Trad Gang
Main Boards => The Bowyer's Bench => Topic started by: Appalachian Hillbilly on March 16, 2022, 08:22:39 AM
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Being a new guy, 3 piece designs seem to be the easiest as far as mold changes and r and d go because it is easier to build a limb mold for that than a one piece.
I love the look and design of Kirk's limbs and some of the others that have what appears to be a stiffer section in the area of the fades and this leads to a shorter working section, and less string angles than bows that start bending immediately from the riser with short fades. I think the first design leads to better performance as well.
Looking at the pics some people have posted of their lam layups you will see a long wedge, maybe a power lam, cores and a tip wedge, and glass.
My questions are about taper rates with these designs. If you are using a power lam, what is the taper rate of the power lam? Then are your cores tapered as well? Tip wedges. Same question about rates?
Tapered power lams, parallel cores, and tapered tip wedge? Or
Tapered everything?
With the price of glass, it is going to be pricey to try everything in my head. Just want to eliminate the "hey, I could have told you that idea want work" ideas!
These are hybrid long bows by the way.
Thoughts, pointers ?
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EDIT This is not the only way to do it
Some of the other guy's use a long butt wedge
First thing is I build Recurves.
I use a .005/.002 taper, 1 lam
2nd lam is parallel for my recurve
Example on how to make a .005/.002 taper SLED 40" long, or .007/.003, what ever
If you make a .005 taper and a .002 taper, cut the .005 18" long. cut the .002 22" long, butt them together on a 3/4" thick parallel sled and glue them to the sled.
(1) they have to be the same thickness where they butt together
(2) The sled profile has to be opposite of the lam that will be sanded on it (the .005 will be thinner on the left and thicker at the intersection of the .002, and the .002 will be thicker at the far right.
(https://i.imgur.com/vAoTwVX.jpg)
So the .005 taper will be thicker coming off the fades/butt wedge, and get thinner (bend more at the .002 taper.)
Now with a 40" lam, you can cut 2" off the butt end, or 4/6" off the butt end to get the bend you want.
The .005 area is going to bend, not as much as the .002
Your bow design is different that other design.
My 2 cent's
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Again Recurve
Tip wedge
With the bow on a tiller tree (horizontal) Braced
A tip wedge will push up on the last 3rd/4th of limb from the wedge.
A 4" radius on the recurve will be stiffer than a 8" radius and a tip wedge may not be needed on the 4".
a 2-1/2" radius will be static without a tip wedge.
My 2 cent's
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Max, had to think about that for a minute, but with that sled you end up with a lam that is progressive. Starts out at 5 thou taper rate and then at 18" , switches to 2 thou taper rate.
Thanks for explaining that ! That helps!
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:thumbsup:
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Looking at the pics some people have posted of their lam layups you will see a long wedge, maybe a power lam, cores and a tip wedge, and glass.
My questions are about taper rates with these designs. If you are using a power lam, what is the taper rate of the power lam? Then are your cores tapered as well? Tip wedges. Same question about rates?
Tapered power lams, parallel cores, and tapered tip wedge? Or
Tapered everything?
I'm afraid Max might have complicated things for you a bit going into details a bit heavy. Its obvious he's been doing this stuff awhile.
How bout we start with basic taper theory and a few facts first...
If we are talking D shaped long bows. These are typically very narrow width profile compared to RC limbs. A faster taper rate of .004 is very common on long bows. Typically 2 .002 tapers are used. The same long lean fades used on TD limbs to push the working limb portion out further towards the tips is still very desirable, but is harder to do shaping a riser block on a one piece bows, and that is where power lams come into play. You can use 16"-18" riser block material and push the fade tips out to 22-26" placing the power wedge 4" past your riser fades.
Power lams can be used on TD limbs too to extend the fades of a shorter wedge assembly, but most guys just mill longer lean wedges. In some cases like TD Bear aftermarket limbs, or wild curved wedges on some designs, its easier to use a power wedge in combination with your milled wedges like an ILF toggle wedge for example.
Getting back to taper rates... You can go with faster taper rates like a pair of .002 for depp core long bows, but going with RC limbs, or RD long bows (Limbs with a lot of deflex / reflex) or even hybrid long bows like mine, you need to come down on your over all forward taper rate to maintain limb stability. For example: i use .004 FT on my Flatliner design. .003 on my hybrid long bow, and i go with .001 on my RC limb design. I even drop down to using just parallel lams in my low poundage RC limbs to keep the limbs from going sideways.
There are a lot of guys that go up to .002 forward taper on their RC limb designs with fairly good results. But it depends on the actual limb shape how stable the results will be. There are a lot of guys that used to use .002 and tried an .0015 then a .001 on RC limbs and figure out they get better overall stability in lighter weight bows using less forward taper, and often times better performance.
that should give you some basics to chew on...
