Pocket NC Touch Probe – Mechanical Hardware (Part 2/4)

Last time in part 1, I talked about why I wanted to add a touch probe to my Pocket NC. This time, I’ll cover the basic hardware necessary to make it happen.

I decided to start with an inexpensive probe so that as I was figuring things out, I wouldn’t be too sad if I smashed it a few times. I’ve seen a number of other hobby machinists use the “vers.by” probes, so I decided to give them a try too.

This probe requires 5V-24V power, has a 6mm shank, and provides a NPN-NC output with a USB connector as the physical connector. Note, it isn’t USB, but just uses that connector for power and the signal.

Mounting

To start with, I needed to get the probe such that I could mount it in the spindle of the Pocket NC. The V2-50 I have can handle a 4mm shank at most, and that is what I primarily use. Obviously, 6mm is bigger than 4mm, so something needed to be done.

So, I wouldn’t be a quality engineer if I didn’t have the brand new toy disassembled within hours of receiving it:

What I ended up doing was turning down the 6mm shaft to 4mm on one of the Artisan Asylum’s manual lathes.

This was pretty challenging. First because the shaft was already permanently mounted into that relatively thin base section, so getting the part trued up in the chuck took some time. Second, because it sticks out so far, I could only take excruciatingly light cuts. In hindsight, I should have worked harder to get the opposite side supported. The entire operation took something like 3 hours. However, when done, I had a probe with a 4mm shaft!

And hey, it fits!

After a bit of tuning with my 2 micron dial indicator, and the provided adjustment screws, it seems to pretty dialed in.

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