Myford Tachometer

About time, I've had the bits for over 6 months and just needed to make a sensor bracket and bracket mount and wire the thing up!

Connections -

Display Connector - Socket 1 - Socket 2
1 ------------------------ 1 ------------ 1
2 ------------------------ 2 ------------ 2
3 ------------------------ 3 ------------ 3
5 ------------------------ 4 ------------ 4

Power plug and sensor plug are wired appropriately and it doesn't matter which socket they connect to.

Sensor siting -

It's a non-standard Super 7 but a cylindrical magnet through one of the holes in the front gear wheel and a bracket taking the sensor to the rear of the gear works fine for a standard Super 7, the sensor will pickup a magnet at 90 degrees just passing the front edge of the sensor.

Edited By Nick Hulme on 09/05/2018 11:20:55

Edited By Nick Hulme on 09/05/2018 11:21:26

Edited By Nick Hulme on 09/05/2018 11:22:19

Are you saying that the tacho does not work?

If so, have you tried reversing the poles of the magnet?

It works fine, I wired it up on the bench and tested it thoroughly before fitting & wiring on the machine 

It's just an example of possible sensor positioning and fixing and convenient wiring connections.

Edited By Nick Hulme on 09/05/2018 15:41:16

+1 for reversing the magnet. Before you do much else, pass another magnet over the sensor to see if you get a reading.

+1 for testing things before fitting them to a machine where (like this) it is possible, and I did, that's why it works! :D

BTW it's a Neodymium magnet with a 3mm bore and one side countersunk, I wouldn't have used it if testing had not shown the countersink to be on the correct side

So, it worked on the bench with the grey box wired as it is now with the two connection sockets wired up in parallel ( You say the two sockets are wired the same). But I assume you had to disconnect the sensor plug to pass the sensor cable through the end cover. and then re-connect it. To me, that needs a double check.

I'll leave it how it is, reading my posts should clarify why :D

Yup! I read your first post as simply for info of how you did it - and that it was working perfectly.

I have fitted a hall effect sensor to my S7. I found a neodymium magnet that nicely fitted into one of the holes in the front gear. It is super glued in place with about 1.5mm sticking out. The bracket is mounted where the worn rubber bump stops were placed. I drilled the holes deeper with a 7mm drill until it just broke into the casting. Tapped M8 as deep as possible finishing with a plug tap. Vacuumed out the swarf from everywhere. I also noticed the variations in the casting, so trimmed the height of the screws to be about the same as original the original bump stops. New rubber will be placed inside the 5mm hex remaining, as well as painting the bracket. The hole centres on my lathe was 111.3 for the M8 holes. It started from 1.8mm thick ali angle extrusion. 2, 3mm screws attach the bent bracket piece that holds the hall effect sensor. It needed to be closer for stand along box to work compared to the Ditron DRO box. The sensor is connected to a DB9 connector, It is wired Blue wire (Signal Earth) to pin #2, Black wire (Signal)to pin #6, Brown(+5v) wire to pin #7.

Installation

Working-RPM display box only

Working- Ditron DRO box, with RPM display

Now to tidy up all the installation,

Neil Lickfold

MEW has an article I wrote a year or 2 ago on using and altering the sensor to a device half the size of a matchhead - so small it can be hidden almost anywhere. Noel.

Noel,

Have you got a reference to which issue number? or month/year obviously

Fitted mine similar to Nick and has not missed a beat in 6 years (touch wood)

Dave T, I think it was late 2019. I will dig the MEWs out and check. Noel.

SS41F seems like a good candidate, cheap as chips from ebay

Dave T, I cannot put my hand on the copy, but my own paperwork shows it was writen in early December 2019 and I had a note from the publishers early March 2020, it is not March 2020, I have that one so it must be Jan or Feb 2020. Good Luck Noel.

It's issue: 290 (Feb 2020) page 34 - Cheers