Struggling with coordinate system on bCNC

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Crchisholm
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Joined: Fri Mar 09, 2018 1:29 am

Struggling with coordinate system on bCNC

Post by Crchisholm » Sun Apr 29, 2018 4:11 pm

I have built a small engraving/PCB milling cnc and am using bCNC/GRBL with Protoneer/RP3 for controller. Everything is going very smoothly, but I seem to be in a fog when it comes to bcnc’s coordinate system. For instance, when I home the machine, X and Y move to the upper right corner and Z goes all the way up. I understand Z, nut not X and Y. This sets the upper right corner to 0 so everything in the work area is in negative coordinates. I am from the 3D printer world and thought home would be lower left corner with everything in the work area in positive coordinates.

Can someone ether straighten out my thinking or tell me what I may have setup wrong?

twforeman
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Re: Struggling with coordinate system on bCNC

Post by twforeman » Thu May 03, 2018 6:23 pm

The standard for CNC machines is for machine zero to be in the upper right and all work to be in negative space.

That said, you can move the spindle to anywhere you want and set your zero there.

See: https://www.shapeoko.com/wiki/index.php ... te_Systems
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northbear
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Re: Struggling with coordinate system on bCNC

Post by northbear » Thu May 03, 2018 10:17 pm

My understanding was upper left was zero on many industrial CNC machines as that is the typical location of the hard stop for work holding. (clamps push the part up and to the left).

That being said I set my machine zero as lower left 'cause it makes the most sense in my head.
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