Spindle Speed

[RobboParticipant @robbo]

And to think that all this started out as a question about measuring spindle speeds!

 

For that purpose I  use, when deemed necessary, a hand-held tachometer got via Ebay from the USA, no doubt made in China.   It works a treat.  Once a speed has been checked, it can be remembered by the noise the machine makes (near enough).

 

Robbo

 

[Ian S CParticipant @iansc]

Theres still people using foot powered lathes-would’nt have a motor, not enough control! Ian S C ps Thats not me.

[CirclipParticipant @circlip]

Well, after the latest triadibe and swarf slinging, just seen on another foureye that a car type rev counter with a “Hyundi” cam position indicator was used to look at the shaft speed.

 

  Just as an aside, if you’re listening to the “Noise” Robbo, save the cost of an electronic Tacho.

 

   Regards  Ian.

[mgjParticipant @mgj]

Well come on – measuring a spindle speed isn’t a 2 page  problem.

 

You buy/make a proper unit as Les Jones suggested, or you buy a hand held tacho – optical or vibro – of which there are many. End of discussion really?

 

Or you can put your finger on it and see how hot it gets in how long, to get an answer like slow, fast and sh..ugar.

[KWILParticipant @kwil]

  Do you think this one has been “spun” out for long enough? [and I have VFD and DROs on four machines!!]

[Steve GarnettParticipant @stevegarnett62550]

I don’t care what the absolute speed is, either on a mill or a lathe. But in the past, in a noisy environment with several machines running, knowing that a mill has slowed down slightly under load when you can’t hear it clearly has been useful information – and to find this out effectively means that firstly, you need to know pretty accurately what speed it’s actually running at, in order to resolve the differences, and secondly that this speed indication should be independent of the driving system – so using the analogue output from an inverter won’t do. Also, I don’t particularly want to do this with a hand-held tacho either – I’ve tried that before and whilst it might be okay for some, it’s not for me.

 

Obviously I recognise that this generally wouldn’t apply in a home workshop, where generally only one machine at a time is running, and you can hear what’s going on. But that still leaves the ‘anal’ reason for wanting to know, of course…

 

As for DRO’s – well, what Meyrick said, as far as I’m concerned. But my DRO is definitely in a case!

[Sub MandrelParticipant @submandrel]

I built a tachometer, largely because I wanted to get into AVR microcontrollers and it looked like a good starting place. It does have one really good use, that I haven’t seen mentioned elsewhere.

 

With a fairly small, low powered machine (mini lathe), one can keep an eye to how much the revs drop when you put on a cut. It’s surprising how much you can increase the depth of cut/feedrate before the revs drop more than a few percent, and it’s a much kinder approach than waiting for it to stall, start labouring or popping fuses.

 

FWIW I also replace the fuse with a circuit breaker.

 

Neil

 

 

[Steve GarnettParticipant @stevegarnett62550]

Posted by Neil on 06/02/2010 22:14:26:

 It does have one really good use, that I haven’t seen mentioned elsewhere.

 

 So you didn’t read the post previous to yours, then?

[Ian S CParticipant @iansc]

It would give you a comparison between sharp and blunt tooling,and also the effect of cutting oil.Once you’v checked the rpm against the speed control and perhaps noted the speed/ possition you will rarely need the tacho on the machine. Ian S C

[Bill Davies 2Participant @billdavies2]

Found this on our website:

Strobe disks

Go down the page.

Bill

[Bill Davies 2Participant @billdavies2]

Ooops, added to the earlier thread; go up the page!

Bill, blushing.

[Peter G. ShawParticipant @peterg-shaw75338]

The easiest method is to use a cheap & cheerful bicycle speed computer. These devices have to be set to match the wheel diameter, and on the one I bought, this can be adjusted down to about 100mm diameter or thereabouts. It is necessary to then experiment to see what the display shows – I used my lathe which has 9 fixed speeds.

If you can find them, try ME page 432 dated 11 Apr 97 where Ron Wallman describes the idea and in issue dated 04 Jul 97, DAG Brown recommends the Sigma Sport BC500. Also, MEW178 (Jul 2011) where Michael Cox describes a cycle computer with a RPM range.

Peter G. Shaw

[Pete RimmerParticipant @peterimmer30576]

Many good lathes fitted with variable speed have also been fitted with a tacho or speed readout.

Rivett 1020, Smart & Brown 1024, Holbrook minor, Monarch 10EE – all top-bracket machines. If those manufacturers saw fit to fit them then it's perfectly reasonable for a machine being retro-fitted with variable speed to also have one fitted.

[oldveloParticipant @oldvelo]

Hi

Pete says "Many good lathes fitted with variable speed have also been fitted with a tacho or speed readout." mine is only mediocre and has one fitted. Mill and Drilling machine share at the flick of a switch.

Variable speed power feed is also a good option. An Amp meter fitted to the main motor leads will help keep from overload when using a heavy cut.

Eric

[ANDY CAWLEYParticipant @andycawley24921]

I checked the spindle speeds of my Chinese import lathe some yeas ago using the sweep hand on my wrist watch, a length of all thread, a nut and a felt tip marker pen. All of these items were in my shed so I didn’t have to spend any money.

I put two marks on the rod as far apart as possible. Whilst holding the nut by hand I ran the lathe at various speeds and timed its travel between the two marks. Having measured the distance between the marks and knowing the pitch of the thread it was simple enough to calculate the rpm. I made sure the free end of the rod was inside the tail stock to guard against the possibility of flailing should the rod get out of hand. I was very conscious of this possibility however things never really showed any signs of running amok.

The speed control on the machine was a simple rotary knob so I put marks on the machine casing using the marker pen and wrote speeds against the marks.

I make no claims about the precision of this method but it was good enough and dead easy to do and it got me going with the lathe. The further apart the marks are the more accurate the results.

[Ron LadenParticipant @ronladen17547]

I added one of these to both the mill and lathe, cheap as chips reliable and accurate. Comes with a 4 digit display and easy to fit, there is always a place somewhere on the mill and lathe where it can go.

[ANDY CAWLEYParticipant @andycawley24921]

Posted by Ron Laden on 26/09/2020 09:04:44:

I added one of these to both the mill and lathe, cheap as chips reliable and accurate. Comes with a 4 digit display and easy to fit, there is always a place somewhere on the mill and lathe where it can go.

Looks god, what is it?

[Ian HewsonParticipant @ianhewson99641]

Look for digital tachometer on the bay, £8-99 or so. Easy to fit and work well

[Author]

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