Micrometer break in?

[Munty Scruntfundle]

Hi there.

Due to being fed up with replacing batteries every other day I purchased a couple of mechanical micrometers, the Starrett 461 in this case. I have to say I love the things, very pleasingly tactile and the feel of the moving parts is lovely. Mostly.

One of them has a very sticky adjusting ring, don't know if anyone has a solution for freeing it off a little? It's very difficult to move it with the supplied spanner and I'm a little worried of damaging something.

The major problem I'm having is consistency. If I've been using them for a while I can get a very reliable reading. If I then put the thing down for a couple of days and pick it up it reads low, I have to spin the clicker a lot faster to get the reading to zero than before. This had led me to two questions, `1 is there a "break in" period for these things, and 2 are they at all temperature sensitive?

Getting different readings on different days is obviously not ideal, neither is having to calibrate them every times I use them.

Any ideas?
Many thanks.

 

[John Hall]

You don’t say how old they are….I’m thinking maybe any old lubrication dust etc may have hardened causing them to stick…a squirt of brake cleaner or WD40 may help..

 

[Lorenzl]

The adjustment rings are tight to stop easy movement but as you say can be very tight. I have worked for years with mechanical mics and Vernier's and they rarely needed adjusting.
As you suspect if you are keeping them in an unheated shed that can cause a change in readings. All/most metalworking instruments are standard/calibrated at 20C so everybody's should read the same.
There shouldn't be a break in period and if you get used to not using the "clicker" you can be just as accurate.

 

[J-G]

There shouldn't be a break in period and if you get used to not using the "clicker" you can be just as accurate.

The point about the 'clicker' (clutch) is that it makes it easy to always apply the same pressure to the part being measured. Tightening a Mic. using the barrel it is likely that the amount of pressure applied is dependant upon your own state of mind and fitness

The Clutch will always act at the same pressure point so therefore provide consistent readings (when all other factors - temperature etc. - are the same).

 

[deema]

Unscrew it, if you keep opening it up the barrel should come away. Thorough clean and very light weight of oil applied sparingly and it should be good to go. If it’s brand new Starrett need to replace it.

If it’s secondhand verify that the measurement anvils actually touch with no light showing anywhere. They are often sold due to being dropped and as a result slightly twisted causing inaccuracies in measurement.

 

[Fergie 307]

Unscrew it, if you keep opening it up the barrel should come away. Thorough clean and very light weight of oil applied sparingly and it should be good to go. If it’s brand new Starrett need to replace it.

If it’s secondhand verify that the measurement anvils actually touch with no light showing anywhere. They are often sold due to being dropped and as a result slightly twisted causing inaccuracies in measurement.

Only time I have ever disagreed with Deema, but was always taught that the last thing you should ever use on a micrometer is any form of oil. It attracts dust/debris. I always use powdered graphite. Good for locks too.

 

[Fergie 307]

And reading back over other posts please don't use WD40. The solvent in it evaporates over time leaving a varnish like residue, last thing you want. Plus Gas is much better anyway as a penetrating oil. If you think it needs cleaning then take it apart and clean everything in isopropyl alcohol and dry it thoroughly, I use an air duster. Then reassemble using graphite powder sparingly on the threads.

 

[deema]

I think @Fergie 307 has the best solution……but oil for micrometers is sold.

 

[Peri]

If it’s secondhand verify that the measurement anvils actually touch with no light showing anywhere. They are often sold due to being dropped and as a result slightly twisted causing inaccuracies in measurement.

If you've got a slip gauge set or a good quality feeler gauge you can measure those - if it didn't come with a setting standard.

 

[Sandyn]

I'm sure you know, but some mechanical micrometers have a barrel lock. If it was partially engaged, it would make the adjustment feel tight.

 

[philip sewell]

Lorenzi, what's the reason for not using the clicker (I've seen many utube vids where the user doesn't use the clicker and I've always wondered why). I always use it as to my mind you get total consistency with the torque applied and the reading but I'm a cabinet maker who does some engineering. You are obviously a proper engineer.

 

[J-G]

The main reason for just using the Barrel, rather than the Clutch, (with small components) is that one would normally hold the component in one hand and the Mic. in the other. The 'Frame' being held with the small & next finger against the Palm leaving the Thumb & Forefinger to turn the Barrel.

To use the Clutch, you need to hold the Mic. in one hand and use the other hand to operate the Clutch -- unless you have extraordinarily long fingers

With a larger Mic. (say 4"/100mm and above) it is just as easy to use the Clutch as it is the Barrel.

As @Sandyn has shown, not all Mic.s have a Clutch!

 

[philip sewell]

Thanks for explaining that J-G.
Phil.

 

[Dalboy]

Like J-G explained I sometimes just use one finger to turn the barrel when holding the mic and the object because I am only using one finger there is only so much pressusre turning the barrel that it is always the same giving a true reading. This is assuming that the mic is free turning and does not have any stiff spots which they should not have

 

[Inspector]

One more tip on using the barrel one handed. You don't use the knurl, just the smooth portion of the barrel with the graduations and it will slip easier between the fingers and more reliably than the knurled portion.

With the ratchet you should use it the same way each time. Three clicks for example, not spinning away. Bore micrometers however state three full turns.

My preference was to use friction barrel micrometers as they are shorter, no ratchet. They cost a little more but in my opinion work better.

Pete