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New DTI "Glass"

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William Chitham30/03/2020 18:13:03
125 forum posts
52 photos

I picked up this DTI at a jumble back in February. It was a bit sticky and the pointers were out of phase so I didn't pay much for it. I dismantled and reassembled it and works fine now but the plastic "glass" is yellowed and loose enough to pop out without much encouragement. Any thoughts about replacing the glass? I'm thinking maybe 1mm acrylic which seems readily available but I don't know if that is oil resistant.dti.jpg

Former Member30/03/2020 18:21:14
1329 forum posts

[This posting has been removed]

Former Member30/03/2020 18:21:15
1329 forum posts

[This posting has been removed]

Pete Rimmer30/03/2020 18:26:45
1075 forum posts
69 photos

An Etalon dial gauge is definitely worthy of repair.

I would make a new crystal from a welding mask lens cover. You can pick the screen covers up for peanuts as they are disposable and you'll get a few tries at it.


Edited By Pete Rimmer on 30/03/2020 18:27:32

V8Eng30/03/2020 18:56:14
1634 forum posts
32 photos

You do not say what size this but it may be worth looking at Pocket Watch crystals/glasses, up to 50mm seem readily available, possibly some larger sizes as well.

Try an online search or on Ebay Amazon etc.

Edited By V8Eng on 30/03/2020 18:58:36

Clive Foster30/03/2020 18:57:39
2838 forum posts
103 photos

Watch crystals are available in a wide range of sizes from around 1/2" to 2" (ish) diameter. Good chance that you will find something to fit.

Need to look carefully at the retainer to decide what thickness is appropriate and whether the glass shold be flat or domed in greater or lesser degree.


V8Eng types faster.  Google search should bring up some size tables.

Edited By Clive Foster on 30/03/2020 18:58:44

old mart30/03/2020 19:59:10
3349 forum posts
208 photos

I would try the 1mm acrylic, after all, it is a precision instrument, not something to splash oil all over.

William Chitham11/04/2020 14:57:16
125 forum posts
52 photos

etalon before after.jpgThanks for all the suggestions, looks like I could have bought a watch crystal to fit but I wanted to try making one and it turned out pretty well, an improvement on the original anyway.

If anyone is interested I put some photos of the process in an album. In brief I turned a wooden male form; balanced a 1mm acrylic blank on top; heated with a hot air gun till floppy; pressed down over the form with a plywood "washer"; put the acrylic wrapped form back in the lathe and "parted off". It took a few attempts to learn to read the state of the hot acrylic and it was tricky to cut accurately to a diameter but I managed to get a good snug fit in the bezel eventually and only used one A4 sized piece of material.

V8Eng11/04/2020 15:03:05
1634 forum posts
32 photos

Well done! That looks good and it’s nice to see the end product of a question on here.

Edited By V8Eng on 11/04/2020 15:07:49

Michael Gilligan11/04/2020 15:58:27
18992 forum posts
945 photos

Excellent looking result, William

... and nicely illustrated : Thanks


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