the pump all the way at the front?
2. What's the draw length?
3. How good is the pump seal with the U-cup?

1. Not that bad. It's not actually the far forward, in the last picture you can see that lining the handles up the pump grip in both blasters line up fairly well. The big problem is that the choice of pump grip style and material was quite poor. I need to switch it out for a vertical priming grip or attach a tacticool rail to the bottom

2. A tad short of 6.5"

3. Very good, on par with the super bushings in the rainbowpup and latex blaster Ryan/Kane have been making.

Edited by Zorn's Lemma, 21 December 2012 - 10:53 PM.

[therealnerfjunkies]

I really like it. It looks awesome. Three questions, not about the actual blaster itself, though. Is that pink PVC? If it is, where'd you get it from? Is it thin-wall? I am SOOOOO jelly right now.....

[makeitgo]

Nice work. I'm glad to see your Fal has evolved.

[Daniel Beaver]

So basically the best gun ever?

[blitz]

Question: instead of using the lathed catch face, would it be easier to use the beveled washers that you used in mk1?

[Zorns Lemma]

Question: instead of using the lathed catch face, would it be easier to use the beveled washers that you used in mk1?

Yes and no. For people without a lathe, the beveled washers will be easier to obtain. However, you will need to use a length of 10-24 threaded rod (90013A150) or 1/4-20 threaded rod (90013A175), and then find creative ways to attach that to the plunger head, and possibly also a thin enough tube to cover the thread, although the threads shouldn't really contact anything with guiding tube between the plunger rod and spring.

Another possibility is to use smooth rod and a die to cut your own threads.

If you don't have a lathe, you can use a plastic that is less abrasion resistant such as polycarbonate or PVC and just use a Dremel to get the slopes. Turning to a sharp point is not really required, just turning it down from 1/2" to 1/4". Depending on how far you turn it down you will need to adjust the resting height of your catch plate so the ramp can correctly engage.

[snakerbot]

I used a [k26] spring; use of a [k25] spring would enable 1/2" PVC to be used to center the spring (or some other tube of choice).

[k26]'s fit really nicely inside 3/4" thinwall PVC. Then use 3/4" couplers to mate that to the plunger tube.

Edited by snakerbot, 22 December 2012 - 07:23 PM.

[spencerak]

Could you post a pic of how the wye is held in the blaster, and of the pump grip around the wye. It would be much appreciated. I am specifically interested in how it is held in place for the front seal to connect with it.

Edited by spencerak, 23 December 2012 - 10:56 PM.

[koree]

So basically the best gun ever?

Almost certainly.

[Meaker VI]

Excellent work here; I'd come up with the exact same setup to reduce blaster size, but couldn't get it to work. I'm glad you figured it out, the core of that thing looks sleek.

[Zorns Lemma]

Since I've gotten a lot of PMs about this blaster, I took more photos of a breakdown. If you understood how the blaster functioned then you can basically build your own but if you wanted specific measurements of exactly what I did (not necessarily best implementation of design) then most of these pictures are taken with a reference length.

Unfortunately due to since camera lens there is a bunch of issues with perspective so the reference length should be used relatively rather than absolutely. There are also some issues with Photobucket not rotating photos correctly, or not propagating those changes through their database.

The plunger rod is slightly under 5.5" in length from where the spring rests against to the front of the catch surface.


The plunger rod overall is slightly over 8" from front coupler slice to back of catch ramp


Spring is 10.875"


The rear portion of the blaster is 14.5" long
The catch is standard rainbow catch design, except 3D printed to be a solid piece 1.125" long


I measure the "rear portion" as starting from the start of the rear section of the furthermost coupler
The plunger head is 1.5" long and slightly under 1" from where the spring rests to the skirt housing
This means that the plunger rod at rest should come to 1.5" from the front of the tube


The pump tube is cut from a piece of 3/4" thinwall that is a tad under 13" long (this length is irrelevant)
The pump tube has a slot for the wye cut starting .875" from the edge of the tube. Adding in the UCup and holding disk, it comes to 1.75"


The skirt is mounted with a .375" length of coupler so that there is at least 1/2" of recess between the pump tube, protruding 1/2" PVC, and ucup housing to seat well around the wye


The wye slot ends 1.75" from the front of the pump tube


There is a second slot cut in the pump tube to accommodate the mounting screw for the wye that begins ~2" from the back of the pump tube and extends forward 6.5" to overcompensate for the 6" of draw


The pump housing is 13" long


The front section of the front coupler is trimmed down to .75"


This matches the front pump housing

Notice the screw hole in the pump housing underneath the wye cavity. This mates with the wye and matches the rear of the screw slow in the pump tube


The pump housing has slots cut for the pump grip to engage with the pump tube starting from 4" from the back of the housing and extending 7.75" to the 11.75" mark


The pump housing, pump tube, and front section of the blaster fit together with the wye like so

Edited by CaptainSlug, 01 November 2017 - 07:46 AM.