Need source for a decent caliper to measure shims.

[mp183]

Need source for a decent caliper to measure shims.
Me and another few guys are getting a community
tool kit for the bikes we have.

[werase643]

Harbor Freight
has a digital caliper... usually on sale for about $15
measures in IN or MM
i have had one for a yr or two seems to work great for the $

[Kerry]

Harbor Freight
has a digital caliper... usually on sale for about $15
measures in IN or MM

Here's a direct link.

[Rema1000]

I have a Harbor Freight cheap analog caliper; and a micrometer from same.  I also had the kit and its digital meter when I changed shims.  

I found the digital meter to be the most "fiddly": you could check the same shim 3 times in a row and get three different numbers.  I was comparing with the dial calipers and micrometer to be sure, and found that if you close the digital calipers, and press Zero, then the next reading is OK.  But you need to Zero between every reading.  The analog calipers would hold consistent for several readings.

The micrometer turned-out to be the most consistent, and the mechanism felt good (no loose play), so I ended-up using that.  I checked a few shims in several places, and found very little variation in thickness.  Unfortunately, the micrometer and analog calipers measured in inches.

[Kerry]

In that case...

6" DIAL CALIPER WITH SCALE -- $15.99

6" DIAL CALIPER -- EZ to Read -- STAINLESS STEEL -- $19.99

6" DIAL CALIPER -- Stainless Steel Frame -- $19.99[/list:u]I started out with a $20 SAE unit, too.  Multiply the reading by 25.4 to get millimeters.

Example:  .104in x 25.4 mm/in = 2.64mm

Or, just use the inch values on my Replacement Shim Selection Chart directly.  

[cobalt135]

If you want somewhat close measurements get a caliper
If you want REALLY close measurements get a micrometer

I use both everyday at work and they are both calibrated on a regular basis.  You will almost always get a different reading with the calipers vs. the mics.  The mics would definately be the better tool to measure the shims.  Mitutoyo makes good quality measuring tools.

[V8Pinto]

For general work I use a caliper (analog) that I got at Autozone for about $25 bucks.  I can get reasonably repeatable results with it.

I have a Mitutoyo digital dial indicator that ROCKS THE HOUSE.  Everytime I use it I am completely amazed - I cannot say enough good things about this tool.

With the 6" caliper, the Mitutoyo, and a high quality (and very old) 1" micrometer I have built two serious engines (and a couple not so serious).

[dgyver]

Measuring valve shims with a caliper will not give accurate readings. As the shim wears, the center becomes thinner than the outer circumference. A micrometer is the only accurate way to measure them.

[Rema1000]

Measuring valve shims with a caliper will not give accurate readings. As the shim wears, the center becomes thinner than the outer circumference. A micrometer is the only accurate way to measure them.

I agree that the caliper is te "right tool for the job".  If you had a micrometer, and you want to measure the thickest part of the shim... couldn't you just measure near the edge, in two spots to be sure?  I measured near the center, and near the edge, and didn't find much difference on the shims I had.  But I guess they were not very worn (many were brand new).

[sledge]

To accurately measure a shim or any other piece across parallel flat surfaces you need to use a ball-ended micrometer. The end of the jaws are shaped like half spheres, they make minimum contact with the piece and are less affected by high and low spots. Flat jawed micrometers should only be used to measure outside diameters like bearing journals and round bar.

[gavin]

Harbor Freight
has a digital caliper... usually on sale for about $15
measures in IN or MM

Here's a direct link.

I have that one.  Bought it at a local flea market.  Works really well.

-Gavin

[GeeP]

Just buy a 1" vernier micrometer.  MSC is currently selling a Chi-Com 1" vernier for $9.99.  (Order number AS06400410)  I use the same thing everyday for most work.  A good Chinese mic will repeat 10ths (slang for 1/10 of a thousandth, or .0001") with no problem.  No need for spherical anvils unless you're doing toolroom work on ground surfaces or measuring tube walls.

Measuring errors with micrometers are generally due to operator error, so a few tips are in order:

1)  Always use the micrometer at room temperature.  This includes ensuring that what you're measuring is at room temperature.

2)  Cradle a 1" micrometer in your palm, with thumb and index finger on the thimble and gripping the frame with your other fingers and palm.  Always grip the frame at the plastic insulation plates to prevent transferring your body heat to the micrometer.  This leaves your other hand free to hold the work.

3)  Use the ratchet or friction advance to ensure repeatable readings unless you have good "feel".  This can be tough if you have small hands like me.  You'll just have to use the thimble and feel.  

4)  Ensure that the work and anvils are spotless.  Dust is thicker than you think.  

5)  Practice, practice, practice!  Practice on a standard or gage block until you can repeat readings with a deviation of .00005".  This depends somewhat on the quality of the instrument.  Obviously you can't expect a non-vernier mic to be this repeatable.

6)  Don't force it!

7)  Roll the micrometer thimble on your wrist to open it.  Don't swing the frame around, or run it down your pant leg.

I think that covers the most common mistakes.  If somebody wants to host a vid, I'll make a short one on proper use.