Help with Trav A Dial height gauge

[PeterH48]

Like my old shop teacher used to say "The only stupid question is the one that you don't ask" I picked up an old Trav A Dial height gauge at an auction cheap last year. It seemed to function properly, but was missing the scribe and clamp. I found both parts and replaced them. There is a knob on the top of the unit and when you turn that, the head holding the scribe moves up and down the scale and the dial vernier pointer moves. Has anyone ever seen this gauge in their shop? I posted a picture of the gauge and I have no clue what the other knobs do. There is a small knob next to the vernier and it's marked 1/10". But it does not appear to move when I turn the knob on the top. Also a knob on the left hand side behind the vernier scale and another on the right hand side of the reader head. i'm guessing one might be some sort of a lock, to lock the head and the other maybe for fine tuning a measurement. But I have tried turning all the knobs in or out and to me, I don't see what they do. I have tried not to overtighten any of them for fear it might break something. I tried finding some sort of manual for the gauge, but so far no luck. Anyone have an idea what those freaking knobs do? I'm hoping someone can point me in the right direction on this. Thanks

 

[L Vanice]

The knob on the left of the dial is clearly marked, "Do not adjust." That may tilt the measuring wheel to calibrate the dial reading, just like the ones that run on lathe bed ways. The wheel has a curved edge contour, so tilting it changes the dial reading for a known travel distance. If the knob is not for calibration, then it is to adjust the force with which the wheel presses against the column. Obviously, the wheel and column must be kept clean and dry.

The 1/10 knob can be turned to set your zero position. You might want to make the scriber rest on the surface plate and set the 1/10 knob and the indicator dial to zero.

The knob on the right of the column could be a lock, which a height gage should have.

Larry

 

[Mtndew]

Wow, I never knew they made height gauges.
Loved them when I was running engine lathes back in the day.

 

[AlfaGTA]

Believe the knob labeled "do not adjust" is the clamp that secures the read head unit to the gauge.
Cheers Ross

 

[FredC]

I never knew SWI built height gages. I was inclined to think it was shop built till I enlarged the photos and saw the details. I would think that 2 of the screws or knobs would not normally be adjusted. When you purchased a new travel dial there are 2 things that will affect the calibration. The hardness of the material the wheel rolls on and the tension of the wheel. I understood the softer the surface the wheel contacts the more the wheel will turn when traversing a set distance thus the crown the Larry mentioned. It seems like the more pressure put on the wheel the more distance it would show when traversing a set distance.
From the manual when you set a Trava-Dial on directly on a Hardinge dovetail the dove tail was so hard the crown would be neutral, on a softer bar like added to an HLV-H the unit would need to be calibrated to read exactly the amount traversed on Jo Blocks.
I remember the Trava Dials on HC chuckers rolled directly on the rear dovetail. My HLV-H runs on a 1 x 2 inch cold rolled bar mounted behind the dovetail.

One thing I forget to do as often as I should is oil the felt pad adjacent to the roller. Just checked and you oil the way surface on either side and traverse the unit back and forth. You cannot even see the felt when the unit is installed.