Problems with mach3 turn

Hi all. I am midway through a cnc lathe conversation and have hit a problem. I am using a closed loop system. I have played around with mach3 for years and have never had this problem so it could be an equipment problem. On trying to calibrate the z axis the motor moves very slowly. I have been able to get the correct steps per distance which turned out to be 1000 steps. However no matter how I set the motor tuning the motor just moves slowly. However if I jog the motor it moves at speed. Can anyone think of what’s going on here. Thanks.

Set the jog percentage higher, it has probably been set far too low, I had this happen to me spontaneously..

Martin C

The way I read his post, he says jogging is OK. TO me, his post reads as if it is movement under G00 or G01 that does not appear to be correct. It is worth checking though to see how the jog speed relates to the rapid speed (maybe it is set to 400%, which would confuse the diagnosis).

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It is not to clear what the OP means by 'get the correct steps per distance'. Does this mean 'calculate the steps per distance' or 'verify the steps per distance with a tape measure' (even if it is moving slowly during the test move)?

So, first, make sure when you command it to move 100mm, it does move that distance. Then set it to move some distance at a known feed rate. Use your watch and see what the actual feed rate is. Do a rapid move some distance and a 'feed rate move' back to the starting point. Is thate any difference in speed?

This might be a complete red herring but have a look in the motor/driver documentation to see if it has any kind of internal electronic gear ratio that needs setting. My only relevant experience is with a Mitubishi servo motor - at 1:1 electronic ratio, it needed a gazillion pulses per revolution. Mach could not output the pulse train fast enough to drive it at the speed needed, so I had to set the ratio in the servo driver itself to make it work.

Simple answer is to type F100 into the MDI to reset the feed rate. Default seems to be 6mm/minute.

What is the displayed feedrate on the MACH main screen while the axis is under feed ( not rapid.)?

F100 would not reset the feed rate, but set it to 100 units/min.

If your axis calibration routine has not set a feed rate it would default to either that as last set, or MACH's default - not sure what that is - it is slow and might be John's 6mm/min..

Use midi to set a feed rate that you want - use John's F100 to try - and try the cal routine again?

Joe

At the moment I am waiting on a better power supply. Will start again when that’s wired in. Thanks for the interest

I had the problem as described. I tried all sorts of things to fix it and changing the jog percentage fixed it. I know it does not sound logical but it fixed the issue for me.

Martin C

Hi Martin. A few updates. First mistake was following a video on calibration of lathe on utube. It was the completely wrong way to go. Have then read and reread the mach3 manual and the replies on this site I did the maths. And also input the g code into mack3 correctly. This sorted the motor speed problem out. However it also showed why the z axis was not moving a smaller distance. The original belt pulley had a fair bit of wear on it allowing to much movement of the pulley before engagement of the teeth. So I am now waiting for a new pulley to turn up and with luck this will sort it all out.