Drifting belts?

G

Guy Thomas

Joined
Feb 1, 2000
Messages
1,370
Krept's post on flat grinding made me wonder about my grinder. I have a used Pro-cut and when I flat grind on the platen or slack grind the belt drifts back and forth quite and bit. Is this normal, am I causing this by uneven pressure of the knife blade across the width of the belt?
 
I have that too, increasing the tension helps most. Don't really know the answer though.

Dave
 
I've had the same thing happen slack belting on a Burr-King.
A good part of it is uneven pressure.
To make sure that it is not idler wheel crown. Build up the center with about 3 layers of tape wrapped around the center of the idler.3/4" wide tape, duct type should do it. Try it after that and see if it doesn't improve. And also make sure, like Dave said, to keep the tension high.
 
I had the same problem with my Bader BIII, and tried the tape trick. Never have the problem anymore. I just wrapped some duct tape around the drive pulley and no more drifting. Thank goodness it worked, because it was driving me crazy!
 
I'll give the tape thing a try. The tension on a Pro-cut isn't really adjustable per se, the idler arm assembly is a square tube which fits into a slightly larger square tube which is part of the contact wheel assembly. A heavy spring in the larger tube pushes against the base of the idler arm assembly for the tension. Hmm, I suppose I could build up the base of the idler arm assembly to increase the tension or replace the spring with a slightly longer or slightly stronger one.
 
Hmmmm... I think I'll try the tape trick on my B3; added insurance! It does get old thinking I'm grinding and discovering the belt is half off the platen. :o

Dave
 
Hi,
I want to preface this response by saying I have yet to make a knife on the machine I own.
That said and done, I have spent some time tweaking my machine in regards to tracking. Increased tension and tape on the idler wheel are good suggestions and may remedy the problem. Your contact wheel might also need some work. The arm that supports the the idler wheel might not be rigid enough. You may have to shim your pillow blocks to get correct tracking.
I have found that the contact surfaces of the two wheels, above and below where you are grinding, should be parallel in regards to the x-axis of rotation. If flat grinding, your platen should also be parallel to the contact surfaces of the wheels.
In short, try playing with whatever areas of adjustment your machine allows you. You might be suprised with what dials it in. I was.
Regards,
Greg
 
I have seen the tape work on a three wheel machine. On a 2 wheel machine with square tube fitted inside a larger tube and spring loaded
it was fixed by shimming the gap in the 2 square tubes. Just a right angle shimm the angle stopped the shim moving and allowed the small pipe to move in and out not side to side. It was some years ago I am not sure wheather it was shimmed on just the horizontal axis or weather it had the vertical axis as well.

Stay happy
 
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