Roughing Pass & Finishing Pass (what am I doing wrong)

After reading this post I’m still left confused.

I have started with the CNC modal, & created a design in Fusion 360. I have created the roughing toolpath & successfully run it. I have created the finishing pass & changed out he bit. When I go to the work origin & lower the Z axis (using the card to get it into position, then start the finishing pass it follows the correct paths but about 4 mm above the (remaining) stock after the rough pass cleared it away.

Any idea what I’m doing wrong?

Did you set your origin correct in Fusion?

Did you let it finish the job completely? Maybe you just forget to tick “rest machining” so it tries to cut everything away again?

Best to share the settings of your fusion project, else it’s just guessing.

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You are setting the z-origin on the controller, and not just hitting start when it’s in position?
Just making sure, cuz it doesn’t do it automatically.

Otherwise everything @brvdboss said.


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I let the rough pass finish - loaded the finishing pass & lowered the Z to where it touched (wedging the card that came with the snapmaker like when I do a 3D print) between the bit & the top of the relief carving and then “set origin” - then started it thinking it would take off from there. (it can’t go down more but when started goes up about 4-6 mm).

Work origin should be a consistent point. A reference point that doesn’t change or get carved. If that’s the center work origin, then great. If it’s off to the side or an extra piece of material that works too.

There are 3 or 4 settings where heights and work origin are set/affected - both in setup and toolpaths. Without knowing your settings we’d just be guessing.


I could screenshot anything from both toolpaths if that would help.

Screenshots of toolpaths and setup would help.


Any particular screens?

~Don’t forget to be awesome!~

The configuration settings of your toolpaths

What tools/tool sizes are you using for each path? The ones listed seem a bit excessive…

Yeah, those tool sizes are huge. If you’re using the correct SM configuration file it should warn you about coolant being ‘flood’. Just set it to disabled.

I personally don’t like adaptive and use pocket. Adaptive is more clever about toolpaths and more efficient but it also kind of assumes you’re using a real cnc machine and doesn’t always take into account that the SM is underpowered. Do you have stock to leave turned on on adaptive. Clearing passes should have it turned on and generally set to .5mm to 1mm.

You didn’t mention what type of wood you’re using, but the step-down is way more than the SM can handle (even with smaller bits.) 1mm is about max. And the speeds, even for softwood are at the upper end. Spindle speed just keep at 12000 on any wood. Only with acrylic or metals do you need to change it.

You don’t need rest machining on a first pass (although it really won’t change much having it on)

Also need to see your setup settings. That’s probably where your work origin issues are happening. Heights look fine in toolpaths.

Stock is approximately 12" x 12" x .75"
Rough Pass

Next I was going to use

Then do a final pass to smooth it all out (bit unknown as of yet)

I don’t know how the coolant got turned back on but SM doesn’t have one (I believe).

Stock to leave is set at at .7 mm for both Radial & Axial.

What can I show you to let you see the “setup settings”?

The test run is in Pine but the final piece will be an oak stock.

Thanks for taking time to respond.

Are you actually using a 1/2 and 3/8 ball mill? Those are massive for what you’re doing. Also, they’re the wrong type. You should be using flat end mills. For reference, I use a 2 flute 3.175mm flat end mill for all my rough clearing.

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Should be using a flat end for clearing. No reason to use ball. Just takes more passes to cut the same area. Clearing you’re trying to get rid of as much stock as you can as fast as you can. 1/4" bits is largest SM can really handle. (Spoilboard bits can be bigger but only doing flat surfacing)

Have you tried running a simulation and seeing the end results? You’re not going to get much detail with those size of bits.

You’ll want to set your speeds differently for pine and oak. You can run tests on pine faster, but then 2/3 or even half that for oak.

Setup is where you set size of stock, machine type, work origin.


Wouldn’t that take many many more hours? Even with the 1/2" thr roughing pass was over 3 hrs for the 12"x12" piece only going yo a max depth of 15mm.

~Don’t forget to be awesome!~

Yes and no.
The SM is always going to be slow. 3 hours isn’t that long for SM.
That’s a large and deep piece. 24 hours + milling time for all passes in hardwood isn’t unrealistic.

With a flat end mill you can have a stepover almost the size of the bit.
And a smaller bit you can run faster and cut deeper so it doesn’t end up being that different.

If you go too fast (besides burning out your machine) you won’t get as good of surface finish.
If you want fast, get a real cnc machine.

For pine, with that 3.175 mm I mentioned, you could rip it at 1000mm/min at 1mm depth. That’ll cut your time down a good bit.

(Sorry, wrong link. This is the right one).

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sfj544 - fair enough.

Thanks for your time & input.