[craig00747]

Hello Gents

I have done the calibrations of the stepper motors, using a dial indicator, to measure the distance each stepper motor traveled. Used a steel ruler, to check the longer distances, which each axis traveled. All is 100% correct there.

Now I machined a circular pocket of 20 mm dia. It measured 19 mm.

Machine is in Constant Velocity Mode.

The stepper motor drivers have been set for micro stepping.

I do my designing in Fusion 360 and then send the file in a .nc format, to the UCCNC software.

Any suggestions, to where or why this is happening?

Regards

Craig

[craig00747]

Hi Gents

I must mention that I was using a feed rate of 50 mm/min, which is very slow and used a 1/8" ball nose end mill @ 6000 Rpm. Machined a pocket into a piece of aluminium. Looks very nice, but 1 mm smaller in diameter, than the drawing. Very little chance of tool deflection in this scenario.

The holes in the 16 mm MDF of the spoil board, was also smaller than what the drawing stated. Hense, the calibrations are 100%.

All the axis`s are ball screws and rails.

So the machine`s construction is rigid.

Regards

Craig

[ger21]

Cut the same thing in the opposite direction, and see if it's the same size?

[craig00747]

Hello Gerry

Thank you. I will give that a try. One thing, which I did see, was that the spindle was turning clockwise, as it should do, but the end mill`s tool path was machining anti-clockwise.

When I view the tool path in Fusion 360, I see two red arrows, pointing in an anti-clockwise direction. Must these arrows point in a clockwise direction?

Regards

Craig

[OlfCNC]

Check your Constant velocity parameters.

[craig00747]

Hello OlfCNC

I checked the constant velocity parameters and they are all still default settings. I have been using the constant velocity mode and not the exact stop mode. Maybe I should try that with the same tool path and see if the measurements changed?

Regards

Craig

[OlfCNC]

Hello OlfCNC

I checked the constant velocity parameters and they are all still default settings. I have been using the constant velocity mode and not the exact stop mode. Maybe I should try that with the same tool path and see if the measurements changed?

Regards

Craig

If you working in Inches then lower the Linear addition length and Linear unity length to 0.001
If you working in millimeters then the default should be fine.

[craig00747]

Cut the same thing in the opposite direction, and see if it's the same size?

Hello Gerry

I just ran the program again and this time, I made it cut in a clockwise direction. No difference in the measurements. Kept the feed rates exactly as they were.

Regards

Craig