Heat bending or flipping tips?

[wapiti1997]

I have yet to attempt flipping tips, putting a recurve in, with dry heat without the wood cracking.  I use a quart can for the curve template on a 2x6.  I heat until the wood is hot and turning brown and apply slight pressure beyond the stave weight. 

I wonder if I need to thin the limbs more?  I do this just before I hit my desired thickness, 3/8-1/2".

The one that I did with my last bow was maple, and it was not a fatal crack.

The current bow is osage and both limbs cracked on the belly, and appears to be the top growth ring only...

I'm learning, this is my 3rd bow, I really like the look of the slight recurve and the feel of the bow compared to a straight limb.

Appreciate any advice as I'm sure this is not only happened to me...

[Danzn Bar]

Joe,
I've found that I start out about 3/4" thk. and chase a ring on the belly, less chance of raising a splintering during bending.  I use a heat gun on low and heat very slowly for a long time, using vegetable oil so it won't scorch.  I also use a metal backing strap between the belly and clamps as I bend the wood a little at a time.  Slowly Heat, bend, clamp, repeat. repeat etc.   I might use 4 or 5 C-clamps on one tip.  Real tight bends usually crack a little with dry heat.  But if you start out thick, they disappear with thinning.  I wouldn't try it thin, if it cracks or splits then you have no material left.  I think the trick to dry heat is to do it with low temp and slowly.  Steam is only 212 deg.  I think most heat guns spit out 500 on low and 750 on high. Pretty hot and you could be getting the surface too hot and the middle not hot enough.

Hope that helps,  There has been some good build along posted, you might do a search that would have some pics for you.
DBar
 

[Gordon]

I usually don't flip tips with dry heat until I have a bow nearly tillered.

[Dan K]

I usually don't flip tips with dry heat until I have a bow nearly tillered.

I tried flipping tips on my vine maple when close to final and it cracked.  Same story as wapiti.  Followed St Louis's video to the tee, used pine pitch varnish and that seemed to work well.  Maybe the metal backing or the slower heat is the secret.  Still have a lot to learn.

[blackhawk]

Trying to dry heat a sharp radiused bend like that is dang near impossible(unless thickness was close to 1/4" thick)...try steam with sharper bends like that...usually the thinner it is the easier it becomes to bend and not crack too...and flipping tips with dry heat needs to be done slowly and in steps ...you can't heat it up and make the bend all at once like you can with steam or boiled...you have to half inch it down,then put the heat back on it,then another half inch down,etc..repeat until your desired bend is achieved...and more practice helps too

[Pappy]

I do like Gordon,usually have no problems with Osage,not as good with white wood,so I stam or boil them most times. Slow and easy is the key and close to where you want the limb to be as far as thickness,I leave them a little thicker in case I pop a small splinter and can usually scrape it out.
   Pappy

[crooketarrow]

   DRY HEAT ON SEASONED WOOD
  STEAM ON GREEN WOOD
  If your woods heat checking. It's because the woods not totally seasoned. When you add heat,exspecially if you add to much heat to quicky will really cause checkering. All the exture moisture is pushed out through the belly to fast. THIS CAUSES CHECKERING. Same as if you don't paint or seal the ends of the stave when cut. Don't do it and all the exture moisture will go out the ends causeing checkering. SAME THING.  HEAT SLOWWWWWWWWWWWWWWW. Use a oil. This way after the tips are bent. There's still enough wood to even out the tips and wrasp out the exture oil you've used to help with the heating.
  Leaveing exture wood also alows the surface heated wood ,which the wood cells at the surface layeds have been damaged. Now you can rasp all the damaged wood away. Leaveing  the undamaged wood under the burnt outer layers.
  E
  NEVER HEAT THE BACK ONLY THE BELLY
 I'D LIKE TO HAVE ALL THE TREE'S I'VE THROWED IN THE STOVE.

[crooketarrow]

  I never use heat only on non working parts. TIPS AND HANDLES and I don't flip tips unless someone wants it done. A lot of work for a few FPS. I think most people just likes the looks anyway.