Est. 1998 — 27 years of woodworking knowledge
Glueing Cocobolo?
Ruth Niles
>Hi,
I've been having a slight problem glueing a waste block to cocobolo. I tried putting grooves for the glue to settle in, I've tried using a rasp to rough up the wood and I've used CA or Titebond II.
Some bond just fine while others don't and fly off, naturally, when I least expect it!
Any suggestions?
Thanks,
Ruth
Re: Glueing Cocobolo?
Richard Allen
>Hi Ruth
Cocobolo has natural oils. The oils can inhibit glues from forming a good bond. Acetone will remove the oils from the surface. The wood will quickly (in a few minutes) replace the oils. Acetone is good because it evaporates quickly so you have some time between the solvent being gone and the oils reappearing. In that time you can expect your glue to do it's work. Slow glues with slow penetration can become overwhelmed by the natural oils. If you can speed up the penetration you can use slower glues. For epoxy you can speed up the penetration by warming the wood before wiping it down with acetone. The heat will thin the epoxy permitting it to penetrate into the wood.
For attaching a waste block I would use medium CA glue with two smooth mating surfaces. Apply the glue to the waste block. Wipe down the Cocobolo then clamp the waste block to the Cocobolo. I would leave the clamps on for 15 minutes.
Please note that the waste block should be mounted to a faceplate and trued up on the lathe. The center of the waste block should be dished out so the bowl blank makes good permitter contact with the waste block. Any glue at the center will have very little holding power. So a bead of glue around the true and flat inch near the rim of the waste block is all that does any good.
Good luck
Richard
Re: Glueing Cocobolo?
Wally Dickerman at Green Valley, Az.
>Ruth, using acetone as Richard has suggested is a good idea. However, I disagree on dishing out the center of the glue block. As in any glue joint, there should be good contact throughout. Instead, I suggest that you cut a small tenon on the bowl blank, and a corresponding opening in the glue block. Makes a secure glue joint. I use this method also when turning end grain pieces.
Wally
Re: Glueing Cocobolo?
Ruth Niles
>Thanks Richard and Wally.
Two excellent suggestions that worked.
Wally, I had read your suggestion of the tenon to another turner awhile ago and just forgot about it; thanks for the reminder.
Ruth