Messages

1

General Mach Discussion / Re: Rotational speed

« on: August 21, 2010, 02:58:42 AM »

Thanks.  That's it.  I set it to 1200 units/min, or roughly 3 deg/sec, and speeds came up to a reasonable level.

OK, now I think I've found all the necessary settings.  Clearer documentation would help.

2

General Mach Discussion / Re: Rotational speed

« on: August 21, 2010, 01:00:48 AM »

OK, I've been trying a few things. (Again, I'm testing on Mach 3 Version R3.042.040 in demo mode, not on the actual CNC machine, which has a registered version.)

This is an engraving-like job on the outside of a cylinder.  (I'm making a print wheel, which is a reverse engraving job,
but I'm debugging by trying to engrave simple patterns on a cylinder.)

The radius is set to 2.0" in Mach 3, and the A axis is set as rotational in Setup->Toolpath, where I also set Axis of Rotation
to X axis, and set "A rotations enabled" and "Use radius for feedrate".
The 3D display reflects this; I see the proper A axis rotation in the tool path display.
So Mach3 is properly understanding the setup geometry.

I set the feedrate in the Gcode as F100, and I have coordinated moves in X and A.  Y=0.0 at all times.  What seems to happen is that
I get rotation at 100 degrees/minute, and linear motion at 100 inches/minute.  Even for coordinated moves where
both X and A are changing. So X movement is as specified, but A movement is far too slow, by about a factor of 10.

I tried putting a "Y0.0" after all A moves in the GCode, thinking that perhaps it would make Mach do the "coordinated move" feedrate
calculation as described in the manual. That had no effect.  I've tried making small changes to the X coordinates so that the moves
in the A axis aren't pure A axis rotations.  That had no effect.  I tried exiting and restarting the program after making changes
to Config->Toolpath. No effect.  Reloaded G-code. No effect. Clicked on "Regen Toolpath". Redrew the Tool Path display pane
correctly, no effect on feed speed.

Any ideas?

I can't get that "coordinated speed" feature no matter what I do.

3

General Mach Discussion / Re: Rotational speed

« on: August 18, 2010, 05:08:32 PM »

OK. So can you set the feed rate differently for different axes?

4

General Mach Discussion / Rotational speed

« on: August 17, 2010, 03:28:14 AM »

According to the manual, section 10.1.6, when a move involves at least one linear axis and a rotational axis, the feed rate for the rotational axis is computed using the "correction diameter" to convert a feed rate in linear units into an angular rate which will get roughly that feed rate at the indicated diameter.  That's reasonable enough.

Then, though, the manual says "For rotation of one rotational axis with X, Y, and Z axes not moving, the feed rate means degrees per minute of the rotational axis.". So, every time the program calls for a pure rotational move, the feed rate is supposed to be drastically different than for coordinated moves. Which is usually not what you want, especially with programs that may just happen to generate a move that's a pure rotation.

I haven't tried this on the real mill (which has an older version of Mach 3) yet, but i've been running Mach 3 R3 042 040 (unregistered/demo) on a computer not connected to a machine tool to test the GCode,.  The A "radius" is set to 2.0, the "Radius Correct" indicator is yellow, feedrate is 54, but the A axis never moves faster than about 1 degree/second, which is far too slow for the indicated linear feed rate.