I made (hacked actually) a few changes to the post to help with tool changes. First, I wanted to keep the steppers driven during the change to reduce the chance of moving the the axis out of sync with the origin. The pause, M25 (or M1) does keep the steppers active during tool. The problem is that Marlin has a default timeout of 60 seconds after which the steppers are disabled. I did not want to modify the configuration.h file just for this and found that M84 Sseconds can be used to temporarily change the default timeout. An argument of S0 will disable the timeout all together. Also, on my current MPCNC build, I made the Z standoffs too short and I don’t have a lot of headroom for retracting enough to get the bit out for thicker stock. I usually have my origin at the lower left corner of the stock, so on a tool change I moved XY to a location beyond that to give me room the get the bit out.
I use an LCD’s SD card reader for input and have not used a USB host driver like Repetier Host in ages so my changes will probably not work over USB. I’m sure some minor change will make it compatible with a host.
My changes are something like:
`- Removed odd characters
– M25 (or M1) keeps steppers active during tool change,
Problem is that the steppers are disabled after a 60s timeout,
So “M84 S1800” was added to preamble to change the timeout to 30 minutes.
– On tool change:
Retract Z15, X-30, Y-30,
Display “Change to Tool T#” to LCD
– To resume after tool change select “resume Printing” from menu`