I recently started working for a shop that has a 20" Crescent bandsaw which they recovered the wheels on within the last year or so. The problem is, neither of the tires has a crown to them which in my understanding of bandsaws is that the crown helps keep the blade tracking at or close to the center of the wheel so not to track off the wheel. Am I correct on this point?
I'm no expert on bandsaws, but what I've seen is while most smaller bandsaws do have crowned tires for tracking, some of the bigger saws do use flat tires. If the blade tracks correctly I wouldn't worry about it. If not the tires can be crowned on the machine with a little ingenuity. With a little searching you'll turn up several methods for doing so.
Bandsaws historically have crowns, all of them. The way the physics works, the blade wants to run to the high side, contrary to what one might think. It is best practice to let the bald find its comfortable spot on the crown, and then bring the guides up to it. Do not use the guides to 'place' the blade.
I worked in a shop where one guy decided the crown in the wheel was wrong and spent all day sanding a hollow in the wheels. It would throw a blade in seconds - absolutely would not work.
The link has a fairly good dialogue with some good and some fair info. The video is the reason I re-posted it.
Thank you all for your responses! The 36" Tannawitz I had did also have a noticeable crown on the tires as well as my first big machine, a Yates (pre-WWI). I have always been of the same belief as Mr. Sochar in regards to the physics of it. I will be talking to the boss about another retread in this since it won't track properly the way it is now. Thanks again to all.
Be sure to tell your boss that other machines don't. I had a 32" Fay and Egan that had no tire on the top wheel when I bought it. In those days, aftermarket tires were next to impossible to find. I bought some 1/8" rubber belting and contact cemented it to the rim, with a skive joint. It ran perfectly for years. There is a lot more to tracking than crown in the tires. I'm not certain of the engineering, but as an example, I would question that a 1/4" blade even sees the difference between a crown and a flat. How much crown in a rubber tire will it contact? 1" blade, maybe different? Just saying it is absolutely not a necessity in every case.
It has been a couple of years since I worked for this company but I have never forgotten this issue.
I don't know if the Crescent machine they had, had a crown in the wheel casting or not but I do know that the surface of the tire put on it was truly flat and that no matter how I tried to adjust it, the band would never stay on track. When I took off the guides, the blade wanted to either race forward or backward off the wheel, there was no in-between. Ultimately just so I could move on, I set it up so the blade would track back to rest on the guide bearings while running. Since then I have decided for myself that I would never have a saw without crowned wheels, Just makes sense to me.
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