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#1 Maniacal Coyote

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Posted 04 January 2017 - 03:57 PM

For the catch of a SNAP, how far does the nail need to travel? Also, do I need to have it mounted on a clothespin, or can I attach it to something else? (Like the catch of a Sharp Shot)

 

I'm asking these so I am able to start Project #3 (a SNAP) as soon as I finish Project #2 (My Xbow). 


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#2 jwasko

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Posted 04 January 2017 - 04:24 PM

It sort of depends on the design that you are using, I suppose. Is there a particular SNAP writeup you are following?

 

In general I'm going to say between 0.25 and 0.5inches (closer to 0.25). If you made it very precise you could maybe get it down to 1/8".

 

You mean this sharp shot, right?

 

You really only need to have something that can transfer the action of pulling your finger back into pulling a nail down. The sharp shot does this pretty simply with only two moving parts, but I'm not sure that its trigger and catch will be strong enough to yank the nail downward. A bulked up, similar design could work. Check out the Purple Catch, for instance(click the image archive button after following that link).

 

If I were you, I'd make one with a basic clothespin trigger first. Then you can modify it to have a fancier handle and/or catch. And note that there are loads of people who have used a plain old clothespin but used a handle from a nerf blaster or airsoft/paintball gun.


Edited by jwasko, 04 January 2017 - 04:29 PM.

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#3 Meaker VI

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Posted 04 January 2017 - 04:32 PM

Nail just needs to travel enough to stop and release the plunger. I expect you'd need more travel with a sloppier setup and less with a tighter one.

 

It needs to pivot, it doesn't matter what it's mounted on - clothspins provided cheap easy pivots.

 

I'd recommend doing a rainbow or Durendal though if you've got the tooling. Rainboid catches are easily replicable; the cost/benefit of a SNAP is that it's finicky and takes quite a bit of fiddling and adjusting to work correctly, but it's doable with almost no tooling and a huge variety of different parts.


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#4 Maniacal Coyote

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Posted 04 January 2017 - 04:52 PM

Jwasko, I'm kinda following the Mk 8, but I don't like it not having a stock. I was thinking along the lines of a snapbow stock, but with the priming handle having a PVC T sliding along a second, lower stock rod.

 

Meaker, I don't have the tools to do anything fancy. That's why I'm attracted to your design.


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#5 Meaker VI

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Posted 04 January 2017 - 11:01 PM

You can bolt a stock onto the top of a Mk 8 easily enough.

 

You can probably replicate Slug's Durendal with just a jigsaw ($10ish), a drill (need one for any blaster really), a good knife (you should have one anyway), and some sandpaper or files ($10ish) since he releases templates. He also includes a stock in the files.

 

The reason I'd point you away from the Mk 8 is because it's really meant to be a total intro to blaster building. A "true" SNAP would be a better build if you know something about what you're doing, a rainboid will feel more 'solid'. The Mk 8 is less fickle than a true SNAP, and less time (or tooling) consuming than a rainboid, so if you haven't done any building it is a good start.

 

Do you have access to a 3d printer? If you have one around I've got a no-fuss printable rainbow catch I'm toying with.


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#6 Maniacal Coyote

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Posted 05 January 2017 - 02:01 AM

Well, there is a 3d printer lab at school. But, the printers don't print at actual size, and I can't remember the deviation. I think it is +0.02" for outside diameters and -0.02" for inside diameters. They're Printrbots, if that helps any.

On the Mk8-esque SNAP I'm building, the plunger head has a bunch of friction, enough to hold a [k26] back at full compression. Am I doing things correctly?
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#7 jwasko

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Posted 05 January 2017 - 11:46 AM

On the Mk8-esque SNAP I'm building, the plunger head has a bunch of friction, enough to hold a [[k26]] back at full compression. Am I doing things correctly?

 

 

No, that's definitely not right.

 

I'm assuming you are using a rubber washer for the seal.

 

It is apparently too big or you tightened the screw on the plunger head too much. That'll squash the rubber washer and make it too big.

 

Or perhaps your washer is folding backwards over the plunger head. If anything it should cup forwards (towards the barrel).

 

You say you want a stock. Try the Snapbow MkV: http://nerfhaven.com...w-mk-v-revised/ for inspiration


Edited by jwasko, 05 January 2017 - 11:47 AM.

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#8 Meaker VI

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Posted 05 January 2017 - 07:35 PM

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Well, there is a 3d printer lab at school. But, the printers don't print at actual size, and I can't remember the deviation. I think it is +0.02" for outside diameters and -0.02" for inside diameters. They're Printrbots, if that helps any.

On the Mk8-esque SNAP I'm building, the plunger head has a bunch of friction, enough to hold a [[k26]] back at full compression. Am I doing things correctly?

