9" disc sander runout?

NickWheeler

NickWheeler

Joined
Dec 3, 1999
Messages
9,437
I built a new stand for my disc sander/controller... when I put it all back together I noticed my disc wasn't running true.

I set up a dial indicator on the motor to see if I could pin-point the problem (much like zeroing a 4 jaw chuck on a lathe). The motor shaft and perimeter of the disc look good.

But on the face/backside it was 0.020" out at the same point as the set screw. Just to see what it would do, I slipped a tiny shim on the opposite side of the shaft.

It got me within 0.010" on the set screw side.

What do I need to do to it to get it dead nuts on????? It's a Frink CNC machined disc, so I know it's not a problem of a cheap disc.

I didn't have any shim in there before, and didn't have any problems. Is it a problem with the key?

Any help would be appreciated! :)

THANKS!

EDITED TO ADD: I thought about adding another set screw exactly opposite of the one that's in it, but don't want to cut into that disc at all if I don't need to. :)
 
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I would definitely try a new key first . Is your disc seated all the way on the motor shaft ? I'm surprised you were able to slip in a shim . I would make sure the key fits in snug to hold the disc tight on the shaft opposite the set screw . We use to fit the keys where they needed to be tapped in .
 
First thing I would do is remove it and ensure your shaft is still true. Maybe it got knocked out of true when you were working on it.
Chris
 
I will may another suggestion that may be better for you in the long run, Nick. Does the disc's current condition prevent you from using it as intended? If not, then LEAVE IT ALONE!!! I know that this will be difficult but try it :eek:;):D
 
If the shaft was out it would show on the OD of the disk when he checked it. The problem appears to be that the disk is not completely square to the shaft. A new tight key may help. Before tightening the set screw with a new key try checking the run out and giving the disk a tap here and there to get it square then tighten and recheck.
 
Thanks guys.... well... maybe not that Mandt character. :p :D

Good point Jim... I'll give that a try. I think it may be that my key is a little small.

My "shim" was a little 1/4" strip of pop can... LOL

Maybe I should go back to files!!! :D
 
EDIT... My suggestion was not in the best interests of safety, my apologies. Thank you for pointing this out Stacy. Point taken.:thumbup:
 
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There should not be enough room to slip a "pop can shim" in the socket of a properly fitting disc??? Check that it is seated fully. With all that, it is difficult to get a disc that was not trued on the existing motor shaft to run dead flat. They will always be a little out.

Gixxer - With all respect, you should not suggest running a tool in a dangerous way to others. If it worked for you, fine ( well not really fine), but you have no idea who will try this with what type of setup or loose fitting wheel. The results could be bad. The set screw is there for a reason. Tools that don't need then have tapered shafts and sockets.

Stacy
 
gixxer said:
I had a problem with runout on my disc. I checked stuff, tried a new key, checked this and that. Eventually I ended up running my disc without the setscrew tightened. It was the setscrew that was taking up the slack in one direction. The friction fit is good enough for government work and the disc does not ride up the shaft or back out either way. Runout problem solved.
Click to expand...

Running a metal disc at high speeds that is not even secured?? Not the smartest thing you could do.
 
So , Nickie , what did you figure out ? Inquiring minds would like to know . Don't leave us hanging .
 
Nick, I've had the same problem with all the discs I've ever had except 2, both of them were left just a hair small at the end and R. W. Wilson said he hand reamed them the last wee bit. They needed to be lightly "tapped on" with a leather mallet before tightening the set screw. They run smooth enough its hard to tell if they're running or not, and pray to god I dont have to ever take them off, good luck.
Ken.
 
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