MachTach
About
The MachTach is a machine tachometer which is used to display the speed of any machine tool. Machine speed is important because it determines how quickly you may remove material and is closely tied to the material, cutting tools to be used, and surface finish. The MachTach is capable of displaying revolutions per minute (RPM) and surface feet per minute (SFM) or surface meters per minute (SMM). It requires only a simple sensor to make its measurements. IR reflective, IR slotted, hall effect, and gear tooth sensors can be used.
Four Modes of Operation:
Revolutions per Minute mode - 0-9999 RPM
Surface Feet per Minute mode - 0-9999 SFM  or Surface Meters per Minute 0-9999 SMM
Diameter Entry Mode for SFM - 0.01" - 99.99" (.01" increments) or 0.1-999.9 mm for Metric
Slot Entry Mode - You can program any number of encoder slots/targets/magnets/teeth 1-90
1 RPM resolution - Minimum speed displayed depends on number of slots - 5 RPM w/ 6 slots
1 second display update
(Slot and Diameter values are saved between sessions so they will not need to be re-entered)

Many Module Configurations:
The MachTach PC Board can be built as is or cut in half to create a 2 layer module which is smaller but deeper. Either style module can be mounted inside your machine tool or inside an external enclosure.
1.  3.3" x 2.9" x 0.5" Full size PC Board module
2.  3.3" x 1.45" x 1.0" Half size, two layer module
3.  3.3" x 1.45" x 0.80" Compact Half Size (uses shorter spacers)
3.  Two 3.3" x 1.45" x 0.5" Two halves mounted in different locations (display and controller)

The Full size module can also be mounted inside an optional plastic enclosure
4.   4.25" x 2.75" x 0.9" Optional Serpac 31i Plastic Enclosure

Power: 7-9V at ~ 200 ma