axis scale calibration

I am using mdf as the base and spoil board

Nothing wrong with using a sufficiently thick piece of good quality mdf.
After all this looks to be a cnc router and the mdf gives a good sacrificial surface to attach to, is stable and easy to replace.
You can also use your cnc router to mill the surface flat on the machine.

If you are taking light cuts with sharp tools all should be fine.
What does the manufacture recommend for the base?
If you think there is flex make a cut, measure it, then makes the exact same cut in the same spot again and then measure if there is a difference.

Rick G

The V90 comes standard with MDF as the base table. The drilling versus cutting could be a problem, but I used and end mill as the drill bit which should provide a flat bottom versus the angle of a drill bit. The z axis shows no binding etc. On the tests for calibration I have been using pine which is soft enough that it shouldn't cause too much flexing etc. I think I may be expecting too much precision. The V90 is described as a machine that will cut on wood and not recommended for metal although many are using it on aluminum. The variations are .020 or less and for hobby projects are not really noticeable. The zeroing on the machine seems to be right on and returns to the same x,y and z locations.
Thanks for for all the input, and I will try all of the suggestions.

I used and end mill as the drill bit

Be sure the end mill is the center cutting style for a plunge cut, not all end mills are and it may take more force to make a plunge cut than a straight cut.

With the type of light cut you are talking about I think you should be able to do better than .020, but keep in mind wood working has different acceptable tolerances than metal working, wood moves a lot with humidity etc.

Perhaps try this...
Touch off the machine to the test wood surface.
Set a cut speed.
Turn on router.
Make a cut such as
g1 x2 z-.25
g1 x0
g1 x2
g1 z.20
m05

Check the depth at several spots on the cut.
g1 y1
Try again.


Rick G

I'm thinking that your info on the end mill may be a part of the problem. I will check the end mill I am using and make sure I use a plunge cut in the future. A weak spot on the V90 is the z axis and any extra force exerted against the plunge does cause some flexing in the axis. I believe now that is what is happening. Thanks!