Hi folks. Im using Fusion 360 to program my CAM for a guitar neck. I appear to be having issues with my final finishing pass 3D Parallel with my .25" ball nose tool. From what I can gather, the tool appears to be cutting deeper than what has been programmed in the CAM.
The model is designed to be .62" thickness at the 1st fret. After completion of the part on my CNC, I measure the part to be .59" at the same position. I’ve cut this part out 3 or 4 times and each time I achieve the similar results.
I have a OneFinity Journeyman 3’ X 4’ CNC. Not sure if this is a calibration problem at the CNC or something I’ve done wrong inside my Fusion CAM settings. I’ve set the flat surfaces to “no touch surface” but the tool continues to ride up and over, cutting slightly deeper than it should.
Just to clarify: similarly bad each time or they have been similarly good before until this time?
Two things which are basic places to start: verifying Z0 setting and verifying code. If the previous times have been good then rule out the code. If previous times have been bad it could be code but it also could be a problem with Z0 setting or calibration.
How do you verify your Z zero before you start the cut? If it happens to be the top of the flat area in the picture do you bring the tool down to Z zero, with spindle off, and move over to verify it is not too deep on that surface?
After I use the touch probe, or even after I use the paper method, I move the tool away then bring it back to the origin X Y. Check that that looks sane. Then bring it back to the Z0 and move the tool back to touching the top of the part to check the Z axis is really reading zero on the screen.
There have been times when doing this check showed that indeed something went wrong with the way I did the touch off.
Now if all 3 or 4 of your parts were too deep then this is not the issue in this case. It still could be code or calibration.
I have seen this issue before. It is when I forget to take stock off the top of the part.
It defaults to .04 on top of the model. So I have to make sure it’s set to No additional stock or Add stock to all sides. But not the top.
The thing is if Fusion has .04 stock on top it will cut every thing .04 deeper that what you expect.
Here is an image of the screen after homing the machine. I could probably use a bit of help to ensure that the machine is properly calibrated. The Z axis shows OVER and the X shows UNDER, so not sure if this is the problem.
Not saying this is the issue, but it is the issue I had.
I had to measure my touch probe, and adjust the settings.
That is how I fixed it.
You can also change movement per revolution on motor 3 if you are using a bb controller like I am.
I would do some test cuts.
I ended up working off the spoil board as zero (normally I go off top of stock) and with a piece of stock say 1/8" over .62" mounted I probed Z with a 1/4" flat bit and use the MDI tab entering Z to move the distance I wanted manually typing in G01 Z15.75 F100 (the .62" is 15.75 in mm since I’m using mm).
Then start router and manually with joystick make a cut across edge of stock and measure. You can use your ball nose bit… but that’s a lot of back and forth to get a flat spot to measure.
If it measures too small you can just increase your block thickness as a temp fix, and re probe z. On the opposite side if it measures too big adjust block thickness to be thinner.
This is temporary to get by. If your probe thickness is correct on the bb then you need to calculate how much z travel is out. I would suggest contacting support if your block thickness is correct on the controller, because then you are in into movement per revolution of the z motor settings. Support is better equipped to assist you on those changes, if they are needed.
Hope this helps some, I have not dabbled into making a guitar yet, it’s on my list, I just have not found a blank that screams “it’s me, I’m the one!”
