Bubinga question

[Biff Johnson]

I've glued up two small sections of bubinga with a section of oak in between. I'm turn the long grain side and the whole piece is about 12" long and started out 2" square.

I'm having a problem with tear out in the bubinga where it meets the oak. I think my tools are plenty sharp and I seem to have the best luck with the scraper. I'm supposing the problem is due to the density difference between the oak and bubinga. Do you think if I epoxied that line I would have better luck? Pretty soon I'm going to be working with a toothpick!

[Gary Max]

CA would do a much better job than epoxy.

[Biff Johnson]

Thanks, Gary. Would I try to fill the chipped parts in or just use the CA to stabilize the joint line?

[Doug W Swanson]

If you can remove a little more wood without hurting the design, I would just use CA along the joints.

If you are already near (or at) the finished dimensions, I would try to fill in the chipped parts.

[Bernie Weishapl]

I agree with using CA. I have did this before and it works pretty well.

[Biff Johnson]

Grrrr, still having the trouble and I can't figure out why. I filled the chips and the whole seam with CA. It still chips in random places along the glue line.

I tried cranking the speed up a little, sharpened the tools again.....it just won't stop. I will post a pic in a bit and maybe someone will have an idea.

Thanks!

[Faust M. Ruggiero]

Biff,
Have you noticed very few posts with bowls made from oak. White oak isn't too bad but red oak is a splintery wood that most woodworkers avoid. Can you saw out the oak and disc or belt sand the bubinga flat and glue in a wood that may be tighter grained. The very nature of oak with early wood and late wood growing in layers makes it prone to exactly what is happening to you.
faust

[Biff Johnson]

chipout.JPGchipout2.JPGHi Faust...it isn't the oak that's chipping, it's the bubinga

[Faust M. Ruggiero]

Wow, that's odd. Time for a new project. Are you using the tool as a scraper or in a cutting position?

[Bruce Pratt]

I think this is, like most problems, a combination of factors. 1) it looks like the grain of the bubinga is perpendicular to the long grain of the oak, so essentially you are chipping out bits of end grain, 2) bubinga is denser/more rigid than the oak which is not supporting the end grain as the bubinga is cut, 3) you didn't mention what kind of glue was used; I would use Titebond, or some other space-filling glue to the best support between oak and bubinga and 4) scraping is probably not the best approach here, as it will be applying maximum forces parallel to the bubinga grain, helping to pull out bits of end grain; I would suggest you try shear scraping with a gouge, using a skew, or at a minimum, rotating the scraper (CW if cutting left to right; CCW if cutting right to left) 30-45 degrees so you are getting some shearing action as well as scraping.

Hope this helps.