Autoleveller and USB CNC

[booski]

I've got one of those Planet CNC USB controllers here.

I was under the impression that the controller (MK1) has built in probing. It doesn't!

So I'm wondering whether anyone has tested out autoleveller with this before and it's software?

Or even whether it would work?

[daedelus]

As memory recalls, I do remember a guy using USB CNC to generate the GCode but mach3 to do the actual milling. And I think it worked OK. You may need to convert arcs into straight line segments, not sure but it should be OK to generate the GCode, run it through Autoleveller and take the new code back to USB CNC for probing / running. Not sure if variables etc. are the same in USB CNC as I have never used it.

As Autoleveller works on the Gcode only. It shouldnt matter which program generated the GCode in the first place. Having said that, Autoleveller only uses a very primitive parser for the GCode which may or may not support your GCode flavour. Currently, I am working on a parser library for use in Autoleveller which will improve things and make it easier to maintain seperately: https://bitbucket.org/daedelus1982/gom.

Other, future software such as a planned toolpath optimiser will also use the parser.

[booski]

Well, I don't intend on using USBCNC to generate the gcode, that would be done elsewhere and put through autoleveller and then use USBCNC to control the machine.

Basically, I'm looking to do away from my clunky all in one pc to a modern laptop that I can plug and play rather than having to leave permanently set up.

It's a little awkward though because the USBCNC is MASSIVELY complicated, no where near as easy to use as LinuxCNC BUT it is USB. Something that LinuxCNC doesn't support because it doesn't have the hardware layer.

What variables are used in auto leveller? As I might be able to find out if and what they are in USBCNC.

[Country_Bubba]

The main variable that you need to find out is the one that is set when the probe touches. It also may not set one (I use turbocnc and it did not and had to recompile so it would).

[daedelus]

I think Art, your turboCNC uses G31 as the probing command, same as mach3? Come to think of it USB CNC probably uses something different (linuxCNC uses G38.2 if memory serves me). So I'm guessing that without changing the code to support it, Autoleveller wont work with USB CNC. I could be wrong.

P.S. the normal variables used start at #500 normally, for linuxCNC and mach3

[Country_Bubba]

Correct, turbocnc uses G31 for probing and the variables set when probing are the same as Machs of 200x for each of the axis X,Y,Z. The Planet CNC website indicates the G code is compatible with Linuxcnc so I would assume it uses G38.1 for probing and would check to see variable #5422 is set when the probe makes contact. If it does, then the linuxcnc post can be used.

[booski]

Hmm, I might get the board out later and have a play with it.

The trouble is, because it's an MK1 style board there are no inputs as such. You can apparently set the Z- limit as a probe input.

I might later tonight have a play with it and see what happens. It's massively complicated and so may take a while.

[booski]

Short answer. No.

Long answer, tried to use a piece of Gcode previously transformed with AL in the USBCNC Software and it just spat out an error message about using L something with G something instead of something else. I didn't think to write it down but if it's spitting out error messages straight off the bat then I think it's safe to say that it isn't compatible.

Not to mention I blew my controller board whilst experimenting.

[daedelus]

The error message you refer to sounds like the line that sets Z to 0 (the line with the L in it). Different versions of linuxCNC reject this line and I have received a few queries about this line recently. I should replace it with something more universally compatible at some point.

This is only one line at the start of the AL GCode file however and can easily be replaced manually. The line you are looking for is:

Code: Select all

G10 L20 P0 Z0

replace with:

Code: Select all

G92 Z0

The previous line tells linuxCNC to set the Z axis to 0 in the coordinate system refered to by P. P0 is the default G54 as I recall, except P0 is not recognized by all linuxCNC versions. G92 Z0 does the same thing, except G92 tells linuxCNC to reset for all coordinate systems, which is only a problem if you use more than one.

The replacment line, should work in USB CNC too. Replace the line, then see if USB CNC complains when you load the file.

[booski]

Might be a little while now James. My board has a blown chip on it which it's going to be a while before I get another to replace it unless I steal another from another now broken board.

I can just try to see whether the code will load perhaps but the tricky thing is getting the touch probe to work.

Simply put, it doesn't! I have a mk1 type USBCNC board of which doesn't support any inputs, only a single 'tool sensor' input on the Z- limit input. I've tried to set the Z- as an input and it works, but when I had the machine running earlier and tested the input, it detected it as a limit switch and stopped the machine as it should, but wouldn't let me back it off. Might be because it wasn't really set up properly, I don't know.

I just got frustrated with it and gave up because it really is an overly complicated piece of software unlike LinuxCNC.