The Arbalist Guild

Would you like to react to this message? Create an account in a few clicks or log in to continue.

Crossbows - Everything about Building, Modding, and Using your Crossbow Gear

Home Gallery Latest images Search
Search Query
Display results as : Posts Topics
Advanced Search
Register Log in

You are not connected. Please login or register

Latest topics

» [solved]Skane/Lillohus crossbow thread
by stuckinthemud1 Sat Aug 10, 2024 3:16 pm

» Colletiere a Charavines continuing experiment
by stuckinthemud1 Fri Aug 02, 2024 7:13 am

» What you building?
by hullutiedemies Tue Jul 09, 2024 12:39 am

» 12th Century Chinese Crossbow Chronographed
by stuckinthemud1 Fri Nov 24, 2023 3:50 pm

» Crossbow Stock
by kenh Tue Oct 31, 2023 6:19 am

» Cocking - how
by stuckinthemud1 Thu Aug 03, 2023 4:24 am

» Questions around heavy crossbow lath buildin
by stuckinthemud1 Wed Apr 26, 2023 1:10 am

» Arab Crossbow
by stuckinthemud1 Tue Apr 25, 2023 7:57 am

» prod angle, and lever trigger for sale anyone?
by stuckinthemud1 Mon Mar 20, 2023 5:54 am

» flexible string
by jasper1978 Mon Mar 20, 2023 1:25 am

» jens sensfelder
by jasper1978 Wed Mar 08, 2023 11:58 pm

» 400lb Windlass crossbow bolts weight and accuracy shooting high.
by stuckinthemud1 Sun Mar 05, 2023 2:53 pm

» Codex Löffelholz crossbow
by stuckinthemud1 Tue Jan 24, 2023 4:14 pm

» Digitar prodsc
by stuckinthemud1 Sun Jan 15, 2023 2:42 pm

» Troubleshooting
by Andy. Fri Jan 06, 2023 12:29 pm

» Wood Prods
by stuckinthemud1 Fri Dec 30, 2022 12:47 pm

» Colletiere a Charavines crossbow
by stuckinthemud1 Fri Dec 30, 2022 8:54 am

» Simplified Löffelhotz speedloader
by stuckinthemud1 Fri Dec 09, 2022 4:05 pm

» Fiberglass H-bows
by c sitas Sat Nov 12, 2022 8:44 am

» Bad Antler
by drawknife Sat Nov 12, 2022 3:48 am

» Anyone make their own bolts?
by Juniper Mon Oct 17, 2022 8:20 am

» Josef alm in English
by Juniper Sat Oct 15, 2022 4:22 am

» Qin/Han lock drawings
by kenh Fri Sep 23, 2022 8:16 pm

» stirrup dimensions?
by stuckinthemud1 Thu Sep 01, 2022 1:49 pm

» Skane/Lillohus lockbow information needed
by stuckinthemud1 Sun Aug 14, 2022 6:23 am

4 posters

Question about prod specs

Daniel Levesque

Daniel Levesque: Tinkerer
If there is a will, there is a way.; Posts : 65
Join date : 2016-12-06
Location : Quebec, Canada

Post n°1

Question about prod specs

by Daniel Levesque Mon Jan 16, 2017 8:43 am

Hello everyone,

For now at least, I give up the idea of working on a wood prod. I'll build a composite one in the future though.

So, I wanna build a spring steel prod (there's a metal shop nearby who sells 5160 springsteel flatbars...lucky me Smile

Smile

)

Anyway, I want to use the same tiller I was to use with my wood prod... it's quite massive but I'm a big guy as well. The draw length would be 12,5 inches (I'd say I'd brace the prod at 3-4 inches and the rest would be the power stroke. The prod should be 2" at the centre and tapered toward the knocks but I'm not quite sure how I should do it (I would work it carefuly with an angle-grinder and have someone at the shop to heat-treat it. In the final, I'd like the bow to be around 250-300 pounds of draw weight. I guess the prod knock to knock should be around 34-35 inches to be safe ?

Any ideas about the specs ? I did some research but I'm still pretty much in the dark right now...

