Optical bore guage

I was down the car boot today and got 4 optical guages made by a company called Technica A-G. I have never come across them before but they are fantastic. There is a small plunger that pops out and measure the bore. There is a small window which you peer into and can read the measurement directly if a vernier scale, which is very cool. Unfortunately two of them are faulty. One has the plunger stuck in and the other has thevplunger stuck out I'm hoping the just need a bit of a clean. Does anyone know how I would go about freeing them?

Thanks

Colin

The plungers may be stuck because whtatever lubricant was used, has congealed, through lack of use, and poor storage.

In which case, a small squirt of WD40, or somthing similar, MIGHT do the trickmto free off the plungers.

Hopefully, it will be no more than this rather than mechanical damage.

If this does then trick, and you want to relubricate them, you could try, literally, a spot, of watch nr clock oil.

HTH

Howard

Doesn't WD40 contain waxes that will congeal over time?

Martin C

My understanding is that WS40 contains mostly paraffein (kerosene) and very little oil.

The objective is to free off the plungers.

Once that has been done the correct lubricant can be applied in small doese.

Forget WD40. What you wat is Plusgas or even Diesel.

Roy

My go-to for instruments is lighter fluid - dissolves most old oils and grease and leaves a very slight oily residue. The cheaper it is, the more oily it tends to be.

Rob

I second the use of lighter fuel which I use to clean off gummy residues from clock and watch mechs before running them through the cleaning machine which uses IPA.

CS

Don't use 3 in 1, that definitely goes gummy over time

Edited By duncan webster on 01/10/2023 23:26:44

Your bore gauges aren't something I'd known about before and had to Google for a video showing what they looked like and how they measure a bore. No doubt those were very expensive when new. And I'm a bit envious Colin.

The very best de-greaser and cleaner I've found so far would be an electrical contact cleaner. It's extremely thin and will get in where not much else will. But I most definitely wouldn't want it getting into the optical area of those gauges. For where it's safe to use it drys almost instantly and leaves no residue of it's own. But there are some brands that will affect some types of plastics. Most oils will dry out after enough time, but a lot of the causes for issues with metrology equipment is the lack of understanding about how much lubrication is enough. In many cases a single drop of oil is excessive. In a lot of ways the lubrication requirements are much like a fine mechanical watch. As an example, I have a decent Starret indicator bought new about 40 years ago and it's movement started to become sluggish. Pulling it's back off and since all it's inner parts are metal, I just used that contact cleaner to flush it clean. For re-lubrication, A wooden toothpick or even dress makers pin with a less than a drop of oil on the end and lightly touch the rack in a few places. As you use it, the pinion gear will pick up and transfer that minimal amount along the rest of the rack. At that point it was back to working like new again.

In some cases, cleaning and no lubrication would be better than using even a little bit too much. In my opinion using a designated watch and clock oil is likely the best to use. But those bore gauges also appear like there something fairly delicate with no doubt quite complex internals. If it were me, I'd only use that contact cleaner on the measuring end of the tool. Hopefully that will be enough to free them up. Given how I suspect the internals work, there's an internal spring and operating rod to push the measuring tip out. The video I watched really didn't show the finer details. If that shaft can be unscrewed or removed from the body then that may also be where there's congealed lubrication as well. If you can't easily separate that shaft from the tool body, then finding a proper metrology repair shop that has the experience to properly disassemble and clean them would be my next step. Since I've no real knowledge about those bore gauges, I can't be of much help.

Just thought you might like to see this on ebay, Colin

**LINK** https://www.ebay.co.uk/itm/394734119321

They also have a metric one

MichaelG.

Blimey I did get a bargin!! But I think mine might be an older model

Edited By colin hamilton on 02/10/2023 17:05:12