Setting Z zero with MakerCAM/UGS?

Hi All,

Using a Shapeoko 2 - haven’t gotten the x-carve upgrade yet, I want to machine some Corian. On the bandsaw, I will cut the corian in half or so, so that each piece will be approximately 1/4" thick by 2" wide by 8"long. I will put the flat side down on a spoil board of some sort, and I want to mill the corian to .165 thick by 2" by 8". From that point, I will reset the z axis to 0 on the corian and make the pieces I ultimately need as normal. Using MakerCam (I haven’t gotten into Easel yet) and UGS, how would I set my z-axis to accomplish this?

Would I set z=0 to my spoilboard and then jog the machine up using positive z values? Or set z=0 to something just above the piece and run the machine to bring it down?

Does any of this make sense?

I would set my z=0 right on the surface of the piece in most cases if not all.
Is your Corian piece not smooth on the surface?
If not, it may be trial and error to get the depth/features you desire.

You should sent your Z Zero off the top of your milled stock. So once you have your stock halved, then milled down ( I would use a bit much like this style ( to mill the stock flat and to spec.

I would fist though mill a pocket in your sacrificial waste board a bit larger than your stock to make sure it is nice and flat in respect to the spindle on the mill so your facing operation on the stock will give you the best results.

To set your Z Zero on the facing cycle. You should get a set of feeler gauges. Place the thinnest gauge you have under you End mill then SLOWLY move the end mill down while moving the gauge back and forth. Once you make contact and you can JUST feel tension on the gauge. ZERO your spindle… Now raise the spindle up to say 2mm or so over your stock and jog OFF your stock… Lower the spindle to the NEGATIVE number of the gauge you used… So if you use a .02mm gauge. you will jog over to away from your stock then go to z-0.02mm THEN REZERO the Z Axis. This is now your true z zero on the face of the stock. Raise the spindle up to say 5mm… Jog to X0Y0 and start your facing job. This will give you a true zero and close to the result you want. You will need to do this on EACH piece of stock as each one will be a bit thinker or thinner since it is being hand thinned before hand.

For me, I do the following.
Using UGS,

  • I set the Step Size to 1 inch
  • Then using the manual jog buttons, I move the tool to a spot relatively close to Z0, but situated fully over the work surface (but greater than 1 inch away from it)

I change the Step Size from 1 inch to 1 millimetre (simply because that’s a convenient unit change that only takes one mouse click). I then jog the Z axis of the tool even closer to the work surface (in UGS this is done using the PageDown button), stopping within a millimetre or so from the surface.

I adjust the jog setting from 1mm to 0.1mm and place a piece of scrap paper between the tool and the work. I rapidly move the paper side-to-side as I slowly jog the tool downwards in 0.1mm increments. Eventually, the tool will trap the paper and you won’t be able to move it any more - this is pretty close to being 0.1mm above the surface. Remove the paper and jog down a further 0.1mm and then click the “Reset Z Axis” button to set Z0. At this point, the Z axis has been set, but X and Y are still to be done.

Change the Step Size back to 1mm again, and then jog the tool upwards 1mm - just sufficiently to clear the work.

Then using the arrow keys, jog the tool to the position above the work that you’ve chosen to be the XYZ0 point (usually the left-front corner) and then press the “Reset X Axis” and “Reset Y Axis” buttons.

At this point, with all axis set, I move the Z Axis up an inch or so to allow me to fit my dust shield (clips on with magnets), I’m then ready to load and run my code.

If you’re doing tool changes mid-job, I’ve found it worthwhile to do the following.
I’ll actually set the 0 point a millimetre or so inwards from one edge and then move the tool downwards (in 0.1mm increments) sufficiently to just ‘kiss’ the work and leave a tiny mark (say with a V Bit).
If you change tools, you’ll normally only need to re=set your Z Axis (which can be done anywhere on the work, as described above), but if something has gone awry and you need to re-set the X & Y axes, having this mark will give you a chance to find the exact spot that you originally chose.

Get some scrap timber and practice. This is a pretty important skill you’ll absolutely need to know. Whilst the steps may change with apps other than UGS, the basic principles will be the same.