Author Topic: Straightening an ash bow, dry or wet heat?  (Read 3605 times)

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Offline HDF

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Straightening an ash bow, dry or wet heat?
« on: May 16, 2014, 11:56:03 am »
I've recently started an ash flat bow, my first ever bow from a stave, it has a bit of character and one limb needs to be brought over by about 3/4 of an inch. I'm just wondering whether I should use a heat gun and gentle pressure, or steam the limb and clamp it in place? Which would be best for an ash stave?

Offline Pat B

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Re: Straightening an ash bow, dry or wet heat?
« Reply #1 on: May 16, 2014, 12:16:45 pm »
Have you gotten your ash bow to low brace yet? After checking the string tracking at low brace would be a good time to clamp it to a caul , straighten it then temper the belly. I'm sure ash would benefit from belly tempering.
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline Dan K

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Re: Straightening an ash bow, dry or wet heat?
« Reply #2 on: May 16, 2014, 01:28:22 pm »
Do you have a picture?  That would help from giving blind advice. I would do what Pat said and bring the tiller in to low brace. Sometimes that's all it takes. If you need to bring it in more (laterally), steam the handle and clamp it on the side to a caul. A small bend at the handle moves the tips exponentially and doesn't put too much stress in the wood this way. If you have a propeller twist in a limb, you may get some lateral movement by clamping the limb flat and taking out the twist. Hard to say without seeing it. Good luck brother!  Keep us posted.
Excellence is a state of mind.  Whether you think you can or can't...you're right!

Offline HDF

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Re: Straightening an ash bow, dry or wet heat?
« Reply #3 on: May 16, 2014, 02:03:05 pm »
It's at the floor tiller stage at the moment, the plan was to sort the limbs out then chuck a string on it but if you think it would be best to get it on a low brace first I will. I lashed the whole thing to a plank while seasoning with a couple of inches of reflex in, but there's still some deflex in the tips I also want to get rid of. This is my first time working from a stave and I've got some knots I'm finding tricky to work with, I'll get some pictures up soon!

Offline Pat B

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Re: Straightening an ash bow, dry or wet heat?
« Reply #4 on: May 16, 2014, 04:52:25 pm »
Pics really would help.  You won't know how the string will track until you brace the bow and get it under tension.
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline HDF

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Re: Straightening an ash bow, dry or wet heat?
« Reply #5 on: May 16, 2014, 06:35:31 pm »
Here are some pics. It started as a 4 inch ash sapling, I've got the bark off the back of one limb, it's about 73 inches tip to tip, a good 2-3 inches at the fades and I' looking for 40-50 lbs at 32 inches.
Here you can see the reflex I put in when it seasoned, and the natural deflex in the tips I'm considering getting out


Here's the handle section, I've been gouging wood out in the centre of the fades, I've seen the odd bow done like this and it seems like a logical thing to do with a heavily rounded back?


The snakey limb I was talking about:


The worst of the knots I'm dealing with:



And here are the deflexed tips, should I leave the or try to straighten them out?





I'm planning on making a set of scrapers out of some old saw blades soonish and then I'll clean up the channels I've gouged out and start thinking about putting some knocks in and putting a string on it once it's bending a bit more at floor tiller.

Offline Dan K

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Re: Straightening an ash bow, dry or wet heat?
« Reply #6 on: May 17, 2014, 02:40:15 pm »
I understand this is your first bow. Let me begin by saying I am no expert having only made 6 bows that have survived my hands. I've learned everything I know to this point from people on this site. Some of which have become pretty good friends. You will benefit by staying with this group, listening in on as many threads as possible and reading all 4 Bowyers Bibles. Any other book is good but these 4 will teach you all you know. The authors are personable and some frequent this site. Now some comments on your bow. Your handle is a bit long for me. If it's the profile you're going for then ok. The dimensions I use are 4" handle with 2"-3" fades. The longer the bow the longer your fades. For 72" I would go with 3" just for aesthetics more than anything else. For ash, I would keep the width at 2" from your fades to about 2/3rds the way towards your tips and then gently taper to 1/2". This will give you a good even displacement of stress throughout your limbs. I'  never hollowed out a bow like this but simon in Bavaria is a master -look him up! At 72" long you may consider cutting it down a few inches and move the tips a bit when relaying out your profile. See what you can do with this stave and once you have it cleaned up to the above specs retake pictures and post before you do any steam bending. Don't worry if you trash your stave just make a bow. If you end up with firewood,  BBQ some burgers and send me a PM. I have a garage full of Oregon ash and I'll send you a new stick. Welcome to the family my friend!  Good luck and cheers!
Excellence is a state of mind.  Whether you think you can or can't...you're right!

Offline HDF

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Re: Straightening an ash bow, dry or wet heat?
« Reply #7 on: May 17, 2014, 05:10:32 pm »
This is my first attempted stave bow, my 30lb board bow was so fun to make the moment I saw this sapling in the woods I pounced on it! The Bowyer's bibles are on my list for when I have a bit more cash!
I've got the tips at 3/4 of an inch, I'll thin them down to half an inch then and yeah I agree the handle section is too long, I wasn't paying attention when I roughed it out with an axe. I've looked at some of his bows and I'm certainly not going for anything as ambitious as that first time round, but just a gentle channel that tapers out at the tips. That's a very nice offer, and as much as I'd like some Oregon ash I think me living in England will make any such plans difficult!

 Today I thinned the limbs out a bit and put some temporary knocks in and started to pull it a bit, and worked up to a low brace, here's how I left it:

String alignment and limb twist issues:



On the stick:


Started to pull it a bit:


The obvious thing I need to sort out is the right limb, I think loosen up the outer half? I'm just worried about removing much wood around the knots in that limb. Then I'll thin the tips and try and sort out the limb twist and alignment issues, how would I best do that?

Offline HDF

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Re: Straightening an ash bow, dry or wet heat?
« Reply #8 on: May 18, 2014, 02:50:18 pm »
ended up as firewood, went between the knots on the right limb, baaaaah

Offline DarkSoul

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Re: Straightening an ash bow, dry or wet heat?
« Reply #9 on: May 18, 2014, 05:33:40 pm »
That's a shame.
It's a bit misleading in the last two pictures that you switched the bow around...
Remember that a knot must be left stiff in the tiller, but a knot itself spans only about 1" of wood. So a limb with two knots, should have two small areas of 1" each that remain stiff in the drawn bow. The rest of the limb must be working. In your case, it appears you overcompensated for the knots, and left areas of 3" of limb stiff. The rest of the limb starts to work too hard, and that results in set or worse: a broken bow.
The inner areas of both limbs were not working at all. They are visually thicker than the rest of the limbs, and should have been flexing a lot more. It's a pity you didn't wait for critiques on the tiller, but just went for it, as eager as you were. Now use this eagerness and get yourself another piece of wood to start a new bow! :P
"Sonuit contento nervus ab arcu."
Ovid, Metamorphoses VI-286

Offline HDF

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Re: Straightening an ash bow, dry or wet heat?
« Reply #10 on: May 18, 2014, 06:07:15 pm »
I didn't realise I'd swapped the bow round, yeah that is very misleading! I had a whole day spanning ahead of me so I wasn't in the mood to wait unfortunately. I ended up removing too much wood in the section between the knots in an attempt to loosen that limb, and it promptly snapped on me.. At least the wood didn't cost anything, and there's plenty more where it came from, shame I have to wait for it to season!