What causes slitting blade mistracking?

The TIR of the arbor face that the blade rests against is just under 0.0005". I can measure it more closely, but have to dig out my better DTI. As far as I can tell, the arbor face is in spec.
 
WobblyHand said:
The TIR of the arbor face that the blade rests against is just under 0.0005". I can measure it more closely, but have to dig out my better DTI. As far as I can tell, the arbor face is in spec.
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No need, that face is fine. Something was causing that blade to flex up and down. Of course, the blade deflecting to one side would cause similar flexing as it entered and exited the kerf.
 
A thought: Saw blades for wood which have a fairly large diameter to thickness ratio will heat on the rim due to friction and the blade will warp into a potato chip. For a slitting saw with a high diameter to thickness ratio, the same can happen. For wood saw blades, the common cure is adding radial slits to the blade. For slitting saws, I would recommend decreasing the rpm and feed rate and use of a coolant/ lubricant to keep the blade cool.
 
That is not a slitting saw, it is a screw slotting saw; a slitting saw would have much coarser teeth with much more room for chips.
 
MrWhoopee said:
No need, that face is fine. Something was causing that blade to flex up and down. Of course, the blade deflecting to one side would cause similar flexing as it entered and exited the kerf.
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I turned down a 2" screw to 1.25". The head on this screw has a 0.002" TIR. The problem is pretty obvious now. If I start the screw in the arbor, the screw head hits the edge of the counterbore in the arbor cap. The counterbore in the cap is not concentric with the screw head. So either the threads aren't coaxial with the bore, or the cap is off. The concentricity error is over 0.030".

This side of the cap screw is hitting the top of the arbor.
PXL_20220407_021529411.jpg
Now rotate the arbor 180 degrees about the spindle axis. See the gap?
PXL_20220407_021549045.jpg
This screw head is 0.005" wider than the stock one. I could turn down the screw head diameter by about 0.010-0.015" as a test.

Don't know, but this arbor is looking more and more like it is the source of the problem. Cockeyed screw camming the arbor cap. Might be saveable, but in my humble opinion, that's not good workmanship, and worse quality control. Not an import.
 
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benmychree said:
That is not a slitting saw, it is a screw slotting saw; a slitting saw would have much coarser teeth with much more room for chips.
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You are probably right.

However, McMaster seems to call them High-Speed Steel Slitting Saws independent on the number of teeth.

www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
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WobblyHand said:
I was attempting to slit a piece of solid steel stock in half with a slitting saw. It appears the saw started mistracking and started cutting off at a downward angle. I was preoccupied with trying to feed the saw and didn't notice the mistrack until too late. Saw was 0.020" thick. Material was 1018 5/8" thick. Was the saw defective? Is the answer a thicker saw? What causes the mistracking? There was plenty of oil. Sierra American SA-1000 arbor.
PXL_20220406_205047602.jpg
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You're gonna need a bigger arbor for that blade Wobbly ! :grin: Never seen one do that . How were you cutting it ?
 
mmcmdl said:
You're gonna need a bigger arbor for that blade Wobbly ! :grin: Never seen one do that . How were you cutting it ?
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I don't understand. You're the second person to mention this. What do you mean? Or is this just a joke? As a joke I get it, yeah the hole in the saw is bigger, so I need a bigger arbor.

I was cutting from the back of the piece going from right to left. Teeth facing to the left where contacting the work piece. Saw turning CW when looking down from the mill head. Saw arbor had clearance from both the vise and the work piece.

Honestly think the arbor cap counterbore is not concentric with the screw hole in the arbor. I will check if the screw threads are concentric with the arbor shaft. The original screw head hits the arbor cap every turn. So it cocks the cap every turn for an angular sector of say 60 degrees. Outside of that region, the arbor cap is flat with the arbor. There's clearly something wrong with the arbor, everything should be concentric with the spindle axis. The screw shouldn't bind every turn against the cap. Without the cap the screw goes in without binding.
 
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