That sounds similar to my experience, here's a file you can try that seems to work so far that *should* have those tolerances built in:

Attached File  v3 Catch w Guide.stl   3.03MB   108 downloads

 

Then if you need I have this for a handle - scale up by 25.4 as apparently I messed up the export (I did something like 1.6mmx20% and the first one failed; this one is beefed up so maybe it'll be fine but upping the shells to be safe might be a good idea. This is the biggest file by far):

Attached File  DGrip V2.stl   3.14MB   113 downloads

 

And this trigger:

Attached File  v3 trigger.stl   1.04MB   110 downloads

 

And this plunger head, which I feel like I've shared before:

Attached File  MK10_PH.stl   1.08MB   101 downloads

 

These files are preliminary - I've gotten them all to work but have made modifications since my first handle sheared off. For all these files try 4 shells (1.6mm) and 20% infill at .25mm layer height with 1.75 top/bottom (if you can, if not 0.2 mm and 1.6) If that breaks step it up to 100% or do more shells. Altogether you're talking 110 grams of filament and ~8 hours print time.

 

You'll need some #6x3/4" machine screws, a small spring (pen spring, I used one out of a $5 harbor freight set), a #6 washer, #8x1.5" machine screws and nuts, a two-way bolt like this one, a dash 216 oring (1/8" by 1-3/8" OD), a 1-2" wood screw, a 1-1/4" fender washer, a 1/2" rod, and a couple of barrel nuts and screws. I've found all that stuff at ACE, probably at HD/Lowes as well though the two way might be trickier. You can replace it with any method of joining two 1/2" rods with a small gap between them.

 

The large circle part is a template that goes over 1-1/4" PVC and allows you to accurately drill out the PVC for the catch. The part with legs is the frame, the one with the sloping hole and a small hole through it is the catch, the other one keeps the catch in place and may fit tight. You may need to sand that down a bit for it to fit easily and not break the frame.

 

To attach the handle, draw a straight line through the small hole from the circle template (Ideally use an architectural ruler, but I have used a corner between two smooth surfaces). This will be your bottom center line. Then position the handle along that line so that the large cutout is roughly centered on the small hole. Use the notches on the side of the handle by the holes to mark where to drill along the centerline. Drill these out for your barrel-nut screws (mine were 1/4"). Drill opposite those holes and do what you can to countersink them from the inside of the PVC. Your PT machining will be done once the screws fit, they don't need to be flush but it'll help.

 

You'll need to cut your 1/2" rod to fit your spring, then use the two way bolt to fix it together with a gap. Put the PH file with the oring on it on the appropriate end, run a wood screw into the rod with the fender washer. PH done.

 

To install the catch, put the catch pieces together (legs, catch, catch holder plate), run the #8 screws through the side holes on the PT, drop the catch in and orient it so it fits, and run the #6x3/4" with the washer and spring into the catch plate (Catch, PT wall, washer, spring, #6 head).

 

To install the handle, run a #6x3/4 through the side of the handle into and through the trigger, then put the barrel nuts in the holes in the handle. Run the 1/4" barrel nut screws into the handle.

 

Drop the PT into the blaster and through the catch assembly, add a 1"x1/2" bushing on the front (as with any pistol-type homemade) and you're done.

 

Let me know how it goes, I've needed a guinea pig for more extensive testing on this for a while.


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#9 Draconis

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Posted 20 January 2017 - 04:54 PM

Oh wow, these are beautiful pieces, Meaker.  If anyone would like to see the pieces, but doesn't have printer software or anything to preview with, this site is great: http://www.viewstl.com/


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#10 Maniacal Coyote

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Posted 20 January 2017 - 06:14 PM

Eh, to hell with fucking around with polycarb plates, clothespins, and all that bullcrap. I'll try out Meaker's idea, after I try out my own. Although, I might just scale mine up to handle 1-1/4" PVC instead of 1-1/8" ID polycrap.

 

Also, any suggestions on how to cut a slot in 3/8" square PVC rod?


Edited by Maniacal Coyote, 20 January 2017 - 06:16 PM.

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#11 Meaker VI

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Posted 20 January 2017 - 10:04 PM

Oh wow, these are beautiful pieces, Meaker.  If anyone would like to see the pieces, but doesn't have printer software or anything to preview with, this site is great: http://www.viewstl.com/

 

Thanks! So far I only know for sure that the catch *works*, but not how durable it is. Primarily because of my experiments with wooden plunger rods.

 

Edit: Added this image of the catch:

 

Catch.png

 

I'll try out Meaker's idea, after I try out my own. Although, I might just scale mine up to handle 1-1/4" PVC instead of 1-1/8" ID polycrap.

 

Also, any suggestions on how to cut a slot in 3/8" square PVC rod?

 

Mine already is for 1-1/4" (Sch. 40) PVC?

 

Depends on the slot. End slot - saw, middle slot - router or drill + chisel.


Edited by Meaker VI, 24 January 2017 - 12:02 AM.

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