Mystery DTI

But what is put in contact with the workpiece? I have a couple of finger types and several more plunger types but this one shows no way to use it as far as I can see

.

The link that I posted previously is dead … but here’s what it should look like externally: **LINK**

http://www.europacprecision.com/files/products/126/1/f40.pdf

Note the short plunger shaft labelled M2,5 - 6H

That is, I believe, what is/was stuck on Geoff’s specimen.

If it moves … usage should be self-evident

MichaelG.

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Edit: __ This should help

Edited By Michael Gilligan on 02/07/2021 15:56:51

I use mine quite a lot on my Sieg milling machine, mount in either the drill or collet chuck and it's so easy to run the table along and square up a vice or angle plate etc.

John

Commonly know as a back plunge indicator. Very handy item.

regards

Thanks for advice and diagram etc. I finally got the plunger to move after using clock oil, it returns exactly to zero every time either from a short movement or several rotations of the needle, it just gets stuck if pushed all the way in so still perfectly usable

Edited By vic newey on 02/07/2021 17:20:32

Just to add, I have found lighter fluid to be quite good at freeing off items like this, and it leaves a very slight oily residue as a bonus.

Rob

Late to the party, I fear...

3-in-1 oil is vegetable-oil-based. It's a fair lubricant, but only until it oxidises - rapidly - into a tenacious, sticky gum, which clogs things up and is difficult to remove. Horrible stuff!

Aha, thanks for that John. I have a Starrett back plunger gauge but never thought of using it like that!

I'm not disagreeing with your comment about gumming up the works, but I'm not sure about the vegetable reference.

Here's the COSHH sheet, which only seems to refer to mineral oils unless I'm missing something.
https://cdn.wd40company.eu/3-in-one/en-GB/uploads/2012/02/22093915/3-IN-ONE-Multi-Purpose-Oil-Liquid.pdf

Bill

Bill, I'm always happy to be corrected. Perhaps 3-in-1's formulation has changed. The last time I used the vile stuff was probably nearly half a century ago, shortly after which I vowed never to touch the stuff again. Perhaps I shouldn't harbour grudges...

3-1 used to be vegetable based, but all things change...

I find a stock of sewing machine oil valuable for 101 uses, its the thinnest grade of mineral oil readily available.

Neil

Wow!
Didn't expect my post to spring back to life with all the info I needed👍👏

Michael,

Thanks for posting that link & attached diagram.

A stat of interest 70°-90° of hand usage depends on the thumb!

Geoff - I agree wholeheartedly with that statistic with my left one out of action for some time as it heals

I have been advised never to use oil on the plunger. Instead use a solvent like mineral spirits (naptha) to loosen the congealed oil that is causing the plunger to bind.