Z axis homing problem

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08-25-2008, 10:51 PM
BillTodd

Z axis homing problem

Hi all,

I've just configured EMC2 for use with my homebrew engraver/mill. I'm really pleased with the way it went, pretty much hitch free (once I'd read the manual :)). Much nicer than the TurboCNC I'd been using previously.

The machine has only a small Z movement. I've configured the axis to home to a switch at +15mm.

Most of the time, pressing 'home', winds the Z axis up to the switch then up/down before reseting the machine position display to 15.000 (exactly as expected). However after I've run an air cut, zeroed the axes with g00 x0 y0 z0, then press home all (or Z only) it'll home up to the switch jiggle (at about 15mm) then reset the display to 14.300.

I don't think the Z axis is losing steps (and in any case the home should reset to 15.000 every time shouldn't it?)

Any ideas?

Oh and while have your attention; How do you get EMC to start full screen? (I'm a linux newbie)

http://www.cnczone.com/forums/attach...5&d=1217953810
08-26-2008, 12:15 PM
cyclestart

Quote:

Originally Posted by BillTodd

Oh and while have your attention; How do you get EMC to start full screen? (I'm a linux newbie)

You would think think that would be simple, right? Not so. Search the linuxcnc.org wiki for the term devilspie . I considered that advice briefly and decided clicking maximize or hitting alt+F10 was less bother :)

Can't think of the answer to the homing question. Maybe after some coffee.

Interesting looking machine. If that's a homebrew you have some obvious fabricating skills. I love homebrews.
08-26-2008, 03:24 PM
Big John T

Bill if you are doing an offset and not resetting it after like in the MDI window EMC is correctly reporting your offset position after the home. Just do a G92.1 to clear the offsets and reset the variables to 0.

http://www.linuxcnc.org/docview/html...,-G92.1,-G92.2,

John
08-26-2008, 03:34 PM
BillTodd

Devils pie indeed :)

It's bad enough that the computer world is filled with jargon, but when Linux developers use stupid names for applications etc. they shoot themselves squarely in the foot. It simply puts me (and many other people) off the idea of using the operating system :(

Alt-F10 is is then :LOL:

Quote:

Interesting looking machine.

:)

It's been in development for a decade. Most of it is parts recycled from other machines. I had only an old delta pillar drill when I started it, so I had to re-use any precision parts I could find (e.g. the lead-screw bearing blocks are cut from the end plates an 8" FDD drive motor).
08-26-2008, 08:55 PM
BillTodd

Quote:

Originally Posted by Big John T

Bill if you are doing an offset and not resetting it after like in the MDI window EMC is correctly reporting your offset position after the home. Just do a G92.1 to clear the offsets and reset the variables to 0.

http://www.linuxcnc.org/docview/html...,-G92.1,-G92.2,

John

Thanks John.

It wasn't actually offsets, but your post did remind me to check and edit the tool table. :oops:

I didn't realise EMC had a default set of tools, one being 0.7mm long!