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David Drabenstot




Location: Indianna
Joined: 06 May 2011

Posts: 2

PostPosted: Fri 06 May, 2011 2:26 pm    Post subject: Crossbow creations         Reply with quote

Hey, I'm new here. I was linked here be a friend of mine after I had a few questions.

YOu see, I wish to make (or buy) a crossbow. I honestly know -nothing- about crossbows. I get the general idea of how they work, but that's about it. I am engaged in a LARP game, Amtgard, and I wanted to have a crossbow for it. The two rules for the cross bow itself is that A: It has to be 450 inch-pounds or less and B: It cannot be compound

I want to make a hand crossbow, for various reasons, the main being simple mobility. It doesn't need to be incredibly artistic or anything. I'm mostly going for function and price. I don't have a lot of cash. >.> I would like it to look pretty historically accurate, at least being comprised primarily of wood. Although there's no rules against modern materials at all.

Also, i'm worried about accuracy, considering I will probably be making this myself. The bolts i'll be firing are significantly heavier than normal bolts, as they will have foam padding on the end. (About the size of half a stress-ball.) But I believe most of this will come from me gaining experience firing the heavier bolts than the crossbow itself. (I can't increase the power at all remember.)

So, in short:
Hand Crossbow
450 inch-pounds
cost-effective.
'Accurate'


I'd appreciate any input, any kind of tutorial or the like would definitely be helpful. If this goes well, I may even make more of these and sell them to fellow players.

Sincerely
~David
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Kurt Scholz





Joined: 09 Dec 2008

Posts: 390

PostPosted: Sat 07 May, 2011 5:19 am    Post subject:         Reply with quote

www.atarn.org has lots of information on crossbows and archery.

The chu ko nu might be the best weapon for you because it has low energy and fast reload time. you can modify it into a a fast precision weapon by installing a blocker at the end of the drawing before the release and add a trigger that releases via a rising platform. For the bolts not to drop out add a slight spring-locked door at the releasing end. The material fpr the prod can be several split bamboo planks with differing length, giving you a simple and effective "recurve" bow with high acceleration speed that is important for light projectiles and it's not difficult to construct.
http://en.wikipedia.org/wiki/Repeating_crossbow
http://www.arco-iris.com/George/chu-ko-nu.htm
The bolts for a safe chu ko nu are an interesting case. This prod construction allows very light bolts with low energy and a soft tip. However, the tip is likely to interfere with a magazin, so you have to remove that, but you gain by creating a rifled chamber through which the bolt is made to spin, similar to a bowgun.

Another option would be to create a schnäpper/balester. It shoots balls instead of bolts. I suggest soft clay balls or even better little sacks filled with sand. So you take out the whole magazine construction of the chu ko nu and remove part of the stock to reduce friction when the projectile is propelled forward. That's a weapon that was used to hunt small game like birds and hares.
http://de.wikipedia.org/wiki/Balester

There's lots of material on youtube and in the web about these crossbows, so just google them if you need to know more.
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David Drabenstot




Location: Indianna
Joined: 06 May 2011

Posts: 2

PostPosted: Sun 08 May, 2011 5:49 am    Post subject:         Reply with quote

The Chu Ko Nu is certainly interesting, but I'm not sure it's feasible for what I'm after.

You see, the arrows will have 2.5" diameter of padding, As you've said, I would almost definitely have to remove the magazine.

The 'prod' as you call it currently worries me, as I'm not quite sure how to go about making one with enough elasticity to fire the heavy bolts, while not snapping from prolonged use, you've suggested bamboo, but I've seen bamboo used, and I've seen it break at the joints multiple times. Although perhaps the bamboo itself was shoddy.

I've brainstormed a number of different mechanisms for actually firing the bolt, it seems relatively simple.

How would one go about finding the draw weight on self-created crossbow?
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Kurt Scholz





Joined: 09 Dec 2008

Posts: 390

PostPosted: Sun 08 May, 2011 7:07 am    Post subject:         Reply with quote

Thick bamboo is the simplest solution for the prod.
A balester will probably be the safest construction.
There is a lot of material in the web about constructing a chu ko nu and it's one of the most simple crossbows, so taking this pattern and modifying it gives you access to lots of information.
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Joel Minturn





Joined: 10 Dec 2007

Posts: 232

PostPosted: Sun 08 May, 2011 9:23 am    Post subject:         Reply with quote

Bamboo works well for prods but almost any hardwood would work as well. Or a bamboo backed hardwood prod would be better than either alone.

One quick question how is 450 in-lbs calculated? Is it just max draw weight X power stroke or more accurately .5 X max draw weight X power stroke? Just wondering I guess.


Another resource for crossbow drawing and related crossbow building help http://thearbalistguild.forumotion.com/ The Arbalist Guild forum site. Lots of information on how to build crossbows and different mechanisms.
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Joel Minturn





Joined: 10 Dec 2007

Posts: 232

PostPosted: Sun 08 May, 2011 9:40 am    Post subject:         Reply with quote

More details on prods:

http://www.alcheminc.com/crossbow.html sells steel and Aluminum prods. They may have some light weight enough for your needs. They are not too badly priced. Maybe more than you wanted to spend initially but at least this way you know the prod will be good and durable.

Another place to look for how to make prod could be http://www.primitivearcher.com/smf/index.php While not directly related to crossbows they would be a good source on how to make wood bows.

If your really determined to make your own prod. Some good combinations would be
Bamboo back Hickory
Bamboo backed Ipe (maybe sold as decking material were you live also called Brazillian Walnut)
Hickory Backed Ipe. Ipe is a good choice for this because it can take High compression loads while hickory and even more so Bamboo does well in tension.

Making either wouldn't be too difficult. If you need more help with that just drop me an IM or ask here.
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