Re: [CAD_CAM_EDM_DRO] wood sander rebuilding

At 11:13 AM 3/8/01 -0800, you wrote:

>The working drums are about 300 mm diameter and little more than 1,40 m
>long.
>The pivoting drums for tensioning and positioning are diameter 175 mm
>and 1,38m long. They have their pivot close to the middle of the drum.
>where the tensioning cylinder is.
>
>What I need is:
>First: How is the appropriate barrel form of the tensioning drums?
>One is completely worn and the other some genius turned it straight!
>I guess at the moment that I need in the centre 2 mm more diameter than
>on the ends and the form is a radius.

I can't help you on the other questions, but a trick I have used
successfully to cheaply renew and enlarge the diameter of rollers in this
sort of situation is
1: the easiest if it fits, use heat shrink tubing and bring it up in any
contour you want because each layer is quite thin and you can step them.
Then average them with a final heat shrink tube that goes over the whole
length of the roller.
2: the cheapest if you just need straight increase in roller diameter. Use
flexible polyvinyl tubing and an air compressor. The compressor (fitted
with a pipe-to-airline fitting you can easily make up) provides air
lubrication and stretching. Sometimes you have to heat the end of the
tubing to get it stretched enough to start onto the roller, but then the
air compressor does the work. Often it takes a helper or two to feed the
vinyl onto the roller. I suspect a sander would let you shape the vinyl
after you get it onto the roller. I have used more than one layer of vinyl
tubing to get substantial thicknesses. This is much cheaper than heat
shrink tubing, but I would shape the inner layers, then add a full
thickness outer tube to average the surface.

Ted