Want to increase K40 bed size, but lightburn adding extra space to the top instead of bottom

Im trying to increase the bed size of my K40 (running a cohesion 3D board) from 300x200 to 300x220. When I go into the machine settings and change it there it seems to add those extra 20mm to the top of the bed instead of the bottom. So what happens is I home the laser, then when I go to frame something it will try to go up past the homing point. So for example I have a piece thats 210 tall. Instead of going down those extra 10mm it tries to go up. What do I change? If I change the point of origin that just seems to make everything worse.

Something else is happening. It just uses the size entered based on the origin. It can’t add it ‘above’ anything.

When your machine is home, does it show a 0, 0 position?

What is “Start from” set and what is the job origin?


Origin is bottom left (which is what its supposed to be set for the cohesion board). Home is top left. 0, 0 is bottom left. Start from is set to absolute cord, and job origin is top left (but I dont think that matters with absolute cords set). Also if I set the bed size to 220 and hit “Go to Origin” it goes to the same place if I have my bed size set to 200. Its like the bottom left is set in stone.

inside the config file the basic bed size is listed (particularly the Y distance. it is preset to 200mm. When initializing it goes “UP” to the limit switch and sets that as “home”. Origin is 200 mm "down’ from there. When you specify 220mm Y distance it tries to go 220mm from origin.
You need to go into the config file and increase the Y span to your 220 mm. Sorry I forget the line number.

You know when someone says something, then you feel like a totally idiot? Yeah, thats how I feel now. Googled “cohesion3d change bed size” and it was the first thing that popped up on what I have to change. Its beta max which is line 265 for me.

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