I don't know about all machines, but the ones I am familiar with will execute a G0 at the fastest rate (traverse) in each axis, which means the tool may arrive at the destination in one axis before it arrives a the destination in the other.
On other words, the path traveled is not necessarily a straight line with a G0.
(My machine in particular will execute a G0 when the spindle is stopped but it will not execute a G1 unless the spindle is running and since it does not have the ability to start the spindle, I have to manually start it.)
On the other hand, a G1 command will always be a straight line to arrive at the destination, using the specified feed rate (linear speed) to set the speed of each axis.
If you want a particular X-speed then the Y-speed will vary based on the angle of the line being cut. And vise-versa.
You can't independently specify the speed of each axis when the lines being cut can be any angle.
The movement of one axis is going to dictate the the speed of the other in order to arrive at the destination in a straight line.
That all being said, if you want to set separate upper speed limits for the X and Y axis, the way I would approach it would be as follows:
1) In the DXF2GCODE conversion specify a very high cutting feed rate.
2) Write a post-processor that would evaluate every G1 move and would assign a specific feed rate for each one, such as to limit the speed for each axis.
(The reason for the initial high feed rate is that I would personally write the post-processor such that it only reduces the feed rate, never increases it.)
A final option would be for you modify the DXF2GCODE to do what you want. Even better would be for you to submit your modification back to the group!
When I have time, I have a mod to support the Bridgeport BOSS-5 that I need to finish writing and testing and put back to the group.
