Community Snap Thread
Posted 26 March 2011 - 09:43 PM
The trigger was cut from 2 pieces of .210" polycarb that were fused together, and simply provides a slope for the spring and the catch-cap to slide over.
Obviously this is WIP, but it does catch and fires about as hard as a +bow. I plan to do a bullpup version, and work on miniaturizing this design. As it is, I had some fun tying the string to my shoulder and using it one-handed, but this is really too powerful to be appropriate for one-handed use. The spring is 1 foot of K14, and it has 5.5" of draw with about 2" precompression. The "catch spring" (shown here as a wooden block and a bunch of rubber bands) needs to be pretty strong, but it's not difficult to prime or to fire. Also, I think the lever-trigger piece could be made with much weaker materials than polycarb--Even wood. The allowed size (It could be much thicker than even my trigger, which was .420") should make wear a non-issue, and it definitely gives lots of room for error.
Posted 27 March 2011 - 05:55 PM
Also, I think the lever-trigger piece could be made with much weaker materials than polycarb--Even wood.
That has been my observation as well in these styles of catches, though it seems counter intuitive. I get the feeling that everyone has been over-building the hell out of catches for years.
Posted 20 April 2011 - 08:35 PM
Bullpup variant of the lever-snap.
This one is 1" wood, in a dremelled out rectangular hole. The direction of the catch is reversed.
I bought some nifty new catchsprings that should be strong enough for this trigger. The rubber bands have got to go.
And the duct tape. My snap handle required duct tape because it was in two pieces, one of which could not be screwed in because it was part of the skirt path.
The plunger is the following material
[3/4 CPVC cap][skirt][3/4"CPVC cut cap][ gap ][3/4 PVC bored to fit a 3/4 CPVC endcap]
in that order, over 3/4" CPVC pipe. Before assembling I drill a hole through the nested caps at the rear, and insert a string and a knot. Then it gets closed up, with knot inside, and the string pulled through the spring, to the priming mech. You could use the CPVC for a plunger rod if you were to use one, or nest something in it and use that, or whatever. The trigger should be compatible with regular snap plunger heads as well, while causing much less wear than a nail.
edit: In my case the priming mech was a steel Ubolt substituting for a pulley, and tying the string to a handle for pump action.
Edited by KaneTheMediocre, 20 April 2011 - 08:54 PM.
Posted 22 April 2011 - 02:22 AM
Edited by shardbearer, 22 April 2011 - 02:35 AM.
Posted 22 April 2011 - 02:25 AM
Kane, when you post pictures like those it only leads to hours of wonderment and painful reverse engineering. I am still baffled by your priming mech. Did you use a pulley to come out the front of the PT and reverse the direction? How did you keep it from tangling in the spring or causing excessive amounts of friction as it is fired? And why not cut off the useless couple inches at the end of that tube, moving the priming handle backwards if necessary? I am assuming you are using a plunger similar to boot did. Your designs baffle me.
It's quite simple actually, I already reverse engineered the non-bullpup one. The bull-pup/pump action one is my next challenge, but it shouldnt be to hard.
Posted 22 April 2011 - 02:41 AM
Posted 22 April 2011 - 03:12 AM
Kane, when you post pictures like those it only leads to hours of wonderment and painful reverse engineering. I am still baffled by your priming mech. Did you use a pulley to come out the front of the PT and reverse the direction? How did you keep it from tangling in the spring or causing excessive amounts of friction as it is fired? And why not cut off the useless couple inches at the end of that tube, moving the priming handle backwards if necessary? I am assuming you are using a plunger similar to boot in his snap compact. Your designs baffle me.
The string is wrapped around a U-bolt is to reverse the direction of the priming motion. This should be done with a pulley. For this prototype it was done with a U-bolt. There really aren't any useless couple inches--in fact it needs to be lengthened to prime comfortably without ramming your priming hand into the front of the handle. The string causes terrible friction while priming (which a proper pulley should fix), but no friction at all while firing.
I haven't seen boot's snap compact. Perhaps you could edit in a link?
I'll do a writeup sometime. But until I get around to that, some people will figure it out anyways if I just post a pic and a few sentences.
The first one is self explanatory, but the bullpup pump action introduces tons of new variables. Such as how it would push the string back into the PT after cocking it,which I think would get it tangled with the spring. I thought of this very design a few months ago, and decided it would never work.
The string loses 5.25" of distance out of about 18". So there's not that much slack created, and most of it tends to be behind the spring in the first place. Besides, for the string to get tangled while the ends are constrained (as they always are when the blaster is put together) would require the string to make a sudden and drastic bend after exiting the spring rest, and force itself underneath the barb of the spring. So it should be damn near impossible with this setup, and I've fired it quite a bit without encountering problems of that sort. Most people that I've talked to who have done wire or string priming had reported a miraculous lack of entanglement, so I didn't expect any problems.
Posted 26 April 2011 - 07:29 PM
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