Author Topic: Newbie questions regarding the making of limbs  (Read 1952 times)

Offline muskrat man

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Newbie questions regarding the making of limbs
« on: March 31, 2018, 08:39:33 PM »
Hello, I am interested in recurve making as a hobby for myself. I am pretty handy and have a shop that is fairly equipped. I wanted to start slow and progress as time and funds allow. I thought a decent place to start might be to try making limbs for some old discontinued T/D bows I have.  I realize I will need a form which I assume I can make using an original set of limbs as a template.  Basically I'm wondering if someone can point me in the right direction as far as where to acquire materials, how to calculate formulas for approximating draw weight by the thickness of glass/laminations,  etc etc. Since I am a total Newbie i'm just looking for some general idea of what I need to be doing and I can figure the rest out trial and error.
Thanks in advanced for any guidance
Have a wonderful Easter
Eat Mo' Possum

Offline skeaterbait

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Re: Newbie questions regarding the making of limbs
« Reply #1 on: March 31, 2018, 08:42:06 PM »
You can never go wrong with Kenny.

www.kennysarchery.com
Skeater who?

Offline mwosborn

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Re: Newbie questions regarding the making of limbs
« Reply #2 on: March 31, 2018, 10:08:36 PM »
You can never go wrong with Kenny.

www.kennysarchery.com

I agree with the man in a hat with horns.
Enjoy the hunt!  - Mitch

Offline skeaterbait

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Re: Newbie questions regarding the making of limbs
« Reply #3 on: March 31, 2018, 10:10:49 PM »
You can never go wrong with Kenny.

www.kennysarchery.com

I agree with the man in a hat with horns.

I prefer horny carnivore.
Skeater who?

Offline Forwardhandle

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Re: Newbie questions regarding the making of limbs
« Reply #4 on: April 01, 2018, 06:13:51 AM »
The good part about going with Kenny is if you get in trouble with your build you can call him 24/7 for help 😃 he particularly likes calls early in the morning 🤡 but seriously he will go out of his way to help you out your just not buying materials from him , plus the old guy is a pretty good problem solver !
If you fear failure, you will never try ! But never except it!!

Online kennym

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Re: Newbie questions regarding the making of limbs
« Reply #5 on: April 01, 2018, 08:47:11 AM »
LOL , there are a couple times I won't take a call, but I will call you back as soon as I can.  I won't go into detail on that.... :biglaugh:

You certainly can make a form by tracing the existing limb. Be sure to give it a little extra curve or hook , like a quarter inch. You will have some springback off the form. The woods and glass you bent to the form will want to return to their natural straight position. The laminating holds the curve in but not quite all of it.

The router method will give you the best form in my opinion, it will be very square side to face. This is important, especially on a recurve because if the form is twisted or off a couple degrees, you have just built limb twist in your bow. When you trace your limb, I make a 1/4" plywood template , bandsaw and sand close to line, then bend a still piece, like a pc of glass or a metal yardstick around the curves and hold to light. This will show dips and flat spots you can't see or feel. ( won't tell you how I found this out!)

This is a one piece form but will be same basic method...

https://www.kennysarchery.com/buildalong/

For the stack, do some measuring on the old limb if you know the weight on it. A set of dial (or digital) calipers will help a lot.

Check width, (write it all down in your new bow notebook for future reference) go an inch past the end of wedge( TD) or fadeout (end of riser on a 1 pc)  and get a thickness. Now go out 10" and get another , divide the difference by 10 and you have your taper rate (recurve prob .002" per inch) .

Now you have a baseline from the old limb, and can do some SWAG to get the weight close on the first one.

Since you are going to make a form and a guess on the first bow , I would pick a bow design I really liked so you don't have to do it again after the trial run...  ;)

And what's this old guy crap Ritchie?  :)

Welcome to the fun brother!!

Stay sharp, Kenny.

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Online Roy from Pa

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Re: Newbie questions regarding the making of limbs
« Reply #6 on: April 01, 2018, 08:53:28 AM »
 plus the old guy

 plus the old guy

 plus the old guy

 plus the old guy

LMAO....................

 :laughing: :thumbsup: :laughing: :thumbsup: :laughing: :thumbsup:

Offline Forwardhandle

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Re: Newbie questions regarding the making of limbs
« Reply #7 on: April 01, 2018, 08:55:12 AM »
Lol   :cheesy:
If you fear failure, you will never try ! But never except it!!

Offline muskrat man

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Re: Newbie questions regarding the making of limbs
« Reply #8 on: April 01, 2018, 12:36:03 PM »
Hello men thank you all for the response.

Kenny, also thank you for the email response! I did some measuring on my limb and here is what I found.

Original limb set is for a 48" bow, on a 13" riser, they are marked 63# @ 28 1/2". So that should put it around 62# @ 28" estimation

the Limb width tapers from 1.48" to .610"

Thickness at the points you instructed measure .201" and .170" my math is not the greatest but that should put it at about .003" taper per inch, correct?

At the wedge the overall thickness measures .623". The wedge appears to measure .395" thick, the lams look like .059" each and the glass .050" each.

So, is there a formula  to determine how much thinner I should go on the lams to drop say 10#-12#? To make a 50ish pound set of limbs? So If I wanted to make say a 50# @ 28" set of limbs

Also, should a separate form be made for each limb? Or does one make one form and cut the limbs apart at the butts once cured?

Thank you again for the information and guidance
All the best
Kaleb
Eat Mo' Possum

Online kennym

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Re: Newbie questions regarding the making of limbs
« Reply #9 on: April 01, 2018, 01:31:10 PM »
"Thickness at the points you instructed measure .201" and .170" my math is not the greatest but that should put it at about .003" taper per inch, correct?" 

