Twangy recurve...what's the cause?

[mikkekeswick]

Hi, I've just made a 58 inch ntn recurve and i'm afraid it's got quite a 'buzz' to it upon release. It's 56# at 28, 1 3/4 wide limbs, 18 inch riser. I used 0.50 glass belly and back. I got the plans off the net and in them he says to use core lams with no taper. Unfortunately I can't find them again...For the width taper he says to leave it full width for 3/4 of the limb and then taper into the nocks.
Now i've only ever made wooden bows before and those plans eg. no thickness taper and parallel width limbs would make a dog of a wooden bow however I decided that being the beginner with glass bows I would just go with it.
The tiller is just under a 1/4' positive.
So what i'm asking is am I right in thinking that the rules regarding width verus thickness taper for a wooden bow apply to glass bows just the same (I think they should). Is handshock/vibration on release normal with a short  glass recurve? Are there any other possible causes?
I have also made a couple of r/d 64 inch longbows and they shoot with zero handshock.
Thanks for any answers!

[tenbrook]

I would start off by trying to get the tiller 1/8" + or less.

[JamesV]

With no thickness taper in the limbs, it adds weight to the tips and could be where the hand shock is coming from. Your choice of string material could also add to the buzz or twang. If you are shooting 3 under, your tiller should be closer to zero and you will still have more noise than split.

James

[bamboo]

play with the brace

[mikkekeswick]

I shooting with a mediterranean loose.
Tenbrook - thanks i'll give that a try.
James - I've just got a heavy 16 strand B50 string on at the moment. With a wooden bow if you have parallel width limbs then you should have an elliptical tiller is where I was coming from. I agree on it adding weight for sure but it's also not bending enough in the outers by my eyes.
Bamboo - yes i'll have a go at adjusting the brace height. It's braced at 8 1/4 inch from the very back of the handle.

[peanut39350]

I built a recurve of the same length but it was a binghams design, when I first shot it; it had a terrible buzz to it.  I called binghams and asked about it and Elmont said to adjust the brace height. on his design he recommends about 10-12" from the back of the bow, not sure what your design will come out to be, but 8 1/4" off the back of the bow sounds real low for a recurve so I would start by raising the brace height a little at a time and it should get better, my guess would be that you want at least 10" from the back of the bow that will give you around 8-9" to the throat of the grip which is where most people measure to.

[mikkekeswick]

I didn't get a chance to work on it yesterday but i'll give the brace height a try as well today.

[Roy from Pa]

Times two on higher brace height.

[bornofmud]

Yeah, probably the brace.  Different limb designs like different brace heights, probably more so on recurves than longbows.  I would raise it up till it's dead in the hand, then slowly lower it until you notice a difference in the shot.  Should give you a good idea of the range you want to be in for that design.

[mikkekeswick]

I managed to get a bit of time to work on it yesterday and got the tiller to 1/8th positive. It seems a bit better now. Today i'll make another string and see.

[frank bullitt]

Yeah brace height like peanut and others suggest.

I have always measured from the throat of the grip, or center of riser, handle. 7.5" is a low/ good start.
For most recurves.