No-mark chucking method

[Tristan Croll]

An excellent idea this one - unfortunately not my own, it's described by Jack Cox in his excellent book Beyond Basic Turning (ISBN 0941936252 for anyone who's interested).
For hollowing out bowls (after the outside has been turned) he uses a variation of the glue chucking method. This is how it goes:

Take a small disk of metal (aluminium works well) about three inches in diameter (he claims this will hold a 12" diameter bowl). On one side turn a spigot for an expansion or compression chuck (yes, you need access to a metal lathe), and drill a small hole through the centre to help place it on the workpiece. Make sure the other side is perfectly flat. Now, place it flat side up on an old clothes iron on medium heat (man-made acrylic setting apparently works well). Allow it to warm up and then apply an even covering of hot-melt glue. Pick it up (using tongs, unless you like it hot) and centre it on the base of your bowl. Wait for the glue to set, chuck it and turn as normal. When you've finished to your satisfaction, place the bowl on the iron for a few seconds and the disk will slide right off.

Neat, huh?

Tristan Croll

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Cogito cogito, cogito ergo sum
- I think that I think, therefore I think that I am

[ubeaut]

Yeah, real neat Triston, but think about it.

When you've finished to your satisfaction, place the bowl on the iron for a few seconds and the disk will slide right off.

O.K. Now how the hell do you get the hot melt glue off the base of the ugly flat footed bowl.

Don't know the book, but I'll bet it's English.

Cheers - Neil

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Nemo mortalium omnibus horis sapit.

[Tristan Croll]

Hey, the base of the bowl doesn't have to be flat, as long as there's a flat space in the centre big enough for the disk. As for the glue mark, if you're quick you could wipe most of it off with a rag while it's still hot. As for the rest, a quick hand-sanding would do the job.

[ubeaut]

Sorry if I ruffled the feathers Triston. But if you have a chuck to hold this glue chuck in why don't you use the expansion or compression chuck to hold the piece. Done right this is also a no mark chucking method.

I think you will find that even hot the hot melt glue won't just wipe off. If you don't believe me try it. As for sanding it off by hand I think you will also find that it doesn't like to be sanded.

A hot melt system like that is often employed for specific turning jobs but usually not because of no mark chucking but because it is convenient. Usually the foot of a bowl etc will be turned off as the final step in the job. Eliminating the need for a no mark chucking type like this.

If using hot melt glue like this you will probably find that placing it in a freezer for a while to make it cold will make for easy removal of the glue from the base. That is, if it hasn't keyed itself into the pores of the grain because it has been applied too hot.

[jamesy]

Tristan The rings you refer to can be bought commercially from Woodturning Supplies at quite a reasonable price. I have one for rough turning to set a foot up on my bowls. They are convenient if you don't want to take your scroll chuck of the lathe but I personally find you can't beat 4 tech screws and a face plate to start shaping an unbalanced chunck of wood. Ihave to agree with Neil. If you have the facilities to do the exercise you refer to, then you would probably be best to turn the recess and have your bowl centred perfectly. Leave the ring in your draw of other miscellaneous novelties that we all collect.