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Message started by GmanGomez on Mar 23rd, 2009 at 1:02am

Title: making a crossbow
Post by GmanGomez on Mar 23rd, 2009 at 1:02am
i have been making simple traditional crossbows for a while out of bamboo but now i am trying to make a modernized version but i wont make it compound so that it can still remain a bit more true to the original but i just need to know what to make the limbs of the crossbow out of i was thinking fiber glass but if there was even a small fracture on it my high tension string is gonna snap back at me i was gonna go aluminum but aluminum doesn't go back to its original form so it won't spring back to its original form it will just be a bended thing so what material should i use? i already ruled out wood cos that will just make it into a traditional crossbow again

Title: Re: making a crossbow
Post by Aussie on Mar 23rd, 2009 at 1:12am
Medieval crossbows were very often made from steel. Automotive leaf springs are a ready source of good quality steel but makes for a very powerful weapon. Make sure you know what you're doing and make sure it's legal as it's definitely not legal here.

Title: Re: making a crossbow
Post by Markmyster on Mar 23rd, 2009 at 7:07am
I would go with fiber glass laminated with contact cement. You can get tension rods for chain link fences at home depot very cheap. They are a bit narrow but you can make a workable bow. Aussie is right if you play around with a lot of power, a string or bow break can be very dangerous. How do you plan to make the trigger this is always the bigger problem?

Title: Re: making a crossbow
Post by GmanGomez on Mar 23rd, 2009 at 11:27am
i am gonna copy the trigger system of the crossbows you can get at hunting stores right now i am just waiting for the parts to be done fabricating and i was also wondering if i should use standard crossbow string from hunting stores but if anyone knows something stronger or can decrease the risk of a string snap please do tell i would rather use that oh yeah and nice idea with the leaf spring i was wondering though if the draw weight would be so great that i might just need to make it compound cos right now i am just aiming at around 70-95 lb draw weight

Title: Re: making a crossbow
Post by wellslung on Mar 23rd, 2009 at 1:37pm

Markmyster wrote on Mar 23rd, 2009 at 7:07am:
... You can get tension rods for chain link fences at home depot very cheap. They are a bit narrow but you can make a workable bow. ...


As a professional fencer I would highly recommend against using these. They are really not very strong, even if you stacked and welded several together.

Title: Re: making a crossbow
Post by p8ntballa100 on Mar 23rd, 2009 at 1:41pm
when i made mine i used pvc as the bow it worked pretty good.  Then we used a bent nail as the trigger system, it worked pretty good. ;D

Title: Re: making a crossbow
Post by Markmyster on Mar 23rd, 2009 at 8:19pm

wellslung wrote on Mar 23rd, 2009 at 1:37pm:

Markmyster wrote on Mar 23rd, 2009 at 7:07am:
... You can get tension rods for chain link fences at home depot very cheap. They are a bit narrow but you can make a workable bow. ...


As a professional fencer I would highly recommend against using these. They are really not very strong, even if you stacked and welded several together.


Sorry I should have said fiberglass tensor rods. I take by your use of the word welded that you thought I was refering to steel.

Title: Re: making a crossbow
Post by Markmyster on Mar 23rd, 2009 at 8:22pm
[quote author=GmanGomez link=1237784570/0#3 date=1237822069]i am just waiting for the parts to be done fabricating

Is someone making them for you? Did you give they some kind of plans?

Title: Re: making a crossbow
Post by Bikewer on Mar 23rd, 2009 at 10:14pm
I did a lot of research on this last year when I was making a prototype.   I made a wooden (oak) bow using standard bow-making technique and backed it with silk.  Only pulled about 50 pounds.

There's an awful lot of "just use an auto leaf spring" stuff on the web, but almost nothing about anyone who has actually done this.   Leaf springs are not "tillered" (tapered) the way a bow (the actual term for a crossbow is "prod") is, and as they are made they would be very inefficient.
The material is OK, but you would have to do a great deal of cutting, grinding, and shaping, and then have the entire thing re-tempered.  It must be "spring tempered", of course.

Much easier just to buy a pre-made prod from a firm like Alchem:

http://www.alcheminc.com/crossbow.html

Which specializes in medieval crossbow parts.

Fiberglass is very tricky to work with.  You could conceivably make a wooden bow and apply standard bow laminates of fiberglass, but this requires special adhesives and must be "cured" as well.

Were I going to make a functional medieval crossbow, I think I'd just buy the prod from Alchem.


Title: Re: making a crossbow
Post by GmanGomez on Mar 23rd, 2009 at 11:52pm
humm thanks of the advice i alreayd know about the cutting and grinding part but do i really need to still have it spring tempered?

Title: Re: making a crossbow
Post by wellslung on Mar 24th, 2009 at 12:15am

Markmyster wrote on Mar 23rd, 2009 at 8:19pm:
Sorry I should have said fiberglass tensor rods. I take by your use of the word welded that you thought I was refering to steel.

Oops yeah I did. A warning about those though is they get worn down very easy and can make your arms very itchy when they do. I'm not a huge fan of PPE so little things like that tend to get me :P

Title: Re: making a crossbow
Post by GmanGomez on Mar 24th, 2009 at 12:33am
http://www.youtube.com/user/meanman1992  i was lucky enough to find this on youtube

Title: Re: making a crossbow
Post by Lycurgus on Mar 24th, 2009 at 6:01am
These are nice, with the bonus that you can use the same ammo for your sling.

http://www.todsstuff.co.uk/stonebows.php

Have a look at the rest of the site. I have seen some of his stuff up close and he is a real craftsman. His sling was a bit poor though!

