Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Himark on October 08, 2009, 06:23:41 PM

Title: Homing a machine without limit switches installed
Post by: Himark on October 08, 2009, 06:23:41 PM
Is it possible to home a machine(Mill) without limit switches installed?  Ideas or procedure to do this would sure be a big help.

Thanks
Title: Re: Homing a machine without limit switches installed
Post by: Konrad K on October 08, 2009, 06:39:26 PM
Hi Himark,

homing without home switches? So to say, as a manual procedure?

Before I equipped my "prototype mill" with limit switches, I did it as follows:
(I was running on soft limits)

- first, switch the coordinate DROs to "machine coordinates"
- then, jog the machine to the desired reference position (you can define the individual reference position of your machine in "Config - Homing/Limits - Home Off.")
- press "REF ALL HOME", and the "Home Offset" will be written to the (machine-)coordinate DROs.
- switch off machine coordinates to see again the work coordinates.

--> The Limit switches must be unassigned in Ports and Pins, and "Auto zero" in "Homing/Limits" enabled.


On very small machines with low torque drives, it might also be possible just to drive against the mechanical limits until you reach the soft limit, but this is not nice to your machine.   >:D


But on the other hand, it's really worth the trouble to put limit switches on the machine, because it saves much time and.... IT'S AUTOMATIC ;-)


regards,
Konrad

Title: Re: Homing a machine without limit switches installed
Post by: Himark on October 09, 2009, 12:59:39 AM
Thankyou for the help.  I will try this in the morning and see how it goes.

Thanks again.
Title: Re: Homing a machine without limit switches installed
Post by: bowber on October 09, 2009, 04:57:36 AM
I have 2 machines.
One is a smallish mill with quite large steppers, this has home switches which are just N/C micro switches wired in series to one pin, works great and is very close on repeatability. I wouldn't want to use any mechanical stops as it'll just damage something or even snap a casting, this thing drove the collet chuck through a clamp and only lost a few thou in steps.

The other is a home built router with out any switches, this one I just home till it stops and then click the ref all, again very repeatable but it runs quite small steppers so not much chance of mechanical damage.

Steve