Not sure where the fault lays

[terry1956]

hi, For some reason my router is machine the circles to large. I want 22mm dia circles but it machines 49mm ones. I have ran the g code in a sim and it works ok, the circles are the correct size. I have checked the machines calibration and that's ok. I am using mach3 with a CS-LABS MISO/IP-M motion controller. anyone have any ideas whats going on.

[magicniner]

Try a square and a rectangle too and report back.
If they are all 2.2 times too big it's likely your step settings are incorrect and you will be able to use a bit of simple maths to get your settings very close.

- Nick

[terry1956]

hi, no its only circles. Its a Mach3 thing which needs sorting. I have been told that if I put G91.1 in a line below G90 in the g code it will work normally. at the moment I am using fusion to make the g code and the circles are ok.

[magicniner]

at the moment I am using fusion to make the g code and the circles are ok.

What are you using when the code for circles isn't OK?

[magicniner]

Give a full example of a problem program?

[Chaz]

Yep, share the code. It sounds like a mixup of settings (G91.1 sets Incremental mode).

G90 & G91 Distance Mode
Interpretation of Mac code can be in one of two distance modes: absolute or incremental.

To go into absolute distance mode, program G90. In absolute distance mode, axis numbers (X, Y, Z, A, B, C) usually represent positions in terms of the currently active coordinate system. Any exceptions to that rule are described explicitly in this section describing G-codes.

To go into incremental distance mode, program G91. In incremental distance mode, axis numbers (X, Y, Z, A, B, C) usually represent increments from the current values of the numbers.

I and J numbers always represent increments, regardless of the distance mode setting. K numbers represent increments in all but one usage (the G87 boring cycle), where the meaning changes with distance mode.



You also want to be sure you are not mixing MM and Inch.