Ozbow

Hi crew, I've got a heavy bow that's really nice and would like to reduce its draw weight if possible.
It's glass on back and belly.
Can i scrape or sand the sides of the limbs and then refinish after a desirable weight and tiller is achieved?
Thanks all.

Hi There Tom. You can reduce the weight a bit by filling the edges of the limbs with file or rough sandpaper Work from riser to tips bevelling the edges until there is a " corner" of wood chowing. It is. possible to drop up to 5 # doing this. If it hasn't had a lot of sanding then some more on the faces of the limbs with ,240 grit may deliver a little more. After that apply your finish

It will depend on the type of bow but as Bob says it is possible to reduce the weight by rounding the corners of the limbs. Some bows come with the corners already quite rounded so it is more difficult to remove weight. I dislike having to remove weight as when finished the bow doesn't look the same and sometimes it doesn't look too good either.

Jeff

Hi Tom,

By how much do you want to reduce the draw weight and what is the bows’ marked draw weight?

Trapezoiding the limbs to the back of the bow i.e. as in some Black Widow longbows could shed a fair amount of poundage but if not done properly the correct tiller could be destroyed.

Under my direction / instruction I had a customer reduce the weight of his flat laid glass / bamboo longbow by over 30# but he did it on the understanding that if he slipped up the bow would be ruined.

Although a slow nerve racking exercise the operation was a complete success.

If the bow does not have any sentimental value it may pay dividends to sell it and buy a new bow.

Daryl.

Thanks all for the advice. I will give it a go and see what happens.
The bow is marked 61# @ 28" but I'm drawing closer to 30".
So should i only remove material on the back, belly or both?

greybeard wrote:.......By how much do you want to reduce the draw weight?........

TomMcDonald wrote:.........The bow is marked 61# @ 28" but I'm drawing closer to 30".........

greybeard wrote:

greybeard wrote:.......By how much do you want to reduce the draw weight?........

TomMcDonald wrote:.........The bow is marked 61# @ 28" but I'm drawing closer to 30".........

Daryl, sorry. 10lb would be ideal but I'd settle for 5. Anything less and I wouldn't bother.

Hi Tom,

Rounding the edges of the limbs and with back and belly sanding a 5# weight reduction should not be a problem.

Hopefully .050” glass was used in the bows construction.

Keep in mind that when drawn, the back of the bow is in tension and the belly is in compression, removing too much belly glass could cause belly failure over a period of time.

A trapezoid cross section [to the back] may be more beneficial in achieving a 10# reduction and maintaining a full width belly should help in compression.

Try to maintain a constant sanding pressure and count sanding strokes.

Daryl.

Disclaimer

"There is no guarantee that the above procedures will not damage the bow, undertake the work on the bow at your own risk."

The elastic modulus of Botuff is about equal for tension and compression. However the tensile strength and strain are about double the compressive strength and strain. Considering this, I always remove more from the back than the belly when trying to lose weight on a bow. Some bowyers even build with 40 thou back and 50 thou belly (for this reason I imagine).

My first take down recurve weighed in at 75#@28" when I first roughed it out (0.050 back and belly). After taking approx. 0.008" off the back and 0.002" off the belly, it dropped 10# in the rough and then another 2# in the finish sanding (including riser final shaping).

As Daryl said, it is an arduous process with constant checking on the tiller and calliper measurements, but it is achievable.

Thanks for everyone's help. I appreciate it.
I'm still not sure whether I'm gonna go for it but I'll post results up here if I do.
Cheers.