Author Topic: replacing crystals on dial indicators  (Read 2074 times)

Offline AlanT

  • Jr. Member
  • **
  • Posts: 14
replacing crystals on dial indicators
« on: March 08, 2015, 10:53:41 AM »
Perhaps your clock looks like this:
https://flic.kr/p/rwm6zi

replacing the crystal will make a big difference:
https://flic.kr/p/rf1dz4

I started by starting new crystals for 2in Mercer gauges which are dead easy because they are flat.
You just need a friction drive like this:
https://flic.kr/p/rd8NRX

But other gauges have domed crystals.
These are cut from flat sheet, like the Mercers, and then pressed in with something like this:
https://flic.kr/p/rws4DM

Here is the same thing for smaller gauges:
https://flic.kr/p/reTGFj

You use 1mm Lexan, polycarbonate sheet, and for 2GBP you have enough for a dozen gauges.

I hold these tools in my Rubberflex chuck which makes secure, repeatable holding dead easy.

It takes a bit of experience to know how tight to cut the blank and how much stretch you need to press in.
But the answer is basically very tight and quite a lot.







Offline Arbalist

  • Hero Member
  • *****
  • Posts: 677
  • Country: gb
Re: replacing crystals on dial indicators
« Reply #1 on: March 08, 2015, 12:26:05 PM »
Nice job!  :thumbup:

Offline AlanT

  • Jr. Member
  • **
  • Posts: 14
Re: replacing crystals on dial indicators
« Reply #2 on: March 27, 2015, 12:28:00 PM »
The bezel on common UK made indicators, Mercer, Baty, John Bull etc can be easily removed because they are held by an obvious screw or clip.

Not so with Starrett. These have a hidden wire clip. This is tricky even if you know what its like.
If you have no idea what it's like then this is even harder.

Here is one I replaced recently. This is a "small" one but the bigger ones are  probably similar.
https://flic.kr/p/rwKLVa

The two bent-over ends go in holes near the top end of the plunger.
Just a bit further round there are two "bumps". You must press these in and prise the bezel over them.