Are defined feed rates of any use?

Converting bitmap images into paths and then Gcode using Inkscape - I noticed that the bitmap trace conversion into vectors produced Gcode output that meant that the tool was, in simulation, at times "rushing" from one G01 code line to the next (i.e. at a high feedrate) while at others it had to process a large number of G01 code lines to traverse the same physical distance (a much slower feedrate). This appears to me to mean that feedrate makes no sense when defining the cnc tool parameters. This could be a problem in materials such as plastic, liable to melt or burn if the tool resides too long at one place. Aluminium routes or engraving could also be a problem. Am I wrong?
If the problem does exist - how do cnc-ers adjust the recommended material feedrates to cope with the accelerating and decelerating tool?

Some times the ideal just isn't possible with your machinery. The art in it is determining what compromises can be made, to achieve adequacy.

Such as in your situation, milling plastic. If accelerations limit your feed rate, slow your spindle speed to maintain acceptable chip loads. Playing with G64 blending settings can also help you find a balance between accuracy and speed.

Hi Andy,

Yes - I'm using 2.7 but the apparent change in operational speed as the vector tracing went from multiple lines to single lines for the same horizontal distance came as I viewed the progress in the online Gcode simulator ChiliPeppr Hardware Fiddle (chilipeppr.com/tinyg) which I use in the comfort of my office to sort out whether the actual engraving will work or not.
Perhaps this is all an artifact of the online Simulator?

On a similar tact - and the reason that I use the simulator. Quite often and for no apparent reason the Inkscape Gcodetools process often produces code that,on a relatively simple curve, will often produce code that causes the tool to go back on itself or duplicate exactly the same code line before carrying on. I use the simulator to identify these regions and modify or delete code lines to create a proper progressive engraving line. I haven't found out yet whether this is a fault of the bitmap tracing or the gcode production. If I knew where to find the mathematical vector descriptions in Inkscape I could nail this problem to one or other of the processes.

Eventually I hope to use Blender and a dedicated CAD-CAM package to do my artwork-gcode production but Blender is a steep learning curve and I haven't mastered it yet. And as a strictly LInux user, my options are slightly limited in the CAD-CAM production area. For the time being I'm finding the Inkscape-Gcodetools process to be useful and instructive in these early days of my cnc education.

Hi Andy,

It seems the only stand-alone linuxcnc simulator package is for Ubuntu distros. I'll try and compile my own version for use on Mageia 4 unless you know where other pre-compiled versions are? I'm running Mageia 4 on a dual screen setup which makes it very easy to view simulations on one screen while having the gcode open in an editor on the other screen. MY workshop Debian linuxcnc machine has only one screen and working your way through a simulation with editor on a single screen while stood up is not very pleasant and leads to mistakes.

Thanks for the info regarding SVG files - will look into that.

I use VNC to remote into the computer on my mill. Then I can run simulations from in my office without going out to the actual machine. I have a sim config that is set up with the same machine limits, max speeds, accelerations as the real config for my mill.

Hi Andy and nitromethane

Just tried to install the uspace version from the git repository using linuxcnc-uspace rather than linuxcnc-dev - seemed to go ok - downloaded the files and exited normally . Went into the debian directory as required and then tried all the stated ./configure modes but only the ./configure uspace option seemed to work partially with the following
unknown distribution: Mageia-4
configuration may be wrong!
successfully configured for 'uspace-Mageia-4'-'uspace'.
but the make failed with "make: *** No targets specified and no makefile found. Stop."

tried ./configure -a but no rt kernels found
so need to install an rt kernel for my Mageia machine before trying again.

But I could follow nitromethane's idea and VNC to my workshop machine - bit of an inconvenience having to go and turn on the workshop machine and then back to the office - but if that is what I have to do - then so-be-it.

Thanks again to both.