Just got a chance to try your suggestion and it works just fine, but I did have to put in a
M564 H0 as U was not homed.
Thanks for your help.
I have a home built tool changer along the lines of an e3d system but to save weight and allow for a heated chamber I am using a suction cup to couple the tools and a flexy drive to the tool with a single extruder motor serving all the tools. For this design the tools and the tool holder have a splined shaft connection and if it is not aligned properly the tool change can fail. My intention was to giggle the extruder motor backwards and forwards a few degrees as the coupling was made so the splines would engage. So far my tests show this will work.
The problem I have hit is the software will not let the extruder motor move until it has finished running the
_ Pre.g file and selected the tool.
I can think it would be posable with a four pole change over relay to switch to another driver but I am not shore that is a safe way to go and may damage the driver chips, so it would be better to find a solution in the software somehow. I have tried calling a sub program in _Prep.g to bring the tool head forward a few milimeters as I giggle the extruder but I still have the same problem.
Does anyone have any idlers of a way forward so I can move the extruber as I pick up the tool?
I am preparing a motion system I have made myself to be ready for E3d Tool changers when they become available and what to use duet electronics on this machine.
My questions are :
It seems E3d are using a stepper motor on the tool changer mechanism and it has no end stop switch but dose have a mechanical stop, so is there a way to drive it to the mechanical stop with reduced currant and then use that as a reference position?
It also seems form there wiring instructions that there is no mention of end stop switches on the X and Y axis either, so is also posable to do this with the Nema 7 motors?