a little help...please

[fujimo]

right... got my first kenny m bow ready to string uyp- was real careful in marking and grinding to the lines, finished by hand sanding the edges with a block, and rounded the edges.

this is my first R/D bow- ever... can see where thge one limb is weaker than the other, just not sure what to do from here

all help much appreciated
thanks
 

 

[wakolbinger]

The only thing you can do on a glass bow, remove width from the edges of the stiffer limb till it matches. If you haven't shaped the grip yet, make the stiffer limb the lower limb. That's something that's common in the selfbow world but I don't often see in glass bows.

[Hill Hunter]

i may be doing it wrong but that is how I make my glass bows, I let the bow determine the top limb on most of them, I tiller before I cut the shelf. I have put lamination in a couple that were exposed when the shelf was cut, those the top limb was predetermined. I guess when I get a little better the top limb stack could be a little thinner to make it weaker.

[Art B]

Fujimo, first thing I would do is check for equal limb mass. Mark the center of the bow and balance it on something. See what you got and go from there..........Art

[Dmaxshawn]

It depends on how you shoot if shooting split then tiller to 1/8 to 3/16 positive   if shooting three under then tiller the bow to zero meaning equal distance on both sides.  

Make the bottom limb have a shorter distance of 1/8 to 3/16 of inch shorter than the top limb.  youll have to sand the edges of the limbs to get it back close to even

[EHK]

I only have a couple bows under my belt so take that for what it's worth.  My first attempt using Kenny's form looked similar out of the press.  Nothing wrong with the template or the forms of course, but my riser slid during glue-up causing the same thing.  I was surprised that I was able to correct it by sanding the glass side - not the edges.  Whether that's right or wrong, I don't know, but it worked.  I came in 5 pounds lighter than what I wanted, but it worked.  The advice of others suggesting to sand the edges of the stiffer limb is probably more sound, but I think you can fix it at the expense of losing a couple of pounds of draw weight.

[kennym]

Something went wrong there!! Check the taper rate in the limbs to see if you happened to get a taper in backward! Most likely the .oo1 on the belly if any. cause its easy to turn the short stack around when you take it to put it on the riser....

[kennym]

Looking again, is the right limb in the pic shorter? Should measure the same from center of riser both ways.

IE; for a 64" bow, 32" each way from bow and riser center. Center should be in the web of your hand and shelf 1" to 1.25" higher.

[jsweka]

Yeah, something is strange here.  I agree with Kenny's observation that the right limb looks shorter, but the shorter limb should be stiffer and it looks like the left limb is stiff.

Measure everything to check for symmetry - limb length, width, and thickness.

[MoeM]

If the width taper is really same I guess you really put one tapered lam in the wrong direction... I feel sorry for you!
Btw. the first time I see such a clear picture of the ledgendary Kenny M. LB`s profile and it`s funny how much it reminds me of my own^^

[chackworth3]

x 2 on what Kenny and John said

[Dmaxshawn]

After looking at this pic on my desktop I see its a little more than outta whack than what I could see on my phone.

[fujimo]

well went back and checked everything-
the tapers are in the correct way- phew!!!
when i ground the lams- i swapped them around on each grind so they measured the same- nothing wrong with the sander either- pretty close tolerances.

checked the taper widths- and found some discrepancies- so re marked everything- still had a little breathing room, re sanded the sides by hand with a block- sides look better, but when i restrung- still had the same problem.

checked thicknesses with the caliper- and found quite a thick spot---so some judicious tillering- and i think its looking ok now.
have come in about 5# light- but i think that was mostly the veneers i used- i thought they were .030- but when i measured them today  again- they are .024- so i guess a stack .012 thinner will make quite a difference.
so i might just pike it an inch either end- down to a 62" bow- and see how it finishes up.

many thanks all, quite a trick these R/D bows,eh!!

[fujimo]

that center serving was really screwing me up some- flipped the string around- made it better for the old one eye!!   :D  
thanks guys

[Dmaxshawn]

Good deal glad you got her worked out.

[Trux Turning]

If you pike it you will gain about 6#s

[fujimo]

that sounds perfect, trux.
thanks for all the input fella's
i have only built self and laminated bows till now- i thought that the glass bows would be easy by comparison- huh!!!!- just cos they have a kind of a recipe- nothing to go wrong....right!!??!!
they are equally tough to build- just different- the gratification process seems to commence as you remove it from the form- and start getting it all "bowed up"- but tons of meticulous  prep work prior to that. but the wood bows are a gradual and slow process from the first step.
both so different but equally awesome!!

heres wishing ya'll a great day tomorrow!!

[Robertfishes]

before glue up..I like to draw a center line and limb profile on my taped back glass and then put grid lines on it every inch. I check center line after glue up and if still good I grind limbs to the line. I use a compass to check limb width left and right of center then top and bottom at same distance from center..never had a problem doing it like this. Pic is of 5 longbow stacks (glass and amberboo tapers) ready for glue up. Risers were in oven..  

[fujimo]

Thanks Robert
Going to check it out , but I wonder if the riser did not move slightly during air up, I had stacks and risers marked with center lines, but with the excess glue on(even though I did wipe it away after airing)  the lines were not visible, and were lost during the sanding, but doing as you do, with lines on the back...well I will do that next time.great tip .
Thanks