Author Topic: Static limb help  (Read 2253 times)


Online Mad Max

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Re: Static limb help
« Reply #1 on: September 13, 2022, 06:49:03 PM »
First thing is check your glue up form, hold a square on the sides of the form and see if the press side is square to it all the way down.
Check to see if your forms is straight or twisted.
I would do that first.

If you made your tapers and parallels grind some new ones and check them for thickness side to side.

 
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Online Kirkll

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Re: Static limb help
« Reply #2 on: September 13, 2022, 06:58:21 PM »
A few questions:   What is the riser length over all, Limb over all length, limb pad length, length of limb from riser to tip notch, length of wedge fades to riser, and limb bolt to limb bolt measurement?

Where are you measuring your total stack height? At the limb butts, or fades? With or without wedges?


How are you checking both your limbs and riser pads for being dead square when you mount the limbs on the riser. Are you sure your alignment is dead on?

The reason for all my questions is that limb design shape of your looks VERY similar to my own static tip SS limb design, and i run my limb pads at about 15.5 - 16 degrees successfully. I'm quite certain i can help you help with this..

One more question....

look at this photo and measure the thickness at this point.


Offline BO-R

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Re: Static limb help
« Reply #3 on: September 13, 2022, 07:29:14 PM »
A few questions:   What is the riser length over all, Limb over all length, limb pad length, length of limb from riser to tip notch, length of wedge fades to riser, and limb bolt to limb bolt measurement?

Where are you measuring your total stack height? At the limb butts, or fades? With or without wedges?


How are you checking both your limbs and riser pads for being dead square when you mount the limbs on the riser. Are you sure your alignment is dead on?






The reason for all my questions is that limb design shape of your looks VERY similar to my own static tip SS limb design, and i run my limb pads at about 15.5 - 16 degrees successfully. I'm quite certain i can help you help with this..

One more question....

look at this photo and measure the thickness at this point.




Kirk,
Thickness at the base of the tip wedge is .239

Riser as set is 17 inch,, can adjust to 19"
Limb overall length 28"
Lim Pad 4 inch.
Limb length from riser to Notch 22"
Length of wedge fades to riser 5 7/8ths
Limb bolt to bolt is 12".

Stack measured at butt end /no wedge...(.220 with stablecore.)

Remeasured form all square.

I use this test riser on all my standard recurve limbs with no issues

Limbs were square to riser and centerlines.

Thank you..

Offline BO-R

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Re: Static limb help
« Reply #4 on: September 13, 2022, 07:31:54 PM »
First thing is check your glue up form, hold a square on the sides of the form and see if the press side is square to it all the way down.
Check to see if your forms is straight or twisted.
I would do that first.

If you made your tapers and parallels grind some new ones and check them for thickness side to side.

Thanks Max,

Form is square..

before assembly double checked cores.

Thank you.

Online Kirkll

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Re: Static limb help
« Reply #5 on: September 13, 2022, 07:37:36 PM »
Here is how i check my limbs before i mount them. I get a straight line on one edge, nock the buggers off the other side. Then check the limbs for 90 degrees from the limb butts to the tips. If you have a twist in your form it shows up right now doing this. the butts will be dead square and the tips will be different.

Once i have the limbs square to the sanding table bed, then i run them through the drum sander to get them parallel and down to about 1.65 to 1.70 in width. Then they get mounted on the riser and checked for my milling straightness. Even using a vertical mill, it can easily move a bit one way or te other... not often, but enough to check every one.

https://photos.app.goo.gl/T4oSirdugxWQ1jvD9

Here is a good example of one that mounted out of alignment a bit and how its corrected.
https://photos.app.goo.gl/Zvz9YGcc1DmdiALK7

Here is another way to check limb twist once the limbs are mounted. If something is out at this stage you need to back track and check your riser pads for dead square.

https://photos.app.goo.gl/9tFb59pY26jstcge6

Kirk



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Offline BO-R

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Re: Static limb help
« Reply #6 on: September 13, 2022, 07:47:13 PM »
typo on the base of the tip wedge measurement :knothead:

Thickness at the base of the tip wedge is .239  ACTUALLY .209

Offline BO-R

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Re: Static limb help
« Reply #7 on: September 13, 2022, 07:56:52 PM »
Here is how i check my limbs before i mount them. I get a straight line on one edge, nock the buggers off the other side. Then check the limbs for 90 degrees from the limb butts to the tips. If you have a twist in your form it shows up right now doing this. the butts will be dead square and the tips will be different.

