You might have a use for this.

[slowcoach]

Hi All, Having just converted my Harrison L5 to run off a digital phase converter with remote speed control (I know, posh init  ) I had the problem of knowing what the exact speed the lathe was running at when using the speed control (serves you right, you flash git, I here you all cry!) A mate of mine (lucky so and so) had obtained a tachometer from a local power station, once used to measure turbine speeds I guess, he fitted it to his Brown & Sharp lathe and it works beautifully. Not being so jammie like my mate  , I decided to search the good old internet to find a tacho that would suite my requirements. I found a few, but they were a bit on the expensive side, being a Yorkshireman I wanted something for nowt  Anyways to cut the story short I found a little gem of a website that described a simple tachometer to suite my needs. I placed an order for the listed parts and set to work building one from the excellent instructions provided on the website. The circuit is built on stripboard, so construction is easy. I opted for the optical sensor that uses a reflective strip to pulse off. I connected the power supply and fired it up and it worked, no magic smoke  I lashed it up to my Harrison and hey presto a digital tacho, reading out the spindle speed to me, fantastic  So I built another one for my bandsaw!

So I thought I would share my find with you guys, call it a early Christmas present. I cannot take any credit for this unit as I did not design it, some bloke called Les did and what a great job he's done  .

I would of posted it earlier, but I lost the link to the site thanks to a hardrive failure It took me months of searching to find it again, but here it is.

http://myweb.tiscali.co.uk/leshobbies/leshobbies/Tach%20project.htm

Here's a few pictures of the unit I built in its box.








and one of the sensor



and back of unit showing the on/off switch, sensor socket and power socket



Poor picture of the finished board





Cheers and Merry Christmas
Rob 

[andyf]

Thanks for showing that, Rob. I use cycle speedos, but the magnet only gives them a signal once per revolution. Taking as many readings per rev as there are teeth on your spindle gear sounds much better.

Is it reasonably quick to update itself when you change speed?

All the best,
Andy

[Jonny]

Thanks Rob got two Harrisons, but will build one of these for the M300 that goes to 2500 rpm.

Have you the advanced digital the one with 420V outputs or the 220V outputs.
Just returned, well 8 days ago a 220V 3ph output digi but need the plug and play 5.5hp 420V 3ph output for above M300.
Just slapping a 3 axis DRO on two of which are the magnetic type.

[slowcoach]

Thanks for showing that, Rob. I use cycle speedos, but the magnet only gives them a signal once per revolution. Taking as many readings per rev as there are teeth on your spindle gear sounds much better.

Is it reasonably quick to update itself when you change speed?

All the best,
Andy

Hi Andy, my pleasure (Rob Willson has been poking me to post this for a while ), Its pretty fast at updating.

Cheers
Rob

Thanks Rob got two Harrisons, but will build one of these for the M300 that goes to 2500 rpm.

Have you the advanced digital the one with 420V outputs or the 220V outputs.
Just returned, well 8 days ago a 220V 3ph output digi but need the plug and play 5.5hp 420V 3ph output for above M300.
Just slapping a 3 axis DRO on two of which are the magnetic type.

Hi Jonny,
I've got the advanced one 440v output, would'nt be without it now! Have fun!

Rob

[j45on]

Thanks for sharing  I think I will make one for my mill   

[DMIOM]

Rob,

just out of curiosity - I'm a little puzzled by the photo of the finished board.

Most veroboard/stripboard has the copper tracks only on one side and you normally have the components on the non-tracked side and then poke the leads/tails/pins through and solder them to the copper tracks on the non-component side. 

Maybe it just an optical illusion, but your photo looks to possibly have the components on the same side as the copper tracks (and the potential for some of the wire links to short to tracks they pass over) ?

Dave

[slowcoach]

Rob,

just out of curiosity - I'm a little puzzled by the photo of the finished board.

Most veroboard/stripboard has the copper tracks only on one side and you normally have the components on the non-tracked side and then poke the leads/tails/pins through and solder them to the copper tracks on the non-component side. 

Maybe it just an optical illusion, but your photo looks to possibly have the components on the same side as the copper tracks (and the potential for some of the wire links to short to tracks they pass over) ?

Dave

Hi Dave, That particular stripboard I used was screen printed white for some reason, the copper tracks are underneath. It was quite handy at the time, because I could use a sharpie marker pen to highlight where the various components needed to go.
Cheers
Rob 

[Brass_Machine]

Very cool. Bookmarked for later reading.

