Help identify this artifact

I'm gonna guess it's either a tachometer to measure rotation/unit time or an "odometer" to measure the amount of something moved by it.

It looks like the "wheel" on the back could be made to rest against a rotating cylinder and the amount of movement of the dials measured over a time interval to calculate RPMs.

Or, the wheel rests against some moving material and the dials tell how much it moved, or verse visa if the gadget itself was the thing moving along.

Jeff

Rex, That is a Trav-a-dial. Think of it as a poor man's DRO. The modern version is here:

They used to sell these in the Enco catalogs and such. It gets attached to the carrage and is pressed against the side of a lathe bed by the spring. The serrated wheel digs in and counts off the distance the carrige travels. The scale is read vernier style. IIRC they where fairly pricey, over $100.00 but I could be wrong on that.

-AL

That's pretty slick!

- Michael

Oh, so THAT's a Trav-A-Dial. I've heard of them but it never registered what they were for.

Very interesting. Now I'll have to go to the shop and figure out how it was mounted on that Enco.

Thanks much, Al.

Rex

When you build your mount, make sure you can tilt the indicator assembly as it makes contact with the lathe bed. I didn't look at the picture, but if it is, indeed, a Trav-A-Dial, or similar, they are usually calibrated by tilting the rubber wheel, which is not square faced. It should have a radius, which changes the reading as you rotate the indicator to use a larger or smaller portion of the diameter of the wheel. By using a gage block, you can calibrate the indicator to read accurately.

Harold

When you build your mount, make sure you can tilt the indicator assembly as it makes contact with the lathe bed. I didn't look at the picture, but if it is, indeed, a Trav-A-Dial, or similar, they are usually calibrated by tilting the rubber wheel, which is not square faced. It should have a radius, which changes the reading as you rotate the indicator to use a larger or smaller portion of the diameter of the wheel. By using a gage block, you can calibrate the indicator to read accurately.

Harold

This one is not made like that. The wheel is steel, approx 1.125" diameter, and the face is about 5/8 wide, flat and smooth. The pring is very strong though, so apparently it gets enough traction that way. There is no internal gearing, just a straight shaft on ball bearings. Without accurate measurement I'd say one revolution is between 3 and 4 inches. I haven't tried it in metric. Seems like one round should come up to an even measurement of some kind. I'm hoping the lathe has evidence of the wheel having traveled along an otherwise unused section, like the front or back vertical bed surface.

Rex

I checked the link and was shocked at what I read. I've never seen that method of mounting, but I'm obviously wrong in my assessment. Sure am curious how they calibrate the device, it was mentioned, just not described. Can you see how that might be accomplished?

I've used one of the devices, but the design I described. They're really nice to use if you're not inclined to use DRO's, which I'm not. It's been years, many years, in fact, since I used the Trav-A-Dial, so now I'm beginning to wonder if I had the wheel wrong----maybe not rubber faced. I'm quite sure it was calibrated as I suggest, regardless.

I'd like to hear your impressions of the device, assuming you can get it up and running.

Harold

gage block, you can calibrate the indicator to read accurately.

May be a week or so. So far I've just gotten the lathe setting on the factory Enco stand, and I'm not real impressed with the stability. I'll probably build some outrigger feet with casters before I bolt everything up solid.

I'm still scratching my head over the unit of measure it is made for. I guess it could be a decimeter (? 10 centimeters), but that doesn't seem logical. Otherwise, it could be a special-purpose unit. And for that matter, a smaller driven wheel could be easily made. If any smaller, it would be more prone to slippage error. If I made it for

1" carriage travel = 1 turn of the dial, I'd have a roller of around .375" OD

That does seem weird. I recall the old units had a fairly large wheel, but don't recall how it related to turns of the dial. Could be they had gearing inside. I've never seen the guts. Unless you can have it relate to common measurements, it could prove to be quite useless, and that small diameter shaft (pi) sure as hell sounds like it would be slippery. Be sure to post your findings. This thing sounds like a puzzle more than anything.

Harold

Your artifact is interesting, although I don't know what it is. It appears to be operated more like a threading dial, as a reference mark or separation between two points, rather than general use linear measurement device.

The Trav-A-Dial devices mentioned are a product of Southwestern Industries aka SWI. If your gem was one of their products, they might recognize it.

The more recent SWI units that I'm familiar with use a rolling steel wheel (maybe 2.5" dia.) and internal gearing similar in ratio to a dial caliper. The ones I have are electronic (with optical encoders), to provide counting signals to a DRO unit. As Harold mentioned, the rolling wheel has a crown, and the special holder provides the drive tension/pressure, and has adjustments to insure that the wheel is tracking properly.

WB ...............

I am pretty sure this is not a product of SWI. It has a logo on it which is a start with a 'W' over an 'H' or so it appears. Sort of like

|-W-| with the 'W' being much bigger.

I think it must perform the same function, albeit with a much coarser measurement. For the sake of simplicity:

Assume 1" driven wheel, which is coupled directly to the degreed wheel. Degreed wheel has 100 graduations, so each would represent .0314. The vernier on the frame would measure another decimal point, so resolution would be on the order of .003". That might have been good enough for the operations for which it was intended. It's certainly within the tolerances I usually work to :)

The lathe this came with was made in 1986. I would bet this is older, and probably not from China like the lathe. In the shop were also a BP, optical comparators, EDMs, and other things, so it could have been used on other machines.

I think by its construction, it pre-dates Trav-A-Dial as they weren't made until the early 60s, and I never saw a T-A-D that was direct driven like this, they had a reduction built in. It certainly wasn't made to be user friendly mountable to machine tools. I would think it's off a specific manufacturing machine, not necessarily a machine tool.

Tom

Update: Rolling circumference is right around 4 inches, so one full turn of the graduated wheel is 4". Makes me think there could be an intermediate wheel involved.

Also, the logo looks for like HWH