Starrett 220 Micrometer?

[Bo’sunParticipant @bosun58570]

Good afternoon all,

I’ve just purchased a Starrett 220 Anvil Micrometer from a well known auction site.  The Micrometer itself is in excellent condition, although the case is a little tired.

When I try to move the sleeve to adjust zero, it’s stuck firm.  Not wanting to damage anything, any suggestion as to how I can loosen it up?

Many thanks.

[Grindstone CowboyParticipant @grindstonecowboy]

Immerse in Plus Gas, petrol or lighter fluid and leave it to soak would be my first try – always assuming there’s nothing that would be damaged by such solvents, like any plastic parts.

Rob

[John BatesParticipant @johnbates63489]

Hi Bo’sun

In addition to the suggestion from Rob I suggest using an ultrasonic cleaner if you can.

Good luck

John

[HopperParticipant @hopper]

Check with a Starrett manual or maybe one of the Starrett online collectors group etc. Some micrometers you zero by turning the sleeve. Others you zero by adjusting the thimble position on the spindle with a small wrench often included in the box the mike comes in. Not sure which method your model uses. It may be your sleeve is not supposed to move?

[old martParticipant @oldmart]

Having attempted to move the sleeve, I would assume that a little C spanner was used in a hole at the back of the sleeve, otherwise there would be nothing to hold onto.

[Bo’sunParticipant @bosun58570]

Evening Guys,

I have assumed the Mic is zeroed by rotating the sleeve because it has a small hole that neatly engages with the tiny C spanner in the box.

I’ll leave it overnight with some Plus-Gas (Halfords penetrating fluid) and see how it goes in the morning.

[old martParticipant @oldmart]

Dead right, that is what the hole is for. If the barrel has to be rotated more than 10 degrees, it might be time to break the thimble taper and realign it after centralising the barrel. I have only adjusted a barrel a couple of times in the last 50 years. Barrels are meant to be very tight, maybe you are worried about breaking the C spanner.

[Simon Williams 3Participant @simonwilliams3]

I’m embarrassed to admit to having discovered that leaning over-enthusiastically on the little spanner can induce said spanner to slip from its rather delicate engagement with the thimble, leaving a stripe of shame on the thimble.  Go carefully.

My experience is that once the oil between the thimble sleeve and the barrel has set to varnish it forms an effective seal preventing solvents from reaching the solidified gunk.  If I ever tackle another one I’ll boil it rather than just soak it.

Good luck.

Simon

[peak4Participant @peak4]

Just has a quick look at mine, I knew I had a couple of different makes.
From memory, when I got it, I think I probably warmed it up with a mini hot air blower; it works of a butane lighter and a catalytic heating element.

Not too much, just enough to expand the outer part of the body and free it from the graduated tube section.
Once it rotates a bit, ease it back and forth slightly, adjust to suit, and allow to cool before checking a final measurement.

Bill

[Bo’sunParticipant @bosun58570]

Hi Bill,

It’s not the thimble (outer part) that’s seized.  The thimble rotates very smoothly.  It’s the inner sleeve (also used to adjust zero) that’s seized.

[Bo’sun]

On Bo’sun Said:

Hi Bill,

It’s not the thimble (outer part) that’s seized.  The thimble rotates very smoothly.  It’s the inner sleeve (also used to adjust zero) that’s seized.

Yes, I appreciate that; what I was suggesting was to gently heat the body of the mic where that inner sleeve is located, hot air gun pointing at the spot, and along further to the right.
There seems to be a slight variation, in that sometimes the inner engraved tube is a tight sliding fit on an inner fixed tube permanently attached to the main body, and others, the whole tube is a single item engraved on the outside, which rotates in the main body.
These all adjust broadly the same way, with the exception of the Slocomb at the lower centre, where I think the thimble fits on a taper attached to the end of the moving anvil.
The others are M&W 970MF, Starrett 220, & Mitutoyo, left to right.

The Nimrod Microtherm hot air gun, I’ve had for probably 20+ years, and now seems discontinued, but worth seeking out.

Bill

 

 

[old martParticipant @oldmart]

A little heat on the barrel, with the spindle removed, would be a good way to get it moving. The barrel will be a plain tube, but never having removed one from the body, I cannot say just how much overlap there is.

I have just tried to find the length of overlap with a Mitutoyo depth mic and was surprised that it is about 1/2″. If you try with a thin wire, do not disturb the thread adjusting nut.

You could try by trickling hot water over the barrel for a few seconds, that would tend to loosen it before the inner part warms up.

[SillyOldDufferModerator @sillyoldduffer]

This instructable describes holding the barrel in a split block of wood gripped in a vice and then manipulating it by rotating the frame.   Note this is the last stage of a service job that included soaking the whole micrometer in penetrating oil for a ‘few days’, so any rust or gum should have been loosened already.

Grumpy again due to belly-ache, but I have demoted Bosun to Ordinary Seaman for saying in his question that ‘The Micrometer itself is in excellent condition‘.   Oh no it’s not.   Surely a micrometer with a stuck sleeve is in below average condition?

🙁

Dave

PS Useful tool though, I hope some simple remedial work fixes it.

[peak4Participant @peak4]

Re the heat gun I mentioned earlier, it looks like it’s now re-branded as Iroda MJ600, vary variable in pricing and availability, but this seems a good deal if you’re ordering anything else from there

https://cpc.farnell.com/iroda/mj-600/heat-gun-gas-650c-micro-therm/dp/SD01111

 

Bill

[peak4]

On peak4 Said:

Re the heat gun I mentioned earlier, it looks like it’s now re-branded as Iroda MJ600, vary variable in pricing and availability, but this seems a good deal if you’re ordering anything else from there

https://cpc.farnell.com/iroda/mj-600/heat-gun-gas-650c-micro-therm/dp/SD01111

 

Bill

Good morning all,

The liberal application of some penetrating fluid and a little heat has had some effect and allowed me to zero the mic, but the sleeve is still very stiff (overly I think).  Not sure what sort of response I’ll get, but I’m awaiting a response from Starrett.

On SillyOldDuffer Said:

Grumpy again due to belly-ache, but I have demoted Bosun to Ordinary Seaman for saying in his question that ‘The Micrometer itself is in excellent condition‘.   Oh no it’s not.   Surely a micrometer with a stuck sleeve is in below average condition?

Yes Dave, your spot on, my mistake.

 

 

[jaCK HobsonParticipant @jackhobson50760]

As a last ditch attempt I used the split wood block and it worked. But those barrels are very thin! Even if you can’t see deformation, it can impact the feel of the screw. Try everyhing else before clamping the sleeve.

[Bo’sunParticipant @bosun58570]

Thank you Jack,

I had considered that, but as you rightly point out, the barrel/sleeve is very thin.  Also, because the sleeve is so thin, I thought it might just clamp even tighter to the body.  I have at least got some movement, albeit the sleeve is still very stiff.  I think I’ll leave it as it is for now, rather than chance my arm and ruin what is otherwise fine micrometer.

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