Crack in fade on hickory selfbow

[briarjumper12]

Knowledgeable gentleman,
I am in the process of making my second selfbow from hickory.  On this one I was going to use a heat gun and 2.5 inch reflex form to do a heat treat on the belly and reflex it.  I got it floor tillered, heated it up and clamped to the form.  I then started applying more heat to one limb.  
Then it cracked right in the middle of the fade, the crack runs up and down the fade.  One big crack almost the length of the fade and several smaller ones, all running up and down the fade.  
I'll try to get some photos later tonight or tomorrow.
My questions are:
Is there any way to salvage it?
Did it crack because moisture content was to high?
How can this be avoided in the future?
Thanks,
John

[George Tsoukalas]

Did you floor tiller it first at least to get it thin enough? Jawge

[briarjumper12]

I floor tillered it until it measured 0.8 inches 5 inches from the center of the grip.  I layed this one out to have a 4.5 inch grip and 1.75 inch fades.  Was going to cut in a shelf on this one and wanted plenty of wood to work with.  5 inches from the center of the grip is an inch past the fade area and it is 0.8 inches there.  Here are some photos of the crack:
 
 

[marshall brown]

Others with more experience should chime in, but I once had a crack on the fade and filled it with super glue. That was about 12 years ago and that bow is still alive today. It looks as though you have some serious stress cracks going on there and  you might have done more harm than you realize. Again, others with more knowledge could give you more insight.

[briarjumper12]

Marshall,
Yes, I am thinking this one is done for.  Maybe some of the gurus knows something I don't though

[George Tsoukalas]

Looks like you have a few smaller cracks there. I'd fill them with super glue. Then I 'd do a wrap. You could use artificial sinew, bow string material or any nylon thread. Set in a glue like Duco. Use a decorative thread and wrap the other limb in the same spot and it will look like a decoration. I think you'll be fine becure i is with the grain. Jawge

[Pat B]

Those are drying checks. Apparently your wood wasn't dry enough to take the heat. They are running with the grain and not off the stave so you should be OK. I would add super glue let it cure out and continue with the tillering process.

[Eric Krewson]

Those are not bad at all. Like Pat said superglue and proceed like they aren't there.

[DVSHUNTER]

yep, still good. Next time dry longer or slower or both

[John Scifres]

Is your wood dry?  When was it cut?

[briarjumper12]

John,
Wood was cut and split into staves in October.  I didn't put this one in the hot box long enough it looks like.  Based on what everyone is saying I should've left it longer.  I am going to superglue and continue.  It was designed to be overbuilt so I might take out a little more wood in the fade area and off the belly of the handle.

[John Scifres]

Wood in stave form takes a long time to dry.  About 1 year per inch of thickness.  I have worked two year old staves that are still wet.  You can hurry it along by roughing out the bow and getting the thickness under 3/4".  Dry heat and wet wood equal uneven stress and drying checks like you got.

[Art B]

The best way to prevent those checks from heat and/or help eliminate some set is to never go from stave to a working bow quickly. Give your roughed out bow at least several weeks of alone time in a controlled enviroment to ensure proper MC. I leave mine hanging horizonally on my bedroom wall with a humidity/temperature gauge close by for a minimum of two weeks...............ART

[briarjumper12]

Art,
I think I just got in a hurry and took out of the box too soon.  Its back in there now.
Superglued the cracks up and put it back the coffin (as my brother calls it) to cook a while longer.  Lesson in patience I guess.

[Pat B]

At what temp are you "cooking" your stave? You don't need more than about 90deg(F) and it helps if you have a fan in the hot box to keep the air moving. In my box I have a 1" hole at the top of one end and a 1" hole at the bottom of the other end that allow the moisture a place to escape. I can plug these holes if I want to use the box to cure glue.

[ALW]

My drying box is similar to Pat B's.  One inch holes on the bottom of the ends and I just crack the lid to let the moisture escape.  Also you have to remember that the handle/fade area is thicker (usually in a stiff handle stave) so it will take longer to reduce the moisture here.  You might want to try sealing the end grain in the fade area while it's drying.  Moisture will escape quickly here and can cause checks.

Aaron

[briarjumper12]

Originally posted by Pat B:
At what temp are you "cooking" your stave? You don't need more than about 90deg(F) and it helps if you have a fan in the hot box to keep the air moving. In my box I have a 1" hole at the top of one end and a 1" hole at the bottom of the other end that allow the moisture a place to escape. I can plug these holes if I want to use the box to cure glue.

I have 4 100 watt bulbs on a dimmer switch in an insulated wood box with a snail fan at the bottom of one and 1 inch hole at the other.  My workshop is not heated unless I am there to build a fire in the Warm morning but even when it gets cold it stays 85 to 90 F.  I checked it yesterday evening and my gauges said 88 f and 50% rh.

[briarjumper12]

Originally posted by ALW:
My drying box is similar to Pat B's.  One inch holes on the bottom of the ends and I just crack the lid to let the moisture escape.  Also you have to remember that the handle/fade area is thicker (usually in a stiff handle stave) so it will take longer to reduce the moisture here.  You might want to try sealing the end grain in the fade area while it's drying.  Moisture will escape quickly here and can cause checks.

Never thought of that.  I will try that one.  Thanks ALW

Aaron

[Shaun]

All good advice and I agree that the bow will be OK with those cracks filled with super glue. Sealing end grain is important especially when speed drying. The end grain at the end of the roughed out bow is obvious, but there is also end grain exposed at the fades (where your cracks are located). Moisture escapes faster at the pours of end grain causing drying cracks like yours. I like shellac for sealing end grain.

[Art B]

At 50% rh that's only going to get you down to around 10% MC. Between 35-40% would be better for hickory if you plan on heat treating IMO...........ART