Thinking this can be adapted to the mini mill...

Eric

[Jonny]

Also bookmarked for later reading, a job for the new year.
Must finish off this DRO install first.

Sent the 5.5hp digi 220V back a week yesterday, still no call from Direct Drives, needs to be running by 4 Jan and got to get a sparky out.

[Rob.Wilson]

I have one of those  Cheers Rob  ,,  works great 


Rob W

[slowcoach]

Hi Rob, Did you get it fixed up to your machine 

I'm glad I found the link in the end, because I'm no good at writing up stuff, I just don't seem able to explain it very well in text


Cheers
Rob

[madjackghengis]

Hi Rob,  thanks for the early present, my old Logan needs one, and that looks much better than the motorcycle tach I was going to coble together with some sort of drive so the mechanical gauge would read something of value.  I think I can use the teeth of my back gear and get an accurate readout.  Top of the Morning to you mad jack

[trevoratxtal]

Hello Rob
It was last year I converted my Harrison L5a to a 3 phase controller, I find it an absolute boon, I am led to believe the head bearings are rated up to 3000rpm for short periods perfect for polishing, and now screw cutting up to a shoulder holds no fears with any speed from stop upwards..
I thank you for the tachometer idea and will be taking it up.
Cheers
Trev

[Rob.Wilson]

Hi Rob, Did you get it fixed up to your machine 
Cheers
Rob

Hi Rob

I have not fitted it to the mill yet ,,,, but have had a play with it on the lathe     works a charm 


Thanks Rob W

[slowcoach]

Hi Trevor, Yep its a useful bit of kit a phase inverter, I haven't had my Harrison L5 beyond 760rpm (its max speed), I know changing the inverter frequency a bit higher gives you more rpm, but I was worried it might damage the motor. Screw cutting is a breeze as you say  .

Just like a DRO the tacho is a great visual aid to have on any lathe/mill or even a bandsaw in my case
Thanks again must go to Les who developed it, I just wish I had a contact email, so that I can thank him for posting it up on his website.

Cheers
Rob 

[trevoratxtal]

Sorry Rob I should have said!  I converted my motor to 240 by rewiring to delta configuration And upped the size of the pulley on the Motor. I had to delve inside the motor to find the the star connection point.
The reason I converted to 240v rather than 440v is that the converter produces some spiky square waves, the back EMF from them is rather high, and as the original insulation would have been tested for nice sine waves, I erred on the safe side and lowered the voltage. Well it works for me some hundreds of hours later.
This gave me top speed just under 3000rmp with the converter running the motor at 70 Hertz.
The L5a has slightly different Gearing to the L5 , so yours would be a bit different the motors are standard rated 50 to 60 Hertz but are tested up to twice the speed IE 120 Hertz so taking to at 70 seemed safe to me.
If you run prolonged at less than 50 Hertz then fitting a external fan might be a good Idea I used a 240v computer fan fixed to a plate on the end of the motor. I took one from a failed computer power supply, they are also cheep to buy from a computer repair place.
So far I have converted two lathes The Harrison and a 920 Chinese type, also my Mill.
If you would like to chat contact direct.
I will add some photos when it is warm enough to play outside.
Trevor B
 

[M WILL]

hi everyone have a lathe chester 920 in great order being sold new on here can anyone help with the sale or point right direction to sell it.  thanks.

[M WILL]

hi slow coach i have  a 920 chester lathe i know u had one on here for sale i have it for sale too wondering if u had any enquiries that may be interested. cheers....

[Rob.Wilson]

M WILL

Have you just joined Madmodders to sell your lathe ?   

Rob

[John Rudd]

@ Slowcoach/Rob,

the originator of the project is Les Jones... I can pm you his email addy if you want ( to protect him from spammers )

[slowcoach]

Yes please John, that would be great

Rob

[John Rudd]

Rob,

PM sent..

[M WILL]

the lathe belongs to a widow and is in storage and she asked to help to sell to an enthusiast i am not sure how to help her but thought maybe here was the place if offened by the sale then please forgive me.
mat

[slowcoach]

Hello M Will, I have sent you a PM.

Cheers
Rob

[M WILL]

TRIED TO PM ROB BUT NOT SURE IF U R GETTING SO LET ME KNOW AND I WILL SORT.    M WILLS