Flipping tips.....

[AKmud]

So far all my bows have been straight (and somewhat boring...) longbows over 66".  My latest project is a 63" ash board flatbow that I want to experiment with.  At what point during the tillering do I apply heat to flip the tips for a static recurve?  I have it close to floor tillered at this point.  Is it time to flip 'em or do I need to get through the long string first?

[DanaM]

I would get it on the long string and make sure its bending evenly then bend the curves, let it rest for a few days then back to the long string.
Just remember when you recurve or heavily reflex a bow it will fool you on draw weight due the force required to brace it.

[Kegan]

I usually use heat to bend in shapes after floor tillering.

And long straight bows may be "broing", but they're also reliable !

[Pappy]

I usually have them close to tillered out, then flip the tips,also be prepaired to loose a bow when you do this,especially white wood. I would steam or boil.
   Pappy

[bigcountry]

The bow I am finishing up now I debated this.

I had the bow tillered out perfect.  The bow had some natural deflex.  About 2" of it or more.  Which made the bow sluggish.  So I flipped the tips 3" from upper midlimb out. 

Ok, I figured I woudln't have to worry about tiller.  So I got it braced and some thought it was too stiff at the beginning of the flip.  I scrapped and scraped.  And all the sudden a hinge developed out of no-where.

Looking back, I wish I would have kept the bow strung for 4-5 hours and sweated it. 

If it was me, I would flip after floor tiller.  But I am a newbie.

[Pappy]

You can do that,the only problem you have is it is really easy to miss your weight,it will feel much stronger than it really is trying to brace it the first time,if you get by that it's fine.I just do it last and have had no problems and rarely have to do much re tillering after.
   Pappy

[bubby]

if you boil it shelac it first to seal the wood, that will help control excessive moisture absorption

[El Destructo]

if you boil it shelac it first to seal the wood, that will help control excessive moisture absorption

Or Excess Moisture Loss...Steaming will litterally take Moisture out of the wood and make it more Brittle when worked.......JMO

[bigcountry]

You can do that,the only problem you have is it is really easy to miss your weight,it will feel much stronger than it really is trying to brace it the first time,if you get by that it's fine.I just do it last and have had no problems and rarely have to do much re tillering after.
   Pappy

I think I wouldn't have had to retiller much either.  I was thinking the sweatin might have made the bow behave a bit better and show its true tiller.

[ricktrojanowski]

On the bows that I recurved (non-static)  I flipped em when the bow was about 5# over final draw weight.  That way the wood was about as thin and easy to bend as it was going to get, but still gave me a little room for final tiller adjustments.

[crooketarrow]

    This puts alot more stress on limbs.So if you must use heat,steam you should use a stave.Or with a board bow at least back the bow.

[gmc]

To me flipping tips and re-curving are two different things. Flipping tips are bending wood to a lessor degree and can be accomplished with a simple dry heat process (no fuss). Re-curving a limb on the other hand is much more involved.  

If you plan on flipping the tips later on in the process, the degree in which tiller is affected will depend on the amount of working tip involved and the degree the string angle changes as a result. For a new bow builder, I would venture to say the most common practice would be leaving the tips a little thicker (nonbending). However, I'm certain you may find a few bowyers out there that heat in 2 or 3 inches of reflex before they start (tips flipped already, basically), leave the tips thick, start the bow bending out of the handle area working their way into the tips being ever so mindful not to thin too much. This will leave most of the tip flipping done for you, then with some minor touch up with dry heat you are done. Just my guess, thou.  

Also I would caution that bending wood with any heat process requires a little experience thru trial and error. Learning to flip tips on a freshly completed or near completed bow may be the hard way to learn. There are always a few pieces of wood or failed bow attempts lying around to practice on. Settle on a technique and practice a little before hand.  

[gmc]

I completely missed the part about the Ash board, sorry. I have no experience whatsoever flipping tips or re-curving boards so I apologise for not ready more carefully.

[AKmud]

Well......

My first attempt didn't go so well.  The dry heat thing didn't play well with the bow. 

Here's what I started with - 63" Ash board flatbow with rigid handle.  1 3/4" near the handle tapering down to 3/8" nocks.  Thickness was about 5/8" near the handle tapering to 3/8" at the nocks.  Bow was floor tillered so I made a couple of caul's and cleared the bench.  I used Quickclamps since my C clamps weren't deep enough.  I measured out where I wanted the bend and placed the caul's under the tips.  I put a slight bit of pressure on the handle with a clamp and on both tips (only enough pressure to hold things in place basically).  I then went after it with the heat gun. 

After 10-15 minutes of steady heat on the belly of the bow at the apex of the caul, I checked the temp of the wood with my calibrated finger and it said the back and belly were well over 150*!  Since the back felt so hot I figured heat was penetrating so I gave the clamp a couple of squeezes (which didn't even give the tip a real bend) and re-applied heat.  About 30 seconds into more heat and a 3/16" deep crack developed on the apex of the caul.......... . 

So what part of this process did I screw up?  Only thing I can think of is the heat didn't have time to fully penetrate, but then again the pressure that was applied shouldn't have been enough to make it crack....  Maybe steam would have been a better option? 

[Pappy]

That's why I said I don't use dry hear on white wood. I boil or steam white wood.   
It won't break every time but has happened enough to me, I don't want to take the chance.
  Pappy