Roller out or round or is the core out of round?
Hi Everyone,
It’s my first post and I’m in need of some help from the professionals.
I have a rubber roller on my CP10x15 and it looks to be out of round. The center of the roller has a dip on one side and a bump on the other side. Really weird. So I called my roller guys, and they said that they can shave a thin layer off the roller to check and get it back into round. That sounded like a good solution but when I got the roller back today, it was still still not round. I did notice that they took off a thin layer off the roller all the way around. So how could they do that on a lathe and not make it round again. Wouldn’t the lathe show the low and high areas for shaving a layer off to make it even?
Has anyone experienced this before? Are my assumptions completely wrong, and could it be my core that is not round?
Thanks ahead for any advice you can provide for me.
Sounds to me that you have a bent core, in that case unless the core is replaced or straightened you will always have a problem. Most roller makers hold the roller “on centers” in the grinding machine when grinding the surface. When you use the roller in the press you hold the roller on the trucks on the shaft. With a bent shaft you will always get different results from holding the roller in different ways.
Hi Ted,
Thanks for the quick reply. If it is a bent core, wouldn’t the company that recovered the roller be able to tell? or possibly check for that? Is it easy to straighten or would it be best to get a new core.
Thanks!
Dave
One other possibility is what I believe went wrong when I had a 7 X 11 roller recovered (which has, of course, a smaller core than yours). When they put any roller in the lathe between centers to grind it, they first position one end in the headstock. Then they slide the tailstock in so it contacts the other end of the roller, and clamp the tailstock down. Then they crank the tailstock center in further until it is tight. With my roller, they cranked the tailstock center in so tight that they bowed the roller core without realizing it. Then they ground it, and the surface was perfectly straight with the bowed core as long as it was in the lathe. However, when they took it out of the lathe, the core sprung back to being straight, and the roller surface then bowed.
I could see where this could easily happen with small rollers because nowadays, most rollers are much bigger than ours. With the big rollers, the lathe operators can probably exert a lot of pressure on the centers without bowing the cores. They could have done that with your roller out of habit, with the result that they bowed the core while it was in the lathe.
If they did bow your core in the lathe, I think there is a possibility that it may not have straightened out completely when it was taken out of the lathe. So, it should at least be considered that you might now have both a bowed roller surface and a bowed core. In my case, however, they re-used the old core when remaking the roller, and I have not had any trouble with it since. (I did not ask them to remake the roller completely, but I think that is what they did. In my case the bow was so pronounced that taking off a light layer would not have cured the problem).