# X2 CNC Mill Cutting Wrong Dimensions



## papermaker (Sep 21, 2013)

I was milling a rectangular pocket and noted that the mill was only cutting half of the size that I had entered into Mach3. I double checked the dimensions and they were correct . The native units were correct.The tool size was correct as was the offset. Any ideas?


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## Hawkeye (Sep 22, 2013)

Check your motor tuning. I had to slow mine way down to get it to move consistently. We always want to have things running at max, but in this case, slower works better.


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## DMS (Sep 22, 2013)

Can you give some approximate dimensions for the pocket and the cutter?

There are a couple reasons you can run into this. The first is as Hawkeye said, you are pushing the machine too fast, and you are missing step. If that happens, things are going to look pretty bad in all likelihood. The other possibility is that you (or mach) is accounting for the diameter of the endmill incorrectly. If post the expected size and actual size, and the diameter of the cutter, we can probably figure out why. If you have G-code, post that too.

It's also possible to have cutter compensation turned on, and account for the size of the cutter manually as well, which would give you a much smaller internal cut than intended.


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## DAN_IN_MN (Sep 22, 2013)

DMS said:


> Can you give some approximate dimensions for the pocket and the cutter?
> 
> There are a couple reasons you can run into this. The first is as Hawkeye said, you are pushing the machine too fast, and* you are missing step*. If that happens, things are going to look pretty bad in all likelihood. The other possibility is that you (or mach) is accounting for the diameter of the endmill incorrectly. If post the expected size and actual size, and the diameter of the cutter, we can probably figure out why. If you have G-code, post that too.
> 
> It's also possible to have cutter compensation turned on, and account for the size of the cutter manually as well, which would give you a much smaller internal cut than intended.




OP, does your mill have stepper or servo motors?  I believe steppers are prone to loose steps as I've experienced on the CNC plasma cutter I program and run.  On the other hand, *I've read* that servo motors have feedback and know if an obstruction is met or if they're not in the location the program states.


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## papermaker (Sep 22, 2013)

I was wanting to cut a pocket 2.5" x 2.5" x .375"deep. What I end up with is exactly half of those dimensions. I was using a wizard as it was just a simple pocket. 
I tried using another wizard just to cut something to see what the results would be. It to was exactly 1/2 the size that I had entered.


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## SEK_22Hornet (Sep 22, 2013)

papermaker said:


> I was wanting to cut a pocket 2.5" x 2.5" x .375"deep. What I end up with is exactly half of those dimensions. I was using a wizard as it was just a simple pocket.
> I tried using another wizard just to cut something to see what the results would be. It to was exactly 1/2 the size that I had entered.



Try running the program with a piece of wood or other soft material like machinable wax or even styrofoam and see if you get the right size - that would help determine if your steppers are missing steps.  Have you used this set up before or is this the initial run?


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## papermaker (Sep 22, 2013)

Getting the same results in any material. Even cutting script the letters come out perfect except for the size. Exactly half of what I'm asking for. It doesn't appear that it is skipping steps. I think I'll try uninstalling Mach3 and then re-installing it to see if that remedies the issue.


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## DMS (Sep 22, 2013)

Is it possible your steps/gear ratio are off? 

Try this (I'm assuming you have a dial indicator). 

1) Home your mill, 
2) Attach your dial indicator to the mill table, and put the tip against the mill spindle, or head. The dial indicator should be aligned so it will actuate along the X axis. Make sure you have at least 3/4" of travel. 
3) Zero the indicator dial
4) Touch off the X axis in Mach
5) Run the following G-code  "G1 X0.500 F3" (not sure how to do this in Mach3, as I don't run it, but there should be a way to execute individual G-code commands)

The indicator should have registered 0.5000 inches. If it didn't then your motor configuration doesn't match the motors/drivers. Sounds like you are off by a factor of 2 somewhere. You can repeat this for each of the axes to be sure all is well. Of course you could just adjust your motor configuration by dividing your current setting by 2, and try it then. I bet that would fix it.


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## DAN_IN_MN (Sep 23, 2013)

papermaker said:


> I was milling a rectangular pocket and noted that the mill was only cutting half of the size that I had entered into Mach3. I double checked the dimensions and they were correct . The native units were correct.The tool size was correct as was the offset. Any ideas?



Is this a mill that you've had for awhile or one you're just setting up?  Is the scaled pocket a new problem?


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## papermaker (Sep 23, 2013)

I found the remedy to the problem. For some reason each axis was out of calibration. Seemed quite odd that all 3 axis were out by the same amount.
 In Mach3 there is a set-up page and in the lower left hand corner of the graphic page there is a button "calibrate axis". When you click on the box another box opens where you can select the axis that you want to calibrate. Once you have selected the axis and message box pops up asking you to enter the amount that you want the axis to move. Once you hit okay the axis will move and you need to verify how much it moved. Then another box pops up asking how much that axis moved. When you click okay it calculates how the steps should be set and whether you want to change to that setting.
 It couldn't have been simpler and I knew there had to be a way to correct for this but it was just finding it.


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