Relative newbie here. I recently acquired a second hand Harbor Freight 7x10 mini lathe. It works fairly well so far. I tried cutting threads for the first time and the motor kept shutting off. I installed the proper gears for 14 TPI to make a "face bolt" for my son's Beyblade (the old one broke). I put it in low gear. Problem was that motor kept turning off after one or two revolutions of the chuck. I don't think it is overheating because if I disengage the leadscrew, the motor turns just fine. With the relatively high gear ratio needed for the 14 TPI, I think the motor might be overloaded. The motor is not actually stalled because if I turn the speed control knob to zero and then up, the chuck will turn once and then turn off again.
If I put the speed up higher, it seems to run longer but then I can't disengage the half nuts at the right time. Even when the cutting tool is not touching anything, the motor stops so I know it is the gears turning the leadscrew that are causing the problems.
Has anyone encountered this before when cutting low TPI threads?
Put your carriage all the way to the right, loosen the 2 bolts holding the front piece on the carriage, you know the thing holding your half nut, then engage the half nut, now tighten up the face plate again, or whatever its called. Now turn on the lathe, make sure halfnut is still engaged, does it sound better?
The issue is mis alignment in about 4 different places, this is not a fix, but to just help for now. You need to adjust the halfnut, and then adjust the bearing blocks on both sides, etc.. It really is an art, just sit back and work left to right adjusting things, always have the carriage on the end you are adjusting with half nut engaged.
When you say you are disengaging the leadscrew are you stopping the leadscrew from turning or are you disengaging the halfnuts stopping only the carriage and the leadscrew is still turning? If you are disengaging the halfnuts then the previous post applies. However if disengaging the leadscrew from turning is solving your problem then I am inclined to think that you don't have enough backlash in the gear train and the gears are binding in certain positions. Set up your gear train and with the gears engaged and the chuck in neutral turn the chuck, the gears should turn freely with no binding. The reason for turning through several revolutions is that the gears are probably not perfectly true to the bore and may run a little eccentric. Hope all this helps.
Motor keeps stopping when cutting 14 TPI threads
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