Caliper accuracy, unreal!

J

jaymeister99

Joined
Sep 14, 2010
Messages
819
Just wanted to put out a friendly FYI.

I bought a cheap 6" caliper off the auction site. I didn't expect it to be great for $14.95. But figured it would suit my needs and work good enough until I could get a good one.

Well, I took it in to work today to check the accuracy. Pulled out a .125", .25", .450" and 1" calibration blocks. Each one was exactly dead on!!!

I tried one of the inspectors $100+ Mitutoyo, and the cheapo I got was more accurate!
 
Wait a few weeks. ;)

Oh, and how you treat your calipers goes a long way. I have a pairs that are 15+ years old that are better than other guys 2 years old same brand. My ID tips are much shorter though.

One more thing try measuring the pins instead of the blocks. Blocks help to square up the jaws.
 
+1 to what carl said. I worked in metrology for some years, and found that cheap ones were hit and miss. Sounds like you got lucky. I have leather sheaths for mine for around the shop, and foam lined wooden cases for storage and transport. Next try a larger guage block to see if a small error might show up. I don't like dial calipers bcause if they get dropped they can get out of whack pretty easy, so I use vernier. I will sometimes get used ones from the flea market knowing the accuracy won't be there, but repetability for marking steel with the ID jaws is acceptable. I think for a single user the measurment is secondary as long as repetability is there. Multiple users or multiple sets of calipers, then the measurments need to be dead on.

Take care of them and they will last. My 20+ year old Fowler and Starrett mics still pass qualification.


-Xander
 
I bought myself one for $40 at KMS tools... I have no way to check calibration but I liked it because it did fractional inches as well. Is there a cheap and easy way to make sure it is calibrated? Where can I find some of those calibration blocks?
 
At the auto parts stores you have probably seen those round spark plug gaping gauges for $1 or so. Have used one for 15 years and the other day my digital calipers were beside it, thought what the heck, I mic'd it. It was so so far off I questioned the calipers, tested the caliper with feeler gauges, it was right on. I immediately changed the gaps on all my installed spark plugs... why do they sell that crap.
 
For anything important use a Starrett micrometer, for quick and dirty layout and scribing paralells etc. cheap calipers are fine, I use my brown and sharpe dial calipers for a lot of basic shop work, but anything where the fit is critical I have a box of Starrett mics in my machine shop, and I have a bunch of old starrett mics that got scrapped at my last job that I have rehabilitated that I keep scattered around the house, in the car etc.

-page
 
I have 3 different sets of dial calipers meant for 3 different types of work.
A Junk set made from salvaged mititoyo calipers. Mainly used when grinding and sets on the table around lots of crap and grime
A Brown and Sharp set in my pocket kept clean and relied to + or minus .001
Starrett Carbide face 6" Dial calipers that rarely sees the light of day Relied to + or - .001.
Why only + or - .001 on a $250. Set of Calipers?
The calipers and a lot of measuring tools are influenced by wear and how you use them. One bump on the point and you will see what I mean.
When I was up visiting the Starrett plant in Athol Mass. about 30 years ago I was told that the Dial calipers were only reliable
to the finest division on the dial.
Page is right on when he said "For anything important use a Starrett micrometer" or Plus or minus .0001
 
Nothing wrong with the cheapo $15 sets for the average hobbist use. But when you make a living from them the suttle differences between them and the more expensive big brand names come into play.
I find the edges don't stay as sharp if you scribe a line, the flats on the ID jaws won't allow as accurate a reading in smaller holes, the depth and step measurements don't always agree with the ID/OD measurements, the movement on cheaper units feels like click adjustments, sometimes they over shoot when closed fast from where they do when closed more carefully and slowly.
 
For what I needed it for I figured even if it was +/- .002 (or even a bit more) would be fine. So far its like +/- .0002! I'll take it back in a few months just for kicks.

Next on my tool list is a micrometer. That I'm not going cheap on. I can get a new cheap micrometer for $20, I can get a used Browne&Sharpe or Starrett for $20. There's a guy at work that's still using his dad's old Starrett micrometer, it still works perfect. Its got to be at least over 50 years old.
 
When you start playing with thermal shrink fits and interferance fits, the repeatability of the Starrett Mics are indispensable

-Page

David Loukides said:
I have 3 different sets of dial calipers meant for 3 different types of work.
A Junk set made from salvaged mititoyo calipers. Mainly used when grinding and sets on the table around lots of crap and grime
A Brown and Sharp set in my pocket kept clean and relied to + or minus .001
Starrett Carbide face 6" Dial calipers that rarely sees the light of day Relied to + or - .001.
Why only + or - .001 on a $250. Set of Calipers?
The calipers and a lot of measuring tools are influenced by wear and how you use them. One bump on the point and you will see what I mean.
When I was up visiting the Starrett plant in Athol Mass. about 30 years ago I was told that the Dial calipers were only reliable
to the finest division on the dial.
Page is right on when he said "For anything important use a Starrett micrometer" or Plus or minus .0001
Click to expand...
 
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