As far limb design itself goes there are some basics too. But if you built one limb form with no stops set, and sent it to 10 different bowyers, you'll most likely end up with 10 different bows completely. one form can produce 50 different limb configurations shifting the stops, limb lengths, and taper rates.... Its never ending.... Kirk
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First thing you need to do is create a boyers log. I just built a spread sheet in Excel that i can keep adding to. here is an example of my entries.
[ You are not allowed to view attachments ]
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I have a notebook I keep in the shop with all my measurements from each limb, wedge length and taper etc. I need to put it into a spreadsheet.
My current set of limbs from my mold are 27" from butt to tip. I just pulled them out and have not cut them to profile yet. I am shooting for mid 40's draw weight. Think I will be light.
I am using 2 forward .001 tapers with a 9" wedge and a .001 reverse taper center core.
Same basic design as my first set of ILF limbs that came in at 42-3 lbs but with shorter wedge and a profile that started tapering width at the ILF lever pad area to about .650 at the tips.
They shoot well, but not as fast as I want.
I love the look of your hybrid bow you sent in the other reply.
My thoughts on this set of limbs was to extend the wedges and start the width profile a little later, about 1.5 inches or so past the fades.
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How are you going about mounting your limbs to the riser and getting them reasonably straight before limb profile?
one or two location pins?
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I glued a .075 wood pad to the bottom of each limb in the pad area. Set each limb in my mill and face milled the pads parallel with the limb best as I can measure. Then set them on a flat surface side by side on the pads and compare them. I had to remove a few thou on the leading edge of one butt to get the tips even. Once the tips are even and they are as parallel as I can get them, I scribed a center line on each pad using a laser on my table. Laying the limb on its side, the laser runs the whole length of the limb and I can get the center line to run true through the curved sections as well.
On the riser block, I scribe a center line as well and work from one side in the mill.
This limb I only have 1 pin, but thinking about 2 locating pins. I was amazed at how much with even fairly tight pin hole and takedown bolt holt hole, how much you can move a tip 20+ inches away.
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Well if you have a mill, you are in good shape. Takes all the fight out of it with a machinist vise and a vertical mill.
I use an over sized bolt hole in my limbs, two pins in the riser, and when i drill my limbs i do a slot rather than a hole on the outside pins. Those limbs bolt on first time every time doing that, and never make noise. I've also found that 1/4" carbide tipped router bits work better than end mills for some reason. Kirk
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Kirk, I've thought about that slot thing but no mill . Guess I could set up a router table... :thumbsup:
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Got a picture of how you do the pin slot by any chance? Not quite sure I follow exactly.
I have used carbide router bits in the mill for years! They have less rake than carbide endmills and when I do aluminum, they don't gum up like some endmills.
They are generally easy easier to find as well.
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I'm afraid Max might have complicated things for you a bit going into details a bit heavy. Its obvious he's been doing this stuff awhile.
He's Rookie of the year in my book and only been here 4 months or so.
He needs to be pushed ;)
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This is one heck of a rabbit hole. I love it. After being in numerous shooting sports and off road racing, this stuff feeds the inner mad scientist urge. I love the idea of a progressive taper. That might actually speed the process up by being able to make the pretty wood lambs parallel pieces.
I am here to stay. May have to slow down some over the summer to work on our house, but having a healthy local club of about all trad enthusiasts helps.
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I can do a short video when i mill my next set of limbs if you want. But basically i always dill and mill all my limbs and risers the same with one 1/4" pin 1/2" above center of my bolt hole (11/32") and the other pin 2" below center..... The over sized bolt hole gives room for tap drift when you put your inserts in the riser. That and there are plus and minus tolerances of .005 in the inserts themselves. Worst case if you get an insert off is, you need to take a round rasp to the bolt hole. It has no effect on limb alignment.
Milling the slot with a 1/4" shank router bit can drift on you just using your machinist table. That bit can and will flex a bit cutting .265 deep. What i do is instead of drilling 2" to center, i drill one hole at .180 and then another at .220 then move the slide the table to make the slot. Then i knock the edges off with a counter sink bit.
