Elm Stave Bow

[PlanB]

Thank you Marc.

[DC]

The limbs should always bend evenly so "Or do you tiller in a way that corrects the difference so they come out even?" is out.

I usually steam the limb(s) so that they are even to start with. Then you end up with a nice even bend. You can "expect that the tiller curves will look different for the different limbs and work with that? " but I find that that I forget what I'm doing and tiller it to look even. Then I have uneven tiller.

[Springbuck]

Challenging stage, but really good layout, it looks like! 

This is exactly why I harp and harp on restraining elm staves, esp from the  small diameter trees I work with.

[PlanB]

Thanks DC, Springbuck. I'll restrain any elm I get in the future.

I guess even if the limbs had been reflexed the same (or steamed even, DC), one being 2" longer then the other will mean the curves will look different when braced. Maybe they wouldn't with a true bendy handle, but an off center stiff handle just seems like it's going to make them different. So I gotta wrap my head around what it should look like. It's just going to have to be me using my imagination to figure what is right, instead of looking for the same curves.

I looked really carefully at the photos in Gordon's Vine Maple build thread, and I can see a difference in the limb curves when braced. That bow has got a 1" offset handle, and a lot of reflex. So seeing that that helps a lot.

Seems like if I look at each limb individually and just make sure it bends proportionately along its length, taking into account the shape of the reflex, but don't pay attention to the other limb at the time, that might help. Then the main thing would be to bring down the wood on the shallow limb when braced, until the handle is more or less parallel with the string at brace height.

At full brace it's a little different, because Gordon's looks pretty even for both limbs. I dunno, probably over-thinking. I gotta just do this thing and see what happens.

Okay, here it is now with more wood off, reflex is down to 4-1/2" (from original 6-1/2"). I'm just able to flex the limbs past the handle a bit on long string (just long enough to be taught between nocks). I think I'm on the way.

Thank you guys again for your help, and I will definitely use your suggestions in future.

[willie]

anyone,

do you have any tips for how to measure or otherwise judge even bending as you tiller with wonky asymmetrical limbs? or do most do it all by eyeball?

thanks

willie

[Josh B]

Considering where your at on your bow making learning curve, I would have to suggest that you get it to a HEAVY floor tiller and then even the limbs with dry heat.  I say heavy floor tiller because with that much reflex it is going to feel much stronger than it actually is.  At this stage of the game, trying to tiller mismatched limbs is going to be a nightmare and you will have very little chance of success if you attempt it.  Josh

[DC]

Make yourself a caul like this. Don't look at the workbench . Clamp the handle to the center belly side up and work your way out from the handle with a heat gun, clamping it down as you go. Let it sit overnight. Do both limbs.

[PlanB]

Thank you Gun Doc, DC.

Gun Doc, I've been floor tillering pretty heavy and frequently. But I'm not sure I'm understanding properly how you mean it, could you explain?

That caul (didn't know the term) is very nice DC. It looks like it was made long to do both limbs at once, but the holes mainly on one side (and what I think you said) seems that you actually do one limb at a time, have I got that right?

If the belly is facing up, it looks like that caul puts in a large amount of reflex. I'm guessing that would be for a relatively straight stave.

I'm thinking it is that way because after a stave is released the actual reflex added would be less because of spring back, so that caul has a lot of reflex..

Since I'd be going the other way -- reducing reflex, would the caul I'd need for that have fairly low reflex to account for spring back the other way?

Thanks both of you .

[PlanB]

Reading more here, especially Pat B's 60" elm recurve thread in the archives has answered those questions. Lots of different shaped cauls used there, etc. Okay, got it.

[DC]

The holes on one side only mean I got tired of boring holes and haven't needed any on that side yet. I have some long clamps. I get very little(if any) springback when heat treating. Some of the reflex comes out when tillering but not much.

[Josh B]

What I mean by a heavy floor tiller is make sure the limbs are still stiffer than you think they should be.  The more reflex you have, the harder it is to bend the limbs at floor tiller.  This has a way of making bowyers keep removing weight early on only to find that their bow is now greatly underweight.  Josh

[PlanB]

Okay DC. Looks like some do one limb at a time, and some do both, depending on the need (and the caul).

And Gun Doc, thanks that does clear it up for me. It's still very stiff in both limbs, and noticeably stiffer in the more highly reflexed limb, especially considering it is the longer limb and gets more leverage when floor tillering. So it's maybe where it should be, so far.

I will try to even up the limbs with either heat or steam, and remove some reflex for both before going further tillering with a string.

[OTDEAN]

Just even up the limbs using heat and a caul so both limbs are symmetrical before you even begin tiller.  Like the other guys said, if you try and floor tiller such a highly reflexed stave you will be taking off more wood and not realising you have in fact decreased the draw strength because the reflex has fooled you into thinking the limb is stronger than it is.

My process for making bows:

1: Dry stave to near bow dimensions.

2. Get both limbs to be symmetrical using a caul and heat.  Do not even begin tiller until this is done.

3. Make sure taper of limbs is perfect. Paul Comstock: Good taper = good tiller 'Bent Stick' book. 

4. Begin long string tiller until limbs are bending to brace height evenly.  Then brace bow to fistmele and tiller to desired weight and draw length. 

I am still a massive noobe but when I stick to this process and do it in this order, I very rarely make mistakes like I used to.

Hope this helps.

Dean

[BowEd]

Slow even taper is life to these bows.On thickness that is.

[DC]

I do one limb at a time the same as I put my pants on one leg at a time. One right after the other. Although with bows that's not quite as important as it is with pants.