Disc Sander

Walt2

Walt2

Joined
Mar 13, 2001
Messages
1,157
I recently purchased a 12" disc sander and one of the things I use it for is to make sure scales are flat on the side that fits on the tang. Something that I have noticed is that I have a problem with the scales not wanting to grind flat, they sometimes will have a hump in the middle. By this I mean from end to end which leaves a slight gap on each end. The sanding disc is vertical and I have tried holding the scales horizontal and vertical both and still have the problem. Is this something that is common or is it just me?
 
my guess is that you are approaching the grinder from the end of the wood rather than face to face... if I understand your problem. It happens to me as well sometimes, and I just have to grind it down until it is uniform. I think it also helps to stay away from the center as it is moving at different RPM's.

I'm sure someone smarter than me will chime in.
Jason
 
Walt, that will sometimes happen if you move the scale back and forth as you're grinding. As you change direction, you will have just slightly more pressure on the side you're moving towards. The same thing can happen on a surface plate. For surface plates, the recommendation is to use a figure 8 motion to equalize the pressures around the periphery. For discs, I'd recommend a slow speed and not moving the scale around. It helps if you can place the scale flat against the disc and then start it up as well. I hold scales with both hands and apply pressure equally across the scale.

You also want to avoid any heat build up, especially with woods.

--nathan
 
While sanding the handle material I continually rotate the block from left to right in 90 degree turns. This prevented me from having high spots in the center and low spots on the ends.
 
Johnny's idea of rotating the block is a good one. Just stay away from the linear back-and-forth.

--nathan
 
Thanks for the answers. I have tried the 90 deg rotation, but looks like I probably need to watch what type of movement I have if any. Yesterday I kept messing with one until it wound up thinner than what I wanted before I finally got it completly flat, and it was 3/8" to start with.
 
with thin sections, a large factor is where you are applying pressure. if you press more in the middle, it'll end up concave. press more at the ends, it'll end up convex.

what i do - making sure i have a relatively fresh disk on there - is to use the pressure i need to thin the piece by any amount it needs, then back almost all the way off on the pressure, so that it requires very little touch to hold it against the moving disk, then just barely increase the pressure until it grinds quite flat. seems to work every time.
 
Johnny Warner said:
While sanding the handle material I continually rotate the block from left to right in 90 degree turns. This prevented me from having high spots in the center and low spots on the ends.
Click to expand...

Yes this is what i do as well and they stay nice and true.

Bob
 
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