Problems doing tapered glue ups

[Andy Pratt]

I've been trying to glue up some panels out of some uniformly tapered black walnut I recently came across, and the glue joints keep failing.

I've tried three runs, two with different boards and have had joint failures every time. The first time it was in one board on the outside edge, same when I redid that one, the next set it was in both outside edge boards. I've done glue ups a fair amount, and have never had a joint failure of any kind with normal stock (haven't glued up walnut yet though, if it's different), so I'm at a real loss here. Here's the specifics:

Boards are 4' long, 7" wide tapering to 3.5" wide
Black walnut at roughly 9% moisture content, generally flatsawn
Clamping with 2 LV panel clamp set-ups and 4 bessey K-bodys
Using titebond III, shop at 62 degrees
Let glue dry anywhere from 30-90 minutes, no change in results within that
All boards jointed immediately prior to glue up, surfaces match well

Is there something inherently different with glueing up tapered stock that I'm not noticing/taking into account? Any thoughts would be greatly appreciated.

Andy

[David DeCristoforo]

There has either got to be something wrong with the wood(???) or something wrong with the glue. Nothing else makes any sense at all. I'm betting on a "bad batch" of TB. Try a new bottle of glue.

[William OConnell]

Its not the first time Ive heard of joint failure using titebond 3. In all 3 instances I think the joint should have been left alone for a longer period of time. Out of all the water based glues that have a longer open time I think TB3 has the longest. Maybe you should have left it in the clamps longer? I'm not sure. I like to get squeeze out along the whole glue joint when I clamp and then clean up. Maybe more glue?
Hmmm just when I was developing a relationship with TB#3 I start hearing these stories.

[glenn bradley]

I'm with David on questioning the glue. Is it over 6 to 9 months old? When you say "Let glue dry anywhere from 30-90 minutes" I think you are saying you leave the material clamped for that long. Once removed from the clamps are the pieces being left undisturbed for 24 hours, then checked for failure? Or is the failure happening immediatly upon removal?

Unless I am in some sort of a 'production run' hurry and don't have enough clamps, I leave glue-ups clamped overnight. I'm still going with bad glue, though. Oh, I have had no trouble with walnut specifically and I use it quite a bit. . . like that helps ;-)

[josh bjork]

I've had some troubles with that glue when it is too cold. 30 minutes might work when it is 70+ out but when it is colder it turns into an overnighter.

[Andy Pratt]

The glue was about 12 months old, I didn't realize the shelf life was so short. I actually finished most of that bottle and switched halfway through, but one of the joints with the brand new bottle failed also. I've removed the glue from the first failed joint, rejointed the surface and reglued it, I'm going to leave it sitting all night and I'll let you guys know how it holds up in the morning.

Thanks for the help,
Andy

[Paul Simmel]

Andy,

>>> I've been trying to glue up some panels out of some uniformly tapered black walnut I recently came across, and the glue joints keep failing.

"Tapered" as in, like clapboard siding?

[Lee Schierer]

To me your moisture content is a bit high at 9% for a finished wood piece, but that should not be affecting the glue up. Make sure you have the surface well wetted with glue. The taper although slight will expose more end grain which will soak up more glue than a normal side grain joint. If you aren't seeing glue squeeze out about the size of a pin head every 1/4" or so along the length of the boards on both sides of the board you aren't using enough glue. I would also leave the clamps on more than 90 minutes.

[Stephen Edwards]

When you're gluing up these tapers are you using a clamp block that corresponds to the taper so that the clamp jaws are "biting" the glue up at 90 degrees to the clamps? In other words, if you're gluing two of these boards together that means that one end of the glue up is 14 inches wide and the other end is 7 inches wide. If you aren't doing so, you might want to try adding tapered clamping blocks to each side so that the glue up (including blocks) is the same width from one end to the other.

[Andy Pratt]

When I checked the glue up this morning, after letting it sit 12 hours overnight, everything was fine. I whacked it around some and it appeared every bit as solid as normal glue ups. All I can guess is that it was a combination of old glue and not leaving them clamped as long as I should have.

Thanks for all the replies and help,
Andy

[Paul Simmel]

When I checked the glue up this morning, after letting it sit 12 hours overnight, everything was fine. I whacked it around some and it appeared every bit as solid as normal glue ups. All I can guess is that it was a combination of old glue and not leaving them clamped as long as I should have.

Thanks for all the replies and help,
Andy

Andy, glad it is working, but please indulge me... I can't conceptualize the tapper bit. Is it clapboard flat to flat, or longer edge to edge sunrise pieces?

[Andy Pratt]

Second one also turned out fine when I got back from work today, so it looks like the problem is solved.

As far as the taper, it's not on the edges (both are jointed to 90 degrees) it's just along the length of the board. It is 3/4" thick all around with one end being about 8" tapering down to 3.5" at the other, if that explains it better.

Someone made a good point on the increased amount of end grain, that was my initial worry but I think the taper is too slight for it to have a huge impact.

My conclusion is that this whole problem was operator error not equipment or glue, I think I just need to plan on letting stuff sit clamped a little longer than the labeled time, which seems to be what just about everyone does anyway.