I have a Mitutoyo dial caliper, and occasionally the needle gets
misaligned. I prefer that it point upwards (12 o'clock) when closed;
right now it is at 7 o'clock. What is the procedure to adjust the
pointer? I know the use of a shim has been mentioned before, but how is
it accomplished?
TIA,
Joe
You got dirty teeth. You need to brush. (no... really)
A chip has caused the pinion to skip teeth.
You can't _easily_ get the pointer back, except perhaps by running the
pinion over that chip a few times in the hope that it restores.
But you can get the chip(s) out so they don't cause it to happen again --
then take care to keep your calipers meticulously clean -- I don't mean
_clean_ them frequently, I mean make sure they don't ever get dirty. Don't
lay them where errant chips and filings can reach. Don't put them down on
chip-covered surfaces.
To clean out the rack, the simplest way is to use a very fine embroidery
needle, and _gently_ rake out each tooth. Use a magnifying glass, and make
sure every one is clean of chips.
Then, don't ever get them dirty again.
There are fully-shielded calipers available. Most of the lower-end ones
have a sliding shield, but it doesn't cover all of the rack all of the time.
Decent quality optical (digital) calipers aren't prone to this sort of
failure, but you can damage the scale if you get chips between scale and
slider.
LLoyd
Well, there is a way: Use an unrolled piece of flat watch spring and
slide it between the rack and the pinion inside the head, and cause the
pinion to skip a tooth in the opposite direction. The pinion is
spring-loaded against the rack, to prevent backlash, and will tolerate
this without difficulty.
I've also taken a bought-used Mitutoyo dial height gage apart and
cleaned it. Reassembly was not difficult. Resembles working on a
mechanical clock. The main advice is to work on a clean table over a
large pan lined with fabric (so dropped items don't bounce), so you
don't lose any parts. It's also good to vacuum the floor before
starting, so you have a prayer of finding dropped parts.
Joe Gwinn
Yur crazy, they actually make a tool for this. Little thin rod you stick
in the back end of the device and hold the pinion up. Takes like two
seconds.
yes keep em clean.
I prefer Etalons, but they really hate chips
Not _completely_ crazy, just a little. Most folks don't have that tool.
They buy a bottom-of-the-line dial caliper, and wouldn't even think to look
for the adjustment tool.
The watch spring idea is probably more in line with what the average guy
will have just lying around. But selectively "skipping" over the vagrant
chip works most of the time, and requires no tools at all.
You don't have to get the needle precisely at 12:00 o'clock, just close --
it's only a matter of convenience for reading. The bezel will set to zero
anywhere.
LLoyd
On Wed, 21 Mar 2007 11:52:30 -0400, "Lloyd E. Sponenburgh"
Hell..you dont have to have the needle at 12:00 at all. As you say..its
a matter of convience for the anal retentive.
Gunner, ducking and running
"Liberalism is a philosophy of consolation for Western civilization as it
commits suicide"
- James Burnham
THE tool for most is a little key-shaped item made out of shim stock,
the small end is a little less than rack width. Most of the dial
calipers I've seen have the pinion spring-loaded, you take above item
and press it into the rack/pinion interface area to disengage the
pinion, then mess with the thing until the pointer is about where you
want it. Higher quality dial calipers include the tool, it's maybe 5
or 10 thou thick, usually under the foam in the case. Brush your
rack's teeth too, you've got a chip in there somewhere.
Stan
And once it's fixed a trick and old time machinist taught me to lessen the
chance of chips falling in or help chips fall out is to always lay it face
DOWN against it's crystal(plastic?) face.
Oh and for those of you who are the dissasembly kind of people, my father
was a photographer and repaired cameras. He sealed and painted white the
big file drawer in his desk. When it was time to dissassemble a camera or
shutter he'd stick it and his hands in the drawer and close it as far a he
could, THEN he'd take it apart... if any parts fell out or springs flew away
they'd stay in the drawer :-)
--.- Dave
On Wed, 21 Mar 2007 16:35:16 GMT, with neither quill nor qualm, "Dave
Yeah, who -cares- where the little dial is since you won't be able to
read it through the scratched bezel anyway? <gd&r>
-------------------------------------------------------------
give me The Luxuries Of Life * http://www.diversify.com
i can live without the necessities * 2 Tee collections online
-------------------------------------------------------------
Ya know Larry, I though that too.
But I figured my old time machinist friend who worked for Rockwell and made
parts that put men on the moon knew what he was talking about.. the face on
his 30 year old Starett look just fine, I'm going on 15 years now with same
caliper and it's as clear as the day I bought it.
I'll take a few scratchs on crystal over a trashed rack and pinion every
time :-)
--.- Dave
Remove the bezel clamp screw and plastic clamp, and there is a small
slot moulded in the back of the face housing. Find a length of stiff
wire that will push in to this slot and lift the gear clear of the
rack, then set the dial to zero and close the caliper, remove the wire
and job done. This is how its done on the Mitutoyo calipers i have
used unless yours is different.
Paul.
Mitutoyo generally supplies, with the caliper, the tiny tool that permits
reorientation of the pointer. It's that tiny brass finger you thought
served no purpose and threw away.
Harold
Thanks to everybody for the suggestions, especially to Paul. It turns
out that the slot on my calipers is on the top of the dial - no screw
removal needed. Now my "anal-retentive" self is satisfied with the results.
This set is "never" used in a machine shop; it's used for metrology,
usually in a pretty clean environment. Sometimes, however, another one
of the techs will borrow it (for unspecified purposes) and it comes back
with, um, 'altered' characteristics. Previously I would just wait until
it was time to send it out for recertification, and let the outside lab
fix the dial. Now I'm even more valuable to the Company!
I've learned a thing or two since joining this ng 7 or 8 years ago.
Joe
Y'all in the metrology lab must be a peaceful and friendly lot. Man,
in a machine shop you do not touch another's precision measuring
instruments with anything you're not prepared to lose!
Indeed. Dancing in the parking lot or getting sucker punched would be
the least of the consequences.
When you mess with a mans tools..you are messing with his lively
hood..and his reputation.
Gunner
"Liberalism is a philosophy of consolation for Western civilization as it
commits suicide"
- James Burnham
You got that right! :-)
When I was employed, the idea of borrowing a guy's tools was akin to
borrowing his wife. That was back when I was married to my first one.
I used to say I didn't lend my tools or my wife. Turned out I was half
right. I didn't lend my tools.
Harold
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