Changing Home

How to go about changing Home

This is a very popular request, and while it isn’t particularly difficult, there are a several  steps involved.  Note, this can mess with your return location after a job is complete.  Also, we are not changing the origin of the machine, we’re only changing where the module goes when you Home the machine.

• Finding the exact engraving area for the X and/or Y dimension of your machine
  • These are not going to match whatever the manufacturer stated specifications are because we’ve changes some things, and, module sizes have cut into the space
• Offset the distance(s) from the machine’s origin to the location of where you want Home to be
  • Yes, Home and origin are not always the same place
• Change the travel direction for the module when the machine it sent Home.

There is nothing here that cannot be undone, instructions at the bottom.

***IMPORTANT NOTE***  If you are using imperial measurements for your workspace, you need to convert to metric when setting the offsets 

 

Steps

Finding your actual engraving area size (easy)

1. In Lightburn, switch the Move tab
2. On the Move tab, click the Home button, so that the module moves to the current Home position.
3. Notice the X, Y, and Z coordinates at the top of the Move tab, which are telling you where the module is right now (should be 0, 0, 0)
4. Using the jog controls on the Move tab, move the module along either the X or Y axis until it triggers the limit at the opposite side
   1. You need to find that exact point that the limit is triggered (1mm resolution is good enough)
   2. You can change the distance traveled to click to rapidly move a known good amount (eg 300mm) and then lower the amount as need to find the exact point.
   3. Once you find it, test it a few times to be sure
   4. Now you have found the exact number for one axis, record that number
   5. Home the machine
   6. Do the other axis in the same way

At this point, you now know the exact engraving area of you machine.  Besides what we’re talking about here in this instruction, you can use these numbers to set you bed size in Lightburn, so that the workspace presented to you is correct.  (Edit – Device Settings)  For reference, the machine I used to test these instructions with has 345mm on Y (height) and 382mm on X (width). 

Offset the distances (easy)

By default, your machine’s origin and Home are in the same place, front left corner.  This is where we are going to offset from.  Using my numbers above as reference, if I wanted Home to be in back left corner, the machine’s origin would be -345mm from Home on the Y axis and 0mm from Home on the X axis.  Likewise, if I wanted Home to be in back right corner, the machines origin would be -382mm on X and -345mm on Y.  (-382 on X and 0 on Y for front right, for completeness).  All we need to do is tell that to the machine, and tell the machine to report back the workspace.  

1. In Lightburn, switch to the Console tab, which has a command entry block at the bottom
2. Enter in the command: $10=0 and hit enter
3. Enter in the command, G10 L2 P1 X(offset value) Y(offset value) with offset values according to where you want Home to be, and hit enter
   1. Example: G10 L2 P1 X-345 Y0
   2. Your offset value will be a negative number, not a prositive
4. Console messages will appear, noting that steam started and stream completed. 
5. Don’t try to Home the machine just yet…..

Change the travel direction for the module

The last step before you’re ready to try homing.  Right now, the machine believes that in order to find home, it needs to travel towards the front left corner of the machine.  Since you changed where Home is, that’s not correct any longer – the module will need to move in the opposite direction on one or both axis in order to look for Home.  The X and Y axis are independent of each other, making each adjustable to match your desired configuration.  This is done in the machine’s settings, using GRBL.  Lightburn has a nice little UI to make this easy.  Entry you will need to change is the Homing Direction Invert for the axis that needs to change (both, if using back right corner).    

1. In Lightburn, do Edit – Machine Settings
2. Scroll down to the Outputs section and expand it if needed
   1. Ignore any warning that Lightburn might give you that you’re messing with serious stuff
3. Scroll further down to find the Homing Direction Invert for the axis you need to change.
   1. These values are True or False
4. Toggle the value for the axis to opposite of what it is set to currently
5. Click the Write button

 

Testing out your changing home (very easy)

Click the Home button.  The module should now move to the corner you wanted to travel to.

 

Going back (easy)

If changing home isn’t working out and you need to get back to a working state, no problem

1. In Console, enter: G10 L2 P1 X0 Y0
2. In Console, enter: $10=3
3. In Machine Settings, toggle the Homing Direction Invert for each axis you changed previously.