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Accurate Dial Caliper??

T

Ted_D

Sergeant
Full Member
Minuteman
May 17, 2009
198
3
63
Sandpoint Idaho
www.hms.harvard.edu
#1
I need one in extremely bad. I measure my rounds to order my bushings and it is off so now I have bushings that wont work.
mad.gif
Can you guys recommend a good one that is dead accurate??


Thanks for any help!!
 
#2
Re: Accurate Dial Caliper??

Yeah. Brown & Sharpe, Starrett, Mitutoyo are about as good as they come.

But for what you want to do a micrometer will work better.
 
#3
Re: Accurate Dial Caliper??

If it's a standard 6" dial caliper you can loosen the small set screw on top and rotate the face to rezero the dial. If it's off more than just a few thousandths you need the little copper shim wrench that is usually packed inside the padding of the case. If you have never worked with skip wheels, you might want to get somebody in your area to adjust it for you. Most machinists and tool & die makers should be able to set it for you if it's something simple.

Most of the time it's usually something like dust, dirt or small chips that cause the sweep hand to get off. When the dirt gets in the open rack gear it throws the small gear teeth off when it rolls across the grit. That makes the small gear skip teeth when it moves back the other way. If you keep using, rolling it back and forth over the same dirty place it will skip the small gear every stroke it rolls past.

If you have an electronic unit there should be a -0- zero or reset button. Mine are on the bottom where you can zero it with your thumb while you hold it shut. If you are a right handed person.

The only other thing I can think of is if the jaws themselves are actually bent out of square. In that case you have a nice paperweight.

Dirt, dust and concrete floors are dire enemies of dial calipers. Whether vernier scale, actual dials or electronic.

Most calpiers, even the cheap $25 ones are accurate when they come out of the box. Even high dollar ones don't work when they get dirty or dropped. Every now and then on standard dial calipers I clean the rack gears with lighter fluid. DO NOT use an air hose on dial calipers. You're going to blow grit and junk in the small holes and the whole thing will need to be taken apart and cleaned. If that happens it's cheaper to just replace them. I only know of one or two places that MIGHT still work on them.

Good luck.
 
#4
Re: Accurate Dial Caliper??

these are the way to go , I bought a used mitutoyo for $55 on ebay works great and accurate to within .001

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fuzzball</div><div class="ubbcode-body">Yeah. Brown & Sharpe, Starrete, Mitutoyo are about as good as they come.

But for what you want to do a micrometer will work better. </div></div>
 
#6
Re: Accurate Dial Caliper??

Please don't tell me your measuring the bushing hole with calipers...

The size of the bushing tells you what the neck size of the brass (not worked hardened brass
wink.gif
) will be after sizing, not the hole size in the bushing.
 
#7
Re: Accurate Dial Caliper??

You need a ball ended tee gauge or pin gauges and a micrometer, not a dial caliper.

Box your stuff up, take it over to your local gunsmith/machinist, and have him show you the correct way to measure.
 
#8
Re: Accurate Dial Caliper??

The ball ended tgauge is actually called "telescoping gauges".If you use these,you will still need something to measure over the ends of this gauge to attain an accurate reading;for this measuement you can use a standard Browne and Sharpe micrometer. Not only will this give you an accurate reading, but both products can be purchased from MSC.COM online for a great price. You should order the browne and sharpe mic as a standard single piece,not a set, preferably with a friction thimble. you just need to know the rough size to measuer before ordering.I will help with catalogue numbers if needed.
 
#10
Re: Accurate Dial Caliper??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AJ300MAG</div><div class="ubbcode-body">When you get down to small holes these work;

Small Hole Gages

Takes a good "feel" to get the correct measurement. </div></div>

You got that right, when dealing with thousandth's on an inch, "feel" is everything and you dont learn it over night...at least I did'nt. Get a good 0-1" mic and a set of inside snap mics and you'll be good to go.
 
#11
Re: Accurate Dial Caliper??