Once i have the limbs square to the sanding table bed, then i run them through the drum sander to get them parallel and down to about 1.65 to 1.70 in width. Then they get mounted on the riser and checked for my milling straightness. Even using a vertical mill, it can easily move a bit one way or te other... not often, but enough to check every one.

https://photos.app.goo.gl/T4oSirdugxWQ1jvD9

Here is a good example of one that mounted out of alignment a bit and how its corrected.
https://photos.app.goo.gl/Zvz9YGcc1DmdiALK7

Here is another way to check limb twist once the limbs are mounted. If something is out at this stage you need to back track and check your riser pads for dead square.

https://photos.app.goo.gl/9tFb59pY26jstcge6

Kirk

Good info Kirk,,

Are you telling me to start over  :bigsmyl:

Online Kirkll

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Re: Static limb help
« Reply #8 on: September 13, 2022, 08:14:29 PM »
A few questions:   What is the riser length over all, Limb over all length, limb pad length, length of limb from riser to tip notch, length of wedge fades to riser, and limb bolt to limb bolt measurement?

Where are you measuring your total stack height? At the limb butts, or fades? With or without wedges?


How are you checking both your limbs and riser pads for being dead square when you mount the limbs on the riser. Are you sure your alignment is dead on?






The reason for all my questions is that limb design shape of your looks VERY similar to my own static tip SS limb design, and i run my limb pads at about 15.5 - 16 degrees successfully. I'm quite certain i can help you help with this..

One more question....

look at this photo and measure the thickness at this point.




Kirk,
Thickness at the base of the tip wedge is .239

Riser as set is 17 inch,, can adjust to 19"
Limb overall length 28"
Lim Pad 4 inch.
Limb length from riser to Notch 22"
Length of wedge fades to riser 5 7/8ths
Limb bolt to bolt is 12".

Stack measured at butt end /no wedge...(.220 with stablecore.)

Remeasured form all square.

I use this test riser on all my standard recurve limbs with no issues

Limbs were square to riser and centerlines.

Thank you..

All the measurements you gave me were very close to my own 60" RC. Not a 62" . my limbs measuring from 17" riser tip,  to the tip notch is 21.5" on the belly side of the limb. My limb bolts are 10.5'' center to center with 4.5" limb pads.  I use a 57.5" string on my 60" bows with about 7-7.25" brace to the location of the deepest part of the grip.... I got my limbs dialed in first, then measured back to the riser block to locate the grip for a good brace height. i like 7-7.5" myself.

At this stage .....What i would recommend trying is coming back down the hook on each tip to a 60" length from center. This might be just enough to help stabilize it. It's amazing what that little bit can do. If you get a wee bit too far out on the hooks,especially  on a light poundage bow , they do get squirrelly. Heavier draw weights you got more beef at the base of your hook and can get more aggressive.

Next lay up, try running just a par instead of the .001 taper. Your limb shape may be slightly different than mine, but that's what i do on anything less than 45#. My magic number is 200 at the base of the curl for good stability. I can get down to .190 sometimes, but prefer .200.... btw... more width doesn't help much. its the thickness that holds that thing stable just using glass.

Once you start playing with bias weave carbon... all bets are off and you have a different ball game.

Hopefully some of this is helpful.       Kirk


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Re: Static limb help
« Reply #9 on: September 13, 2022, 08:21:19 PM »
Thanks Kirk,

If  you look at the limbs notchs i did try shorten up the limbs with a second set of nocks to try to get them stabil.
same result.

Looks like a do over...

Any other advice on these statics?

I was looking for a new challenge past R/C and hybrids...

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Re: Static limb help
« Reply #10 on: September 13, 2022, 09:06:23 PM »
Here are some things you can do to manipulate the string tension and watch how the limbs are bending once you get your tracking issue resolved.  Play with different string lengths and limb pad angles. Look at the way they bend and what it does to your string angle at 30-32" draw lengths. If you are so inclined, you can set up an in line scale and measure your string tension and compare the different string lengths and preload put in the limbs with your adjustable riser.....

You need not go down a technical rabbit hole with all the DFC charts and testing to come up with a very nice shooting product. A good eye, and some limb balancing will do the trick nicely. But some guys are into all the nitty gritty details. But..... the in line scale will open your eyes to how much just string length and different brace height does to your performance.    an AMO bow length is not measured by the string length. Its tip notch to tip notch around the curl and straight through the riser.

While you are still prototyping it don't matter what bow length you have or brace height either for that matter. Cut it down some more until it tracks straight, then move the stop in your form to add the length you want on the but end......Thats how i build medium and long limbs on my RC and hybrid bows, i have a 1'' longer stop for the long limbs. i used a 10.5" finished wedge on medium limbs, and its 11.5" on the long limbs, with the tip notch in the same location on the hooks.  This keeps the dynamics the same.

 Its how those limbs are bending that matters and how much energy they are storing. The preload or string tension will determine how well your limbs stop, and transfers the energy rather than staying in the limbs.

Here is an example of 10 degrees vs 15 degrees on my SS limbs when i was first getting them dialed in. notice the very straight limb at brace vs the the one with a slight bend at brace. Then look at the two limb pad angles and where the limbs are bending....




