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Establishing Max "X" Position on M2?

Posted: Fri Nov 24, 2017 4:09 pm
by Gwhite
I'm designing an enclosure for my M2E, and I'm trying to figure out how large the box needs to be. I'll be using 1" square 80/20 structural aluminum for the frame, and I don't want to make it any larger than I have to.

The cover will sit a little ways above the extruder, with a slot in it so the Bowden tube can move back & forth. There will be frame members holding the panels in place running down each side of the cover. I want to make sure the top right frame bar won't get run into by the extruder motor when the extruder goes to its maximum X position.

However, I don't know how far the extruder assembly can go under normal operation. Mechanically, it can go over quite a ways, but by the time it hits the hard stop, the extruder nozzle is WAY past the edge of the bed platform. I suspect the extra rail length may be required to work with a dual extruder.

I'm assuming there is a software/firmware limit that prevents it from banging into the hard stop, but I don't know the easiest way to find out where that is. If I just turn the machine on and keep jogging the X position, I can run it into the hard stop because it the printer no idea where zero is. If that can happen in normal use, I will need to accommodate the extra ~1.5" of travel past the edge of the bed.

Once the machine has "homed" and is actually printing, is there a software limit buried someplace that prevents it from going too far? Is there an easy way to send the printer to that location to measure where the extruder ends up? I think I need the equivalent of the following G-code commands:

"home" X-axis
Go to X-Max


Re: Establishing Max "X" Position on M2?

Posted: Fri Nov 24, 2017 4:59 pm
by sthone
The farthest right the extruder travels during normal operation is the purge location during the start of any print.... just start a print and mark where it stops during the purge and I'd think you'd be good.

Re: Establishing Max "X" Position on M2?

Posted: Fri Nov 24, 2017 5:57 pm
by Gwhite
That was going to be my default approach. I was just wondering if there is anything hard coded someplace to prevent it going further than that once it has "Homed".

I looked through the RepRapWiki for useful looking G-codes to search for, but all the good one don't appear to be implemented in the Marlin devices... For example, there is a M360 command that lists out all sorts of configuration info, including the value of "Xmax". I may fire up the printer & try this just in case the Wiki is out of date.