cutting in air

[ZASto]

First, check the mechanics of your machine, usually that is the main problem, Mach3 is the last place where loosing/gaining steps can occur.

Second, do not run your spindle without cooling. If you are afraid of freezing, just use antifreeze. You can leave it in the cooling system even in the summer. Also, I would advise to check if the antifreeze contains any chemicals that prevents algae/bacteria. If not, you can add a little of potassium permanganate in solution.

A friend of mine just rebuilt a 10 yr old Chinese laser and added a bit of permanganate in the cooling water.

[RichardR]

Thank you, I did realise that it would be the machine, but wondered if it was likely to be the drive coupling slipping or something else, I have not taken anything apart yet, in case there are any pitfalls which is why I was asking, also I was told by another member that I would be ok without the cooling, but then he was probably not aware that I would have to do each job twice and on such a slow feed rate, Having said that the motor has never got too an excessive heat. just warm to touch.