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Main Boards => The Bowyer's Bench => Topic started by: shade mt on February 07, 2013, 07:30:00 PM
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I'm currently gluing up another bow. It is a mild R/D 64" In the past i have simply centered my riser and measured up 2" from center line for arrow shelf. 18" riser..both top and bottom fades were the same. limb length was the same. I alway's left the bow tell me which limb was going to be top and bottom and then Tiller as usual.
On the bow i'm currently working on i'm considering shifting the riser, and measuring 11/4" or 11/2" rather than 2" for shelf..center line remains the same,limb lengths remain equal. The only thing that changes is my top fade will be 1/2 to 3/4 inch longer than the bottom, my point of center will now be closer to the dished out portion of the grip. And i will be pre-determining my top and bottom limbs.
I'm wondering am i going to have any problems tillering this bow? Would it be wise to make my bottom limb stack just a fuzz thicker to be sure to end up with either even tiller or just a shade positive. Limb length has not changed So i can't
I can't fore see anything different happening. This bow form has alway's produced bows that require very little work to tiller...but i thought i'd open it up for a few other opinions.
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If you lay up correctly and everything works perfect your tiler should come out even. We all know that is not the case more times than not. I put my shelf 1 in. above center and still let the bow tell me witch limb is top or bottom. So if you do a good layup with quality ground lams you should have no trouble tillering the bow. I have brought them in with as much as 7/8s out but it took some sanding on the glass and tweaking the corners of the strong limb.
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I don't think you want to make the top fade longer,that will make the top limb stiffer and make it harder to tiller positive.
Why not just shift the center of your tapers toward the bottom limb. Doesn't take much,1/2" to 3/4" and you'll build in a positive tiller.
I cut my shelf 1 1/4" or so above center and the bow balances on my fingertip at the grip throat.
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actually i was thinking nothing should really change..my fades still end the same place as alway's 9" from center line both on the top and bottom limbs. My limb length is the same for both limbs the only thing i have done really is shift my handle part of my riser. I like to end my top fade at my arrow shelf..Which before was 2" above center but now will only be 11/4 to 11/2 half whichever i decide.
Normally i took an 18" riser centered it cut my fades to 33/4" or 4" handle area..pick the stiffest limb for bottom limb and go from there simply measured up 2" and cut in my shelf.
But this time I'm simply shifting my handle down a bit to make my arrow shelf lower, hence the slightly different fade from top to bottom and yes i could simply shift my taper..Which would make my bottom limb a fuzz thicker and stiffer.
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I tiller using the centerline for reference before I cut my grip and arrow shelf.
Bow balance to me is something I strive for as I feel I shoot better accordingly. I usually end up about 1-1/4" above center for the arrow shelf using balance as the final determining distance from the grip throat accordingly.
Somewhere I read that the arrow shelf should be as close as possible to the top knuckle of the grip hand. So I strive for this too with enough allowance for fletching clearance.
Also note that I have only built all-wood laminated longbows and this "logic" may or may not be appropriate for recurves and/or selfbows???
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i also tiller from center line and i agree lowering my arrow shelf to 11/4 " above center or 11/2" seems to me to be a logical improvement. Just thought i'd open a discussion see if i could get a few other opinions as to whether shifting the handle will make any difference in tillering. Other than the fact that i'm pre-determining my top and bottom limb.
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stephen
it more than likely will be an improvement---
that and a 4" -5" tip wedge really improved my designs shot feel and performance
if you don't mind me asking what thickness taper are you using?? and limb width@the fades?
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ive used both .001 and .002 together, for a total of .003 or a single.002 taper. both seem fine on this bow form.1 3/8" at the fades tapered to 1/2 inch at string groove..ive considered tip wedges. hate to mess with it to much..really smooth shooting bow..decent speed..and church mouse quiet..has a nice D shape when strung.
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stephen
we are building very similar bows
i've played with the center/shelf orientation
and tried setting the shelf 2" above centered--and it made a good bow----but have found the bows with 1-1/2"--1-1/4"-center to shelf and equal length limbs [adjusted ramps/fades]tillered 1/16"to equal tiller to be smooth drawing and great shot feel--that was with .002" taper----as for the tip wedge--if you can grind your own tapers--its just 1 more pair of pieces to install-i lay them out on the forms[w/a sharpie marker]-and tape them in the stack[out at the end that gets cut off]-and it has allowed me to narrow the tips to 3/8"
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i do grind my own lams. And i think i'll try the tip wedge. I actually considered it a few times, but ended up skipping the idea each time. Thanks for your input.
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the tip wedge doesn't need to be very thick to stiffen the tip section---.004"per inch taper--i also like it somewhere near the middle of the stack-favoring the belly side--4" inside of the string notch works on my 64"and i scootch it an inch inboard on 66"--don't worry if they want to curl up!