Trilam, third attempt

[Jrunner]

I got rid of the ipe with knots and am starting with some nice osage from Troy breeding.

My bottom left limb is really stiff.  I have been scraping about six inches out from the riser.  I just wanted to make sure I'm doing this right.  It looks like the outer tip is stiff but don't want to go to short string and have a hinge there later.  Thanks in advance.

 

[Pat B]

The right limb looks good but you are developing a hinge in the left limb. Get the outer and inner limb bending more to relieve the hinge then match the other limb to it.
Once you do that get off the long string and low brace the bow.

[Jrunner]

Thanks Pat.  I can't believe I'm starting a hinge already but that's why I stopped and asked.  I really can't see it.  You mind explaining what you see that is hinge like.  My last attempt hinged mid lower limb also so I think there is something that I am not picking up on.  Thanks again

[Pat B]

If you look at the left limb you will see it bending more about 8" out from the fade. That is the hinge. You will have to scrape before and after that bend to get the bend in that limb more even. Then scrape the complete other limb to match the first.
 I think you are using the long string too far into the process. Once I get the tips moving about 8" and everything looks even I go to low brace. That will tell you how the string aligns along the limbs and give you a truer reading of the bend. The long string will give a bad reading if you pull the bow too far.

[Roy from Pa]

Video doesn't work for me...

[Jrunner]

Ok so I am going slow and noticed the hinge when I try to short string.  I did as pat said and worked on each side of it.  Now I noticed that the bow tilts in the tree when pulled.  If I let it tilt the string follows the line but if I clamp it down the top limb is stiff.  Shoul I clamp it or let it teeter a little?

[Jrunner]

I think the stiff top limb is what is causing the tilt now that I sit back and think about it.

[Pat B]

The stiffer limb is overpowering the other limb but you need to get the other limb bending well then reduce the stiffer limb. Your bow is only as strong as the hinge.

[Jrunner]

In order to get rid of the hinge and the stiff limb I floor tillered both to get them close.  I was then able to go to a short string.  My weight is a little low but near 45lb.  I was hoping to hit 50 and shoot in to 45.  I am not sure how more work the tiller needs at this point because I will keep loosing weight.  What would you guys recommend ?

[Pat B]

Looking at that first pic it is obvious that one limb is bending more than the other and that there is a hinge in the weaker limb.
The outer 1/3 of each limb is still stiff and both fade areas are a bit stiff still. All of the bend in at the center 1/3 of the working limb.
 Floor tiller stage is where you get each limbs bending evenly early on. From there a long string(only as long as the bow, not hanging down) will show you if both limbs are bending evenly and together. With 8" of tip movement on the long string and everything is even then you move to low brace(3" to 4"). At this point I like to be 10# or so over draw weight then you just reduce the weight as you tiller out to full draw. Also at low brace you can see how the string tracks down the bow.
 Never pull your bow over the ultimate draw weight or over the max draw length. If you see a problem(like a hinge)correct that problem before stressing the bow any.  Exercising between wood removal; 20 to 30 pulls but not over the ultimate draw weight. Remember, each inch of travel will increase the draw weight by about 3# per inch so you can calculate the actual draw weight even at your brace height.

  Have you ever built a selfbow or a board bow? If not I would suggest you do that and learn proper tillering before going to the expense and trouble of building a tri-lam. Tillering is tillering no matter if it is a selfbow, board bow or tri-lam.

[Roy from Pa]

Like Pat said..
The left limb has a bad hinge where I circled it yellow. The right limb is heading for a hinge if you remove anymore wood off of where I underlined it in yellow. At this point you need to remove wood first from the left limb where I have the blue line. Do not touch it where it is circled. That will help relive the hinge, but it might be too late depending on how much you pulled it. Once you get the left limb looking good with a more even bend through the whole limb, then remove wood from the right limb where it's underlined in blue. Don't touch where it's underlined in yellow. I doubt if you will make your weight now but it will be good practice for you.

 

[Jrunner]

Thanks Pat and Roy.  I have tillered a few self bows and didn't seem to have much trouble.  For some reason I don't see the bend with deflex reflex limbs.  In my first post I had only scraped the bottom limb about ten rounds when I formed the hinge that pat saw.  I avoided that spot the whole way through and it is still there.   I can't seem to get to short string without a hinge.  I will definitely keep working on it and give it to my son who is 15.  The good news is I'm getting good at gluing these things up and I have one more set of osage billets.  Thanks again for the time.

[Pat B]

After you glue the next one up cut in temporary nocks and see what the long string shows. Post pics of the results. Exercise the limbs a bit first. If your glue up is close you may not need to take off too much wood.

[Jrunner]

Ok so I've been scraping and this is where I stopped tonight.  Am I correct to say that I should keep working the outer third of each limb?  Also I'm at 40 lb and 63".  Would shortening each limb an inch be a possibility to keep this a 40 something bow?

[mikkekeswick]

Yes and no!
The right limb is pretty good now. The left still has the hinge. When you get a hinge like this it teaches you a lot! You see the wood there is already overstrained and to get it to act like fresh wood again is probably not going to happen with this bow now. It has been pulled too far with a weak spot. The real skill in tillering wood bows is being able to spot weak/stiff spots but at a very short draw - thus not overstraining the weak spots.
Shorterning it at this stage is not a good idea - it won't make it a better bow.
Use this bow as an exercise in getting perfect tiller and forget what weight it comes in at.

[Eric Krewson]

Do you use a tillering gizmo?

[Jrunner]

Yes I have been but it seems like I can scrape forever and the hinge just doesn't go away.  I guess that spot is just too weak like they said earlier.  My hinge was formed before the bow was bending enough to use the gizmo.

[LittleBen]

Sounds like you need to floor tiler more carefully. While floor tillering you should be making sure the limb is bending relatively evenly. That's the time to catch a big error like this because your right ... Now it's going to be a lot of scraping to fix. Probably gonne end up with a 25#er by the time it's done.

[Jrunner]

Please critique my tiller.  I am down to thirty pounds but am trying to get a little more practice.  It's starting to look close when I run the gizmo down each limb.  Right limb looks stiff out towards the tip.  Also not sure about the limbs at the fades.

[Pat B]

Left limb is bending more than the right but is still stiff in the outer 1/3. Get that bending better then match the right to it. Once you get it bending more evenly you can pike the limb tips and gain a few more pounds.