Why do I get "chatter" with my new sanding belts?

S

Sprayman

Joined
Nov 15, 2014
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Hello, bladesmiths.

I've recently been using new belts. The 36, 60, and 120 grit belts work fine (they're ceramic). When I use anything higher than 120, though, the blade bounces off of the belts and makes a chattering noise; the sanding isn't smooth at all. Have you ever had this problem?

Also, if the belts don't have directional arrows on them, how do I know how to position them on the grinder?

Thanks,

Sprayman
 
What type of grinder, variable or fixed speed, type and weight of belt?
That information will help identify your problem. For instance, when I go over 120 grit on my little 1x30, particularly with lighter weight belts I experience that chatter.
 
Sprayman said:
Hello, bladesmiths.

I've recently been using new belts. The 36, 60, and 120 grit belts work fine (they're ceramic). When I use anything higher than 120, though, the blade bounces off of the belts and makes a chattering noise; the sanding isn't smooth at all. Have you ever had this problem?

Also, if the belts don't have directional arrows on them, how do I know how to position them on the grinder?

Thanks,

Sprayman
Click to expand...
I always Slow down the speed as I go to a finer grit.
 
Finer grits normally chatter more because they are normally more flexible and thin so the seam thickness is more of a difference from the normal belt thickness than on thicker, lower grit belts. What grinder and what size belts?

If you can slow down your grinder, it can help and they also get smoother after a bit of use. What brand are the belts? Sometimes cheaper belts will do that more also.

For belts without directional arrows, you can run them either way.
 
DanF said:
What type of grinder, variable or fixed speed, type and weight of belt?
That information will help identify your problem. For instance, when I go over 120 grit on my little 1x30, particularly with lighter weight belts I experience that chatter.
Click to expand...
I'm using a Craftsman 2x42, which of course is fixed speed. The belts seem to be various brands and weights; they came from Phoenix Abrasives.
 
Ian Fifelski said:
Finer grits normally chatter more because they are normally more flexible and thin so the seam thickness is more of a difference from the normal belt thickness than on thicker, lower grit belts. What grinder and what size belts?

If you can slow down your grinder, it can help and they also get smoother after a bit of use. What brand are the belts? Sometimes cheaper belts will do that more also.

For belts without directional arrows, you can run them either way.
Click to expand...
It's a Craftsman 2x42. It cannot be slowed down.
 
Yeah, the Craftsman I had did the same as my 1x30. Pretty much what everyone else said, it's too fast for finer grits. At one point in time I'd take the grits up to where it started to chatter and then would slack belt it or finish the grind by hand.
Hopefully someone else will have better news for you.
I don't know if it works, but I had read in another thread about putting a router variable speed control on one to give it a variable control. I'm going to HF tomorrow to pick up one and try it on an 8" disk grinder. If it works for that it may work on the Craftsman. I'll let you know
 
Chatter (if it's not belt bump) is the result of too many abrasive particles engaging the material for the rigidity of your setup. That's why it seems to occur the most the finer you go. A 400 belt "grips" your part more than an 80 grit belt, even though the 80 grit cuts deeper scratches. Your hands, or even workrest are not completely rigid, you you start getting harmonic vibration. Slowing the belt down or making the setup stiffer are really the only resolutions.
 
What Bill said. I didn't burn up my Craftsman 2 X 42 but it had no power on the speed control.
 
Thanks for that information.

Edited to add; OP, please note the provided information regarding the variable speed control.
 
Last edited:
I mentioned the chatter problem with my HF 1x30" a while back and Kyley Harris (CKC) suggested this:

"glue on a piece of firm leather to the platen. Soft enough that all chatter goes away, firm enough not to give easily and create convex when you dont want it.

with leather, or heavy packed wool felt on the platen, the chatter will go away, and the grinds will be a lot cleaner with less deep gouges so you wont ruin the blade easily.

just set the platen to a position where the belt has to ride over it firmly, not loosely, in the same way it would if it was a wheel grinder."

I haven't tried it yet since the problem is worst for me when I regrind large blades and I haven't done that in a while, but it sounds like it's worth a shot in the future since I can't slow the belt down.
 
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