Homing setup problems

I'm new to LinuxCNC but have been using TurboCNC for a year with this same 3 axis mill.

The mill is xyz gantry style (no moving table), using 3 total steppers,

I've read the Getting Started manual, and have followed along through stepconf. I have the axes moving, and in the correct directions.

There are 2 limit switches on the X and Y axes, and one limit switch at the top of the Z axis. The limit switches on a single axis are wired in series, and they go open (low) when tripped. The 3 axes take up 3 pins on the parallel port, one for each axis.

I have chosen "Both Limit + Home X" and "Both Limit and Home Y" and "Minimum limit Z"

I have moved the X and Y axes to the limit switch near 0,0 on the machine (lower lft corner) but not on the switch.

I need help understanding and setting the Home location, Table travel, and Home switch location settings. I have read the manual, but still don't quite get it.

I've tried for example (X axis):

Home location 0.1
Table travel 0.0 to 22.0
Home switch location 0.0

But it doesn't work. As soon as I Home the axis the axis begins to travel to the right from 0,0,0 increasing in X until I manually stop it.

How do I get the home position to be at the lower left of the table?

Thanks for your help.

Thinking about it -- is it possible that the table travel should be reversed for a moving gantry style mill? ie 22" to 0" instead of 0" to 22"? Does the stepconf program assume a moving table?

Have you read this?
www.linuxcnc.org/docs/2.4/html/config_ini_homing.html

Try changing the sign of
HOME_SEARCH_VEL

Table travel 0.0 to 22.0

Is a standard way to set the X axis. So left side of table is 0 right side 22.

Rick G

Thank you Rick!

Last night I decided to just drop the switch based homing option, and set all switches as limit switches only. That made things easy and I was able to home, touch off and actually cut parts today.

But I do want to understand why it didn't work for me earlier -- what I was doing wrong. So I'm reading the section you referenced, and will also try the change you suggest. I might not use homing switches, but I don't like to give up on learning my system. Thanks for your help!

Some of my machines have home switches and some don't. The ones that do not I have hard stops or reference marks to start with so the soft limits work.
But as Andy said if you have home switches installed on your machine it is worth the effort to get them working. Fast easy accurate start up every time.
Glad you are making progress.
Welcome to linuxcnc.

Rick G

vtcnc wrote:

Thank you Rick!


But I do want to understand why it didn't work for me earlier -- what I was doing wrong. So I'm reading the section you referenced, and will also try the change you suggest. I might not use homing switches, but I don't like to give up on learning my system. Thanks for your help!

I found it confusing when I started with Linuxcnc and its easy to miss as Rick has pointed out putting the - sign before the HOME_SEARCH_VEL will reverse the direction of travel ie -25.000 instead of just 25.000. this is also true for some of the other perameters. ..Clive