Help! > Mistakes, muckups, and dangerous behaviour

Slitting saw and destroying my mill

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redhouseluv:
The final few thou, I cut with a new smaller tool, which was gave a better final finish not the one shown, which admittedly looks bad.

I think my over zealousness with the speed had a great deal to with my problems. Also the arbor I used wasn't the best type (see 1st pic); given the info above I will invest in one of the better, more solid types (see 2nd pic) before attempting another cut

redhouseluv:
Hi all

I have a new motor installed, new arbor and slitting saw; I have reduced the speed to a sensible rpm (without the saw catching), applied some cutting oil and the results so far are excellent. No smoke, no excess heat, no broken machinery and no tearing my hair out ;D

I'm not sure if the workpiece will be useable, but I can always make another - thanks all for your words of wisdom and I have attached a video

Best regards
Sanjay

BaronJ:
The motors on these mills are total rubbish ! The brush holder spade connections make poor contact and get hot reducing the electrical contact further. The clue is in the last picture showing the melted insulation on the wires.
The major problem with these type of motors is the heat generated by the armature windings has nowhere to go other than out through the bearings at the ends. So if you want to monitor how hot the motor is getting its the armature shaft that you need to check, not the outside case temperature. I check mine by feeling how hot the armature is in the center of the bearing at the top of the motor.
Having said that I recently replaced the motor on my mill with a larger 2.25HP treadmill motor, its more than twice the power of the original 1HP motor but happily uses the existing speed controller and is a much better quality motor.

Jasonb:
I think a lot is down to the user, anyone continuing to try and push a slitting saw that has lost all it's teeth through a workpiece is asking for trouble.

Treat them with respect and they last well, 16years and still going on my DC brushed mill and 14 on the lathe

john mills:
I think it is very likely a lot of the the damage to the the original motor was probably already done with previous use with other more robust cutters  also run to fast and blunt cutters the complete failure failure just occurred when the slitting saw was used.Narrow slitting slitting saws   when used at better speeds should not take much to drive .
John

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