How to adjust manual micrometer

ss

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Dec 15, 2014, 12:42:22 PM12/15/14

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Any one know how I can adjust this, slightly out (red lines)
Its an old one made by Ambrose Shardlow.
There is a bit that turns with a rachet in it on the end but that doesnt
seem to have any effect.

http://i64.photobucket.com/albums/h194/scudo/Micr_zps8a32f3df.jpg

Andy Burns

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Dec 15, 2014, 12:48:54 PM12/15/14

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ss wrote:

> Any one know how I can adjust this, slightly out (red lines)
> Its an old one made by Ambrose Shardlow.
> There is a bit that turns with a rachet in it on the end but that doesnt
> seem to have any effect.

Do you have the little spanner that fits the two slits between the
knurled knobs?

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Tim Lamb

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Dec 15, 2014, 1:00:38 PM12/15/14

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In message <%3Fjw.103715$Ea7....@fx16.am4>, ss <wee...@hotmail.com>
writes

>Any one know how I can adjust this, slightly out (red lines)
>Its an old one made by Ambrose Shardlow.
>There is a bit that turns with a rachet in it on the end but that
>doesnt seem to have any effect.

Mine came with a little flat spanner to fit the slots in the shaft.

The ratchet gives a fixed torque setting for accurate measurement.
>
>
> http://i64.photobucket.com/albums/h194/scudo/Micr_zps8a32f3df.jpg
>

--
Tim Lamb

ss

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Dec 15, 2014, 2:13:57 PM12/15/14

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On 15/12/2014 17:48, Andy Burns wrote:
> Do you have the little spanner that fits the two slits between the
> knurled knobs?

Not the original but I do have one that fits, I tried that but without
forcing anything it just appears to rotate the thimble.

Andy Burns

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Dec 15, 2014, 2:19:23 PM12/15/14

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Is there a grubscrew to undo first?

ss

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Dec 15, 2014, 2:41:43 PM12/15/14

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Using a google diagram so I get hopefully the correct terminology:
There is a grubscrew at the top of the frame that the spindle goes
through This maybe a locknut of some kind. Below that there is an
knurled wheel and that is connected in some way to a pin that contacts
the underside of the spindle. The only other screw is on the rachet part
of the thimble.
I watched the video clip on how to adjust (different but similar) and
they appear to slightly rotate the sleeve, it being a friction fit, with
the grubscrew and the pin from the knurled wheel passing through the
sleeve on my version I cant see how that would rotate for adjustment.

Mr Fuxit

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Dec 15, 2014, 4:31:54 PM12/15/14

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>>Do you have the little spanner that fits the two slits between the
>>knurled knobs?

Well, on the other end of that spanner, is usually a "C" spanner, the pin of which
usually is fitted into a hole at the end of the barrel nearest the frame. If no hole is visible, wind-off the thimble and remove it completely; there MIGHT be an adjusting hole under the thimble, on the sleeve. ( There is likely to be a ring on a thread visible, with a pin hole in it. This ring is for adjusting for slackness, and does nothing toward adjusting the Zero error, so don't move it.) If there seems to be no other course, wind a rubber or leather strap around the sleeve in the direction you need to move the sleeve, grip the strap tightly and turn it by hand.
If that doesn't work, try pliers on the strap. HTH.

harryagain

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Dec 16, 2014, 4:41:37 AM12/16/14

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"ss" <wee...@hotmail.com> wrote in message
news:%3Fjw.103715$Ea7....@fx16.am4...

> Any one know how I can adjust this, slightly out (red lines)
> Its an old one made by Ambrose Shardlow.
> There is a bit that turns with a rachet in it on the end but that doesnt
> seem to have any effect.

The "ratchet bit" is what you use to turn the stem when measuring something.
It ensures you get uniform torque so that measurements taken are
uniform/consistent.

newshound

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Dec 16, 2014, 9:53:58 AM12/16/14

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We were taught "three clicks" at school. On working with experienced
machinists / lab technicians in my first proper job I was surprised to
find they did not do this, they did it by touch. After learning how, I
discovered how to measure to two tenths or better.

Andrew Gabriel

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Dec 16, 2014, 1:58:58 PM12/16/14

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In article <%3Fjw.103715$Ea7....@fx16.am4>,

Could it be some dirt on the measuring faces?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

ss

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Dec 16, 2014, 7:21:39 PM12/16/14

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On 16/12/2014 18:58, Andrew Gabriel wrote:
> In article<%3Fjw.103715$Ea7....@fx16.am4>,
> ss<wee...@hotmail.com> writes:
>> Any one know how I can adjust this, slightly out (red lines)
>> Its an old one made by Ambrose Shardlow.
>> There is a bit that turns with a rachet in it on the end but that doesnt
>> seem to have any effect.
>>
>>
>> http://i64.photobucket.com/albums/h194/scudo/Micr_zps8a32f3df.jpg
>
> Could it be some dirt on the measuring faces?
>

I dont really know, I wll dismantle the micrometer , clean it and re
assemble and see what happens.

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newshound

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Dec 17, 2014, 3:22:22 PM12/17/14

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On 17/12/2014 08:13, Chris Hogg wrote:

> I don't think it's dirt on the faces. The dial has gone beyond zero;
> if the faces were dirty, it wouldn't have got as far as zero and would
> be giving a small positive reading.
>
+1. My bet would be wear in the threads, it does look pretty well used.
Should be no problem to adjust the sleeve so that it lines up with the
thimble again.

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