 Yep , forgot to ask how far from limb butt was the first measure?

 And you did go an inch or so past wedge to get a measure for sure clear of wedge?

Then we can add the .003 per inch to length from the measured point to the limb butt x .003 to   .201 to get total stack  at limb butt without wedge.


"So, is there a formula  to determine how much thinner I should go on the lams to drop say 10#-12#? To make a 50ish pound set of limbs? So If I wanted to make say a 50# @ 28" set of limbs"

Most recurves are about .001 per # but on a shortie I'm not 100% on that. If Jess Stuart would see this he could tell up for sure, he makes some amazing shorties!!

"Also, should a separate form be made for each limb? Or does one make one form and cut the limbs apart at the butts once cured?"

I would make one form and glue the limbs one at a time. Then when you go full bore you can make a form to do two and saw apart or 2 forms. Personal preference, but a single TD limb is easier to glue up, EA 40 is like super grease when you are clamping stuff down!!  ;)
Stay sharp, Kenny.

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Offline muskrat man

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Re: Newbie questions regarding the making of limbs
« Reply #10 on: April 01, 2018, 02:05:51 PM »
6 1/2" from the limb butt.

I took the first measurement 1" from where the wedge visibly ended

This bow is a rocky mt recurve, the same bow Jess based his off of (I currently have a bow on order from Jess actually). I had him talked into making a set of limbs for my bow but thought it would be a good learning opportunity for me to have a whack at it myself, I love to tinker with stuff. When I get done pulling my hair out  :banghead: I can always fall back and have Jess make them.

One form sounds good since I don't intend to go full bore, just make a couple sets of limbs for my personal bows. Maybe make a whole bow someday or a 1 piece but that's in the very distant future.
Eat Mo' Possum

Online kennym

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Re: Newbie questions regarding the making of limbs
« Reply #11 on: April 01, 2018, 03:02:57 PM »
By my calc, that would make the stack without wedge at .221 roughly.  So to get 12# less, a guess would be stack at butt without wedge would be around .208 

This could differ by several #s depending on if the glass is .040 or .050 

I'm betting Jess can tell you what glass was used on RMR bows and prob how much thou/lb  is on the stack.

If not we can make a SWAG!! :)
Stay sharp, Kenny.

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Offline muskrat man

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Re: Newbie questions regarding the making of limbs
« Reply #12 on: April 01, 2018, 03:36:03 PM »
Thanks!

I Have another RMR bow with solid color glass and it's definitely .050". This bow is 50" 55# @ 28" the stack is almost the same thickness, within .002" of the measurements of the 48" 63# bow. I Guess the longer limbs lightened the weight up, about 4# per inch?

Anyway that's neither here nor there.

So for a .208" stack I would need two layers of .050" glass for .100" and two .054" lams to make .108" with a .003" per inch taper?

According to your calculations on stack thickness at the wedge, the wedge would need to be about .404" thick

The best I can tell the wedge is 6" long, it's full thickness to about 3 5/8" then starts fading out/tapering
Eat Mo' Possum

Online kennym

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Re: Newbie questions regarding the making of limbs
« Reply #13 on: April 01, 2018, 03:44:22 PM »
On that short a bow, 2" could easily be 8#  , my 64" gains 6# by piking 2" ...

That sounds correct on stack. Will have to go with 2 - .0015 tapers and start a little shorter than norm 36" to save my sleds.

The wedge may well have started at .400 because the glue lines add a little to finished stack.

No prob making that wedge, just takes a bit of time...

Stay sharp, Kenny.

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Offline muskrat man

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Re: Newbie questions regarding the making of limbs
« Reply #14 on: April 01, 2018, 03:49:18 PM »
OK, one more question. Does lam material have an effect on finished draw weight? Say osage VS  maple
Eat Mo' Possum

Online kennym

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Re: Newbie questions regarding the making of limbs
« Reply #15 on: April 01, 2018, 03:53:51 PM »
A little, but not more than a few # in my tests...

http://www.tradgang.com/tgsmf/?ubb=get_topic;f=125;t=001491;p=11
Stay sharp, Kenny.

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Online kennym

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Re: Newbie questions regarding the making of limbs
« Reply #16 on: April 01, 2018, 03:55:29 PM »
Guess that doesn't work from old site anymore, sorry...
Stay sharp, Kenny.

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Offline muskrat man

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Re: Newbie questions regarding the making of limbs
« Reply #17 on: April 01, 2018, 03:58:24 PM »
Awesome, thanks so much for your help. I guess the next step is for me to email you with a materials list, and get a form made!
Eat Mo' Possum

Online kennym

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Re: Newbie questions regarding the making of limbs
« Reply #18 on: April 01, 2018, 04:20:27 PM »
 :thumbsup:
Stay sharp, Kenny.

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Online jess stuart

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Re: Newbie questions regarding the making of limbs
« Reply #19 on: April 01, 2018, 11:42:02 PM »
I use .040 glass almost exclusively only using .030 on the back on lighter weight bows.  I have never used .050 on a recurve don't know why really just haven't.  I began using a .003 taper but, found that stability was less than ideal in lower weight bows and have since been using .0015 on all my recurves.  My experiences with lower weight bows is that they get so thin near the tips that stability becomes a issue but, much less so, with less forward taper. 
Back when I used bamboo in my limbs I found them to come out lighter than a equal thickness of maple which I prefer to use in a recurve.  In fact good old hard rock maple is my favorite core wood to use.  Others may be as good but none have proven better in my experience.  I like most bowyers have many prejudices on what works well and what doesn't bordering on the  eccentric and ridiculous.  LOL

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