A sticky Mercer Gauge

Looking at your photo, the bottom blackened screw seems to be in a slot, and maybe even the top left hand one.
Does the whole of the white plate move slightly to adjust the engagement between rack and pinion?
I have one which was sticky when it came to me; it looked like it had taken a knock, such that the rack and pinion were too heavily engaged and thus jamming,

Bill

Is there anyone out there who could possibly help me to make some further progress on how to dismantle the gauge as recorded in the photo posted on the the 18/03.. My efforts have come to a halt.

Sorry, I’ve never seen that exact model before, but : from your photos it looks like the hairspring is retained by a brass taper-pin … and the coil-spring is [hopefully] screwed in place.

MichaelG.

I don't know whether he covers this exact topic, but Doubleboost on YouTube has a series called Dti Care and Repair with Bob which might be of help.

I don't know whether he covers this exact topic, but Doubleboost on YouTube has a series called Dti Care and Repair with Bob which might be of help.

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Oops … posted that in haste

It should have read: “… and the cross-pin for the coil-spring is [hopefully] screwed in place in the plunger.”

MichaelG.

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Edit: __ these exploded views may help:

 http://www.peacockozaki.jp/e_sub01_91.htm

I will forgive their use of the term ‘Dial Gauge’ 

Edited By Michael Gilligan on 27/03/2022 20:40:56

In Baty gauges at least, the guide pin is screwed into the the rack shaft. I have a Baty 0.300 x 0.0005 dial gauge, and the tension spring is under more pull in the fully-home position than yours appears to be. See if you can find a replacement with a suitable rating and free length a couple of mm less than the minimum from guide pin to bottom anchor.

It's hard to see how it could have happened without other damage, but could the rack have been bent by a few thou?

Problem has now been solved. Decided not to go for complete dismantling and opted in stead to replace the tension return spring. Not having access to a selection of any small suitable instrument type springs to hand I fell back on using a length of 1/8 Dia 30swg s/s spring wire sold by Polly Engineering for use in safety valves which has done the trick. Many thanks to all those who provided help and assistance..