Stewart Warner hand held tach

Haven't used a hand held tachometer previously and on a whim, bought a S-W 757-W. The spindle rotates by hand but pressing the rubber bit up to a spinning lathe chuck has no joy. Should the tach spin just by pressing the rubber bit to a spinning object or does it normally need to be gripped/chucked? Does anyone have an exploded parts diagram/ service manual? Stewart Warner does not and Google Fu has not been helpful.

Lucky7

I have a large collection of speed indicators that counted revolutions. The Stewart Warner, however, is basically the same as a dash mounted tach and uses a spinning magnet as best as I can determine. It should be pressed on the end of a shaft, in the center. No need to attach it.

Dennis

I've got one of those, more as a conversation piece. But is the rubber tip still firmly gripping the shaft?

Yup, the rubber grips the shaft. Guessing a stiff bearing or old oil inside as it will spin by hand but not with the rubber pressing a shaft or chuck jaws. Will (eventually) take it apart.

L7

lucky7 said:

Yup, the rubber grips the shaft. Guessing a stiff bearing or old oil inside as it will spin by hand but not with the rubber pressing a shaft or chuck jaws. Will (eventually) take it apart.

L7

Click to expand...

Worn plain "Oilite I" bearing another possibility.

Waste of time, regardless - trust me. I have "many" S-W, bought NOS/NIB for only about $35 each.

Most are "Marine Diesel" because the top-end of 3000 to 4000 RPM was a better fit to my machinery than automotive ranges, hence greater dial-spread and easier to read.

If you have a genuine need? Mine is the "timing" of DC motors - out of their machine.

FAR better ranges (selectable) and finer granularity of readout would be to see if you can find a used but not abused James G. Biddle with the full kit, instead.

Seriously useful, dead easy to use, and lovely to hold and behold goods, the Biddle tachos are.

Otherwise, non-contact Hall-effect, optical, or mag-prox electronic goods are too cheap and ubiquitous to justify messing with a mechanical S-W unless already built-in at the factory (Monarch 10EE, etc.)

As much as I hate to say it but just go to horror salvage and get one of their non contact digital tachometers. I have a couple of the S/W tachs both bought at auction, one was still factory sealed and don't think I paid more than a few bucks for either and I don't waste my time with them. The HF 25 or 30 dollar tach is the berries.
They are great to use an a variable speed machine to set spindle speed accurately.

Re: #5 Welcome back, Thermite.

Paul

Dad had a S-W tachometer in my younger years. Me put it up to a 15,000 RPM motor just to see what it would do. Well after that, it wouldn't read zero ever again. Tried to reverse that motor to see if it would reverse the damage, still the same off by a mark. I played dumb on it, dad knew who screwed it up. I bought a used one a couple years ago that has all of the attachments. Haven't used it once. Been using a electronic one that works pretty good. Ken

Welcome back Thermite!