Title: Re: making a crossbow
Post by Bikewer on Mar 24th, 2009 at 11:04am
The heat from all the grinding will cause the spring to loose temper; if you tried to draw the bow it would just stay drawn...     Has to be re-tempered to "spring" quality.  In most cities there are heat-treating places that will do this for you.

The Chinese used wooden bows for many of their crossbows, and they were typically much longer than Western models.   Not only was the bow longer, but the draw-length as well.   They look odd to our eyes, but they apparently worked pretty well; that long draw allows the bow to transfer a lot of energy.

Title: Re: making a crossbow
Post by GmanGomez on Mar 27th, 2009 at 11:14am
hummm i am having a hard time finding a leaf spring and i right now already have all of the parts for my crossbow

1.My stock
2.my trigger mechanisim (already in a housing)

i decided to separate the trigger system from the stock itself for easy maintenance and if i do need to make it
a one piece trigger system (incorporated already into the main body of the crossbow) i just take the trigger housing out and put in my integrated one

so far my only problem right now is just my crossbow limbs i have decided already to just go wood since like i mentioned earlier leaf springs are hard to come by but than switching to wood creates another problem since the measurements i have right now for limbs are for steel limbs and limbs made for traditional crossbows (the length of my traditional crossbows differs greatly as the length of mine is based on the length of a store bought one) the wood i am gonna use is Bamboo if anyone here knows the measurements i need please do tell i searched the internet but the measurements are for other types of wood and since i live in a tropical area bamboo is the only wood here that have he properties of cherry wood or yew and is cheap and readily available  

Title: Re: making a crossbow
Post by Bikewer on Mar 27th, 2009 at 11:38am
Well, I wish you luck.    The definitive book on the construction and history of crossbows is Payne-Gallway's old book:

http://www.amazon.com/Crossbow-Military-Sporting-History-Construction/dp/160239010X/ref=sr_1_1?ie=UTF8&s=books&qid=1238167822&sr=1-1

I got a copy from the library.    

There are several problems with making a decent (that is, powerful) crossbow prod from wood.
First, you need to know the essentials of bow-making; how to choose the wood, what sort of grain structure to look for, how to tiller the bow into a shape that will work properly.
Because the bow is so short, everything is rather critical.  

Heavy bows are normally "braced" by means of a device called a false string that is clamped onto the bow arms.   This is not practical with wood; the bow can be damaged.  
Note that Europeans abandoned wood as a material for prods very early in the history of these weapons.  The best of them were reinforced with sinew, and probably only drew a bit over 100 pounds.
A steel prod in the 125 pound range will be lighter, more durable, and shoot better than a wood one.

There used to be a page up on the net of a fellow that makes prods from hickory; but the design was pretty primitive.

Title: Re: making a crossbow
Post by HHornblower on Apr 4th, 2009 at 6:46am
Have a look at these videos on Youtube:

Development of the crossbow by Mike Loades:
(Anna Komnene lived in the 12th century AD.)
http://www.youtube.com/watch?v=-ykrg4rQIO0&feature=related     (maybe try that belt and claw?)

And a build-along made by someone
http://www.youtube.com/watch?v=WgKcbHOgHvw    (=part 1 of 3)
http://www.youtube.com/watch?v=aLTwmOrJTzA&feature=related   (= part 2 of 3)
http://www.youtube.com/watch?v=qveW5SQtias&feature=related    (= part 3 of 3)

Maybe look around at sites like:
http://www.primitivearcher.com/smf/index.php?PHPSESSID=8pp47kh4etqepqj8e4bdp3cpd7&#1

Hope it helps!

Cheers,

Hornblower

Title: Re: making a crossbow
Post by adsi on Apr 16th, 2009 at 12:35pm
how would i make a trigger system out of household things

Title: Re: making a crossbow
Post by castanon93 on Apr 25th, 2009 at 1:04pm
dude... use some commas  :o

Title: Re: making a crossbow
Post by adsi on Apr 28th, 2009 at 3:45pm
sorry ,

Title: Re: making a crossbow
Post by Et Cetera on May 4th, 2009 at 4:43pm
co,mma,s ,,ro,ck, du,de,,!

Title: Re: making a crossbow
Post by David Morningstar on May 13th, 2009 at 9:48am
Good stuff on how to make a crossbow here: http://www.crossbowhunters.com/_sgg/m3_1.htm

Title: Re: making a crossbow
Post by muddundee on May 18th, 2009 at 6:02pm
I once made a crossbow using a leaf spring it was not a success as i did not re temper the  prod & it had gone too soft. I still have the nut i made for the release. Richard Middletons book Man powered bullets is a mine of excellent info if you intend to build a crossbow or stonebow. Traditionally western croosbows had very short draw with very stiff & powerful prods, Middleton has proven that these are far less efficient & slower than those with a long draw length.

Title: Re: making a crossbow
Post by Bikewer on May 18th, 2009 at 6:24pm
I read Middleton's book too; interesting stuff.    Also Payne-Gallway's old book on the history and practice....

The Chinese went this route, as I recall; using much longer wooden/bamboo bows and achieving good results.   The only downside is that the crossbow itself must be much longer, and the whole affair is rather bulky.
European crossbows at their greatest state of development were quite compact, and could be easily drawn with a cranquin, even at very heavy draw weights.
Gallwey talks about late-period crossbows with draw weights in excess of 1200 pounds....Kind of scary.  That's a lot of energy; all the parts must be of top quality.

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