Cherry Board Bow

[Col HJ]

I have a cherry board bow coming along nicely, It's going to be 67' NTN, unbacked, kinda Hill stylish in the riser and looking for 50-53# @ 28." So my question - I want to induce a couple or 3 inches of reflex into it and not being very familiar with cherry I am not sure of the best way to proceed, whether with dry heat or steam.
,or if this is even a good ideal.

I also know that cherry is considered a bit touchy and prone to frets on the belly, and planed to burnish it carefully, unless there is another, better way to prevent or minimize frets?

[Pat B]

I have not worked with cherry this way but with other whitewoods(I consider cherry a whitewood in bow building) I have used dry heat and clamped the bow to a form. Lightly scorching will help strengthen the compression strength and help hold the reflex. Allow plenty of time after scorching the wood for it to rehydrate. The amount of time depends on the R/H of your area but at least 3 or 4 days. More is better.

[John Scifres]

The best way to prevent frets is to make an overbuilt bow.  That means 2" wide for half the limb tapering to 1/2" tips.  68" would be better than 67" NTN if you still have that option.  You can also trap the back to equalize the tension and compression strengths.  Simpy rasp the corners on the back at a 45 degree angle to about half the thickness of the limb.  

Tiller very slowly.  Don't brace it until it is well-tillered and no more than 40# at 20", preferably less.  Don't bend to draw weight until it is bending very well at 24" or so. Lots of exercise.  

I doubt that burnishing will do anything to help.  By its very nature, burnishing is crushing wood cells.  Seems counterintuitive to me.  

I would think that toasting the belly would help though.  Do you have the trad bowyer's bible vol. 4?  There is a chapter on toasting in there.  In my mind, toasting slightly plasticizes and consolidates the cells in a newly reflexed form.  I have done this successfully in the past on set bows.

Here's one:    Fixit

[okie64]

Cherry is stronger in compression than tension, So I wouldnt recommend using heat to introduce reflex. I tried to make a few cherry board bows and none of them made it, couldve been my fault though. I would think the best way to introduce reflex to it would be to glue on a thin backing of some sort. Marc St louis talks about heat treating cherry in TBB4, you might check that out too.

[Col HJ]

Pat / John - thanks for the help!

It's a pyramid all day with almost the exact dimensions listed above with the exception of the NTN length and that was a brain fart on my part - I had 68" NTN in mind from the start and carefully cut the bow to 68".......... overall length. I have the limbs profiled already but haven't started on reducing the thickness, given the recommendation for trapping I'm thinking to make them 9/16" out of the fades tapering to 7/16" at the tips.

Don't have the Bowyers Bible but I have successfully toasted/heat treated hickory and red oak before so will proceed with that, and try get a little reflex in along the way.

[Col HJ]

Hey okie what was the failure mechanism on your cherry bows? The board I have is exceptional, very close to being a single unviolated ring on the back and straight grained as can be.

[okie64]

The first one I'm pretty sure was too skinny and too short(1.5"wide to midlimb and 64" long). Probably wouldve been ok around 40# but I was shootin for around 50 at 28". The other one I didnt do the transition right at the fades. I narrowed up the handle and didnt thicken it enough to keep it from bending too much in the handle and thats where it broke. Tim Baker stated in TBB4 that since Cherry is so compression strong and tension weak it can actually benefit from trapping the belly not the back. Also Cherry works better at higher mc levels than other woods. So if you do decide to heat it make sure you give it plenty of time to rehydrate.