I have been programming and processing CNCs' for a little over 20 years for many different industries,and I can tell you first hand that for 120 bucks the link to small hole gauges from MSC is not what you need.They require practice to develop any kind of "FEEL" for using them.Telescoping gauges start at about .300-.350/inch,if this is too small for your application, you may need to investigate a tri-mic as an investment.This piece of gauging is EXTREMLY accurate and always yields up the correct answer.Only downside is they are slightly higher price wise;but they can be had.
 
#14
Re: Accurate Dial Caliper??

The pins mentioned above can be had,however depending on the class of pin you are purchasing they can become expensive.If you choose to use this method,the unfluted end of a drill will serve the same purpose with much more reasonable prices.
If you want a unit to solely measure an OD,MSC.com has a great selection of OD mics that will actually read in whole numbers AND tenths which are graduated on the thimble of the mic.A new SPI or Talon and several others can be purchased at a very low cost.Any 0-1 inch mic,bought as a single piece should suit the purpose quite adequately.Again,any service that I may render to a fellow reloader is a pleasure,and I check my replys' from this sight quite often.
 
#16
Re: Accurate Dial Caliper??

The pointy part on top will measure inside.

What do plan to do with all those other gauges? Most folks just take the OD of a loaded case and adjust their bushing size accordingly. Pin gauges? Telescoping gauges? What for? A ball mic measures neck-wall thickness.
 
#17
Re: Accurate Dial Caliper??

I've got 4 sets of calipers and none of them read exactly the same. one set is as much as .002 off the mark. The way I check for bushing sizes is to take a tube micrometer and get an average of the case wall thickness, double, add size of bullet and order bushings by how much tension I want on the case. Cheaper way is to look up Forster bump bushing shoulder die and see what three they send in their set. I have the tube Micrometers on hand because I turn neck cases when needed. My eyes won't let me use my Fowler any more so I had to go digital my dial indicator set worked well but once your brother drops them a time or two they are wasted.

My bushings measure what they say they are by the way.
 
#18
Re: Accurate Dial Caliper??

My cousin designed the electronics and wrote the software for the coolant proof digital calipers. I already had lots of calipers, but I bought a pair. The resolution is .0005".
I called him up an complained. Why not give me .0001" resolution, even if you can only give me .0010" accuracy. I could use the resolution. I can chose a pin gauge very close in magnitude to the measurement on the work I intent to make. The pin gauge has 0.0001" accuracy. I can note the discrepancy in the calipers. When I measure the work, I can calculate a correction and produce a measurement with much greater accuracy than the absolute accuracy of the calipers I am using.

That data base in my head is what is now defined as a "Check Standard" by the NIST:
http://www.itl.nist.gov/div898/handbook/mpc/section1/mpc12.htm
--------------------

But with dial calipers, I chose a pin gauge and adjust the dial until it reads the value of the pin gauge.
I wipe off the pin gauge, the caliper jaws, and the work.
I practice for a couple seconds getting consistent readings. That entails:
1) where the pin gauge is placed in the jaws
2) how perpendicular the work is to the jaws
3) how hard I close the jaws
4) I interpolate between the .001" dial lines to get .0001" ~ .0002" resolution.

When I think I have repeatability, I try to measure the same way on the work.
With this technique $20 Chinese dial calipers can make more accurate measurements than $200 Starrett dial calipers that are just zero'd on zero.

----------------------

I find dial calipers are good for outside measurements with their big jaws, but the little pointy jaws for inside measurement have repeatability that is terrible.
 
#19
Re: Accurate Dial Caliper??

Nice method. I'm amused from time to time by people who think that because they can do a calculation with a digital calculator or other device to X-many digits of resolution, that it's accurate to however many digits the device displays.

We used to have a better appreciation for the limits of accuracy when we used slide rules.

And, yes, I'm not only old enough to have done that, but I still have - and use - three of them.
laugh.gif


One is a Post with scales laid on a bamboo substrate. Another is a Jeppesen-Sanderson flight computer, and the last is a Mildot Master.
 
