mac davis wrote:
On 1 Feb 2005 09:53:33 -0800, "Larry Bud"
wrote:

I was thinking of turning the drum on a lathe, but that's a
precision
chore... maybe truing it up on a lathe or DP after it's glued up?

I don't see how that helps. The point of truing it is to make sure
it's parallel to the bed.

Maybe "truing" was the wrong word....
What I'd want to do first is be sure that all the disks were round
and
identical....
It seems like if even one disk was out of round or out of line in the
glueup, it could provide enough variation to not sand flat??

As in wood turning, you can have something parallel to the bed that
isn't necessarily treu/round and lined up with the shaft... it can be
off center and still parallel, I think...

Again, that's what the point of truing the drum is. The sandpaper goes
on the table, and as the drum turns the high spots hit the sandpaper,
and eventually the drum is a perfect circle relative to the centerline.

I finally got it to work last night. What I did was take a 50 grit
belt sander disk, contact cement it to a piece of 1/2" hardboard the
same size as the belt.

I first drew some relief marks on the drum with a pencil as the drum
rotated so I could see high and low spots. Then I raised the table so
the belt just touched the drum, and moved it along the length of the
drum (with the hardboard down on the table). Stopped the machine and
checked to see if there were still low spots. If there was, I'd raise
the table by probably about .05" and repeat.

This worked better because the whole drum didn't grab the piece of sand
paper as was happening before...

Took about an hour to get it completely round.. Just waiting for my
velcro and sand paper strip to come it to complete this project.