"Start from line" enforces all tool changes from start to happen...

...but why?

Regards,
Daniel

Answer: github.com/LinuxCNC/linuxcnc/issues/246#issuecomment-423049528

mydani wrote:

Answer: github.com/LinuxCNC/linuxcnc/issues/246#issuecomment-423049528

You found the elephant behind the tree in the room.

QTPlasmaC got around this issue I think by loading a temp file starting from the line you selected and it does not have these behaviours because it is like loading a new file and starting from scratch. This is amazing and all the other screens should do the same thing and that may fix the issue with run from line and a remap. But I dont know as I havent tried a toolchange remap with QTPlasmac and it may never come up until someone tries to change tools (torch) on a QTPlasmac machine.

I have never had an issue with the run from line in QTPlasmac. It just works everytime.

just ranting..... sorry

All good. I think there are some possibilities to hack-in a skip of remaps in the interpreter in case of ongoing "start from line", or maybe some hack in the remap which exists w/o being a queue-buster, or similar...

Just need to dig into it... *sigh*

What kind of lines do you guys run from? This isnt a linuxcnc specific question, im curious how other people use it on other controllers as well. I understand for plasma its a different situation, but for the cnc mill/lathe users, what lines do you run from and what do you expect to happen?
For example, if you start in the middle of a surface profile toolpath and you start on line " g1 x56 y78"
will it move in only x and y until it receives a z move? or does the spindle/coolant/etc start up and it rockets to the correct position? or does it move all 3 axis at once (like 3d diagonal) into position?
I ask, because I've never really started from any other line than a tool change at work or home on linuxcnc, and Ive never had the issue with it cycling through all toolchanges or anything weird/scary, but i only ever start from lines like this, i would start from n24

andypugh wrote:

bevins wrote:

QTPlasmaC got around this issue I think by loading a temp file starting from the line you selected and it does not have these behaviours because it is like loading a new file and starting from scratch. This is amazing and all the other screens should do the same thing

I disagree. There are too many case like this where a particular screen has a clever workaround for something that should be fixed elsewhere in the code so that it is fixed for every GUI.

Normally i would agree with you but since most of these hacks and workarounds stems from using a 40 year old interpreter i dont mind having the gui’s changed individually to get the functionality needed. I have had customers drop linuxcnc because of some of these issues.

Run from line is not as simple as it first seems

Is the spindle on? Should it be? RPM?
What work offset?
Z height?
Many other complications.

For some GCode it will be easy - starting at a toolchange often will have all the important code like ME, RPM, correct X,Y,Z moves.
But a long file without tool changes won't have those things and starting from the middle may be problematic.

I personally also start from a tool change line, and my cam sets all required parameters afterwards, so no checks at all required.
Call it a "dumb start from line". Combined with a possibility to manually (MDI) preset everything, e.g. G17/.., Fxx, Sxx, M3/4, ... this dumb start from line would be really helpful for the intermediate user.