#20
Re: Accurate Dial Caliper??

I get all warm and fuzzy when Millwrights measure the bearing diameter on a CNC mill ballscrew, and then the bearing bore of a Class-9 bearing... with dial calipers.

And then have the balls to tell me they don't fit.
mad.gif
 
#22
Re: Accurate Dial Caliper??

Clark,

Good job on the explaination.

Lindy,

I still have 2 or 3 slide rules. They're from pocket size to 14" (I think) I also have 2 different flight computers. One is heavy laminated paper and the other is printed on aluminum.

I agree.

A lot of people, I'm not saying people here, but a lot of people READ something in .0001" and think that's a wonderful thing. I want all my stuff to be ,0001" But in real life it isn't that easy. And indeed a lot of stuff doesn't need to be that close.

I love reading text from people that post here throwing around .0001" like it's a stick or something. After being involved in machining and fabrication almost 40 years, I have decided a lot of people don't have any idea what they're talking about. But everyone here that DOES know, understands what I'm saying.
 
#23
Re: Accurate Dial Caliper??

fwiw,
A Micrometer with a thimble ratchet and carbide faces. Etalon is the best, however, they no longer make inch reading units. A true shame.

Dial calipers are useful but limited in accuracy. Again Etalon/Tesa makes the best in the world.

Regards, Matt Garrett
757-581-6270

Btw, Avoid Starrett Dial Calipers. The jaws are soft and will quickly develop a bur under daily use ruining their accuracy. Their Mics are passable...
 
#24
Re: Accurate Dial Caliper??

That Long Island outfit seems to speak highly of what they sell and service, but are quick to denigrate other's products. I own or have used Mitutoya, Starrett, Brown&Sharpe and Peacock instruments. The Peacock caliper seemed very nice, but I didn't know the brand and thought it to be a nicely crafted knockoff. When I compared it to my Mitutoya instruments I came to the conclusion that the latter is a utilitarian piece compared to the craftsmanship and detail in the Peacock. Others more knowledgeable than myself may have a different appraisal, but I definitely don't share The Long Island appraisal of Peacock. I know that I shouldn't expect them to service it. I use the Peacock caliper daily and leave the Mitutoya instruments in their plain, plastic cases.
 
#26
Re: Accurate Dial Caliper??

fwiw,
I own and use what I recommend. I've found that working everyday in a machine shop or the machinist duties of a full service gun shop are night and day to what "most" folks subject their tools to. This also reflects recommendations and is one reason Practical Machinist is a likely a better forum than this. Go where the machinist complain...(grin) My Starrett Calipers were plagued by soft jaws and developed a .0035" ding within the first three weeks of use. It goes without saying that everything wears out with enough use. Hell even Glock 17/19s and AWs MUST have a point of no return. That said I've not found that point with either...fwiw & imho

Regards, Matt Garrett
757-581-6270

Btw, Dunno or expect to find out on Peacock, however, I've found the Long Island Outfit more right than wrong..imho.
 
#28
Re: Accurate Dial Caliper??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: XXX</div><div class="ubbcode-body">I need one in extremely bad. I measure my rounds to order my bushings and it is off so now I have bushings that wont work.
mad.gif
Can you guys recommend a good one that is dead accurate??


Thanks for any help!! </div></div>

may i recommend a digital ?? they are inexpensive and very accurate, accurate to 1/1000th of an inch.
CP8806-T.jpg


i have one and thinking about getting another one for my shop. the one i have now is at the reloading bench which is about 50 yards from the shop.
 
#29
Re: Accurate Dial Caliper??

fwiw,
I should mention that the Etalon/Tesa Dial Caliper, which (fwiw & imho) I consider to the be the best in the world, are regularly available for $125. Get on the e-mail list with Enco and MSC(Same Company). They run one day discounts that often offer substantial savings.

Regards, Matt Garrett
757-581-6270
 
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