What causes slitting blade mistracking?

FOMOGO said:
Are your decimal points in the right place re blade thickness?
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0.020" saw, just like the picture shows. Was only using 0.002" as an example. I had a 0.020" Malco slitting saw. Yes, that is past tense.
 
Was it a new slitting saw? Examine the teeth closely. Slightly dull on one side or uneven grind will cause the blade to deflect. I'm betting the part didn't move, the blade flexed due to unbalanced cutting forces.
 
MrWhoopee said:
Was it a new slitting saw? Examine the teeth closely. Slightly dull on one side or uneven grind will cause the blade to deflect. I'm betting the part didn't move, the blade flexed due to unbalanced cutting forces.
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Yes it was a new slitting saw. I will take a look at it.

Toolmakers vise. I did find the piece wasn't seated on the parallels correctly. The right side of the vise had a 0.0015" gap. The left side had 0.
PXL_20220406_233603045.jpg
But the smoking gun is the arbor itself. It is new. Sierra American SA-1000. I noticed the screw was kind of strange when tightening. It seems it is slightly eccentric. The cap screw hits the arbor cap every turn. And guess what, that cocks the arbor cap and I see more light on one side vs the other. Of course that can cock the saw. (Which could cause mistracking...) Unfortunately, that is hard to take a picture of. Once the screw is turned enough, and the eccentric part is no longer interfering, it is flat again, and no gaps on either side to let light through.

The original cap screw has worn some of the blue on one side, because it is hitting the arbor cap. I will try to replace the screw first. Of course, I don't have the right length... As a test, I can cut off a 2" partially threaded SHCS. If that doesn't solve the problem, it is a manufacturing defect in the saw arbor. Hope it is the screw...
PXL_20220407_001053147.jpg
Think I will chuck up the screw and indicate the head.
 
Looking again at the picture of the blade, it was obviously flexing around the arbor cap until it fractured. Chuck up the arbor by the shank and check the runout of the face that contacts the blade.
 
Firstram said:
If your going to chuck it up, just skim the head so it's concentric.
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I did put it in a collet. The TIR of the head is 0.013". Pulling out a random 5/16"-18 2" long SHCS and doing the same thing shows a TIR of 0.002". I don't want to turn the original screw head or alter it in any way, in case I have to return the arbor. I will turn down the 2" screw to 1-1/4" and try it. If it works, then all is good, except I am down a saw blade.

If it's the arbor that is the problem, I'm going to contact McMaster and tell them that the arbor they sold me was defective and they owe me both a new arbor and a new saw blade.

If it is just the screw, I may still contact McMaster. I mean, one does expect to receive compliant product. An arbor that doesn't run true isn't compliant. If it really was the screw, it still cost me a blade. I'd expect some recompense, but I am not sure what that would be.
 
MrWhoopee said:
Looking again at the picture of the blade, it was obviously flexing around the arbor cap until it fractured. Chuck up the arbor by the shank and check the runout of the face that contacts the blade.
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You are keeping me busy :) That is a good idea. Having found the SHCS with a 0.013" TIR makes me want to measure the TIR of the face.
 
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