2 pass carving - registration issue with the 2nd pass

Hi all,

I attempted my first 2 pass carve today - photos attached. This is on a 2nd hand machine (18 mo old) that I acquired. I’ve read previous posts on 2 pass carve registration issues…

First pass was with a 1/8" downcut bit (new). 2nd pass was with a 60 degree v bit.

Material was taped and superglued and definitely didn’t flex or move.

Machine is set to lock motors, and router didn’t move during bit change. I did re-home the machine and used previous XY.

Registration is off to the right by a small amount. I’m wondering if this is a y-axis belt tension or a worn/stretched belt issue. Am I on the right path here?

Any tips on chasing this down would be appreciated.



You’re limited by the precision of the homing switches when you do this. Best practice would be to not home the machine between operations.


Hi Neil - thanks for your reply. I did another run without re-homing, and the same result happened.

I have checked the machine - the belts seem tight (although I’m waiting for my fish scale to arrive so I can test properly). The v wheels are also all tight.

My next step will be to replace the belt and see if that will fix it…

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try using a ball nose instead of an end mill. That should take your steps away.

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It kinda looks like the vbit used isnt the same angle as the one entered to create the toolpath.

thanks for the feedback Ken - you’d use a ball nose for the roughing pass? Do you recommend one in particular to balance the issue and overall speed of carve?

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Thanks Seth - I’ll recheck this , and I’ll also check to see if the v-bit tip is centered

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you need to set up multiple g code and/or project pages.

a roughing pass >a finishing pass to where left off with the roughing pass so you’re not cutting air.

CNC first roughing/finish operation - YouTube

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Thanks Ken I appreciate your time and responses - and sorry if I’m slightly obtuse here.

To clarify - you’re saying to do this in addition to the 2 pass carve I set up in Easel? So I hog out roughing pass (1/8" downcut) as a page? Then a "2nd stage rough (ballnose) and a detail pass (60 degree v Bit) as a separate page? The video was just showing a s standard 2 pass - which seems to be similar to what I did in Easel.


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Looks almost like one pass was done with a 60 deg and another with a 90 deg

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not Quite, but you’ll need do a couple test run. hit the scrap pile :smile: :grin: :laughing: :innocent:

You will need a larger cutter for roughing one file. then a finishing pass with a smaller cutter (.125 possibly) second file. a third file cutout and release.

Now, this where the stepover will need adjusted accordingly. If done correctly you should barely no sanding if any.


Hi Johnathan,

This is correct - the roughing pass was done with 1/8" downcut sipral bit, then detail pass was done with a 60 degree v-Bit.



Hi Ken - got it! I’m going to take a more detailed look at the stepover settings. I also need to buy some scrap!

Your work looks beautiful - I’m hoping to get there in time. The learning curve is a wonderous thing!


No scrap? try some foam insulation board like pink or the yellow stuff. make sure you use vac suc-it boot

Sounds like a good idea - I was running out of wood that I was wanting to sacrifice! Thanks

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