"billh" wrote in message
. ..

snip

I am curious about drum chucks though, having never used one. I assume
that
they're like jam-fit chucks where it's best to make a custom one for
each
job, unless you've already made one that just happens to be the right
size?

- Andy



I also use 19mm MDF. Rather than mount it on a faceplate, I drill and tap
a
hole in the MDF to directly screw onto my spindle. I then true it up.

I originally tried that but my spindle is threaded past the headstock
casing, so unless I went to the extra effort of finding lock washers, the
MDF'd spin itself in until the edge met the bottom of the casing (it's
tapered back for accessibility) and promptly self-destruct.

You can make a few different sizes of drum chucks. They don't have to be a
tight fit at all just use the largest for the job since you will get more
area and thus holding force.

I use ABS (black sewer pipe) straight connectors which come in several
different diameters. You can also use a short length of the pipe as well.
I
make a recess with a parting tool (or whatever you like) such that the
fitting sits in it with a snug fit. It only need be a 1/4" (6 mm) deep or
so. I then epoxy the ABS fitting to the MDF. I then true up the open rim
of
the pipe and hot glue on some foam for a gasket and that is all there is
to
it. Note that the vacuum force will hold the pipe in the groove in the MDF
so even if the epoxy fails the joint should still hold.

Considering I make many tools/parts myself (having a tiny budget) I'm
surprised I hadn't thought of that. For some reason I've been thinking of
turning them out of scrap wood. Thanks for pointing me in the right
direction.

A drum chuck like this is even handy in non-vacuum applications say for
truing a warped external tenon on a dried roughed bowl. Just put on the
drum
chuck. Place the bowl over it and bring up the tailstock and true the
tenon.
You could even finish the bowl bottom with this method if for some reason
it
can't be held under vacuum.

That gives me a handle on another problem I have at the moment... I've
recently finished turning the foot/tenon off an 8" English Yew bowl with
cole-jaws and in my eagerness to marvel at my accomplishment was careless
enough to clip the edge of the tool-rest which, of course, I hadn't
removed. (I know, I know. You can't say anything I haven't already said to
myself...)

The Yew is a truly lovely piece of birds-eye which had been sitting in a
packing case for many years; it's almost impossible to replace nowadays.
Certainly not on my budget.

Rechucking's out of the question and the foot-print is too small for the
vac-chuck/faceplate. I assume it'd be feasible to mount the base of the
bowl in a drum chuck, bring up the tailstock (padded) and trim the edge that
way?

Just checking for feasibilty from someone who may know before I go
trail-blazing for myself and discover something else I didn't expect.

- Andy