Thought I'd share my results from "probing" my B table

I thought it would be fun to “probe” my B table using the paper touch off method to see how square and repeatable things are. I put the 1/8" dowel in the spindle and touched it off to set the TLO, then set A to 90 and checked 4 “corners”, rotated B 180, checked roughly the same 4 corners, then dropped A back to 0 and spun the B around and touched off w/ Y every 90 degrees.

Here are my results:

  • A90
    • B0
      • Bottom left: -0.8317, -0.8313
      • Top left: -0.8280, -0.8282
      • Top right: -0.8299, -0.8297
      • Bottom right: -0.8328, -0.8328
    • B180
      • Bottom left: -0.8314
      • Top left: -0.8275
      • Top right: -0.8308
      • Bottom right: -0.8344
  • A0
    • B0: -0.8367
    • B90: -0.8364
    • B180: -0.8373
    • B270: -0.8364

My manual lists .8364 as the B table offset.

I did the first set of measurements twice, the second time after moving Z all the way + and then back to see how repeatable the motion is and how consistent my paper touch-off is.

Pretty interesting results, the A0 results are very close to the reported value in the manual, but w/ A90 things were off by up almost 10 thou in some cases This could definitely explain some issues I’m having leaving 5 thou stock in one op and then facing in another, but getting raw stock remaining w/ A set to 90.

The machine is fairly new, I got it in May. I certainly have had a few bumps, but nothing too crazy, maybe I’ve put something out of whack, or maybe there’s something off w/ the tool probing.

I’d be curious to hear from PNC if this is about as expected, and it would be fun if anyone else wants to try this and share their results.

Hi Jake,

This is interesting data for sure.

After looking closely at your numbers, it does seem like something is a little off with your machine. It is hard to say exactly what is causing the discrepancy you are seeing without some more info, but we would be happy to dig into that with you if you would like.

If it comes down to it, since your machine is still in warranty, we can recalibrate your machine and see if those measurements change.

Feel free to reach out to us at whenever it is convenient and you are up for a little troubleshooting!


Q Rothing
Applications Engineer, Pocket NC

Hi folks, just jumping on this topic. we recently purchased the V2-50… Fantastic bit of kit to be fair…couple of things though, is there a how to video for probing parts??? i want to check axis alignment from the part collet holder to the spindle axis…during a part rotation exercise (like a mac 2 setup) we noticed poor concentricity on 2 circular features…we think a workpiece offset will fix the issue…now take into account im extremely new to this…thanks for any help…

Hi. I noticed your post. Shoot me an email at and share with me the serial number of your Pocket NC V2-50. I can provide you support on your machine and I can show you how to measure your B disc runout.


Chuck Knighton
Technical Support Specialist
Penta Machine Company

Thanks a million, just forwarded a mail for support, thanks again