Milling machine operation

Eccentricity of circular saw blades can be caused by the method used to sharpen them. Old methods used a spring loaded pawl to position the blade for sharpening. A search for circular saw sharpening will bring up plenty of images of cheap machines that do this. Any initial eccentricity gets amplified by this system. I arrange for cold saw blades to be resharpened 40-50 at a time and now specify that they must be sharpened on a modern machine that electronically indexes the blades. Before that we were getting major eccentricities as blades were repeatedly sharpened.

Martin C

Hello Andrew (Johnston),

I use my slitting saws on a horizontal mill Centec 2B). The saw is aligned accurately with the table and everything is tight (no detectable wear). I still get the saws running off and I am now at a loss to work out why. There is no perceptible eccentricity and the saws are new, by good quality manufacturers.

I have tried varying the speed and depth of cut, not to mention tooth size. Hence my query "are slitting saws good for anything!). I am using free cutting mild steel so that can't be the problem either! The thinner the blade the worse the problem.

Andrew

Is the blade heating up? As stated in earlier posts the blades distort if they get hot. Flood coolant in industry avoids this but most home machinists don't use it.

Martin C

It's a mystery! I've never had any problems with slitting saws on a horizontal mill, although the thinest one I've used is probably 1/16". Can you describe the running off? Is the cut not vertical or does it wander horizontally? There's a clue that thinner saws are worse. That implies that the thinner saws are less able to resist whatever force it causing them to wander. What happens if you put a DTI against the side of the saw? The saw could be running true (no eccentricity) but still be wobbling slightly from side to side if there is dirt or a nick on the arbor spacers for instance.

I suspect it's a case of back to basics, look at everything and post it here; someone may be able to see that an assumption about something in the set up is incorrect.

Andrew