Lathe Rev Counter

I would 2-sided sticky tape it down onto a piece of sacrificial material (MDF, chipboard,...) and then machine the OD and ID to suit.

Regards, Tony

A CD? You know that they are brittle like hell. I wouldn't use them (after machining) for something rotating at revs in the 1000's range. Use an old hard disk instead.

Nick

Thanks Tony.

"working holder" think I meant work holding! brains turning to cheese..

Regards

Steve

Wensleydale or Stinking Bishop?

Regards

Grommit

Welcome to the club!(:-)

Alan

Actually they're not, it's more 'tough as hell'. They are made from Polycarbonate and are not in the least bit brittle, but the material is however very notch sensitive.You can hit Polycarb with a club hammer and it will just bounce right back at you, but lightly score a line on the surface first before you hit it and it will happily fracture.

Mind you, an old hard disk platter sounds like a good idea and will ultimately be more robust in the long term.

Peter

Isn't brittle the contrary of ductile?

You will make a lot of notches when machining.

Nick

Sorry, can't help you there. I have thrown away my HD-collection (more than 30, starting at 5 1/4 with 10MB) a year ago. I only know, that there is nothing that is 3.5" at at 3.5" floppy. They are 90mm whide. :-)

Nick

"Steve" said

If I had been asked that without having stripped an old drive I would have said "No, that's the size of the case".

In fact the Case is 4" and the platter I have just measured is 95mm x

JG

I missed the start of this one, somewhere back in the mists of time, but why not use a standard proximity detector off one of the gear teeth and feed that into a simple display circuit?

You can get detectors in M8 threaded bodies now and they are very sensitive compared with the old 14mm ones we used to use on engine governors. The display can be either analogue or digital.

You lose the fun of drilling a CD or HDD platter though :-))

Peter

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Nick_Müller said

Why didn't I think of that?

Of course the 3 1/2" comes from the fact that the 1.44Mb disc package is

JG

Partly because it's the first real use for naff CD's I've come up with in probably 10 years!

I've breadboarded the electronics which is effectively a frequency counter with a 1second gate time, so 60 holes works well. It would be dead easy to swap the magnetic sensor, but there isn't a 60 tooth gear that is "permanent" on the machine. There is a smaller gear though which I could use if I increased the gate time - that is probably worth thinking about, it would need much less work to fit than the CD approach too.

Thanks

Steve

That was my main point, there are already gears that can be accessed on most lathes, and a bit of electrickery around the display can make use of almost any number of teeth, especially if you go analogue, but digital is MUCH nicer.

What display and driver are you using?

Peter

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I'm using a 4535 BCD to 7 segment driver and 4554 Counter. Current version uses a 4060 counter to produce a gate time but at weekend will re-work using a 4024 to do a divide by 50. The display is a four digit red led with .5 inch high digits.

Most of the designs seem to use PIC's and I just don't have any enthusiasm for machine code these days or investing in the tools. The chips I'm using are "cheap as" I think 75pence (average) * 6 = very cheap rev counter!

I looked at the data sheet for magnetic sensors and they suggest

Regards

Steve

I think we have some 4-1/2 digit display drivers for LED or LCD around here, Intersil or Harris. have you looked at those at all?

Peter

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The only 4-1/2 digit counters I found were LCD only and c£10. I did find an LED version in but marked obsolete, which is why I ended up with the 4554, which is 3 digit, not best choice for a 4 digit design!

Steve

Intersil did both, and we used them for one of our battery testing machines. It was a simple timer doing a count which the display racked up in A/Hours or mA/Hours, depnding on the settings.

Probably still got some display PCB's as well.... All the electronics was on the display board, either LED 7-segment or an LCD assembly.

Peter

-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk Web:

Have you looked at the CD40110B (and it's sisters). A cascadable up/down-counter (1 digit) directly driving LEDs?

Nick