Re: Dial indicator crystals (new rabbit hole for me!)
开云体育Hello Andrei I have a crystal press with a variety of different sized domed anvils – concave anvil on top and a convex anvil on the bottom. The bezel and the crystal go in and the crystal is distorted enough to allow the rim to fit into the annular groove on the bezel. Once you have a good fit all round the pressure is released and you get a good dust-tight fit. ? That being said I have seen solid brass formers made for use in a vice similar. ? Melt shaping could work but I don’t think that it would produce the long-term joint tension required for a good tight fit. Others may be able to comment on this point. ? You are correct about the distortion, but in practice this is quite minor and does not affect the ability to read the gauge correctly. Also some crystal are preformed and not flat – usually those for the smaller gauges (like the Starrett 711) so the distortion created by fitting is reduced. ? Cheers John Bates Sydney, Australia ? From: [email protected] <[email protected]> On Behalf Of Andrei
Sent: Thursday, December 14, 2023 4:59 PM To: [email protected] Subject: Re: [SouthBendLathe] Dial indicator crystals (new rabbit hole for me!) ? I always wondered how they domed the crystals without optical distortions. The glass ones are ground or melted over a mould, but what about the plastic ones? Does melt shaping work on them, too? ? Get From: [email protected] <[email protected]> on behalf of John via groups.io <reproturn@...> ? Hello George I usually don’t have much to say on the group, but on this occasion, I may be able to help. ? Like you I also repair gauges. Normally I buy replacement crystals from G-S Supplies in NY . No commercial connection just a happy overseas customer for more than 20 years. They are great to deal with. The website has a lot of data about crystal sizes and types. Prices are reasonable. ? That said, I have made a few crystals because G-S does not carry/make many of the bigger sizes unless you want to order 500. Biggest problem I have with that here in Australia is finding acrylic sheet thin enough. But I’m sure there is a supply in the US. ? Turning is the only method I have tried but a punch would probably do just fine and if necessary you can turn a bevel afterwards. ? As to the bevel edge I can’t speak for every make and type of gauge, but many regular size gauges made by Mitutoyo, Starrett, Federal, Standard, etc. use bevel edge crystals. However, that only applies to domed crystals (by the way they start out flat and you deform them to fit the bezel). But (there is always a but) some gauges including ones made by the above makers have flat crystals and no bevel. ? Hope that helps. Cheers John Bates Sydney, Australia ? ? ? From: [email protected] <[email protected]> On Behalf Of George Meinschein via groups.io ? Hello all, First off, I apologize for any cross posts. ?Lately, I’ve been fixing a few “parts only”?dial and dial test indicators that I picked up on eBay. ?I’m thinking about getting some 1/25” clear?acrylic sheet and making some nice new?dial crystals. ?Anyone ever worked with acrylic sheet? ?Is this something I’d?knock out with a punch and die setup? ?I did see one guy on YouTube make?his dial crystal on a lathe. Clamped the acrylic sheet between two silicone rubber pads and turned the O.D. ?The Mitutoyo crystals have a beveled edge, so maybe the lathe is the way to go. ?Thoughts and comments from the the collective group?brain power please! ? Thanks, George H. Meinschein, P.E. Firearm and Ballistics Engineering LLC 150 Brittany Drive ? ? Sent from for iOS
|
John