Headstock Tachometer

This topic has 12 replies, 10 voices, and was last updated 23 May 2011 at 17:27 by ChrisH.

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22 May 2011 at 21:09 #69037
ChrisH
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@chrish
Was thinking earlier that it would be useful to have a tachometer giving me a readout of the actual headstock (chuck) speed, as opposed to believing what the adjusting handle of the stepless drive pullys was indicating would likely be the speed, all things being hunky dory. I would need to have some sort of pick up (mechanical or more probable electrical) on the headstock output shaft, linked to a digital or analogue readout in some way. I could use my handheld techo, but a permanently fixed one would be more useful as it would be, well, permanently displaying the info. OK, it’s ‘nice-to-have’, not ‘need-to-have’, but would be useful all the same.

And that is as far as I have got.

Not got far researching this on the ‘net’, totally devoid of ideas from there.

Anyone got any bright idea/s to point me in a useful direction?

ChrisH

Edited By ChrisH on 22/05/2011 21:11:06
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22 May 2011 at 21:09 #5521
ChrisH
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@chrish
22 May 2011 at 21:14 #69039
Steve Garnett
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@stevegarnett62550
We had a huge great thread about this ages ago – you might well get some useful ideas from it. It’s here.
22 May 2011 at 21:23 #69040
John Coates
Participant
@johncoates48577
Sigma (or other make) bicycle speedometer. Magnet on chuck or mandrel or backplate and small bracket for the magnetic pickup . Isn’t there something on this in next month’s MEW?
22 May 2011 at 21:23 #69041
The Merry Miller
Participant
@themerrymiller
Chris, you may not be aware that in next month’s issue of MEW (no.178) there will be an article on building a rev. counter using a bicycle computer, something I’m looking forward to making.
22 May 2011 at 21:53 #69044
Steve Withnell
Participant
@stevewithnell34426
Not sure it’s worth the effort to be honest. I’ve a variable speed lathe so built a tacho onto the spindle. Never completed the display, bought an optical tacho off eBay cheap as chips and calibrated the dial with a permanent marker, job done. You really don’t need to know the spindle speed to +/- 10 rpm and probably not even +/- 50rpm. (At 50rpm you can count the revs!)

My tuppence worth.

Steve
22 May 2011 at 22:18 #69049
Dennis
Participant
@dennis66942
hi Chris I made a rev counter four years ago out the £5 bicycle computer its still works today,look forward to see it in MEW next month . Dennis
22 May 2011 at 22:26 #69050
mgj
Participant
@mgj
Hardly worth the trouble to build anything special. A dab of white paint and hand held impulse/optical tacho and you have your answer. You don’t want to put any effort into it, because once you have a reading and mark as Steve has implied, you never need the tacho again. Not that one ever really needed it in the first place, because the tool is either cutting properly or its not, and it won’t take long to get oneself sorted.

At the end of the day, does one actually need to know revs at all – I have a geared head on one lathe, and pulleys on the other, and I have no idea what each ratio provides, but I know what settings cut right at what diameters.

But, if you really want to find out, they do them for testing the speed of electric motors. (and all sorts of other ranges) so Scrrewfix might well stock. The model aircraft ones with a digital readout (available from most model shops) are about £15 -£20, and they will give you a reading at 600 rpm on a 2 blade prob. 4 or 8 bits of reflective tape on your chuck and you are well in the range of one of those at lathe speeds.

Calibrate against 50hz.

But are you sure that it is time or money usefully spent?

Edited By mgj on 22/05/2011 22:27:50
22 May 2011 at 22:41 #69053
Les Jones 1
Participant
@lesjones1
Hi Chris,

The Design that Steve Garnett refers to was submitted to MEW about February 2010. As so much time has elapsed I do not think it will be published. If you are interested the design is on my website.

My website

Les.
22 May 2011 at 23:16 #69056
harold
Participant
@harold
Hi Les

I’m very surprised that evidently it’s not being published. The two that I have built have given impeccable service. It’s a lot less electonically complicated than many recently-published devices and the call for a workshop-friendly tach is a frequent one.

Regards,

John
23 May 2011 at 08:26 #69067
David Clark 13
Participant
@davidclark13
Hi There

I am going through all the old articles.

Occasionally some get overlooked.

The Tachometer one was due to email problems.

I have now found it, it was forwarded to myself and has not been sorted until I saw the post on here.

Some get published after two or more years although most are sooner than that.

I still have some passed on to me by Dave Fenner and the odd one submitted to Geoff Sheppard.

regards David
23 May 2011 at 16:09 #69085
ChrisH
Participant
@chrish
N
23 May 2011 at 17:27 #69088
ChrisH
Participant
@chrish
Thanks to all who replied, and thanks to Les for his link to his tacho design.

I had not thought of using a bike speed computer – not thinking sideways enough – but now await next months MEW with added interest.

I can of course use my hand-held tacho, but it seemed like a nice idea to not have to do this and still get the speed reading.

Chris.

Edited By ChrisH on 23/05/2011 17:42:28
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