For guys that just have drill presses i would strongly recommend buying a machinist 2 axis cross / slide bench to mount on it. This thing takes all the fight out of precise drilling and milling for TD bows. Check this out... Of course you'll need a good vise to mount on it too.
https://www.vevor.com/rotary-table-c_10128/compound-milling-machine-work-table-2-axis-cross-slide-bench-drill-vise-fixture-p_010230619047?utm_source=bing&utm_medium=cpc&utm_term=&utm_campaign=PLA-All%E9%AB%98-US-All%E9%9B%86%E5%90%88-2%E6%9C%88%E4%B8%ADTest3-eCPC-20220218-mxy-zzp&msclkid=cdeec995a72a1b567ef4aba72aeb85fe&utm_content=Ad%20group%20%231
I run a power feed on mine for just the X axis and have slide micrometers attached for X,Y, & Z.
It would be nice to have an electronic DRO set up, but it was expensive, so i used slide micrometers. Kirk
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I would be lost without a cross slide and machinist vise!
All the router bits I use in my mill are large shank. That helps with deflection.
A tip for using a tap and keeping it straight. The square end of the tap has a divot in the end. It is for a live center to keep the tap straight. Leave the work in the exact same position, and use the bit you just drilled the hole with to keep the tap centered.
A little light pressure down with one hand on the drill press while you turn the tap with the other. Or you can chuck up a center etc.
Most of yall probably know that, but maybe it will help someone get the tap started straight.
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Good tip, Thanks...
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There are a lot of beginners that use all sorts of self centering drill guides to get their limbs mounted and struggle with accuracy drilling by hand. I was one of them years ago. The best ones I’ve seen were made by machinists, but it’s still tough to be accurate with both riser and limb drilling.
The best system I found that was truly accurate was not using a drill guide at all.
I laid out the limb pads, got the bolt inserts installed, then bolted the limbs on with no location pins. Then I straightened the limbs with a straight edge and drilled clear through the limb butts into the riser for the location pins, and finished up by doing limb butt overlays.
This system was very accurate, but good luck putting a second set of limbs on the same riser. It wasn’t happening… lol
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I would be lost without a cross slide and machinist vise!
A tip for using a tap and keeping it straight. The square end of the tap has a divot in the end. It is for a live center to keep the tap straight. Leave the work in the exact same position, and use the bit you just drilled the hole with to keep the tap centered.
A little light pressure down with one hand on the drill press while you turn the tap with the other. Or you can chuck up a center etc.
Most of yall probably know that, but maybe it will help someone get the tap started straight.
I did this a lot back in the day when tapping big threads (3/4" 1") because the tap would slip in the chuck, it's not good for the chuck either, and always used 2 people. :thumbsup:
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I've always done my tapping by hand. felt i had more control over it. Never tried it in the drill press/mill. i was always afraid of stripping out the threads i just cut. Do you guys turn the chuck by hand doing this? Kirk
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I've always done my tapping by hand. felt i had more control over it. Never tried it in the drill press/mill. i was always afraid of stripping out the threads i just cut. Do you guys turn the chuck by hand doing this? Kirk
We are talking about tapping by hand Kirk, look at the top end of a tap, it has a center hole in it, use like a center punch in the chuck, pull it down into the center hole of the tap to hold it square and turn the tap with a tap handle. ;)
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I use my drill press for tapping all the time. Works great, just don't turn it on :biglaugh:
Also helps to disconnect the belt or drive system, easier to turn the chuck by hand without the tension.
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This divot. Just leave the work in position, raise the chuck high enough to get the tap in and lower the bit down gently into that divot and just use it to keep centered.
Technically you would swap out the drill bit for a live center.
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Well turning my mill by hand to tap a hole is going to be rough to do just gripping the chuck. I can easily do it with a T-handle..... Sorry.... This doesn't make sense to me guys... I mean... I don't do that much tapping, and rarely have any problems. I just start the tap, eyeball it for square, and do the deed.
Maybe i'm just dense, but i still don't see what the divot or hole in butt end of the tap has anything to do with this procedure. :knothead:
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If your chuck is big enough go ahead and put the T handle in there then you got to turn it with. For me I have a block that is threaded straight to guide the tap. My eyeballs ain't that good.
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Tap guide. They even make some that are spring loaded. On larger taps with coarse threads, they are awesome.
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OK.... thanks for the photo. I get it now. Kirk
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Keeping limb stuff in the same thread.
I chronod my new set of limbs for my 3 piece. 42 lb draw at 28 and with a 418 grain arrow and B55 string I got 160 fps.
What can be achieved with long bow speeds? Is there another 10 fps on the table somewhere or maybe just another 5 without going up in poundage and going to recurve?
Thoughts?
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With a Fast Flight string you can gain 3 to 4 more fps I am guessing ( it has been so long since I have messed with B55)...
A good average high speed is 180 to 184 fps for R/D bows and 184 to 188fps for recurves... All at 10 gpp... You can go higher if you work at it and refine your design...
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Thanks for the reply, sounds like I got some experimenting to do!
