Coned shaped blade guide rollers

[woodbowl]

I've heared several reasons now why the blade guide rollers on a band mill seem to wear in a cone shape. I've been through several sets and they all start wearing on the tooth side first, then gradually toward the back.

Why do they wear in a cone shape and not evenly across?

Has anyone had other patterns of wear?

[Tom]

I can't answer "why" but I can tell you that I never had the problem bad enough that I discarded a wheel.

As long as I could adjust the wheel to keep the band level, I continued to wear it out.  The important thing for me was that it was cutting straight.

What would finally cause me to discard a wheel was the back flange wearing razor thin.

[ely]

could be because the band itself is shaped like a barrel hoop. or cone shaped on the inside if that fits you better. i have not had that problem yet either but i am still a newbie compared to most others here about.

[woodbowl]

In my case the wear is straight, not curved.

If it was inclined to wear according to the barrel shape of the band, why would it not wear in both the front and back rather than just the front?

If the barrel hoop shape was turned the other way, why would it not wear in the center only? I've never had one like this, only front wear.

[Tom]

Just a guess, but, the front is probably where most of the blade control is conducted. 

[pineywoods]

I just about wore out the adjustments on my mizer trying to get the blade to track correctly, until I finally discovered the guide rollers were worn cone shaped, worn off on the tooth side.
My scottish ancestry leans toward doing things in a frugal ( er cheap) manner whenever possible. No sweat, I have a small lathe, I'll turn them back down flat. I don't know about other manufacturers, but the rollers on a woodmizer are some kind of HARD. A carbide lathe bit won't even scratch them. I had to use a tool post grinder to cut them down. That solved the tracking problem completely.
I still haven't figured out why they wear that way, and some mills don't seem to have the problem. Meybe it's the hours, mine has over 6000 hours on the meter.

[DR Buck]

Could it be they wear that way because they are not parallel to the blade, but tilted toward the idle wheel side?


Could also be because the tooth side has the set of the tooth sticking out farther and maybe applying more friction as it passes across the blade guide rollers?

[Tom]

The teeth shouldn't be touching the guide wheel.   I've been sitting here thinking of the angled wheel idea and can't picture the dynamics.  I don't know if it would cause the blade to scrub minutely or not.

My bet is that there is more pressure on the wheel on the outside lip because it is controlling the tilt of the blade there.

[beenthere]

Does the location of the wear relate at all to build-up of pitch and sawdust on the blade? 

I was also thinking if both rollers were cone-shaped, then it wouldn't be caused by dirt and sawdust carried out of the cut and under the tip of the roller. But if it is happening to just the one roller on the output side, it might be a contributing factor.

Are the guide rollers about the same hardness as the blades? or one less hard than the other?

If the roller was at an angle to the blade travel, I'd think there would be a difference of surface speed at the interface which might cause wear. Think of the wear on front tires on a car that are not aligned pretty parallel with the direction of travel. The wider the tire, the more effect the differences would be. The greater the angle, the more friction would result.

[rewimmer]

I have not had this problem as of now because the mills I owned in the past had bearings for guides. My TK b-20 has the rollers and this problem will creep up sooner or later. I did machinist and engineering work for over 30 years and there could be a simple fix for saving $ on new rollers. Depending on the hardness of the rollers, you can true them up on a lathe and if they are too hard to turn, then precision grind a new true surface. You should have enough adjustment to compensate for the material removed. I plan after reading this post to check my rollers with calipers regularly for wear.
(everybody knows a machinist, which could amount to a freebee)
Robert in Virginia

[Dale Hatfield]

Isnt that why the mill comes with a blade guide alignment tool, to prevent from wearing the blade guides into a cone?
Dale

[customsawyer]

I have been giving this thread some thought  and the best thing that I have been able to think of is the fact that most of the time you have sap build up it will be on the top of the blade and that makes most it to where if your gets a little dull the first direction it will want to start waving is to the top and I think that the way the sap creats more drag on that surface of the blade it might make some more drag that puts a constant pressure on the leading edge of the roller. This is some thoughts don't know how right they might be.