Centroid Community CNC Support Forum

You can also try one of the included files in CNC12. Pawn is pretty popular. I believe it is 1" stock

Ok thanks Marty, I'm not near the controller ATM, but the things you suggested will be my next move.

If you have an encoder installed there are files that use ENCODER in another directory in the NC files directory

Always F8 Graph the part first and make sure it looks right and you get no messages back from CNC12

Thanks Marty, I do have an encoder, so I'll use that file. Is there a metric version?

Hi Marty,
I have attached my test file for you to look at. I tried running the lines of the file individually using the MDI as well. Some of the lines do nothing, for example G90 X24.6 Z-9.95 leaves the Z at 0.5mm on the DRO, and there is no movement from the axis on the lathe.

Manually typing G0 Z-9.95 moves the Z axis to -9.95mm though.

I tried running the PAWN-MM - enc.cnc file and the X Axis moved back more than 80mm from the centreline of the lathe and broke the belt when the ballscrew reached its limit. I think I'll setup limit switches before I try anything else.
Just an observation, however, the X axis was showing 26mm on the DRO prior to the catotrophic move. I had commented out the G28 moves, since I didn't have home switches.

Finish setting up your machine. Read the lathe operators manual on setting up tools. Always F8 Graph the part before you run it, set your feedrate over ride way down when you first run a part, perhaps use single block mode on the first part ( you have to press cycle start for each line of code)

Is this your first CNC lathe and first time operating one?

What was your return position set at? First thing the Pawn program will do is move to the return position to perform a tool change. Did you have the spindle turning and a feedrate specified when you MDI'd "G90 X24.6 Z-9.95' and pressed cycle start? G90 is a turning cycle so it won't do anything in feed per rev when the spindle is not turning.

Also in your example program, you have a feedrate set of 300mm per revolution of the spindle. I suspect your z-axis to fault almost immediately with the spindle turning 800 rpm.

martyscncgarage wrote: ↑Thu Oct 15, 2020 9:44 am Finish setting up your machine. Read the lathe operators manual on setting up tools. Always F8 Graph the part before you run it, set your feedrate over ride way down when you first run a part, perhaps use single block mode on the first part ( you have to press cycle start for each line of code)

Is this your first CNC lathe and first time operating one?

Marty, whilst this was my first CNC machine (back in 2001ish) it is not my only CNC machine. I used Mach3 and steppers initially, then upgraded to servos. I don't remember any issues with that original iteration, but it was all a long time ago and it became just another tool in the shed. I almost always used the wizards in M3, so I didn't really need to worry about machine co-ordinates vs part co-ordinates etc. I would just face the part to find Z0, take a small pass on the diameter, measure it and set my X axis accordingly. The Gcode generated by the M3 wizards was fairly simple, I think.
As I said (and you confirmed) I will finish setting up the limits, to prevent a possible repeat of the previous issue and look at the manual as you suggest.

tblough wrote: ↑Thu Oct 15, 2020 10:23 am What was your return position set at? First thing the Pawn program will do is move to the return position to perform a tool change. Did you have the spindle turning and a feedrate specified when you MDI'd "G90 X24.6 Z-9.95' and pressed cycle start? G90 is a turning cycle so it won't do anything in feed per rev when the spindle is not turning.

Also in your example program, you have a feedrate set of 300mm per revolution of the spindle. I suspect your z-axis to fault almost immediately with the spindle turning 800 rpm.

Tom, perhaps I was too ambitious with my first try at using the lathe after changing to Acorn. 300mm per Rev of the spindle is way too fast, I was trying to replicate what I did sucessfully in the M3 wizards, but obviously got it wrong. By "return position" do you mean tool change position? I'm not sure if the spindle was running or not when I commanded G90 X24.6 Z-9.95. I'll check and see after I fit the home switches.
Safety second