Lamination Slip

[EvilDogBeast]

So I got my first D/R laminated the other day and ended up with some sliding on the form.  It cost me some glue lines but other than that everything appears to be sound.  My stack was:

- Glass
- Veneer
- Core
- Riser
- Core
- Veneer
- Glass

Of that stack, everything after the first veneer listed slid about 3/8" to the right on the form.    I left my ends 2" long in case I ran into problems, but marked them where they needed to be cut to length.  My question is, should I adjust my cut lines 3/8" in the direction of the slide to make up for it or just cut on the original lines?  I don't have a picture of the tips right now, but imagine one end with an extra 3/8" glass and veneer hanging off and the other end with the core and belly glass hanging off.  Will upload a picture of it when I get home.  Thanks in advance for the help!

[Bowjunkie]

You have several issues in my opinion. After the riser and lams are all glued and stacked up, but before you put the first piece of rubber on, you should wrap some 3/4" strapping tape around the whole works, right in the middle of the riser, and/or clamp it, pulling it down securely. Then, an inch or two from each fadeout, wrap the riser and lams with the same tape. Do the first wrap with moderate pressure, check your alignment, and if all is well, go back over it again pulling it down more tightly. Do it also tightly right at the fadeouts, and part way up the riser. Work back and forth from one side to the other, and then wrap a few places out each limb, and keep checking the alignment. Before any real pressure is applied with the rubber pieces, it should be held quite firmly by the tape.

Then cover the whole works with plastic wrap... like Saran Wrap. This keeps the glue off of your bands, and your hands.

And when you get to applying pressure with the rubber bands, start at the riser and work outwards, alternating working each side a little at a time until you're well past the fadeouts.

Next, your riser shouldn't end at an angle like it does. It should look more like the bottom of a ski slope, curved and gradual. They also end too abruptly, and should gradually get thinner and thinner, down to 'paper thin' at their ends. I don't know what's going on with that fadeout lam/power lam. It looks like it gets thinner, then thicker, and has some weird angle on it right there where the riser block fades out. It appears the gaps in the glue lines are more because of the fadeout issues than the shifting.

You also have only two core lams which seem pretty thick. How thick are they? Thinner lams make the bends at the fadeouts more easily and reliably.

[Crooked Stic]

The very tip of your fade needs to be paper thin out on the end. Yours is not. The spot up the ramp either needs more pressure or be a flat area.

[Buemaker]

I use zip-ties now. If you are using an airhose make holes for the ties in the form at appropriate places and strap them on top of your metal strip. Fill the hose with about 20 pounds pressure and let it settle a while before pulling out the ties, then go to full pressure.

[EvilDogBeast]

Thank you for the feedback.  I'll try to address them in order:

- I should have mentioned I had 2 bar clamps on the riser during glue-up, I just removed them at the end to get a better picture of the slip.  They were definitely not tight enough (was afraid I'd starve the joint)
- Thank you for mentioning the tape, I didn't think of that.
- Yeah I dropped the ball on the plastic wrap, only had it under the form.
- The rosewood has a maple accent, and the maple is the end of the riser which is why it looks so abrupt (see picture).  Still no good?
- I got the end of the fades down to the point where I could see light through the last 3/4" but was afraid to get it any thinner as it was starting to cup.  Can make it thinner next time.
- The power lam thing is actually the end of the riser block.
- The two core lams are quite thick, and I realized this but was stuck with what I had at that point.  They are both 0.100" thick, one with a 0.001" taper and the other with a 0.002".  Next time I'll make the back lam thicker and the belly lam thinner.
- I do need more pressure on the ramps as we can tell by the slippage, however, during the dry run everything fit together nicely with no gaps under a relatively light pressure which is why I think the lines are a result of it slipping.

Please keep the feedback coming, and if anyone can tell me if I need to adjust my tip cut lines it would be greatly appreciated.  I wish I would have taken a picture of the dry run now...

[Bowjunkie]

Ok, I see what you did with the riser. That makes more sense, and it's OK like that if the fadeouts are thin enough. I think the very ends of the riser (the maple) should either be thinner, or there should be more pressure there. You shouldn't be able to see that gap right after the fadeout.

Don't make a decision on lam thickness yet until you know if you hit the target weight with this one. But as a 'for instance', if I were going to do this one over again, same stack, same taper rate, I would make the lam on the belly side of the bow (on the ramps) about .040 parallel, so it will lay down in there more nicely, and then make two .080 tapered lams for on the back of the riser. Thinner lams all around. That should help with your glue lines because I think the .100" lam on the belly side was trying to bridge over the curve of the riser.

[EvilDogBeast]

Thanks for taking another look.  I definitely need more pressure on everything all around.  I was a little unsure because my dry run went so well and I didn't want to starve the mating surfaces.  I can see now that more pressure was needed to pull it all together and get more squeeze-out in the fade tips too, and I think the slip exaggerated that on the one side.  Ugly lessons learned, but I suppose it could have been worse for a first attempt at a glass bow.  Hopefully everything is structurally sound and I can get it shooting.  Any advice on trimming the tips?  Still wondering if I need to adjust my previously marked end cuts to account for the riser being out of place by 3/8".

[Bowjunkie]

Forget about your previous marks. Find the center of your riser and start there with your layout. From there find your bow center, tip location, etc.

[EvilDogBeast]

Will do.  Thank you for all the insight, it is greatly appreciated!

[arachnid]

I`ll add that it`s better not to let the accents go into the fades.
Keep the 2-3" of the fade solid wood. I had a bow delam and brake due to poorly executed fades.

[EvilDogBeast]

I`ll add that it`s better not to let the accents go into the fades.
Keep the 2-3" of the fade solid wood. I had a bow delam and brake due to poorly executed fades.

Good to know.  I was thinking next time I would avoid that, and now I think you have given me a good reason to do so!