Best current advice for XXYZ servo gantry?

I am in the process of configuring a XXYZ servo gantry using a Mesa 7i93+two 7i40s + a 7i37TA. I installed from the iso, configured usapce and I am able to move motors. I see there is some significant work in master regarding Joint Axes and gantry. Based on that, I am wondering what path people here would recommend for getting a machine going right now. Should I work with what is available in 2.7 or is it worth moving to the bleeding edge? How sharp is the bleeding edge currently with respect to independent servo homing?

Thanks for the advice!

Scott

Version 2.8 is the next distribution which is not far away so if you want to keep right off the edge. From 2.8 and on, there are better features for gantry machines which I've used on my gantry machine using master branch since 2015 without too many problems.

I presume this will take me even further off the pncconf path than a gantry machine would in the first place? I'm not against that per se, but I just want to understand what I'm getting myself in for.

Thanks!

Scott

Fantastic, thank you!

andypugh wrote:

Possibly not, I have a feeling that 2.8 pncconf might understand gantries.
But you certainly want to be using the 2.8 pncconf rather than making a 2.7 config and converting it.

I'm sure pncconf in V 2.8 understands gantries becasue I was asked to test it about 2-3 years ago.
Before that point, it was suggested you make a XYZA machine and edit the A by hand. So I'm sure it would be harder in V 2.7

Great, I am hoping to be able to try this within the next week. I'll update with my results.

I tried this tonight and it seems that while stepper gantry (tandem) pncconf configuration is supported in 2.8, servo gantries are not fully supported until 2.9.0-pre0 (github.com/LinuxCNC/linuxcnc/commit/825b...1e6def81c871afe60f5b). The config was close though, so I think some minor edits should get something workable.

Secondly, the instructions on the forums for 2.8 currently have you end up with 2.9. To get 2.8 installed I had to add the following to /etc/apt/sources.list.d/linuxcnc-buildbot.list:

deb buildbot.linuxcnc.org/ wheezy 2.8-sim
deb-src buildbot.linuxcnc.org/ wheezy 2.8-sim

(I believe, I am away from the machine right now). This seems like a minor documentation bug, as buildbot.linuxcnc.org/ currently does not provide a documented way to get 2.8 installed.

I have not run the machine yet with this config but hopefully will have a chance to play with it this weekend.

Thanks for the help getting me this far!

Scott