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There are a lot of bows out there that shoot 160-170 FPS at 10 gpp @ 28".... So it's not bad.... But like Shredd stated, with some tweaking , you can increase your performance significantly. I have some designs that shoot better at 30" draw than 28" with the same gpp . These have shorter limb travel than most bows. Kirk
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Super thread! TTT
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Keeping limb stuff in the same thread.
I chronod my new set of limbs for my 3 piece. 42 lb draw at 28 and with a 418 grain arrow and B55 string I got 160 fps.
What can be achieved with long bow speeds? Is there another 10 fps on the table somewhere or maybe just another 5 without going up in poundage and going to recurve?
Thoughts?
One more thought for you bro.... Go to a fast flight string like BCY -X or Mercury, or even D-97 is better than B-55. The string type will add to your performance.
Another thing to do on a new design is change the string length and brace height. Typically a lower brace will give you better performance. If its a 3 piece, try shimming your limbs at the end of the riser slightly and that can increase preload....
The best bet is to have an adjustable riser to change your limb pad angles and adjust the pre load. then find the sweet spot that limb is bent at brace, and measure back from the string about 7" to 7.25 to the deepest part of your grip.....
I'll share a little secret here.... If your string is only 2.5"-2.75" shorter than you bow length, and it's preload is 2X the draw weight on the string using an in line scale.... You are going to start seeing some excellent performance increases.... Food for thought. Kirk
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Keeping limb stuff in the same thread.
I chronod my new set of limbs for my 3 piece. 42 lb draw at 28 and with a 418 grain arrow and B55 string I got 160 fps.
What can be achieved with long bow speeds? Is there another 10 fps on the table somewhere or maybe just another 5 without going up in poundage and going to recurve?
Thoughts?
I hear if you collect old bows, 50's, 60's,70's bows you need to use a B55 type string, I don't know exactly why ?
Maybe to keep the shock down on the limbs ?
I use Horn, Sheep/Buffalo on all my NEW bows and a D97 type string. You can use wood lams under and on top of the horn but your string groove needs to be down into the horn.
What other types will hold up to a D97 type of string? I would think Phenolic
I was told you can't use layers of glass?
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My overlays for tips usually 2 .040 glass and matching wood on top. The string lays on the glass. D97
When I first started building never used any glass or phenolic. Two layers of most times Osage with FF string. Only can remember one failure.
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My overlays for tips usually 2 .040 glass and matching wood on top. The string lays on the glass. D97
When I first started building never used any glass or phenolic. Two layers of most times Osage with FF string. Only can remember one failure.
Some Osage Selfbow guy's use D97 but they twist short B50 strands in the loop to keep from cutting the Osage.
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Kirk, so you are saying to measure how much tension the string is at while at brace height? Not how much it takes to pull on the string .
Never thought of looking into that aspect!
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Kirk, so you are saying to measure how much tension the string is at while at brace height? Not how much it takes to pull on the string .
Never thought of looking into that aspect!
Yes at brace
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I will have to try that! I almost have the last vehicle left in my shop done, then it is converted full time to my bow making hobby.
I almost have my adjustable riser plans complete. Will be used for testing and even for a shooting machine. Will be able to do 15-19 inch riser designs with adjustable limb pad angles and a bolt on adjustable shelf . The shelf will be adjustable for venter shot and for different brace heights, reflex deflex etc.
Can be mounted on the wall for tillering or on a bench for speed testing and draw stacking stuff.
Working on the shelf design right now.
Can't wait to play with it.
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I will have to try that! I almost have the last vehicle left in my shop done, then it is converted full time to my bow making hobby.
I almost have my adjustable riser plans complete. Will be used for testing and even for a shooting machine. Will be able to do 15-19 inch riser designs with adjustable limb pad angles and a bolt on adjustable shelf . The shelf will be adjustable for venter shot and for different brace heights, reflex deflex etc.
Can be mounted on the wall for tillering or on a bench for speed testing and draw stacking stuff.
Working on the shelf design right now.
Can't wait to play with it.
Any picture of the drawings? :bigsmyl:
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Kirk, so you are saying to measure how much tension the string is at while at brace height? Not how much it takes to pull on the string .
Never thought of looking into that aspect!
This aspect is the single most important part about obtaining higher performance in a set of limbs, as well as shock and noise elimination. Believe it or not…. The highest performance bows are also going to be the quietest, and most dead in the hand.
It’s all about stopping the forward limb travel dead, and transferring the stored energy to your arrow shaft. The higher string tension at lower brace heights do this….. but of course your limb design decides how much energy is stored. The shape of the limb, taper rates used, and wedge configurations all play a part of it too…… there is no free lunch….. Kirk