Contemplating upgrading to 2.7

I am thinking about upgrading to 2.7 for the improved trajectory planner. I ran a couple of programs on my mill using 2.6.8 that contain HSM toolpaths and they don't achieve or stay at the requested feedrate due to acceleration and deceleration. I am using G64 P0.005 in inch units and with a F value of 84in/min I am getting an actual feedrate of around 40in/min max due to the short arc and line segments in the HSM path.

I am hearing that the trajectory planner is much better in this respect with the 2.7 pre releases. Are there any drawbacks to using the 2.7 pre7 version other than it may have some unknown bugs. Does anyone know of any drawbacks for mills using 2.7 pre7? Is there a way to keep a 2.6 version installed and have the 2.7 version installed also?

You can install from git using a RIP (run in place). This will let you install a second or multiple versions of Linuxcnc on the same system for testing purposes.

There are instructions here,
wiki.linuxcnc.org/cgi-bin/wiki.pl?Installing_LinuxCNC

I've only ever successfully done it once myself, but I'm sure others could help if you run into trouble.

Am I thinking wrong that 2.6 was the start of the improved TP? Or is 2.7 even more improved? Also, I cannot find documentation of .ini entries to turn on/manipulate improved TP. It seems like 2.6 pre ran smoother than the 2.6.8 I am running now. Maybe the "pre" I was running (from last year) was actually 2.7pre.

I will try 2.7 when it's released...

?
Paul

The new TP is only included in 2.7 or master (2.8)

Paul,

I believe the new TP is just part of the 2.7 build and was never part of the 2.6 builds. However the experts can confirm this. (EDIT: The expert PCW has beat me to the punch and already confirmed it. HA!)

I've run 2.7 on my plasma for some time now for the improved TP. It is due to be released in a few days so it is pretty solid at this point.

John,

I am going to update to the 2.7 pre7 tonight. You say that 2.7 is to be released soon. If I upgrade to 2.7 pre7 per the instructions located here then is the upgrade path to the official release of 2.7 easy enough. I don't want to create myself headaches in the not so distant future.

Thanks,

Jim

Upgraded to 2.7-pre7 last night. Works much better! The new trajectory control shaved 3.5 minutes off of a HSM toolpath that was previously 22 minutes long.