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Grob Bandsaw: two blade slots in table

car2

Stainless
Joined
Sep 19, 2009
Location
Apex, NC
What tracking adjustment? i don't see anything on it.

Edit: Never noticed that teeny little thumbscrew before. Ok, i have the top wheel tracking nicely on the crown, the blade is running in the guides, the lower wheel, it tracks out on the edge still. I probably need a lower tire at least. I can shove it into the bottom of the guides when cutting, but the blade works out to middle when done cutting. It's good enough to keep it in the guides for now, i can get my 2 exhaust jobs done. That thing is SLOW on 60hz slowest sheaves.
The blade tension can also sometimes affect tracking, so you might tinker with that. Also, perhaps drop a string over the top wheel, thru the guides to maybe see if someone left out a spacer or something on the bottom wheel shaft assembly, with the wheels not in the same plane. The tires should have a very slight crown on them; haven't looked at the Grob, but most replaceable tires have a small crown machined into the wheel surface. With the guides moved away from the blade, the blade should run pretty much in the same general position on the wheels.

For cutting round stuff, I use a Palmgren bench vise to clamp the part (part flat on the table), to keep the part from rotating; those vises with all sides machined allow clamping round parts on the end or over the top while keeping the part on the table surface).
 
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neilho

Titanium
Joined
Mar 23, 2006
Location
Vershire, Vermont
Car2's advice is on the money, and the the Grobs of that era do have a crown machined into the (cast iron) wheel.

If the lower wheel bearings are sloppy, the wheel could tip with the result that the blade would track at the outside. And if the lower blade guide were out of whack, the blade would track to the outside. And if...

Lots of ways for the blade to track incorrectly. Unless the lower tire is obviously no longer crowned, or cracked, seems like something else is the culprit.

I like to check any changes that could affect tracking by rolling the wheels by hand. There was the case of a new blade being ruined by starting the machine right up after a blade change, just assuming it would track correctly the first time. DAMHIKT :D
 
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86turbodsl

Cast Iron
Joined
Aug 12, 2004
Location
MI, USA
Ok, i pulled tension off the blade, the upper wheel is nicely crowned to the center, the bottom wheel is a mess, wavy if you will. The bottom wheel has about 1/8" play at the rim, checking like a wheel bearing on a car. I'm thinking it needs a lower tire and bearings.
 








 
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