/diy/ - Do It Yourself

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Crossbow Anonymous Mon Dec 29 11:34:33 2014 No.747643 [Reply] [Original]

Alright fellas, fa/tg/uy here. I need a bit of advice.

I'm going to be building a pistol crossbow. Nut-&-trigger lock, I have some nice hard wood on hand and I like the system (not prone to jams, few moving parts, etc). but I'm having trouble figuring out how to make a prod for the thing.

Specifications are as follows:
>no more than 18" wide when unstrung
>no recurving or compounding
>must deliver 80 lbs of draw weight at a draw distance of 5 1/2 in (this is very close to the legal maximum for pistol crossbows in my area...I'd make it stronger but I want to be safe)

I'm thinking either PVC or scrap leaf springs. I'm banking on the former...there are not many junkyards in my area so leaf springs this small may be hard to find.

Can this be done, /diy/, and if so, how?

>>	Anonymous Mon Dec 29 12:08:44 2014 No.747660 >>747643 Why a pistol crossbow? What are you going to be shooting with it? Also >80 lbs draw weight at 5 inches >PVC >mfw I have no face for this

Anonymous Mon Dec 29 12:16:39 2014 No.747663
File: 77 KB, 768x1024, F4U4N9OHERLT5L2.LARGE[1].jpg [View same] [iqdb] [saucenao] [google]

>>747660

The guy I'm building it for intends to use it for Amtgard-rules LARP.

And yes, I think achieving 80 lbs with PVC is possible. I think it can be done by layering flattened tubes like pic related.

Anonymous Mon Dec 29 12:19:08 2014 No.747664

>>747643
the no recurving or compounding can be difficult

I guess you want something like this: Cobra 80 Pound Pistol Crossbow

if the size is important you can make this one, sadly it only has 40 lbs draw weight
https://www.youtube.com/watch?v=OWheHsz8G2M

>>	Anonymous Mon Dec 29 12:20:40 2014 No.747665 >>747663 but he didn't want recurving or compounding if you can use compound bows it will be a lot easier and for sure possible

>>	Anonymous Mon Dec 29 12:25:41 2014 No.747666 >>747665 https://www.youtube.com/watch?v=ZNpsVAMxDgU

Anonymous Mon Dec 29 12:27:28 2014 No.747668
File: 136 KB, 845x562, Medieval-style-trigger-and-rolling-nut-meets-modern-compound-technology[1].jpg [View same] [iqdb] [saucenao] [google]

>>747665

I should clarify. 'compounding' refers to using extremely rigid prods and camwheels/pulleys to turn a short flexing distance on the prod into a long draw distance, like so.

>>	Anonymous Mon Dec 29 12:29:09 2014 No.747670 >>747666 >OP asks for non-recurved non-compound design >post a recurved compound design You're not helping, anon.

Anonymous Mon Dec 29 12:32:59 2014 No.747673

>>747668
yes I am aware of that , the compounding enables you to make shorter/stronger bows

I am just saying that without recurving or compounding it will be hard to reach 80lb with pvc pipe
to laminate the pvc some recurving will need to be done I suppose ? or he needs to find flat pvc pieces

>>	Anonymous Mon Dec 29 12:35:29 2014 No.747674 >>747670 well I just posted it for other people that might be interested in a bow, I would like to see OP make a bow with 80+ pound and stay within the 18" wide when unstrung without compounding

>>	Anonymous Mon Dec 29 12:38:46 2014 No.747675 >>747673 PVC can be flattened by heating it, then pressing it until cooled. It becomes like rubber at ~60 C. I saw some really interesting things made that way.

>>	Anonymous Mon Dec 29 13:02:24 2014 No.747681 >>747675 yea but why not recurve it then it seems better then laminating plat pieces

>>	Anonymous Mon Dec 29 13:15:52 2014 No.747687 >>747643 >no weapons on /diy/

>>	Anonymous Mon Dec 29 13:22:03 2014 No.747693 I wouldn't trust PVC unless it has better strength when flattened. I have had a few pvc projects break on me. Maybe the UV resistant pvc would be better because you can be sure there was never any sun damage making it more brittle

>>	None !2Code3TV3M Mon Dec 29 15:00:50 2014 No.747725 >>747643 when you buy leaf springs from a store they usually come in sets, and you should be able to buy them from any hardware store that does car parts. short of that there are plenty of bowmaking threads on the archives

>>	Anonymous Tue Dec 30 21:53:32 2014 No.748520 File: 804 KB, 2704x1348, 1331866263454.jpg [View same] [iqdb] [saucenao] [google] >>747643 here

>>	Anonymous Tue Dec 30 21:54:35 2014 No.748522 File: 1.39 MB, 4484x1352, 1331866654812.jpg [View same] [iqdb] [saucenao] [google] >>747643 and here

>>	Anonymous Tue Dec 30 21:55:39 2014 No.748523 File: 1.52 MB, 3600x2680, 1331866853796.jpg [View same] [iqdb] [saucenao] [google] >>747643 and this old chestnut

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