Author Topic: How to use an old calculator as a turns counter....  (Read 8488 times)

Offline John Hill

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How to use an old calculator as a turns counter....
« on: August 21, 2009, 08:43:47 PM »
.... now do not get too excited, this is not a description of how to use a $2 calculator to convert your shop to CNC or even as a substitute for a DRO system but it might have some uses anyway.

The simple calculator which has been around for a few decades is really a pretty nifty device!  The bigger ones, which are often the cheaper ones, can be opened and slightly modified to become something quite useful in the shop.

But before opening the poor thing take a moment to play with the keys.  For example press the '0','+','1' and '=' keys and the display shows '1' (no suprises there) press the '=' again and it increments to '2' and so on.  Your simple calculator is acting as an even more simple counter.

Instead of entering '1' enter some number with a decimal value, for example '0.254' and imagine that each press of the '=' key represents one millimetre in which case the display shows the equivalent in inches.

All very interesting, I am sure [yawn] but how to make use of it....?  Open the calculator and locate the connections that go to the '=' key, attach a couple of thin wires and extend those to the outside when putting the cover back on the calculator. 

What you use it to count is up to you but dont forget that you can count other than unitary values so, for example, knowing the pitch of your lead screw  you could get a direct readout of carriage travel in metric, inches or any other measurement system you prefer.


OK, not all that useful but what did you expect from a pocket calculator? :coffee:
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Offline Darren

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Re: How to use an old calculator as a turns counter....
« Reply #1 on: August 22, 2009, 03:43:50 AM »
All not very "yawning" at all....

A couple of problems I see is that while certainly interesting it's still too basic. Only full turns can be counted...so OK add more switches, as many until it becomes practical which won't be many. So the resolution will be a little on the large side.

Then there is counting backwards. We can do this by some quick manual input, but not very convenient in real terms.

It's a nice idea, but it's limits are going to be.....erm...quite limited.... :lol:


Would have been excellent when I was winding transformers and chokes though.....truly excellent......
« Last Edit: August 22, 2009, 04:01:14 AM by Darren »
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Offline sbwhart

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Re: How to use an old calculator as a turns counter....
« Reply #2 on: August 22, 2009, 03:46:27 AM »
Hi John

What do mean not very usfull, I think thats very usfull especialy when using a DRO keeping count of where you are will prevent you from dropping a B****k (making a mistake), I've got a project planed  :proj: of the time keeping sort, where that will be invaluable.

Thanks for sharing


Stew
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Offline Darren

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Re: How to use an old calculator as a turns counter....
« Reply #3 on: August 22, 2009, 03:57:05 AM »
TBH, if it was used just for counting the No' of turns then I could see it being quite helpful.

How many DRO's do you see on RT's?

Or if you had no DRO on say your mill and had to make repeated multiple turns.....On my recent Gib I had to make five holes at 2" intervals. That's 10 turns per 2".
10 is not a big number, but I got lost a couple of times all the same. 40 or 50 turns and I could see some real issues arising....maybe it's just me, but i thought I could count to 10....... :ddb:
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Offline John Hill

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Re: How to use an old calculator as a turns counter....
« Reply #4 on: August 22, 2009, 04:09:53 AM »
Darren, if you need 'more switches' you could use something like a reluctance circuit as was/is used in car distributors or you could use some variation of a Hall Effect device to count the teeth on the cogs,  another would be a slotted disc and photo interrupters.

You will find that although the calculator can count quite fast the display will not be able to keep up more than a few interruptions per second.
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Offline Darren

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Re: How to use an old calculator as a turns counter....
« Reply #5 on: August 22, 2009, 04:48:30 AM »
Interesting...if I ever find "that" spare time and the need I'll come back here knocking on your door......just too many tuits at the mo.... :ddb:
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Offline Chuck in E. TN

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Re: How to use an old calculator as a turns counter....
« Reply #6 on: October 31, 2009, 08:01:03 AM »
First 10 minutes as a member, and you have inspired a project. I will adapt this idea to counting the twists in making furled leaders. Might improve my quality control!
Thanks for the inspiration!
Chuck in E.TN
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