Tillering problem

[keef]

 Hi Folks
I am in the process of tryiing to make a 70" elm longbow at 70lb draw weight.. It hs a D section, with a flat back and rounded belly, and 3" of natual reflex.
 I have got it to floor tiller and moved on to a long string on the tillering stick, However, the bow seems to want to flip round in the hand or on the stick on even the slightest pull ( So thet the bow is in reverse!)

I cant really fathom out why this is happening

Any thoughts or help would be most appreciated.

Keith

[Inuumarue]

Keith,
I've had something similar happen to me when I forced a bow into too much reflex and made the profile a bit too thin.  She kept sliding around the handle and ended up with the string across the back.  That happened to me on a 45ish bow with about 4inches of reflex and about 1in at the handle.  It liked to do it when I took the stringer off after bracing though.  What are the dimensions of your bow?

Adam

[DEllis]

That's normal(and annoying) with reflexed staves. I have had to get a helper to hold the handle area to keep it from flipping around until I get it bent far enough to stay put. One other thing to watch for is it is easy to miss weight with a fairly reflexed stave and make it too light.........so just a heads up there........you may know this already.
Best luck,
Darcy

[keef]

 Many thanks guys..... So I'm not doing aything wrong then ?   I hope that working past this stage might cure the problem?

By the way the bow is just under 1 1/4 " wide at the handle and 7/8ths deep and i got it tapering down to 1/2" x 5/8ths at the tips, which I want to be narrow and slightly deeper , before I put any bend at all into it

The reflex is just under 4" at the moment when I checked it properly

Should I try to reduce this reflex?

Keith

[markinengland]

If you feel you have the bend straithening out evenly I would go straight for brace height. Once at brace height of 5 to 6 inches it should stop  trying to flip. Work slow and concentrate in getting the shape you want close to brace height, don't pull it too far, work up in small increments and it should be fine. A little set will work in to reduce the reflex and all will be OK.
Good luck,
Mark

[toomanyknots]

Ya thats normal for reflexed staves while long string tillering. If it does it while braced, well, then thats a totally matter... I have to have my a helper too to hold the handle until it is bent enough on the tiller to not flip.

[DCM4]

It's called lateral stability, or more precisely the lack of it.  The bow wants to rotate on it's lenght axis because the string is pulling off center.  Be sure your string grooves are cut evenly, and that the limb(s) don't have twist.  Staying to center line is important on long, narrow bows.

[Kviljo]

With such bows I firstly make sure it is wider than it is thick, and that the center line is good. Then I give it a good floor tiller, and simply pull it to near brace while gripping the bow on the tiller. If it is still unstable at brace, I usually reduce the thickness to make it more stable. Reduced draw weight traded for stability is usually better than a broken bow. Leaving it braced in a jig for some hours may also help get rid of some reflex, to make it more stable. - just make sure the tiller is fairly good before doing that, to avoid hinges.

[keef]

Thank you for all the replies.. Really helpful.

I now have this bow ready for long string tillering, and the problem is solved

Now to make it into a bow!!

Will of course post my results (Good or bad!)

Thanks again

Keith