Finishing mounting dovetail socket before chucking?

thelastgizmo · 24 Jan 2017

I have a large (15") oak bowl on a faceplate at the moment and have finished the underside. I have a 100mm dovetailed socket for my new chuck (when it arrives!). I'm using a hard wax finish. Do I put finish in the socket at this stage or do I leave it until the bowl is complete? I'm not sure how this finish will affect the gripping power of the chuck. The bowl is about 2 1/2 inches deep (so almost a thick platter).

CHJ · 24 Jan 2017

The finish will have little to no effect on your chucks ability to grip, having the socket diameter matched to the design PCD of the jaws is more critical.

I take it you don't intend to reverse mount and clean up/remove the base socket when completing?

Your jaws may impart some compression witness marks on the socket given that you are going to apply significant cutting loads in hollowing out the inner.

SVB · 24 Jan 2017

As Chas says, the chuck jaws will leave whiteness marks so even if your not planning to reverse to remove chucking point, I'd leave plain and then hand dress out the whiteness will a bit of 100 grit and up when you're done and finish then.

Nice project btw!

S

thelastgizmo · 25 Jan 2017

Thanks Simon. I haven't done any turning for a decade or more and needed to make some friends a thankyou present. It was a good excuse to recommision the lathe. Now that I'm retired I can spend a bit more time turning.

Useful comments from you both. Chas, I don't fancy making a jam chuck for something that size so only get one go at the base!

CHJ · 25 Jan 2017

thelastgizmo":s573njxv said:
.... Chas, I don't fancy making a jam chuck for something that size so only get one go at the base!

If you completely finish the very centre of the socket base before you mount it, you can make a wood disk 'face plate' to fit on your chuck then sandwich the bowl against it with a piece of none slip material and and tailstock with a padded revolving centre.

This allows you to do a careful clean up of base if required.

A bit more of a fiddle to align than a jamb chuck but more a universal fit method.

thelastgizmo · 25 Jan 2017

Sounds a good idea Chas, but my lathe headstock is not attached to the lathe bed. The bowl diameter was too large for the swing of the lathe so I had to rotate the headstock and reposition the lathe bed bars (an old Coronet No.1). But a useful thing to remember!

Phil Pascoe · 25 Jan 2017

Sometimes you can finish the bottom completely first if you do not wish to reverse chuck it, but if the rim is to be anything like delicate or patterned it is can be better to take the finish only half way up the side so that the rim is perfect when finished and any discrepancy in the centering comes on the curve of the side, not the edge.