Problems with lathe

[JohnHaine]

Right, I've just tried this. Look at the Feedrate DRO just above the MDI. If M3 has just been started it probably says 5 mm/min. So if you type in Z-5 it crawls along. To be frank I've never not typed in a G-code word into the DRO so never seen this behaviour, I would always specify a feedrate. If you type Z-5 F100 it moves MUCH quicker and the default feedrate is now set to 100mm/min until you use another F word to define a new one. Doddy is quite correct.

[terry1956]

Hi, all I was asking the stepper motor to do was move a set distance, so I could measure it and set the steps. Unlike mach3 mill, mach3 turn doesn’t have an automatic calibration system. The only way to set the steps is by asking the motor to move, measure and adjust until you get the right number of steps. I did not know that I had to also input a speed. I just had the idea that the motor would move at the same speed it did when jogging. Is this not correct? I am trying to follow a video on utube by a chap who went through this process. But like many things so much is left out. And the mach3 manual is very grey in this area.

[JohnHaine]

Look, it is quite unnecessary to "calibrate" an axis in the way you describe. All you need to know is the screw pitch, any gearing between the motor and the screw, the motor steps/rev, and any microstepping ratio set in the driver. Then there's a simple formula in the M3 manual for calculating the steps/unit that you type into the appropriate config box. Unless your leadscrew is basically inaccurate that will give you a number as accurate or more accurate than a calibration. If you give us these numbers for your machine we can show you how.

Many G codes are "modal", that is once you execute one the machine stays in that mode until switched out of it. G0 and G1 are such modes. This is useful as for example you can profile cut with a G1 X Y then carry on just by giving a string of Xs and Ys (on new lines) for the rest of the cut. It seems like on install the MDI is in G1 mode and set to a low feed rate - I think 6 mm/min. This makes sense as it means that random coordinates typed in aren't going to make the machine head for the hills. If you type in G0 though it will set the machine to rapid moves so then subsequent coordinates will cause moves at the rapid rate just like a G0 in a program. However using G1 mode is a bit more controlled, but to use it you just need to set a sensible feedrate, and as you've discovered 6mm/min isn't! To set a sensible feed rate just type in say F60 <return> and the feedrate box should show this number and now the axis will move 10x faster - but type in a G1 as well just to make sure it's in the right mode.

In general YouTube videos are no substitute for documentation. The M3 manual (you do have a copy?) is pretty good.