Z axis moves really fast in Pronterface

There are a couple of movements after I load a sliced file and Slic3r config along the Z-axis, and I can't figure out where the settings are.

One way to replicate it is to pause the print, manually issue a Z-axis command in Pronterface, and then click "resume." The Z-axis will go back to where it was before I issued the manual commands, or at least try to, with a speed so fast my Z motors can't keep up.

Where is this set? I can't find it anywhere. I have speeds all set at 30 mm/s in the Slic3r config.

I had a similar issue. [forum.lulzbot.com]
pronterface does not have any control over the speeds issued by G-codes, and Slic3r cannot slow down only one axis, (the Z axis in our case). The firmware is the ultimate limiter of the axis speed, and it is not configured correctly for your specific machine.

If you use marlin firmware, or probably any others, you can easily re-set the max speed of each axis with an M-code. but this will re-set everytime the machine is powered down unless you update the firmware with these settings (sometimes an M-code can save the settings to the EEPROM). see the link above for more details.

but basically if you put the code: "M203 X192 Y208 Z4" in your custom G-code before printing area, or manually enter it, it will set the max speeds. In this case X axis at 192 mm/s, Y at 208mm/s, and z at 4mm/s

you will have to experiment with the speeds to see what your machine can actually do. and make sure you move the x and y at the same time when you are testing it.

Edited 1 time(s). Last edit at 07/13/2013 09:06AM by 1013.

Thanks very much for the insight. Your information helped me learn how all of these things are connected. You mentioned the EEPROM, whose Z-max feedrate it seems is defined by DEFAULT_MAX_FEEDRATE in the Marlin firmware config file ("Configuration.h"). This value (the third in the quadruplet) was set to "5" and I realized that's 300 mm/min, which my machine can't do.

I noticed these values are ultimately put into an "M203" command in EEPROMwrite.h, which I would not have understood had you not mentioned it.

I set the value to "3" -- my machine can certainly handle 180 mm/min -- and am going to test it. If it doesn't work, I'll put the M203 command in the custom G-code.

That said, I wonder whether a lot of people's machines can take a Z-axis feedrate of 300 mm/min!? That seems too fast, at least for plastic couplings. But maybe their X-carriage design is more secure than my Prusa, which is secured by two nuts and has more freedom of movement along one vertical rod than the other. I suppose that's a question for a different thread.

Edited 1 time(s). Last edit at 07/13/2013 03:17PM by shiggity.