Sebastian Kuzminsky 2014/12/16 at 9:19 pm
Hi there, I’m a long-time reader and fan, and I’m one of the LinuxCNC developers. I’m posting this comment to point out a couple of inaccuracies in this article as it pertains to LinuxCNC.

Point 1: Branching structures are fully supported in LinuxCNC. We support subroutines with return values, while and repeat loops, and conditionals (if/else statements). Docs here: http://linuxcnc.org/docs/html/gcode/o-code.html

Point 3: LinuxCNC supports rigid tapping. Docs here: http://linuxcnc.org/docs/html/gcode/gcode.html#sec:G33_1-Rigid-Tapping
Here are a couple of videos demonstrating rigid tapping with linuxcnc:
https://www.youtube.com/watch?v=JCEwlfJj__A
https://www.youtube.com/watch?v=qBQ7RSuRAls
https://www.youtube.com/watch?v=jAcFeVlftrw

Point 4: LinuxCNC absolutely can home to encoder index. That’s how i home my Bridgeport, it gives me single-encoder-edge repeatability. Docs here: http://linuxcnc.org/docs/html/config/ini_homing.html#_home_use_index

Point 6: LinuxCNC does have backlash compensation and screw (pitch) compensation. See the BACKLASH and COMP_FILE configuration parameters here: http://linuxcnc.org/docs/html/config/ini_config.html#sub:AXIS-section
We also support multiple feedback devices on a single axis. For example, here’s a big machine with encoders on the motors and linear scales on the table (the original website has disappeared, but the Internet Archive has a copy): http://web.archive.org/web/20120112153115/http://jmkasunich.com/cgi-bin/blosxom/shoptask/wichita-trip-02-20-08.html

Point 8: LinuxCNC does tool compensation, lots of people (including me) use it without problems. There are some subtleties that must be kept in mind when using this feature, and we often get reports of problems that upon close examination turn out to be operator error. I know of no actual bugs in the code. If there are any, we’d love to hear about them so we can fix them!
The tool compensation feature includes support for multiple simultaneous offsets, typically used for nominal tool diameter and wear compensation. Docs here:
http://linuxcnc.org/docs/html/gcode/tool_compensation.html#sec:cutter-compensation

Point 10: I’ve done drip feed to LinuxCNC, but over the network (using TCP) instead of over RS-232. It’s not my preferred way to run a machine, but it does work just fine.

Ok that’s all I have!

Thanks for publishing CNC Cookbook, I’m always happy to read your posts when they come out.

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