Mechanical Ratchet Counter – Source?

[Greg Mihalik]

Edit: Resolved. Going with an electronic counter. Thanks all.

I'm doing some fabric testing and need a mechanical 6-digit ratchet counter. It will get attached to a piston shaft that is compressing a wad of fabric, counting each stroke, at around 50 cycles per minute. I need to keep track of about 3 million cycles.

I've found this Line-Seiki in Japan for $20US + shipping + international money order etc.

I've found a USA made Veeder-Root for $210 + S&H.

And I found some on eBay for $8 that last about 8 hours/24,000 strokes. (China Plastic Junk)

If you have any leads I'd appreciate them.
If you have any ideas "out of the box", I'd appreciate them.

Thanks.

[Dustin Short]

I'm not sure exactly how "accurate" you need your counts to be. But if you have a specific and consistent cycle time can't you just measure time in the testing machine?

At 50 cycles/minute and 3million cycles you're looking at 1000 hours of testing time. At this point even being off by 1 hour is still only 0.1% inaccuracy which is far more accurate than probably just test subject variability.

Also if you're doing 3 million cycles you need a 7 digit counter, not 6.

[Jerry Wick]

McMaster-Carr has a variety. They aren't always the cheapest, but they stock everything and ship very fast. Scroll down about half way for the lever-type counters.

http://www.mcmaster.com/#mechanical-counters/=d5ssma

Jerry

[Kevin Beeden]

You can buy little digital pedometers that clip to a belt. Often for as little as £1/$1.

Get one, and replace the gravity switch with a decent microswitch, or, better still, an IR (non-contact) switch that won't wear out; the cycle rates you're talking about are pretty serious… hmmm… will your test rig survive that many cycles… ;-)

Can't remember how many digits they have; maybe not enough.

Either that, or get some other electronic counter; electronics these days are cheaper than mechanics…

First hit on google.co.uk. About £50. US sources look to be about the same price.

ps. my first suggestion was going to be 'get a cheap calculator, and modify it so that a switch replaces the '=' button, and start if off with +1 =========='. Should be good for 10 digit counts…

[Greg Mihalik]

@Dustin: Testing along the way, mechanical failure interruptions, power outages, and a variety of other things make the manual bookkeeping a challenge. I know… I'm doing that now. I Am able to keep a "hash mark" count of the millions. I just don't want to do that for the 99,999s.

@Jerry: a resettable McMaster-Carr 6-digit is $106 + S&H. Better, but still more than I'd hoped.

@Kevin: I've thought about cycle computers and pedometers, but I don't think any of them are 6-digit.

Hacking a calculator is a possibility. Just need to find the right calculator, a reed switch, magnet……

A digital counter, power supply, actuator…I'll do some searching.

Thanks all for the input.

Anyone else?

[Don Meredith]

You might give a Lufkin measuring wheel a shot. They're less expensive than the counters at MMC and should be just as effective for this application. You should be able to take the wheel off, make a crank arm the appropriate length to get the units to work out and its all gravy from there.

Lufkin Measuring Wheel at Lowes

Don Meredith

lightpack.blogspot.com

[Tohru Ohnuki]

You might want to consider an electronic counter like an omron along with a microswitch. This combo should be good for many more than 24000 actuations. Try ebay…

[Greg Mihalik]

"This combo should be good for many more than 24000 actuations."

That is a little shy of 1 to 3 million.

[Greg Mihalik]

@Kevin – Thanks for the push into the digital age….

I found a counter that is battery operated (10 years), 7 digit, resettable, with a "no voltage" closure input for $29. Every time the plunger comes down it can close a switch. Pretty simple.

[Bob Gross]

"That is a little shy of 1 to 3 million."

What is a couple of orders of magnitude among friends?

–B.G.–

[Kevin Beeden]

> @Kevin – Thanks for the push into the digital age….

I guess being an electronic engineer, I had to fly the flag a bit…

As for the switch input to the counter, I'd seriously suggest looking at a non-contact opto-switch, because the test cycles you're talking about are likely to severely tax a conventional switch. A typical, quality microswitch might have a quoted life of only a million operations. It's the mechanical bits that wear out; hinge, plunger, spring, contacts etc.

An opto switch will just keep turning on and off (although it would be wise to consider the MTBF; different failure modes for mechanics and electronics…)

[Greg Mihalik]

Kevin,
Magnetic and optical all require some sort of additional low voltage power.

So I'm going with a "no voltage contact switch" input to the counter. The counter has built-in "de-bounce" circuitry. I've found a Tamiya microswitch ($2.50 each) that seems to rated at 10,000,000. I'm waiting for a call from Tech Support. And if it is only 1,000,000 I'll preemptively replace it every 750,000. NBD.

Thanks for you input. I appreciate the suggestions and considerations.

Inasmuch as I am flying blind, I need as much help as I can get.

[Jon Fong]

Years ago I needed a counter and found that I could use a calculator. It was a Hewlett Packard with RPN ( you enter 1 first, then enter 1 + repeatedly). Worked great for 50,000 to 100,000 cycles.

Best regards

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