Home Limit Switch

When I home my cnc router, when the Y Axis's hit their switches, they come off and go back to the switch as expected. Then the switch gets smashed and the machine stops. It's not trying to move any further.

Here is the code being used on one Y axis

[AXIS_Y]
MAX_VELOCITY = 150.0
MAX_ACCELERATION = 200
MIN_LIMIT = -0.001
MAX_LIMIT = 838

[JOINT_1]
TYPE = LINEAR
HOME = -12
MIN_LIMIT = -0.001
MAX_LIMIT = 838
MAX_VELOCITY = 200
MAX_ACCELERATION = 200
STEPGEN_MAXACCEL = 220
SCALE = -80.0
FERROR = 1
MIN_FERROR = 0.25
HOME_OFFSET = 0.000000
HOME_SEARCH_VEL = 30
HOME_LATCH_VEL = 5
HOME_SEQUENCE = -1

Easy solution is to switch;
HOME = -12
To
HOME = 12

You have the machine going to this location for the home switch.
HOME_OFFSET = 0.000000

Then ask it to go to
HOME = -12

When complete, which makes it hit the switch. HOME is the location the axis moves after the sequence is complete. I would also change:
MIN_LIMIT = -0.001
To be farther away from your home
HOME_OFFSET = 0.000000
You want to make sure the axis moves far enough off the axis to clear the throw of the switch it self and to compensate for any slop or chips that may be present. Switch
MIN_LIMIT = -0.001
To
MIN_LIMIT = 1.000
Assuming this is all in mm

i'll try this config

Thank you for taking the time to help me with this. After reading your reply, I realized how I should have seen this.

I wonder if my Z is backwards...

When I home all, the Z goes up, hits the switch and back off of it by 12mm's

But in the settings, I have home set to -12

Based on what you have told me above, something seems off in my thinking. If I understand you correctly, Home should be 0,0 and when the axis's move off of their respective switches, the machine coordinates should be moving into positive numbers.

I think what's throwing me is I had an MPCNC and I homed to the rear right corner with that as this one. But when I moved off the switches, I was always in the negative.

I will try your suggestion. It makes total sense to me. Thanks a ton!

Above you were talking about Y Now you are talking about Z

If you are talking about Z then it is common for Z to be going -ve when going down. So -12 should send the Z down 12 units

Thanks Clive. The Y's are working now. But I know there is still something wrong with my thinking about the machine coordinates.

When I push the down arrow on my keyboard, the Y axis moves to the back. So I know that I've got the Y motors wired in the wrong direction. Do I change the sign on Home_Search_Vel to have the gantry move towards the back after?

I think this issue is what made me think I had a problem with the Z

PastorHealer wrote:

Thanks Clive. The Y's are working now. But I know there is still something wrong with my thinking about the machine coordinates.

When I push the down arrow on my keyboard, the Y axis moves to the back. So I know that I've got the Y motors wired in the wrong direction. Do I change the sign the same as on Home_Search_Vel to have the gantry move towards the back after?

I think this issue is what made me think I had a problem with the Z

This all depends where the switches are located front or back I take it the Y is the gantry if so and you have two motors then the sequence has to be a -ve same number on both joints (motors)

You can change the direction of the motors by make the SCALE=xxxx -ve but then you have to change all the rest below

re this:
[JOINT_1]

HOME = -12 .. this will be the final home postion
HOME_OFFSET = 0.000000 .. this is to square the gantry ie 0.5
HOME_SEARCH_VEL = 3 ..If you cange it to -ve it will search in the opposite direction 0
HOME_LATCH_VEL = 5 .. as above
HOME_SEQUENCE = -1 .. this has to be -ve for gantry squaring

When I home now, all joints home properly, move off of the switch 12mm's. Perfect!
But then I'm getting "Exceeded Negative Soft Limit (-0.00100) on joint 1 X
And "Exceeded Negative Soft Limit (-0.00100) on joint 2 Y's

I can see why I'm getting the error as "Home" value is a negative value. What I can't figure out is why the machine is homing properly in spite of it being wrong.

Home is wanted to be at the right / rear of my cnc router

Here are my Y settings:

[AXIS_Y]
MAX_VELOCITY = 150.0
MAX_ACCELERATION = 200
MIN_LIMIT = -0.001
MAX_LIMIT = 838

[JOINT_1]
TYPE = LINEAR
HOME = -12.0
MIN_LIMIT = -0.001
MAX_LIMIT = 838
MAX_VELOCITY = 200
MAX_ACCELERATION = 200
STEPGEN_MAXACCEL = 220
SCALE = -80.0
FERROR = 1
MIN_FERROR = 0.25
HOME_OFFSET = 0.000000
HOME_SEARCH_VEL = -30
HOME_LATCH_VEL = 5
HOME_SEQUENCE = -1

#HOME_SEARCH_VEL = 0
#HOME_LATCH_VEL = 0
#HOME_USE_INDEX = NO
#HOME_SEQUENCE = -1

[JOINT_2]
TYPE = LINEAR
HOME = -12.0
MIN_LIMIT = -0.001
MAX_LIMIT = 838
MAX_VELOCITY = 200
MAX_ACCELERATION = 200
STEPGEN_MAXACCEL = 220
SCALE = -80.0
FERROR = 1
MIN_FERROR = 0.25
HOME_OFFSET = 0.000000
HOME_SEARCH_VEL = -30
HOME_LATCH_VEL = 5
HOME_SEQUENCE = -1

#HOME_SEARCH_VEL = 0
#HOME_LATCH_VEL = 0
#HOME_USE_INDEX = NO
#HOME_SEQUENCE = -1

Thanks for any assistance.

Thank you. I will try that.
On my old cnc, home was back right corner as well. But all the numbers on the dro were negative from home. I'm pretty sure this is why I'm struggling with this software.

I'm having to rethink my work area. Am I right in this?

I was told cnc's all use a negative work area.