Blanks separating from faceplate blocks

I have been using hot melt glue for years, The cheap stuff works fine... I heat it in a electric frying pan, then dip the waste block attached to the faceplate into the glue, then apply it to the bowl blank... I have help bowl blanks over 4 foot in diameter using this method and only ever had one come off in 12 years of professional turning.... If hte wood is we, then dry the bottom of the bowl with a heat gun frist...... I think you will find photos of this process on my web site under Woodturning FAQs.... cheers... Have fun with it.......

-- Ken & Debbie Bullock (Woodturners)

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Sounds like he does not have the surfaces really flat or even concaved I have not had one come apart in three years of turning the same way Ken does his hot glue with up to 29" off center burls Don.

Hi Gary, I don't turn much Koa, but have used a board or two of it before. As I recall its kind of oily/resinous. Your friend may want to wipe the surface to be glued with denatured alcohol or some other agent to reduce the natural oils on the surface. This should hopefully help the bonding process. Like any gluing procedure, too much glue and the bond is weak, not enough glue and the joint is starved. Take a close look at the seperation to see if there was a enough even glue coverage or if there was too much glue or not enough glue at all. When using the CA, don't use too much activator, as this too can weaken the bonding strength of the glue joint. To increase the strength of the glue joint, a good method would be to turn a recess in the work piece and a mating tenon on the scrap block. Doesn't have to be very deep, but it will greatly increase the strength of the glue joint. They do however have to match up in order to be most effective. Hope this helps. --Jim M.

Hey, thanks for the replies.

Hot melt - neat. Have never seen anyone use it before. Can't be more expensive than the cyano :)

The koa we are using is kinda oily. I don't particularly care for it, but it is pretty. Lots of figure. And we have access to lots of it, at really low prices.

I'll pass along everyones suggestions, and see if he can nail down the cause. I guess if worse comes to worst, he can either use his chuck or deal with some screw holes...

Thanks again!

Hi Jim.

In looking at his separated blocks, the glue coverage looks about perfect. He isn't using any activator, other than the moisture in the blanks. I'll pass along the suggestions on reducing the oils and trying a tenon.

I think one difference in our techniques is that I use a single center-screw faceplate, and true up the bottom of my pieces - then glue the block to the bottom. I believe he mounts his blocks before he initial mounts the piece.

Gary

Hi Gary, If he didn't use accelerator thats why the bowl came off. I use medium CA and enough accelerator to just wet the glue block surface and have never had a turning come off. I've turned bowls to 20" using this method. Yellow glue won't work very well on wet wood.

Bob, Naugatuck Ct.

Gary, If your friend continues to use CA the change the formula just a bit and Success should be easy. Begin as noted above and clean the surface with denatured alcohol. Use the thinnest CA available on both surfaces and then plenty of medium on the block surface. Press, clamp, and wait. No Accelerator. The thin soaks into the wood and the medium forms the bond. Works great for end grain also. This is used much with epoxies in boating. Don