Skew adjustment

[Marius Stanciu]

Hi,

Many users have home made CNC routers. But even the professional made ones are subject to usage and ageing. This can lead to skew in the perpendicularity between the X axis and Y axis. So a square is no longer a square but a parallelogram.

It is very difficult and time consuming to make mechanical adjustments when the skew is very small (like 0.1 ... 0.2 mm) but still important when there is a high density of traces and/or drill holes with small diameters.

It will be a big thing if a skew adjustment can be taken into consideration when the Gcode is generated in FlatCAM.

Maybe a procedure can be devised like this:

1. Make a cut like a board cutout of a rectangle with x and y dimensions configurable.

2. Measure the diagonals with a very precise caliper.

3. Knowing the x and y dimensions of the parallelogram and the diagonals we calculate the skew angle (law of the cosines? https://en.wikipedia.org/wiki/Law_of_cosines and parallelogram properties http://onlinemschool.com/math/formula/parallelogram/). This skew angle we store as a default for the program.

4. We use the skew angle to correct the Gcode (for the Geometry, Gerber and Excellon).

[Juan Pablo Caram]

This would be a feature in Geometry Objects and Excellon Objects. At this level it is easy to process geometry. Once is is a CNC Job it is much harder.

[Marius Stanciu]

Added in another version of FlatCAM.