New feature...?

I am running an engraving machine and have recently noticed unexpected blended motion happening at the most awkward time.

In general I engrave PCBs. Machine works wellin general.

In the past ( earlier LinuxCNC releases ) runing a .ngc file from a line would be done with a degree of blended motion if no ngc file run prio to run from line option.

As soom as a file was run whihc included exact path instruction at the start the command would remain persistent and no blended motion would occur thereafter.

Currently however it seems that the exact path instruction is no longer persistent and unpleasant experiences ensued when trying to run a file from line would result in blended motion and loss of wanted copper surface.

Is this a new feature of LinuxCNC.?

Is there a way to permanently implement exact mode within the config file(s)?

I am running current version of LinuxCNC on Ubuntu with Axis interface.

G61 and G64 are still modal commands. But they are not and never were remembered after restating Linuxcnc.

I would recommend putting a G64 Pxxx (with xxx = an appropriate tolerance for your work) in the preamble for all of your files, and adding it to the RS274NGC_STARTUP_CODE = line in the [RS274NGC] section of your ini file. (You can simply add that line if you don't have one.) This does not permanently change the setting, but it does change the default setting when Linuxcnc is first started, until a new G64 or G61 command is given.

If you were used to running older versions of Linuxcnc (before 2.7). You might find the blending in G64 (with no P tolerance) to be more aggressive than before because of higher attainable speeds allowed by the multi line look-a-head.

Todd,
Thanks for Your comments.
as it stands the configuration file contains RS274NGC_STARTUP_CODE = G21 G90 G61 line.

Each .ngc file i generate contains G21 and G61 as the very first line.

I will simply have to be mindful of the issue and try to avoid these unhappy events.

I almost never use g61. I'll try some tests tomorrow.

You can turn off the new trajectory planner in the INI.
This will revert to the previous behaviour. This might not be what you want, of course.

See the various arc-blend options here:
linuxcnc.org/docs/2.7/html/config/ini-config.html#_traj_section

I am not able to replicate this behavior, G61 remains modal and active when restarting a file from a line.