incorrect cutting in a pocket <cutter comp in control vs cutter comp in cad/cam>

[midy]

So fusion design and size is correct but when loaded into cnc12 the measurement shown is approx 0.5mm smaller, taking into account the 6mm endmill?

[suntravel]

Your Modell is with sharp edge, a 6mm Mill cannot mill smaller than 3mm radius, so this measurement must be smaller

You can that see in the fusion simulation also that not all material is removed in the corners.

Use a smaller mill to get this closer to the desired form.

Uwe

[midy]

So are you saying cnc12 will change this number for that reason? I have tried a 4mm endmill - same results. As I said before if I program with a 4.50mm end mill but actually cut with a 6mm endmill (sort of fooling the machine) The pocket cuts perfectly to size?

[tblough]

You are measuring to a sharp internal corner that cannot be cut except with an infinitesimally small diameter cutter. If you are fooling the control to cut this dimension to size, then the vertical dimension will be oversized.

[tblough]

A better test to see if this is cutting "perfectly" would be to check with a gage pin tangent to the three flat sides. You'll never be correct measuring to those internal corners that don't exist on the real part.

[midy]

No what i'm trying to say the measurement in the fusion photo almost 35mm is changed in cnc12 by more or less half 0.5mm?

[midy]

Uwe did the same measurement earlier in thread, its actully over 0.5mm

[suntravel]

Uwe did the same measurement earlier in thread, its actully over 0.5mm

Nope, the toolpath will be smaller because of the mills diameter,

There is nothing off, fusion and CNC12 is a perfect team, but you cannot expect this team to do sharp internal corners with a 6mm mill, because this is simply not possible.

If you want sharp internal corners with a mill, broach them with a sharp tool.

Uwe

[midy]

I'm not after sharp corners. Thats just how the drawing was originally drawn, we know full well that will be a radius (3mm) there with a 6mm endmill, thats actually the fit to the mating part. I have produced hundreds of these tools over the years so I just cannot understand why overnight it started cutting 1.5mm too small?

[midy]

Surely those 2 measurements in the photo's should be the same?