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Agathon
02-07-2017, 04:41 PM
I wonder if the clever and experienced members of this forum can help me with this problem. I have a Fehlmann Picomax 50 machine which I've retrofitted with up to date drivers/motors to be driven with Mach3. The machine uses a quick-change tooling system which is ejected when the quill is fully retracted. The following video will explain the problem far better than many lines of text:


https://youtu.be/hV1g_xGCudA

Here's a general introduction to the project:http://www.mycncuk.com/threads/11067-Fehlmann-Picomax-50-CNC-conversion-refurb

m_c
02-07-2017, 07:57 PM
That could be a bit tricky in Mach3, as you can't reconfigure limit switches on the fly.

My initial thought, is add an extra relay controlled by an output, that overrides/bypasses the Z upper limit switch.

Then in your M6 macro, have it activate the Z upper limit override output/relay, then command a Z move until the tool change switch is triggered, change the tool, then move back down far enough so the Z-limit switch is cleared, then deactivate the limit override output.

A safer option might be command a G53 g-code move up, which would avoid running into a mechanical limit, if the limit switch was to fail. The distance the axis has to move should not change, so using a specified move should work well.

Once you have that working via your M6 macro, adding a button to control it should be relatively easy. In fact thinking about, you'll probably want your M6 macro to pause and wait for a manual input anyway, otherwise it'll drop the tool whenever it reaches an M6.

Agathon
02-07-2017, 09:21 PM
That could be a bit tricky in Mach3, as you can't reconfigure limit switches on the fly.

My initial thought, is add an extra relay controlled by an output, that overrides/bypasses the Z upper limit switch.

Then in your M6 macro, have it activate the Z upper limit override output/relay, then command a Z move until the tool change switch is triggered, change the tool, then move back down far enough so the Z-limit switch is cleared, then deactivate the limit override output.

A safer option might be command a G53 g-code move up, which would avoid running into a mechanical limit, if the limit switch was to fail. The distance the axis has to move should not change, so using a specified move should work well.

Once you have that working via your M6 macro, adding a button to control it should be relatively easy. In fact thinking about, you'll probably want your M6 macro to pause and wait for a manual input anyway, otherwise it'll drop the tool whenever it reaches an M6.

Thanks for this - really helpful. I'll do a bit of research.

I'm coming round to the idea of switching to LinuxCNC so may have to rethink this yet again.