Machtach rpm and sfm meter for the lathe

The Machtach is a pretty neat product, developed by a guy in Orange County, California (Henry Arnold). Seems to be a home developed product that now has a range of accessories including a variety of sensors, housings etc. As well as being a conventional RPM meter, it has some pretty neat additional features:

• Surface speed in feet per minute (SFM) or metres per minute (SMM)
• Metric or imperial units
• Configurable number of slots, gear teeth etc for the sensors
• Direct entry of cutter (mill) or work diameter (lathe) for calculating SFM

I bought a couple of the Machtach kits to build up myself about 2 years ago while my machines were still in storage. I got one for the lathe and one for the Blidgeport, along with one of the Allegro gear tooth sensors. I forget which machine I'd got that for but I think the std kit comes with the reflective IR sensor (LED and phototransistor).

It was pretty nicely designed and the first one went together straightforwardly. Here are some pics I took at the time. Now seems like a good time to fit it to the lathe.

Recently I bought a couple of 3D printed enclosures that have become available recently. I got thoroughly shafted by the customs on the way in to the UK. The total value of the goods was $26 (about £18.50) and they ripped me for £13. Wankers. I would have been better off getting the enclosures sent individually - where's the sense in that?

Anyway, here's the bare Machtach, 3D printed the sensor, sensor cable etc. Just need to slap them together!

There's a green display filter thing:

Display filter fitted (self adhesive):

Now that the enclosure seems to have gone together OK, time to look at the sensor:

Some small heatshrink for the individual wires and a larger bit for the cable ending:

Wires terminate in a small terminal block:

Now to mount the sensor on the lathe spindle. No, I'm not squeamish - I don't mind drilling and tapping a hole (M3) in the spindle bearing housing.

There - sensor fitted:

I need a contrasting series of reflective and non-reflective surfaces for the IR sensor to pick up. So first, I polished the nose with some fine (P180) paper. It actually looks pretty nice now:

Seems to work nicely:

I used a very simple method - black PVC tape in 3 places around the circumference. At some point they will fall off but for now they will do:

Here's what you see with the VFD set to 50Hz and the gearbox at "1020 rpm" setting. Of course, this is unloaded, so is spinning a little quicker than the rated speed. Pretty encouraging though. The Machatch is simply held on top of the VFD with double sided tape. 

There.