OrienM: Workshop Savvy
Did you see my tool collection?; Posts : 195
Join date : 2014-08-01
Age : 48
Location : New Mexico, USA

Post n°2

Re: Question about prod specs

by OrienM Mon Jan 16, 2017 12:18 pm

Have you seen this? Probably a good place to start:

http://crossbow.wikia.com/wiki/Plan_for_a_simple_leaf-spring_prod

Don't lengthen the prod if you want high draw weight out of 1/4" stock; the above design produces 150#, but could be widened and/or shortened a bit overall to increase the pull.

c sitas: Crossbow Junkie
I live here!; Posts : 547
Join date : 2012-11-24

Post n°3

Re: Question about prod specs

by c sitas Mon Jan 16, 2017 1:52 pm

Orien, I made that design. only difference was I cut it out of an old crosscut saw.Made a eight piece laminate. Ended up heavy . It shot alright but had a real after shock.My lam ended up at about 225#.Ended up going to glass. Pretty much the same as Kenh built.Much calmer to shoot, and no after shock.Ken used 1/4" thick stock.That wiki is a good one ,it tells just about all there is on the subject.

Geezer: Master Crossbowyer; Posts : 1194
Join date : 2010-01-12
Age : 76
Location : Austin, Texas, USA

Post n°4

Re: Question about prod specs

by Geezer Mon Jan 16, 2017 10:04 pm

About prod shock (recoil) If you're getting lots of prod shock or recoil at the end of a stroke, try increasing the bolt weight. If that doesn't help, a heavier stock can improve things. Geezer.

OrienM: Workshop Savvy
Did you see my tool collection?; Posts : 195
Join date : 2014-08-01
Age : 48
Location : New Mexico, USA

Post n°5

Re: Question about prod specs

by OrienM Tue Jan 17, 2017 8:10 am

I made a prod based on the wiki plan as well, but much shorter, and used it in this little crossbow: https://thearbalistguild.forumotion.com/t1249-my-second-crossbow-the-little-devil?highlight=little+devil

This prod is only 15" overall, and pulls 150# with a 2" brace and 3" powerstroke. It deals well with a heavy projectile, but shoots rather sluggishly overall, which apparently is fairly typical of a steel prod. The bow is also rather 'kicky', even with heavy bolts.

With old steel prods you often see very short draw lengths used, usually about 2X the brace height...I'd be careful about going much past that, proportionally speaking.

c sitas: Crossbow Junkie
I live here!; Posts : 547
Join date : 2012-11-24

Post n°6

Re: Question about prod specs

by c sitas Tue Jan 17, 2017 8:37 am

For my self,after shooting both types of material ,glass and steel,I'll take the glass. Just my opinion though.Not a purest either. I don't use factory prods either.The steel one I made kicked like a rifle. I think what I use is called pulltruded or something on that order. It's factory made flat stock. I've even had great luck with glass fence post. Not hard to get over 200# there. Orien, that bow you built and showed is a work of art. Has all the right qualities.Being an archer is my problem. I build to get shooting. I make all types and use mostly crap left behind from someone.

OrienM: Workshop Savvy
Did you see my tool collection?; Posts : 195
Join date : 2014-08-01
Age : 48
Location : New Mexico, USA

Post n°7

Re: Question about prod specs

by OrienM Tue Jan 17, 2017 9:26 am

Thanks! Personally I'll take a wood/sinew prod over a steel one...I could never quite get comfortable with any of my steel-prod efforts, and already had some experience with simple composites from making archery bows. Wood/sinew fails in a different way than steel, folding up rather than snapping...longer draw lengths are do-able, and the prods are light and snappy-shooting.I think draw weights up to 250# or so are pretty do-able, above that horn bellies are probably required.

They certainly take much longer than steel prods to make, though, and can't deal with anything like the super-high draw weights that steel can potentially provide.

c sitas: Crossbow Junkie
I live here!; Posts : 547
Join date : 2012-11-24

Post n°8

Re: Question about prod specs

by c sitas Tue Jan 17, 2017 10:33 am

Orien, I surely envy you and your abilities . A wooden prod would surely be the way to go. Light ,fast ,and quiet. Never shot crossbow with one but over time I've had my share of stick bows and compounds.I'm 74 but I still can get excited over a deer. With some sort of weapon in your hand , the hunt is on.It's even fun to hunt with a fence post.

Daniel Levesque

Daniel Levesque: Tinkerer
If there is a will, there is a way.; Posts : 65
Join date : 2016-12-06
Location : Quebec, Canada

Post n°9

Re: Question about prod specs

by Daniel Levesque Tue Jan 17, 2017 11:46 am

You're amazing guys !

Orien, I'll certainly try a wood/sinew prod instead of wood/rawhide (which is no good) but I'll back off a bit on the draw weight... going to 300 pounds was waaaay too much for my (in)experience with crossbows anyway. I tried I guess. My next try is going to be around 150 lbs or so (sounds do-able).

For the steel prod, I want to give it a try anyway (I'll probably build another tiller for this one since woodcrafting has been my addiction lately). I found a place where I can get 8 foot flatbars of 5160 springsteel 2" x 3/8"... I'm still waiting for the guy to give me a price though... I just hope I'm not going to be disapointed.

OrienM: Workshop Savvy
Did you see my tool collection?; Posts : 195
Join date : 2014-08-01
Age : 48
Location : New Mexico, USA

Post n°10

Re: Question about prod specs

by OrienM Tue Jan 17, 2017 12:33 pm

Yeah, I don't mean to get off-topic into composites!

I'd say 3/8" thick steel will work better than 1/4", especially if you want to get 300# and add a bit of length to the prod. Nice that it is new flat stock, not old springs with their holes and potential stress cracks.

You're going to want to bend some deflex into the prod before heat-treating, too...maybe 3" or so of deflex for a brace height of 4". It makes for a fairly low initial string tension, but a much safer prod; with stiff enough limbs, draw weight still goes up quickly as the string is pulled back.

BTW the same general ideas (stiffening limbs, adding deflex, and using a proportionally short draw length) seem to be beneficial with all-wood and wood-sinew prods, too. The belly wood can fail (or steel bows can explode!) if limbs are pre-loaded too much.

c sitas: Crossbow Junkie
I live here!; Posts : 547
Join date : 2012-11-24

Post n°11

Re: Question about prod specs

by c sitas Tue Jan 17, 2017 12:55 pm

Daniel, I found some on knife makers sight. He wanted $2.85 a foot for 5160 spring steel. If he had to ship apiece over 48" ,he wanted an extra 10 dollars .I imagine for some extra boxing . Didn't see anything for freight,but that would vary by lo-cal.

Daniel Levesque

Daniel Levesque: Tinkerer
If there is a will, there is a way.; Posts : 65
Join date : 2016-12-06
Location : Quebec, Canada

Post n°12

Re: Question about prod specs

by Daniel Levesque Tue Jan 17, 2017 1:22 pm

Wow... that's awesome price-wise, it's cheap enough for me at least Razz

Razz

c sitas: Crossbow Junkie
I live here!; Posts : 547
Join date : 2012-11-24

Post n°13

Re: Question about prod specs

by c sitas Tue Jan 17, 2017 3:51 pm

Darn it Dan, I my haste to type I screwed up. It's supposed to be 12.85 NOT 2.85. Dumb me .Sorry to get your blood moving.

Daniel Levesque

Daniel Levesque: Tinkerer
If there is a will, there is a way.; Posts : 65
Join date : 2016-12-06
Location : Quebec, Canada

Post n°14

Re: Question about prod specs

by Daniel Levesque Tue Jan 17, 2017 7:19 pm

Oh..noooo !! I'll still probably buy some, maybe not as much.

c sitas: Crossbow Junkie
I live here!; Posts : 547
Join date : 2012-11-24

Post n°15

Re: Question about prod specs

by c sitas Wed Jan 18, 2017 11:12 am

Stop and think , two feet is less than half of ready made.But, you have to add shipping and that depends on where you live. Corse, you have to have shipping no matter what or where you buy.

Daniel Levesque

Daniel Levesque: Tinkerer
If there is a will, there is a way.; Posts : 65
Join date : 2016-12-06
Location : Quebec, Canada

Post n°16

Re: Question about prod specs

by Daniel Levesque Wed Jan 18, 2017 11:24 am

Thought about that. I think I'll just buy a premade prod from slobows. I can get one for about 90 $ (CAN dollars sucks) including shipping rate. If I buy the steel, I'll need 3 feet at least, shape the prod and have a machine shop to heat-treat it (including additionnal charge for that), It 's bound to get pricey anyway.

I'll still buy a couple of feet of springsteel to forge some knives though Wink

Wink

Daniel Levesque

Daniel Levesque: Tinkerer
If there is a will, there is a way.; Posts : 65
Join date : 2016-12-06
Location : Quebec, Canada

Post n°17

Re: Question about prod specs

by Daniel Levesque Wed Jan 18, 2017 12:21 pm

Sorry all, just one more question here :

I know that for steel prod, the top won't be narrowed down, it'll just be flat and it's the bottom from center to tips that will be narrowed (kinda like an inverted pyramid) to reduce tension and friction for the string on the tiller. Is it the same for a wooden prod or should it be narrowed down equally (top and bottom will be the same) ? (my guess would be NO because of uneven tension (possible torsion) along the bow but since i'm new to this, I prefer to ask).

