Sharp 90* turn in gcode becomes a large sweeping turn

I am having a similar problem on my 4x8 gantry router. The part in the attached photo was cut using G64 P0.001 in the gcode. Obviously the interpreter didn't respect that tolerance.

The only change I recently made to my configuration is to comment out the lines on backlash compensation.

I suspect my issue is related to acceleration values, but I'd like some advice. Assuming machine units of inches, what are typical acceleration values? From memory, I think I'm at max_acceleration = 12 and stepgen_maxaccel = 18. From reading the documentation, it looks like my maxaccel should be reduced or acceleration be increased.

If you have g64 p .001 this should not be possible without some other errors

Are you sure you dont have another g64 command embedded in your gcode?

another possibility is some hal/ini setup error that is generating a large following error

Can you post you hal/ini files?

BTW 12 ips/s is _very_ slow acceleration for a router = .0313 G

There is only one g64 command and no g61 in the code.

What version of LinuxCNC?

2.7.15

can you post your gcode or a portion of it that exhibits this issue?