There are many CNC touch probes of varying quality available for the Tormach. The two offerings from Tormach are a “passive” probe for about $250, and a “digitizing” probe for $1250. I opted to buy a used Renishaw probe on eBay in an attempt to get the quality and performance of a digitizing probe, but for less than the price of the passive probe.

The cost of used probes on eBay vary all over the map, but I got what I thought was a good deal – a Renishaw MP11 for about $150. My eBay probe came with no cable (more on that later) and had a 1/2″ straight shank, but I figure those shortcomings would not be too hard to rectify.

It turned out that my MP11 “deal” was less “great” than I thought because of the “outer diaphragm” issue, which I later found out is common with old Renishaw probes. There are supposed to be two rubber seals that surround the stylus base and keep out dirt while also sealing in some secret oil that prevents corrosion of the contacts. The seals look like tiny gear-shifter boots. They are described (somewhat) in the MP11 manual, starting on page 1-16: