Erich Schulz wrote: ↑Tue Jul 16, 2019 10:21 am
is someone who understands perhaps able to edit this page:
https://www.freecadweb.org/wiki/Path_ToolLenthOffset
simple question really is when would this be set to anything other than 0? and are there any gotchas?
I'd have a crack at that page but I fear I am so woefully ignorant on gcode that I would surely muck it up
G43 is a pretty simple gcode command in concept. Issued with an H-word parameter, it adds that value to the calculated control point. If it has no parameter, it uses the TLO stored in the machine control tool table. Of course this is all done in the machine controller. The Path G43 command itself does almost nothing. It just inserts a G43 command into the path.
How the command is actually interpreted is based on the machine control. LinuxCNC behavior is probably the standard but even LinuxCNC differs slightly from RS-274. LinuxCNC reference is documented here:
http://linuxcnc.org/docs/html/gcode/g-c ... #gcode:g43
The Path G43 operation was implemented early in a simple way to allow compensated toolpaths without hand editing. We should probably think about re-implementing support for tool length compensation in a more serious way. For example, enable tool length compensation at the job level and a G43 could be inserted after every tool change and a G49 at the end.
Gotchas? Plenty. This is definitely not an area for newbies to tread into blindly.
- G43 has to be called after every tool change to apply the offset of the new tool. It isn't modal for the job.
- Behavior can vary between random and nonrandom toolchangers
- Some controls will accept negative values for TLO, others won't.
- Probably more that I'm forgetting