# Installing a $10 Digital Tachometer on a Power-Kraft (Logan) Lathe



## millsrv (Oct 24, 2018)

I realize that there are many posting on the tachometer subject but I thought I would share mine.

Yesterdays project was to install an inexpensive tachometer on a 1953 Logan Lathe. These tachometers can be found on Ebay for $10 including shipping. In addition to the tachometer you will need a power supply that supplies 8 to 24 VDC. These power supplies are commonly called "Wall Warts" and are easy to find, so happens I have a box full of them from no longer used household electronic devices. The bracket for the Hall Effect sensor will need to be fabricated as will a case for the display. There is a small magnetic disc that needs to attach to the lathe spindle. The magnet was epoxied to the spindle (I also wrapped several layers of a quality electrical tape around the spindle and magnet to help ensure the magnet stays put). My lathe happened to have a 3/8-16 threaded hole on the headstock that I was able to use for the sensor bracket. My other Logan does not have this hole so you may need to drill and tap. I have no idea why this hole is there but I took advantage of it.
There is just enough room on the headstock to mount the sensor and still close the cover.
I made an aluminum face plate for the display and mounted it onto a plastic electrical box purchased at Home Depot. I also added a 120V outlet that powers the wall wart when the light above the lathe is turned on. When the light is off so is the tachometer.
I understand that once the RPM's are known for the different belt / pulley combinations and back gear positions that the Tachometer is not really needed but for a small project and $10 what the heck? If I were to change to a DC or 3 Phase motor and VFD in the future then having the tachometer will be required anyway. 
The attached pictures of the display are distorted due the camera being out of phase with the display frequency.


----------



## dlane (Oct 24, 2018)

Should be a good improvement, are you using your tractor bucket for a back chip shield ?.


----------



## MAKEITOUTOFWOOD (Oct 24, 2018)

Could you post a link to the ebay listing? There are a lot of them. I want to add one to my mill.


----------



## millsrv (Oct 24, 2018)

Ha, no it just happens to park there and I raise the bucket to pull it further into the shop.


----------



## millsrv (Oct 24, 2018)

Here is a link to the tachometer I used on Ebay:
https://www.ebay.com/itm/1PC-4-Digi...var=521326555148&_trksid=p2057872.m2748.l2649


----------



## MAKEITOUTOFWOOD (Oct 24, 2018)

Thank You


----------



## markba633csi (Oct 24, 2018)

It has been reported that the sensor wire can pick up interference- route it away from motor wires 
mark


----------



## MAKEITOUTOFWOOD (Oct 24, 2018)

markba633csi said:


> It has been reported that the sensor wire can pick up interference- route it away from motor wires
> mark


How fare away?


----------



## markba633csi (Oct 24, 2018)

Well, certainly not tie-wrapped to your motor cables. I'd say a couple inches. Also, aluminum foil can be wrapped around the wire as a shield
Some motors generate more electrical noise than others.  DC motors and controllers generate a fair amount.  AC single speed ones, not so much once they are started and running


----------

