"The longest-lived micrometer than can be bought." J.T. Slocomb micrometers and stand, all fully restored by myself. Each mic is between 70-120 years old, and they're all still accurate.
Submitted by ExHempKnight t3_115h0nr in BuyItForLife
Of course they are buy it for life.
They:
Mostly true. The threads, spindle and spindle bushing, and (most importantly) the measuring faces, are all subject to wear and corrosion. This brand in particular compensates for thread wear in a unique (and in my opinion, superior) way, compared to Starrett or Mitutoyo. The bushings are also replaceable, which I'm not sure is an option with the other brands.
And as old as these mics are, and as much work as I've put into them... They can almost certainly benefit from having the faces lapped. That's really the only thing keeping them from being good as (or better than) new. But I don't have the equipment to do that, and having it done is not cheap (especially for as large a set as I have).
How specifically does this brand compensate for thread wear?
Also what kind of hobbies do you have which utilise these? I have read all your other replies however am unfamiliar with much of the terminology unfortunately
Mostly, measuring instruments like this are used in precision machining. Metalworking lathes, milling machines... Stuff like that. I have a small hobby shop in my basement with a lathe, a mill, and a couple of other machines.
Machining in and of itself is a big part of my hobby, but it also supports basically all the other things I'm interested in. I've designed and machined a custom hotend for my 3d printer. I've machined mounts and pulleys to mount a supercharger on my mid-90s Saturn. Brackets for valves on my beer brewing rig. Custom feet for my bed, which house scales, which I use to tell my home automation system when I'm in bed. I could go on.
As for the thread wear compensation... I'll preface this by saying that Starrett and Mitutoyo are fine instruments, have been around for a long time, and are basically industry standard as far as I know. Thread wear in a micrometer is not a huge issue, and plenty of those mics are still kicking, and still accurate, with decades on the clock.
So, quick and dirty micrometer terminology:
Starrett and Mitutoyo compensate for thread wear using a tapered, threaded collar at the far end of the barrel. There's slits in the end where the anvil screws in, and the tapered thread is on the outside. As you tighten the collar, it squeezes those slits smaller, which tightens the internal threads.
The problem with that, is it's only those first couple of threads that are taking up the slack.
The Slocomb micrometers use a 2-piece threaded portion. The 2 pieces have serrations that mesh. If the thread wears, you simply tighten the outer collar one or two serrations, and all the slack is gone. The difference here is that by clocking the threads differently, it causes all the threads to be engaged, rather than just a few at the very end.
This distributes the wear over more surface area, which will make it wear slower. Plus, you can clock the threads infinitely, whereas you can only tighten a tapered collar so much.
>- have no moving mechanism
Uh, have you used a micrometer before? They have moving parts, that's kinda their defining feature, the use of a threaded mechanism to get higher precision
By moving I mean parts that are constantly getting wear and tear during operation or even standby. Like a cog in a clock or a piston in an engine.
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