Online Kirkll

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Re: Static limb help
« Reply #11 on: September 13, 2022, 09:20:11 PM »
typo on the base of the tip wedge measurement :knothead:

Thickness at the base of the tip wedge is .239  ACTUALLY .209

 :biglaugh: :biglaugh:  i was just looking at that having a WTF moment...
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Online Crooked Stic

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Re: Static limb help
« Reply #12 on: September 16, 2022, 05:39:28 PM »
I just redesigned a limb myself trying to keep the preload without a curved wedge (a pain to make and lot of waste) so thought I was gonna be cool and cut the string grooves an inch further toward the tip (more hook)  It strung okay but tried to pull it back and went sideways right off. Probably would have been good with 45/45 carbon but not everyone wants that. So 1 inch less hook took care of it. And  I find that .200 thickness to be good at the base of the hook. And if 45 or less poundage go parallel. And when you use a sled for cutting pads and flipping it for each end got be dead square. I have profile jigs for my risers. Keeping the same plane on each end.
High on Archery.

Online Kirkll

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Re: Static limb help
« Reply #13 on: September 16, 2022, 09:10:22 PM »
I just redesigned a limb myself trying to keep the preload without a curved wedge (a pain to make and lot of waste) so thought I was gonna be cool and cut the string grooves an inch further toward the tip (more hook)  It strung okay but tried to pull it back and went sideways right off. Probably would have been good with 45/45 carbon but not everyone wants that. So 1 inch less hook took care of it. And  I find that .200 thickness to be good at the base of the hook. And if 45 or less poundage go parallel. And when you use a sled for cutting pads and flipping it for each end got be dead square. I have profile jigs for my risers. Keeping the same plane on each end.

Right on Mike!  Isn't that amazing how much just a 1/2" location on TN on the hooks will make...

When i was fine tuning mine i'd come down the hook a bit, then flatten out my limb pad angle a bit, then start playing with different string lengths and checking tension levels with the in line scale. But after while , i figured out my preload was pretty much dead on with a 2.5" to 2.75" less than AMO length on mine without getting the in line scale back out.  I suppose that would be different on each different bow, but that same string length works for my hybrid preload  too.    Kirk
« Last Edit: September 17, 2022, 01:51:35 PM by Kirkll »
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Re: Static limb help
« Reply #14 on: September 17, 2022, 08:12:54 AM »
I just redesigned a limb myself trying to keep the preload without a curved wedge (a pain to make and lot of waste) so thought I was gonna be cool and cut the string grooves an inch further toward the tip (more hook)  It strung okay but tried to pull it back and went sideways right off. Probably would have been good with 45/45 carbon but not everyone wants that. So 1 inch less hook took care of it. And  I find that .200 thickness to be good at the base of the hook. And if 45 or less poundage go parallel. And when you use a sled for cutting pads and flipping it for each end got be dead square. I have profile jigs for my risers. Keeping the same plane on each end.

Thanks stic,
I have a mill i use to cut my limb pads and drill all my inserts.

I did try and bring down the hooks nocks to no avail..

on further investigation, I must have had a senior moment and found my limb template moved at the tip area on one limb was not symmetrical causing my issue I believe.

Thanks for your help.

Vince.


Online Roy from Pa

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Re: Static limb help
« Reply #15 on: September 17, 2022, 09:21:53 AM »
I must have had a senior moment and found my limb template moved at the tip area on one limb was not symmetrical causing my issue I believe.


Hell yer only 66, wait till ya hit my age of 74 and see all the dumb chit ya do:)

 :laughing:

Online Kirkll

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Re: Static limb help
« Reply #16 on: September 17, 2022, 10:21:23 AM »
I must have had a senior moment and found my limb template moved at the tip area on one limb was not symmetrical causing my issue I believe.


Hell yer only 66, wait till ya hit my age of 74 and see all the dumb chit ya do:)

 :laughing:

Oh Good…..I can’t wait Roy…  :biglaugh:

 I’m “only” 66 myself , but there are days I feel much older, and do more damage than good in the shop. Those days I’d be better off fishing….

My latest boo-boo was almost laughable. Because I did such a beautiful job of it.  The famous wrong side of the line syndrome while roughing out a Bare Foot riser and gluing on 3/8” thick limb pad bases ended up with my riser being almost an inch short….I did a beautiful job on the millwork and the limbs mounted perfectly. I didn’t even realize my error until stringing the bow and the string was too long….

Unfortunately…… I couldn’t find my board stretcher anywhere to stretch that riser back out, and had to build another riser….I’m quite certain I’ll find a home for the shorter riser at some point, but it was truly embarrassing….

 A senior moment is screwing something up totally…..with confidence, and having a smile on your face while doing it…. Chit happens….  :biglaugh:     Kirk
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Offline BO-R

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Re: Static limb help
« Reply #17 on: September 17, 2022, 10:39:42 AM »
amen to that! cant wait...but I will go a day at at a time :bigsmyl:

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