DAMN!!!!!! Can`t Brace This Thing...--- Tiller Check

[arachnid]

Hi Guys.

I`m working on a tri-lam, ipe, walnut, boo with a eflexed design.
I`ve reached 26" with a long string (yes, I know it`s too much...) and the thing doesn`t want to get braced!
Each time I put a string on it`s eather tears or flips to the back of the bow, like so:



The bow isn`t  too heavy, it pulls about 45#@26" (my target weight) with long string so it`s not over stressed.
So I really need some help.... what can I do?

[redhawk55]

Oh, looks like a heavy reflex. Always hard to bace.
Often back- flipping happens due to a misalignment of the tips? Maybe the string is to long?
A backview would be helpful.
Michael

[Marc St Louis]

That unfortunately is one of the problems when putting too much reflex near the handle.  You will have to raise the brace height.  Give us a view of the bow on the long string at 26", shorten your long string though till it's taught.

[Del the cat]

Need to make sure you don't have a stretchy Dacron string.
Got to a go for a reasonably high brace straight off, can't mess with low brace... it's all or nothing.
Hold on real tight as you are stringing it and try to see if it's bending sideways... I'm working on one that's trying to that at the moment.
The limb alignment was a little out, I managed some sideways correction by clamping it up and heating the belly. I had slats of wood clamped to the sides to keep the heat off the glue line.
Del

[PEARL DRUMS]

If its flipping, your not straight. Either the glue up or your side to side thickness on each limb.

[Eric Krewson]

I don't think it is a problem with limb alignment. Your stringer doesn't look up to the job, too short.

I got old and started having trouble stringing bows to go to the short string. I started leaving my tips clunky and putting a stringing groove in the top nock overlay and a wider groove in the lower limb overlay.

I could use a parachute cord stringer and string any poundage bow this way easily. As I finished the bow I would file off the clunky tips and get rid of the stringing grooves.

Later I realized I liked stringing a bow this way and made my finished overlays with the stringing grooves.

[Badger]

  I have an adjustable bracing jig I use with wheels on each end. It gives me a lot of control over the bow so I can see what is going on when I have a problem bow. Same thing as a bow press but I push it down by hand.

[arachnid]

If its flipping, your not straight. Either the glue up or your side to side thickness on each limb.

Here`s a pic of my limb alignment, back side up:


It`s the first time I have such a problem (guess there`s a first time for everything....) so how do I fix it?

Dor

[PatM]

Remove belly wood on the right side, cut your nocks deeper on the left side.

[Del the cat]

Like I said, you can put in small lateral correction with heat as long as you clamp on some side pieces of hardboard etc to contain the heat on the belly. Clamp it up with 1" of sideways bend apply heat over about a foot in that centre section, just a minute at a time over a 3" section at a time, so it doesn't take too long.... let it cool for an hour, job done.
I apply a couple of layers of masking tape along each edge before clamping the hardboard strip to really make sure there is no hot air blow by.
If the hardboard, hangs down beyond the belly by about an inch it channels the hot air along the belly giving good even warmth.

I'd make sure the bow isn't thicker than it's wide at any point too, that really makes it try to go sideways.
Del

[DC]

How wide is it? In my limited experience the narrower they are the more sensitive they are to string mis-alignment.

[adb]

Depending on the type of glue you used, it's hard (or impossible) to heat correct a lam bow. Get it hot enough, and it will delaminate. I believe your problem is a design flaw. Too narrow, and too highly reflexed = lateral stability issues. I ran into this problem trying to make reflexed warbows. As a result, I either use a small amount of reflex or none at all.

[arachnid]

The bow is pyramidal, 1 1/4" wide at the fade and tapering to 1/2"  tip. I glued in about 4-5" of reflex 'cause I thought it'l take set and sattle at about 2". But that sucker bearly took any set!

I think the reasonable option is to scrap from the sides as PatM suggested but I don't have much width to play with and I don't want to screw this bow (I've worked a lot on it so far and it looked so promising...)

I'll be greatfull if you can give me detailed instruction on how to do it right.

Thanks

Dor

[lebhuntfish]

I to have had this problem. Never built a lam bow though. For the most part it's been string alignment. But I tried a highly reflexed bow once for the same reason "set" and my initial "full"  brace was somewhere near 10". After finish tiller and shooting in it finally settled in at 7" brace. A little high but it worked till I shut it in a truck door! Good luck, should be a sweet bow when you get it lined out. Patrick

[Marc St Louis]

You can actually make adjustments with heat as most modern glues will soften with heat.  The danger is de-lamination when heating areas where there is some reflex but there is a way of doing it