Caliper question

[VaniB]

$15 at Harbor Freight for a 4" digital caliper.

If you want a $10-$15 caliper (4" or 6" ) with the near perfect +- .0005 accuracy range, you will need to physically be there in the Harbor Freight store opening 5 or 6 boxes of calipers to find that one caliper. Don't forget to take a .224 bullet along with you when you head to the store. Unfortunately too, Harbor Freight's "Pittsburgh" calipers are no longer finished smooth. Most now feel rough and gritty.

Ask me how I know all this. 8)

Lot's of luck sending away for any inexpensive caliper vial mailorder. If one doesn't mind a cheap mailorder caliper likely being off +- .001 accuracy or worse, then order it from Harbor freight or any of the shooting sports dealers. There's probably only a couple of different Chinese manufacturers that are supplying all the US dealers who will sell it under a different name for anywhere from $10-$50.

 

[Webster]

My rifle is accurate and used for GH hunting. The only thing I measure is COAL. I don't care what a bullet diameter is or ogive length is as long as it shoots groups under 0.350".

 

[artbosco]

I really dont like the dial type, but how does the accuracy compare between dial and digital? I am looking at a set of Mitutoyo digital ones. 500-196-30 is the number they use. Anyone use these? Any other recomendations?

I purchased an inexpensive General Ultratech Stainless Steel Digital Caliper at The Home Depot a couple years ago.

I QC it with a $38 Mitutoyo .050" Gauge Block from MSCDirect.com from time to time. The General has held its reading "right on" all this time.

You don't need an expensive digital caliper.

Do you QC with a gauge block?

When batteries start to go you get squirrely readings too. Change batteries periodically.

Purchase a Gauge Block. Take a Gauge Block to your purchase site and QC the tool you're thinking about buying. Go home with something that reads the Block correctly over and over a few times.

 

[stool]

i would say, on these forums, you are in the minority.
the title is ACCURATE SHOOTER....not "close enough shooter"
if it is good enough for you then fine, but it is not for most of us.

My rifle is accurate and used for GH hunting. The only thing I measure is COAL. I don't care what a bullet diameter is or ogive length is as long as it shoots groups under 0.350".

 

[tenring]

I am on my second Mitutoyo 6" digital caliper. The first one was identical and began to go downhill after 10 years. My fault is I forget to turn off the battery all the time, but when I return the next day or so, it is still on and the battery runs for a long time therafter. Mine goes to .0005 which is enuf for reloading. And I have found it to be accurate in checking bullet bearing length, OAL, etc.

 

[223Randy]

medic727
OK,
I think we agree, Calipers are not meant for precise measurements. Basically they are good for about plus or minus 0.001" or 0.002" accuracy.

 

[boiler_house7]

another very good one, brown and sharp.

 

[stool]

but if you buy the mitu..it is plus or minus .0005...for a total of .001.....
so sometimes it is wise to spend the extra money.

medic727
OK,
I think we agree, Calipers are not meant for precise measurements. Basically they are good for about plus or minus 0.001" or 0.002" accuracy.

 

[Webster]

Randy is correct calipers were never meant for accurate work.

The website is also called 6mmBR.com and many of us are varmint hunters with a 6BR. OK I should have realized that most of you guys are competitors even though cheap calipers were repeatedly mentioned. I do own 3 micrometers besides my HF caliper. The only one I use is the tubing micrometer. Maybe I can provide a few tidbits that should be mentioned and redeem myself. Comparing a slide caliper to a “C” frame micrometer. The slide calipers do not have carbide inserts to minimize wear. Micrometers do have hardened and precisely ground carbide anvil inserts. The slide calipers entire measuring contact and slides are a hardened stainless steel. The caliper contact surface on my caliper looks like it has a ground finish. I never tryed measuring at different locations along the caliper tip for variation. Years ago I saw the spec for the flatness of the carbide anvils for micrometers. They are extremely flat. I don’t think a caliper measuring surface is ground to the same flatness. Also they will wear much faster than carbide. Carbide is much harder than hardened SS. To sum this up if you want the best accuracy and durability I would always buy a micrometer not a slide caliper mostly because of the very flat hard carbide anvils and accuracy. I don’t know what it cost to send a micrometer or caliper out for replacing worn parts and calibration over the 6” range. It might be cheaper to buy a new one. I was once told a micrometer is only as accurate as the person using it. There are actually classes to learn how to understand specs., use and maintain micrometers. From the below Starrett specs notice how crappy the slide caliper is for accuracy.

Definitions:
Accuracy: The difference between a measurement reading and the true value of that measurement.
Precision:The degree to which an instrument will repeat the same measurement over a period of time.
Repeatability: The ability to obtain consistent results when measuring the same part with the same measuring instrument.
Resolution: The smallest change in a measured value that the instrument can detect. Resolution is also known as sensitivity.
Rule of ten: The inspection guideline stating that a measuring instrument must be ten times more precise than the acceptable tolerance of the inspected part feature.

$254 Starrett 3732XFL-4 Inch/Metric Electronic Micrometer without Output
Micro-lapped carbide measuring faces
Five decimal place read out.
Accuracy (in) +/-.00015"
Resolution (in) .00005"

$239 Starrett 798B-6/150 Electronic Caliper, Stainless Steel, SPC Output, 0-6" Measuring Range
Caliper, Stainless Steel, 0.0005" Resolution, and 0-6" Measuring Range
Four decimal place read out.
Accuracy (in) 0-6”: (+/-.001”)
Resolution (in) .0005"

 

[Joe Salt]

Webster Great thats what I own Starrett's no. 721 & 723's and have had them for years without a problem. But STOOL may not approve. There the best in my reloading room.

Joe Salt

 

[stool]

ok i'll bite..i keep 0-1thru 3-4 inch mic's in the shop for my lathe, but only 0-1 mic and calipers in my loading room.

WHAT DO YOU USE A 3-4" MIC FOR IN YOUR LOADING ROOM ??
inquiring minds want to know ???

$254 Starrett 3732XFL-4 Inch/Metric Electronic Micrometer without Output
Micro-lapped carbide measuring faces
Five decimal place read out.
Accuracy (in) +/-.00015"
Resolution (in) .00005"

 

[Syncrowave]

I am on my second Mitutoyo 6" digital caliper. The first one was identical and began to go downhill after 10 years.

My B&S dial caliper is probably close to 50 years old and probably works as well as the day it was made ... or as well as the $20 jobbies I've bought as backups / shop units.

I don't care whether some dopey $600 Gold-Plated Tactical® caliper shows a THOUSAND digits to the right of the decimal point; all anyone is going to be able to measure reliably with any caliper is going to be about ± .0005"

It's like marking a land surveyor's steel tape in trillionths of a foot. "You'd better 'bob lower!"