I may be missing something obvious,

Mike_Thornbury · August 28, 2018, 1:35am

I may be missing something obvious, but is it possible to move/offset gcode objects around in the Chilipeppr 3D space.

For example, if my machine is homed and I try and run the default/test Chilipeppr mm logo, 0,0,0 is in the middle of the logo and within a few commands, it trips my limit switch.

Line 11 of the logo code is: N11 G0 X39.2659 Y-3.4776 which is the line that tries to send my carriage to negative space.

This isn’t a problem with the demo itself - but how to offset models that have their origin at a different place from 0,0

I guess it’s not a serious problem, as I will be generating my own gcode, but I was interested in how to cope with a situation where a model was built with an unusual origin.

sszafran · August 28, 2018, 8:36am

A workaround:
Type im the console: G28.3 X-50 Y-50 to change machine coordinates without gantry moving.
My very first CNC cut long time ago was a CP logo, unfortunately with no limit switches installed. IT was a plywood based machine with ball screws and I still remember the sounds.

I think this would be better to have the logo positioned in the positive X/Y quarter and not centered in relation to (0,0) to avoid crashing issues. This will also help CNC newbies not to learn the hard way, I did. @jlauer do you see any chance to update logo positioning on the default CP page(s)?

cmcgrath5035 · August 28, 2018, 9:44am

There is no “standard” among graphics/CAD design tools as to where in the X-Y space models are authored. For tinyG users, the default G55 coordinate system is offset from G54 (0,0) by (Xmax/2,Ymax/2), but that is tinyG specific.
Keep in mind that many DYI machines do not have limit switches or homing cycles.

jlauer · August 30, 2018, 3:36am

The more I’ve machined, the more I set the 0,0 in the lower left corner, so yeah, that CP logo is odd to have the 0,0 in the center. It’s not a bad idea to get a different default logo in there.

Mike_Thornbury · August 30, 2018, 4:13am

So is there a way to set up an offset? And I guess there’s no checking of Gcode validity, so ltbb

jlauer · August 30, 2018, 2:58pm

Yes, you move your machine to the center position and could hit “Set Mch Zero” or you “Set Gxx Zero” based on which WCS layer you are in.

Mike_Thornbury · August 30, 2018, 3:22pm

Ok. I was hoping for an ‘offset’ parameter, rather than rehoming, but that works

sszafran · September 1, 2018, 1:56pm

This is what G28.3 XYZ is doing. This command will change coordinates per axis without gantry moving. Only enter values for axis you want to change the coordinates.

Mike_Thornbury · September 7, 2018, 7:40am

Really, G28.3 sets the counter on the axis relative to wherever the machine currently is - not an offset as such.

For example: A CNC machinist adds a laser engraver to his router. When the router is at 0,0, the laser is at 15,20

You do your laser engraving, then your cutting, but zeroing your machine just once, at the beginning of the laser job.

With an offset that doesn’t change the physical 0,0 of the machining tool, theres no chance of misaligning the two jobs.

The alternative would be to do the milling before the engraving and have a ‘pre’ GCode that performs a G0 X15 Y30 G28.3 X0 Y0 or G28.3 X-15 Y-20

Either way, you are changing the setup of your machine to store a different image of the axes from the physical axes.

Having an offset option means the machine never changes once zeroed, but the GCode is offset to account for the different tool.

How does it work with multiple machining heads with different tools?