Limits and Homing (KL6060 + G540 + LinuxCNC)

Hello Everyone!

Newbie poster with questions on limits and homing...

-Machine is a KL6060 ( 24" x 24" x 3" hobby gantry w/ re-purposed Roto-Zip spindle). Each axis has 2 limit switches wired in parallel
-Controller is a Geckodrive G540,
-Using the stock G40 configs set to machine's lead screws, inch units
-Most of the projects are made from sheet goods (plywood, plastics) 3/4" thick or less

The G540 config supplied with LinuxCNC made it very easy to get up and running. So much so I got it running, have been making chips (100 programs in the last year or so) , and never got into the 'finer points' of running or tuning it.

The machine will perform an e-stop when it hits the limits. But I do not know how to configure or make the machine to 'go home' and then to repeatably find a location on the bed.

Questions:
1. Is it possible to configure a home location with the 2 limits per axis in parallel? How?

2. Once the machine can be homed, does this get 'invoked' somewhere at start-up? How?

3. Once the machine is homed, what is the preferred method of finding the stock?

Currently I program my parts to have x0 y0 z0 to be left (x) front (y) and top of stock (z) and I manually move the spindle to find the stock then home my axes to this location. If the stock has thickness 'issues' I will sometimes set z(0) to be the top of the spoil board.

Thanks! -Oops

Hi


1) No.
Limits should be NC anyway, if they are currently in parallel, they must be NO.
If NO, you can completely detach the signal wire and the machine will still run until it crashes

What you need to do is chain all your - limits together in series on one pin and then connect each + limit seperately to a pin as a 'joint home / limit switch'
Then when homing, the limit aspect of that switch will be ignored

See the config I did for MAG45 here
www.linuxcnc.org/index.php/english/forum...error?start=20#55888
It is set up the same way

2) No, that would be dangerous, you have to click the Home button. Any automatic uncommanded movement on power up is a big NoNo for machines.

3) Jog to position, then Touch Off. Usually bottom left hand corner is X0 Y0, with cutter just touching top surface of workpiece for Z0
Home then becomes a place you start at, normally well away from the workpiece, somewhere safe to do tool changes , where you are not preventing workpieces being changed.

regards

Thanks ArcEye!
The switches look pretty standard, 3 terminals, so the rewire should not be a problem.
The Z axis ones are pretty small, will need to find correct spares as the (z) max/home one is missing its lever and roller.

Is it possible to call a different tool change position than home with a M or G code?
(x)(y)(z) max as home will work, but tool changes would work better near (x) min (y) min (z) max which equates to spindle all the way up, all the way forward, and closest to the keyboard.

Thanks, Oops

Is it possible to call a different tool change position than home with a M or G code?

You can set the toolchange position in the ini file

www.linuxcnc.org/docs/html/config/ini_co...ml#sub:EMCIO-Section

G28 will take you to the home position

G53 Xn Yn Zn will take you to an absolute machine position, irrespective of the offsets currently active
eg
G53 X30 Y30 Z0 would move 30 units away from XY home positions and put the Z axis in home position at the top of its travel, if set up conventionally.

regards