Guide rollers

mrcaptainbob · March 10, 2010, 11:37:53 PM

Visited two sawmills today. Both were the same model WM. The first guy had the blade guide rollers a distance back enough from the blade where there was probably a 1/2 inch between the blade back and the roller flange. He claimed that if the blade ever touches that flange you don't have the saw set up right. The second guy says they were many of those guide wheel flanges out. They angle it just a bit so as to allow the blade back to catch the flange on one side only causing it to spin the needed direction. Was shown the difference between new and used. That used flange was pretty thin. So...which is it? Both have been using their mills for over fifteen years with a lot of obvious and impressive work to show for their effort. Touching the guide wheel flange, or not?

sgschwend · March 10, 2010, 11:48:46 PM

I don't have a WM, but my two cents worth is that you need to stay away from the flange. The flange should contact the blade only occasionally. If the blade works against the flange I would expect that blade will take a longitudinal bend (I think Cooks sells a tool to straighten out those bends).

On my machine there are no flanges, just back bearings. The blade rides on the crown of the wheels, when under load the blade may move back a bit (1/8-1/4") but still not contact the back bearings (those are there for short duration issues). If it is moving that much then it is not running right; that would be my fault.

backwoods sawyer · March 11, 2010, 12:45:09 AM

I look at like this. If you are running a double cut band, there is no back of the flange or back bearing, just the crown of the wheels. If the saw is pushing back on the wheel then the saw is not as sharp as it needs to be.
In addition, the back of the saw riding on the edge of the guide wheel will cause friction, there by over heating the back of the saw, which will cause cracking and premature band failure.
On the other hand running the guide to far back away from the saw, can leave the front of the saw unsupported, affecting the quality of the cut. A 1/16-1/8 gap between the flange and the saw seems to be the recommended spacing.

Bibbyman · March 11, 2010, 01:38:01 AM

Quote from: backwoods sawyer on March 11, 2010, 12:45:09 AM

On the other hand running the guide to far back away from the saw, can leave the front of the saw unsupported, affecting the quality of the cut. A 1/16-1/8 gap between the flange and the saw seems to be the recommended spacing.

Ditto...

ladylake · March 11, 2010, 04:42:59 AM

Right 1/16 to 1/8" if the back of the blade didn't need support they wouldn't have flanges or roller bearings back there. Steve

Chuck White · March 11, 2010, 05:21:35 AM

I agree with the 1/8 - 1/16 inch gap behind the blade!

MartyParsons · March 11, 2010, 08:14:33 AM

Hello,
Clearance between the flange of the roller is 1/16 on drive side and 1/8 on the idle side. The roller is angled toward the idle side in relationship to the blade. The blade will contact the flange when sawing. If the blade is in contact with the flange at all times the blade will crack along the back side and wear the flange. All alignment angles need to be adjusted, not just the clearance on the roller flange.
Angle of the roller is important, if the angle is not correct the blade will be pushed away from the roller when coming in contact with the flange (down) if the angle is correct the blade will be pushed up and the upward motion is controled by the surface of the roller.
As you saw you can hear the blade rub the flange of the roller, when you slow the sawing speed the noise will stop. I usually see the roller last about 1000 hours, most times the roller tip is coned shaped. This can be adjusted out. I have seen the flange so sharp you could shave hair with it. There was an alignment issue when the wear to this point.
I have some rollers I have saved for training demonstrations. If you want me to take some pictures I would be glad to.
Hope this helps!
Marty

OneWithWood · March 11, 2010, 11:08:21 AM

We always like pictures ;D

rbarshaw · March 11, 2010, 02:01:31 PM

I ran Cooks roller guides on the first mill I built, had rubber mobile home tires for bandwheels. I kept an aproxamate 1/8" gap between the flange and the blade back while not cutting, the balde would ride against the flange while cutting, unless I went slow.

Chuck White · March 11, 2010, 02:11:12 PM

Quote from: rbarshaw on March 11, 2010, 02:01:31 PM
I ran Cooks roller guides on the first mill I built, had rubber mobile home tires for bandwheels. I kept an aproxamate 1/8" gap between the flange and the blade back while not cutting, the balde would ride against the flange while cutting, unless I went slow.

The blade will ride against the flange while sawing.
The flange is there to keep the blade from coming off the back end of the roller guide.

You CAN'T have a flange on the front of the roller guide (for obvious reasons) and that's why the book says disengage the blade before returning the saw to the head of the mill. If you don't disengage, and you bump a sliver or a piece of bark, the blade will come off of the roller guides and possibly ruin the blade!

Tom · March 11, 2010, 04:01:56 PM

Those flanges on the back of the roller also add to the beam strength of the band. Keeping the guide rollers within 3" of the cant or log is in your best interest to allow the flange to do its job.

ladylake · March 11, 2010, 07:45:57 PM

Quote from: MartyParsons on March 11, 2010, 08:14:33 AM
Hello,
Clearance between the flange of the roller is 1/16 on drive side and 1/8 on the idle side. The roller is angled toward the idle side in relationship to the blade. The blade will contact the flange when sawing. If the blade is in contact with the flange at all times the blade will crack along the back side and wear the flange. All alignment angles need to be adjusted, not just the clearance on the roller flange.
Angle of the roller is important, if the angle is not correct the blade will be pushed away from the roller when coming in contact with the flange (down) if the angle is correct the blade will be pushed up and the upward motion is controled by the surface of the roller.
As you saw you can hear the blade rub the flange of the roller, when you slow the sawing speed the noise will stop. I usually see the roller last about 1000 hours, most times the roller tip is coned shaped. This can be adjusted out. I have seen the flange so sharp you could shave hair with it. There was an alignment issue when the wear to this point.
I have some rollers I have saved for training demonstrations. If you want me to take some pictures I would be glad to.
Hope this helps!
Marty

Marty, thats good info on the flange pulling the blades up or down, something I'll be checking real soon. Steve