Author Topic: An idea for ash bow dimensions & tillering tips  (Read 1110 times)

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Offline Ruddy Darter

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An idea for ash bow dimensions & tillering tips
« on: October 01, 2017, 09:28:23 am »
I got some dimensions worked out for an ash stave, I'm aiming for 120ish at 31 sort of weight. The bow will be 77"-78" in length.
Here's what I scribbled down as an idea (not sure if I'm on the right track) .. I thought I'd run it by you all, any feedback or ideas very much appreciated before I start.

 R.D.
« Last Edit: October 06, 2017, 05:13:59 am by Ruddy Darter »
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Offline Del the cat

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Re: An idea for ash bow dimensions
« Reply #1 on: October 01, 2017, 09:46:52 am »
IMO, start 40-42mm wide, you can always take it narrower later.
I like to start oversize and work it down by tillering.
Del
« Last Edit: October 01, 2017, 09:49:56 am by Del the cat »
Health warning, these posts may contain traces of nut.

Offline Ruddy Darter

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Re: An idea for ash bow dimensions
« Reply #2 on: October 01, 2017, 10:15:09 am »
Thanks Del, to be honest I wouldn't mind it coming out lighter, say 110@31" or even a bit lighter, but I'm not looking for heavier. So I'll go with this if the dimensions and taper read OK.  I want to get it worked down thoroughly and smooth rounded before I start to tiller (I'll  have to peg in a tiller tree in the garden each time when it comes to it)
I will be lightly toasting it too, from the beginning and when needed, heat gun or butane torch recommended? ( I got both).
 Oh, and the finish length will probably be 76"-77" all things considered.

 R.D.
« Last Edit: October 01, 2017, 10:30:43 am by Ruddy Darter »
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Offline WillS

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Re: An idea for ash bow dimensions
« Reply #3 on: October 01, 2017, 10:41:11 am »
Keep the width the same for at least 6" both sides of center.  The dimensions you've marked out will give you slightly too much bend in the handle early on.

Your width and thickness are spot on though, for the weight you're after.  If you can, try and get the stave down to exactly those numbers (making the center width the same as I mentioned above), get the stave rounded off nicely and then spend a fair while sighting down each limb in turn from every conceivable angle to mark and remove tiny lumps, swells etc that shouldn't be there - knots and natural movement in the stave taken into account of course!

That should allow you to brace it up almost immediately and see where you're at.

Tiller the whole bow at the same time - don't go for that middle moving, then tips stuff or whatever.  Ash will kick you in the teeth at warbow weight if you try it!

Ideally, you want to tiller out to around 25", then do a good, deep heat treatment with the bow clamped flat or with slight reflex (heat gun, not butane torch!!).  You want to get the wood so hot that although you're aiming the gun at the belly, the back is too hot to touch, but you don't really want any colour change.  It'll need fiddling about with distance from gun to stave to get it right.  Then tiller to full draw and do another heat treatment before sealing with epoxy or similar.  Danish oil doesn't do anything against moisture, and traditional wax finishes are a pain to upkeep. 

76" is a great length for a 31" draw by the way.  You could go shorter if you come out too light, but as a starting point it'll work well.

Offline Ruddy Darter

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Re: An idea for ash bow dimensions
« Reply #4 on: October 01, 2017, 10:51:47 am »
Great stuff WillS, so good to go...and I'll keep it even for the central 12"', thanks.  8)
I'm aiming to get it worked down smoothly before I start any bend and give it a light toast before I start and concentrate on getting a nice shape on brace, then maybe another light toast when happy and go from there.
Thanks again, I still got to loose a good 5% moisture before I can start so plenty of time to get it worked down nicely.

 R.D.
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Offline Lucasade

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Re: An idea for ash bow dimensions
« Reply #5 on: October 01, 2017, 11:00:35 am »
Have you come across the Norwegian Warbows website? They've got roughing out dimensions for different weights and different woods all in a handy visual format.

Offline Ruddy Darter

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Re: An idea for ash bow dimensions
« Reply #6 on: October 01, 2017, 11:22:17 am »
Yes Lucasade, these dimensions are a shimmy around with I think there 160@ width and bearing in mind previous advice about belly depth compared to width for ash worked out what I though the depth should be to corispond with it.
I've only seen generic dimensions on there website, not dimensions for specific wood types though.
I will use Norwegian bows dimensions (very helpful) as they are for the Pacific yew stave I have, when the time comes that is. I'll get my ash staves ready to roll first.

 R.D.
« Last Edit: October 01, 2017, 11:30:10 am by Ruddy Darter »
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Offline WillS

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Re: An idea for ash bow dimensions
« Reply #7 on: October 01, 2017, 11:38:01 am »
Their dimensions are quite a long way out, from my experience.  I've not used them with yew though, but I did try using their measurements when I was starting out on various ash bows and never found them particularly helpful.  The guy who put them down on the website is a superb bowyer however (possibly the best heavy bow maker in Scandinavia, along with Eirik Diserud - both who are coming to our camp next year ;) ) so it's a good chance the measurements are for a bow left oversized to be worked down, which is fine for beginners I suppose.

I also think the Norwegian whitewoods those guys use are WAY better than the stuff we're lumped with over here!

Offline willie

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Re: An idea for ash bow dimensions
« Reply #8 on: October 01, 2017, 01:34:30 pm »
looking at what I assume to be the thicknesses (bottom row), I see a substantial increase in thickness taper rate in the outer 1/2 of the limb, (with an exception in the last 8" or so). Is that fairly typical most warbow designs?

Offline Lucasade

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Re: An idea for ash bow dimensions
« Reply #9 on: October 01, 2017, 01:35:33 pm »
I used the Norwegian measurements for my hazel and it's about spot on.

Offline Ruddy Darter

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Re: An idea for ash bow dimensions
« Reply #10 on: October 01, 2017, 01:58:00 pm »
looking at what I assume to be the thicknesses (bottom row), I see a substantial increase in thickness taper rate in the outer 1/2 of the limb, (with an exception in the last 8" or so). Is that fairly typical most warbow designs?
Hi willie,
I don't know if what I came up with for the depth taper is typical of what most ash warbows would be made to, that's why I thought I should check on here, I really don't know enough to say. if it doesn't look quite right when I've got it marked on the stave I'll make some adjustment to it.

 R.D.
Mon arc, mon cur. Gardez la foi.

Offline Primortall

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Re: An idea for ash bow dimensions
« Reply #11 on: October 01, 2017, 02:25:03 pm »
I'm also a fan of starting wide and narrowing down. It feels much easier and more natural to me.

Offline WillS

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Re: An idea for ash bow dimensions
« Reply #12 on: October 01, 2017, 02:45:26 pm »
I used the Norwegian measurements for my hazel and it's about spot on.

That's interesting to know.  Which weight category did you use, and what did your finished bow end up as?

Offline willie

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Re: An idea for ash bow dimensions
« Reply #13 on: October 01, 2017, 03:46:38 pm »
Quote
Is that fairly typical most warbow designs?

Ruddy, I am not questioning your design, I honestly have no idea about what is typical with most warbows. I quess the tables I see (such as yours and the others mentioned) are always qualified as starting dimensions. It would be interesting to hear from those who have started with such tapers, and have turned them into working profiles. :)

Offline Lucasade

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Re: An idea for ash bow dimensions
« Reply #14 on: October 01, 2017, 10:28:28 pm »
That's interesting to know.  Which weight category did you use, and what did your finished bow end up as?

I used the 100-130lb category, and it's pulling 110lb on the tiller tree at the moment.