Why isn't my HOME at 0,0,0

Hi ,
I have a new 2017 version 1000mm xcarve. I just added homing switches as I didn’t purchase them with the machine. They seem to work ok but after Homing to the front left corner, the Easel machine inspector consistently says my machine position is;
X -789.000
Y -789.000
Z -1.000
If I reboot, it will report that I am at Machine (0,0,0) but if I then HOME or $H, it shows the above coordinates.

I assume that it is these particular numbers as it is 1mm off my work area of 790mm x 790mm for a 1000mm machine. However I think that would mean that my zero point is actually at the back right rather than the front left where you would normally want it.

I have already tried all the usual trouble shooting - setting the machine to use Homing switches, rebooting and re-loading the firmware.

Any ideas?

Carve => remove material => subtract => negative space

You are correct that that Machine Home, is 1mm off the 800x800 point. This is due to the amount of pull-off (1mm, defined by GRBL value $27) from the Homing switches.
Machine Home can only be at one of the extreme ends.

Easel “Home Position” - or Work Zero can be anywhere within the space the machine can reach.
In Easel you assign Work Zero by clicking “Confirm Home Position” - you are actually telling the controller that that point is work zero

Machine Home provide a consistent reference point of one where to use preset points, work offset etc.
Home Position tell your CNC where to start carving.

If you would like to work in positive space it’s easy to fix. What version of grbl are you running ( since your machine is new most likely 1.1f )?

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Yes I am running 1.1f.

I am not very concerned about running in negative space, it was just not what I expected. When I set my Work zero, it runs positive toward the back right, so I thought that my Machine home coordinates would function the same.

As long as this is 'normal ’ and remains consistent I am not going to worry about it. I added the Homing switches because my USB hiccupped( for unknown reasons) halfway through an hour carve and then I learned the hard way that work zero is lost. A common story I expect.

It is normal.

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If you homed the machine before the project, you can click reuse previous zero. :grin:

I think I got it now. Thanks to everyone for the quick response. :grinning:

I can’t speak to the context issue, however, in grbl negative/positive space and which way homing goes are two independent functions.

Best I can determine the convention for homing is to move the axis in the positive direction.

If you followed the build instructions for the original X-carve positive Z is up, positive X is right, and positive Y is back.

That’s why most people using the earlier machine had to use a $3 setting of three ($3=3) to reverse the direction of movement on X and Y to get the machine to home Z up, X left, Y front.

Larry, quite awhile ago you helped me work in positive space when I was using 1.0c (I think). Are you saying there is a way to do that using 1.1f? I would like to use the variable speed that’s available in 1.1f but I can’t wrap my head around the negative space that is used in 1.1f.

This may help a little. This is a video that explains machine home and x,y home for a project

A link to my channel

Hope this will help to see it in action


There is a conflict between positive space and parking. This version has parking disabled in order to use positive space.

I do not recommend 1.1f for laser work.

I do recommend 1.1f for spindle work only.

grbl_1_1f_20170417_positive.hex (84.5 KB)

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Thank you so much, Larry! I don’t get to use the XC as much as I would like but I hope to get this installed in the near future and I will let you know how I make out.
Thanks again,

Hi Larry,
I haven’t been ignoring you or forgotten about you, I just haven’t had a chance to get back to the XC until today. I got the new version installed today and now I can use the variable speed and still have the positive numbers. Thank you so much. I really appreciate this and also all the other valuable information and advice you give everyone on this forum!
All the best,