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Ed Caffrey's Workshop Talk to Ed Caffrey ... The Montana Bladesmith! Tips, tricks and more from an ABS Mastersmith.

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Old 12-17-2008, 09:24 PM
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Cool Belt tracking ---help!

Dear Ed, and the "gang",, I'm putting the finishing touches on my "bader" style grinder with my own "take-off" of the "Caffrey" platen. I bought the 3" and 1-1/2" wheels from Rob Frink and I have them set up with some other wheels left over from a previous grinder. I have the 3 stationery wheels all in line (I think),, but I'm having trouble getting the tracking wheel in line! I have only a tiny amount of side to side play in the arm that holds the tracking wheel, I vise-grip it on, turn the belt and the belt always goes toward the frame.
I guess I'm looking for advise of where to start the alignment? Should I try to get the tracking wheel 90 degrees to the "frame" first? As much as I try, I get the belt the same place on all 3 of the stationary wheels, turn the belt a few rev's,, and it goes nuts! I'm thinking of putting a set screw on the side of the tracking arm mount to take all of the slop out of the swivel, it's barely a 64th of an inch side to side, but maybe it will help-? Before this, I just used 2 wheel machines, so the 4 wheel thing is all new to me! Any help is greatly appreciated!!! -------Jon


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Old 12-17-2008, 10:04 PM
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Hi Jon!

If I'm understanding the problem, my thought is that the tracking wheel must first be mounted with ZERO play in any direction. All the wheels must be lined up with the centerline of each wheel on the same vertical plane. The other portion that is a must, is that ALL of the wheels be mounted in such a way that they are all on the same 90 degree plane to the machine's frame. This is the main reason that many homemade grinders have issues....its nearly impossible to achieve that level of precision in a home shop, and is the main reason why commercial grinders cost so much. Your paying for the precision.

Anyway, Normally the idler/tracking wheel controls belt tracking by tilting off of a set horizontal plane...usually accomplished through a screw type mechanism. The closer you can get all the wheels on the machine centered on the same vertical plane, as well as the same 90 degree plane, the more precise it will operate. Any "play" that you have on a given wheel, in any direction, is going to adversely affect how the belt runs and tracks.


Thats likely not what you where hoping to hear, and I wish I could give you an easy fix.....but theres just nothing easy about it. Sometimes we get lucky and stumble upon it, but more often than not we get so frustrated with these issues that we finally throw up our hands and start saving our pennies for a KMG!


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Last edited by Ed Caffrey; 12-18-2008 at 06:54 AM.
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Old 12-18-2008, 02:21 AM
cdent cdent is offline
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Hi Jon,
I had issues making my "Caffrey" platen (not Ed's fault), so my first one is just a paper weight. That didn't even include my drive or tracking wheel. I knew the grinder was ok, but my 'learner' platen threw the belt off in a couple of turns.

Ed's right. I'd try to start with a true frame and every thing else is sort of referenced off of that. Maybe see if a short temporary belt will stay on just your drive and tracking wheel. Once those two are ok then you can fiddle with the platen.

My drill press has a bunch of slop, so I had to preload pressure on the quill before confirming square. I scribed the platen shape on some rectangular stock, but I didn't cut it out until I drilled all the holes, It was a ton easier to clamp straight edged stock.

When I welded my 3/4" stub to the platen, I clamped the platen body to my tooling arm (with the stud in the tooling arm hole) to force everything tio stay in line. The tooling arm hole also has to be true.

Sorry if you had these covered, but I figured why not pass along my probs. Since it shouldn't move, I'd start with the drive wheel first (square to frame and in the plane you set). Then as above see if some rigged up belt will run between the drive and tracking wheel. Finally, bring in the accessory (platen, contact wheel, etc.). The belt tension should/might hold the 'slop' in your tracking wheel all to one side, so I'd bet on one or more of your wheels out of parallel.

Best of luck, Craig
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Old 12-18-2008, 09:31 PM
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Cool I got it!

Thanks Ed and Craig! It was the slop in the tracking arm, I held it over tight to the side away from the frame side and spun it a few times, the belt went back over and tracked straight! I see now that I can have NO slop in the arm, I'll fix the problem, and get it running!
I have great respect for Rob Frink, I met him at "Bowies" in Knoxville a few years back. His machines are great, and like any good machine, these days, the price continues to rise. I'm just glad he sells "parts" as well as finished units. It really helps those of us like me who has to start "everything" on a budget!! Thanks again guys! ----Jon


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