BTW, sorry if the structure of my sentences seems off a bit sometimes, French is my main language.

c sitas: Crossbow Junkie
I live here!; Posts : 547
Join date : 2012-11-24

Post n°18

Re: Question about prod specs

by c sitas Wed Jan 18, 2017 2:35 pm

I'm not a expert but, have never seen this narrowing as you mention for a wooden bow. All the final shaping is called tillering,and that is to make all the tension equal,and make the string come right down the center of the mass.Some of the shaping you are mentioning for steel serves the purpose of kind of jacking the string up to relieve pressure on the rail of the stock so you can make a strong mount for the bow. ---I think .If you would draw out a full size picture the way wiki tells you, you would see what I'm trying to say. Pay real close attension to the way they lay it out to start with. Orein would know sure.He makes wooden stuff. There are others here also.

OrienM: Workshop Savvy
Did you see my tool collection?; Posts : 195
Join date : 2014-08-01
Age : 48
Location : New Mexico, USA

Post n°19

Re: Question about prod specs

by OrienM Sat Jan 21, 2017 9:03 am

Hey, apologies for my slow response; my computer was in the shop.

Personally I've been making my wooden prods with a shape very similar to steel ones. They're asymmetrical; the upper edge of the prod is flat, the bottom side curved/tapered.

It does induce some limb twist, but helps a great deal to reduce string pressure on the tiller. I actually think twist is inevitable in crossbow prods...no matter what you do, you'll still be drawing the bow off-axis. A moderate asymmetrical profile seems to be a good compromise; the other option is to increase the angle (forward tilt) of the prod in the tiller, which also increases limb twist and can cause dry-firing, as well.

With steel, you can actually lift the tips even higher, making a concave upper edge; it improves string geometry to a point, but also increases twisting forces at the prod mounting. Go too extreme, and you can split the tiller, or tear out the bridle holding the prod in.

OrienM: Workshop Savvy
Did you see my tool collection?; Posts : 195
Join date : 2014-08-01
Age : 48
Location : New Mexico, USA

Post n°20

Re: Question about prod specs

by OrienM Sun Jan 22, 2017 12:12 pm

Found this old thread here with some excellent info about designing prods; it's focused on wooden prods, but also delves into steel-prod design: https://thearbalistguild.forumotion.com/t1387-wood-prods

Daniel Levesque

Daniel Levesque: Tinkerer
If there is a will, there is a way.; Posts : 65
Join date : 2016-12-06
Location : Quebec, Canada

Post n°21

Re: Question about prod specs

by Daniel Levesque Mon Jan 23, 2017 6:57 am

Thanks Orien, I already saw that link (very good info) but I was more interested to get your views on a flot top prod. I wasn't so sure about the limb twist but since you've done it before and it seems to work, I'll give it a try. I just didn't want to invest time in something that would be doomed to fail from the start. I'll begin work on my prod (sinew backed hickory prod) this week. I'll keep you guys updated. Thanks again for your good advices.

By the way, I know hickory is a solid wood for backings but it performs so-so for the belly. What kind of wood should I use if I want to make a laminate prod with a hickory backing (and please, don't tell me Osage Orange, it's not available where I live) ?

OrienM: Workshop Savvy
Did you see my tool collection?; Posts : 195
Join date : 2014-08-01
Age : 48
Location : New Mexico, USA

Post n°22

Re: Question about prod specs

by OrienM Mon Jan 23, 2017 7:32 am

Unfortunately I don't have much experience with wood-backed laminates; I've made a few archery bows of Ipe wood with bamboo or hickory backs that shot well.

Some of the better bowyery woods (besides osage Wink

Wink

) would include mulberry, elm, black locust, hickory, and hophornbeam (AKA ironwood). Ipe is also good (its portugese name is Pau D'Arco, or bow wood), but it's also incredibly dense...I don't know if it steam-bends very well, either. Hickory can be a very good choice, but in my experience it varies quite a lot...a particularly hard, heavy example can make an excellent bow.

IMHO there's no real reason to laminate a prod if it will be sinew-backed as well. The sinew takes over the function of backing, and is much stronger in the job than any wood, or even bamboo.

Daniel Levesque

Daniel Levesque: Tinkerer
If there is a will, there is a way.; Posts : 65
Join date : 2016-12-06
Location : Quebec, Canada

Post n°23

Re: Question about prod specs

by Daniel Levesque Mon Jan 23, 2017 7:57 am

Understood ! Thanks for the advice. Wink

Wink

Sponsored content

Sponsored content

Post n°24

Re: Question about prod specs

by Sponsored content

Log in

Control panel

Your profile

Social

Private messages

Other

Topics being watched

New Member & Useful Links

Crossbow Building

Crossbowyers
(Custom Crossbows to Order)

The New World Arbalest

Supplies & Accessories

*Arbalist Store* (Coming Soon)
Alchem Inc.
Darkwood Armory
Digitarc

Current date/time is Sun Sep 15, 2024 8:59 pm