Simple circle test on my new XXL

I’ve run about 20 cutting tests since I assembled the XXL last month and I’m having issues on the deeps of cut. Here are the numbers:

And when I Zero All I make sure the end mills is a hair over the top of the 1" think stock but when I run the job the bit only goes in less then half the depth of what I entered in the commands and it looks like the milling pattern is reversed like this: When the job start the bit goes in the stock but as the job goes the Z patterns go higher and higher above the material instead of inside the material. Could I have reversed the Z axis motor wiring? Anyways, I was hopping someone has a simple design like a circle that I can try to test if it’s something wrong with my machine, thanks for reading and helping!

You should be able to test your z-axis by jogging in Carbide Motion. You want +Z (PageUp) to move your router up and -Z (PageDown) to move your router down.

When I Jog on my Mac computer I use the 4 keyboard arrows on the right of the space bar for the X and Y axis and use the < and > keys on the right of the M key for the Z axis like so:

The < key makes the spindle go Z-
and the > key makes the spindle go Z+

Is that the correct set up?

That seems right. You can make sure by using the mouse to click on Z-. Share your print file (egc or nc)?

Direction of movement is defined on the wiki: Shapeoko CNC Router, Rigid, Accurate, Reliable, and Affordable

In a typical Cartesian machine, Z is up and down (up positive),

The problems sound like a typical case of insufficient Z-axis belt tension — it takes a surprising (the first time one does this) level of tension to hold Z position against the cutting forces. There’s a bit on the wiki on this here: Shapeoko CNC Router, Rigid, Accurate, Reliable, and Affordable and with the old style tensioning arrangement I had to use a small pry bar as noted here: Shapeoko CNC Router, Rigid, Accurate, Reliable, and Affordable and wound up with notes of:

w/ the carriage lowered all the way, I’m now getting D 4 (left) and B flat 3 (right)

Thanks William, you put me on the right track for things to check. It wasn’t the Z belt tensions but it was the small hex set screws inside the belt sprocket that were not fully tight. I was able to check that by Jogging -Z and seeing the shaft move inside the pulley sprocket. I tighten the 2 hex set screws as much as I could but bent the soft metal from the hex key. I will have to purchase hardened black hex key for this operation to be as tight as possible. Does anyone know the Allen key size for those set screws?

I believe the set screws have a hole for a 3mm hex wrench. You don’t need to severely over-tighten these, though. Your machine should have shipped with a tube of thread lock. This is the perfect spot to apply it. Once the thread lock is on and dry, the set screw will not come loose due to vibration.

They should be a metric 1.5mm as noted at: — usually a 1/16" will fit, and be a bit snugger, allowing for more torque.

Please note that checking the pulley set screws is a part of the operating checklist: EDIT:

dead link to the operating checklist

Thanks! Fixed to point to: