caliper vs micrometer

I have a dial caliper that I use to measure OAL on my reloads.

Sometimes it seems that a micrometer would be handly when I want to measure bullet diameter or maybe the case mouth diameter when I 'm setting the case mouth expander die....yet the dial caliper will sorta do this as well...I guess its a matter of accuracy.

Which brings up another subject...what do you use to "calibrate" your calipers with guess a gauge block is in order here.

http://longislandindicator.com/p164.html

Guess there is no end to the "toys" a reloader must have!

dad used to send all his to Komp industrial welding supply and they would check their accuracy. I use his tools when I am reloading but I really dont need the degree of accuracy they offer. His mic will go down to .00000 but personally a good caliper is all I need

To "calibrate" your calipers you just set the dial to zero with the caliper closed. The calipers opens and closes a geared track that advances the gear on the dial. If the caliper is out there is not much that you can do except to send back to the factory if it is an expensive caliper. A gauge would tell you if it is acurate.

Nope....

Setting your dial caliper to its zero doesn't prove anything...any more than zeroing your reloading scale....

You use check weights to verify your powder scale...mine happens to be .5 gr off in certain ranges....

You use a gauge block to verify your calipers are correct...sometimes they don't close all the way after many yrs of use etc etc.....I'd suggest a review the previous link I posted.

Best to you

msredneck is correct. but the cheap 20 dollar calipers you pick up at auto zone you just close the jaws and zero the dial and you can get in a good ball park..My tools are Starrett which are alot higher degree of precision. just think 1/1000 of a inch could be the difference in a perfect fit and to tight... This is gonna sound funky but we ruined the accuarcy of a 200 dollar caliper because a summer helper stored it upright instead of lying flat for four months during the summer which caused a very very very slight bow.. =( talk about sensitve

"calibration" was not really what I wanted to get the topic off on...

but the point is...with anything you measure with...especially stuff were you are measuring 1/1000 of an inch...Buy the best tools you can afford......and

Periodically we have to measure it against some Standard...for scales that's check weights....for calibers its a "standarized gauge block"...It all depends on how precise u desire to be.

Now back on the subject...I don't have a good micrometer and I'm wondering how it came help my reloads...or if its really necessary...

for ex. sometimes I'd like to verify if the bullets I purchase (especially lead cast) are the dia the mfg claims they are.

Best wishes to all...

Your current calipers wont give you those measurements?

Finally, something I think I know a bit about! Sure, you close your dial caliper to zero, make sure it reads zero when closed down, and from there on your measurements are only as accurate as the mechanical means turning the dial, typically a toothed rack which rotates a gear.

Micrometers are the same way, except their accuracy depends on a very accurately made screw thread. Typically, the threads in micrometers are hardened and ground, grinding being one of the super-accurate means of finishing close-tolerance metal parts.

Realistically, one-thousandth of an inch, (0.001") is just about the hair's-breath closest one needs to be in reloading ammo. Just my opinion. Take it or leave it.

+1

OK...I gotta admit I'm ignorant here....so let me ask it like this.

For what specific application is a micrometer good for in reloading as compared to a caliper (mine happens to be a dial type)

To me it seems calipers are good for measuring length of "straight objects"

Micrometers are for measuring "around objects" diameter, circumference et al


Somebody help me out here....it can't be that hard....why does a reloader want/need/desire a micrometer....some dies even have them built in....educate me please! If you have both...tell me what you would use the mic on that you wouldn't use a caliper on....

Then I'll leave you alone...I promise!

= ( calipers are good for measureing the length of any object it can get its jaws own. I honestly dont use my mic that often, only to verify what my caliper tells me... As far as why a reloader would want/need/desire a micrometer is beyond me. If my dad was not a engineer I would not have the one I use. The only way I would choose mic over calipers is if i was sorting out bullets for a 1000 yard match, top sniper contest, or shooting an apple off your friends head. I stand by my idea of a reloader does not need that level of acuraccy. If you were thinking about doing smith work then yea pic up a mic but as far as bullet work goes you dont need it. My 2 pennies

P.S a round object is a straight object if you think of it as a series of similar straight lines rotating on its mid-point every degree

Thanks....Looks like No mic needed for me. I don't shoot apples or 1000 yard matches

Can use that $100 on more bullets!

'Neck, I am a machinist by trade. Have Thousands of $ worth of precision measuring instrument and all I use are a quality set of Brown and Sharpe dial calipers for my reloading. As to the calibrating of calipers:
Resetting zero does not infact calibrate the calipers. Massair is correct in that the calipers use a geared rack and mics use ground threads. The calipers come from the factory with zero at the top of the dial. After time or missuse the gear on the dial will "jump" the teeth on the rack, thus causing the zero to move. Usually only quality equipment can be truely calibrated. My calipers have a slot on the back of the dial that you can insert a small object ( opened paper clip) into that will release the dial gear from the teeth on the rack. You then close the calipers with zero at the top and remove the paper clip. As with any often used tools measuring instruments should be calibrated yearly or if misshandled.

Thanks bigsig...I probably ought to "invest" in a new dial or maybe a digital caliper...Mine is 20 yrs old

bigsig wrote:'Neck, I am a machinist by trade. ........

Hey, if you are an "old-time" machinist, can you tell me HTH could my Dad (Tool & Die Maker, 1930s- 50s) possibly keep track of table position on, say, a Bridgeport mill? Big pad of paper and some kind of secret way of counting turns of the dials?

He never got to see/use digitals, poor guy. I put a set on my Bridgeport when I bought it, about 1990 in Phoenix, used, an old one, but gets my jobs done.

massair wrote:

bigsig wrote:'Neck, I am a machinist by trade. ........

Hey, if you are an "old-time" machinist, can you tell me HTH could my Dad (Tool & Die Maker, 1930s- 50s) possibly keep track of table position on, say, a Bridgeport mill? Big pad of paper and some kind of secret way of counting turns of the dials?

He never got to see/use digitals, poor guy. I put a set on my Bridgeport when I bought it, about 1990 in Phoenix, used, an old one, but gets my jobs done.

Sorry massair I'm only 35 Have been machinist for 15 years. Now when I learned the trade we didn't use digital readouts, but all machines should have calibrated dial on them mine do. Now to put this into perspective I'll post a pic of me and my machine.
G]http://i42.tinypic.com/sytsue.jpg[/IMG]

It finally decided to come up for me. Anyway this is me and my machine!

Nice rotary table your standing on or is that just a bed with t slots? Lots of travel in that one. It is so big I cant even tell for certain what it is. Since there is a lot of swarf on the floor I am guessing huge mill? Are you putting a cut on that top part? If so it looks like a nice surface finish.

eddybo, this is a 120" BETTS boring mill, circa1958 I believe. I can swing 126", have about 96" under rail, and each of the rams have 80" of travel in Z. It turns at a whopping 35 rpms max and will feed between .005" and 1.0" per revolution. I have been running mills and verticle turret lathes most of my career. I can run a lathe, but prefer the VTL's. If you look at the upper right of the pic you will see a platform fastened to the right head. While machining the tops of these parts I actually ride up there so I can see in the bore and such. Can you imagine the size revolver cylinder I could make with this machine? Ha Ha

LOL I would hate to load for that revolver.

Back on topic about the only mic you need for reloading would be a ball mic for measuring neck thickness. If you do not turn necks there isn't much need. The way I play with some of these cases and chambers it is pretty important to know the thickness of the brass around the neck. On SAAMI chambers you do not have to worry too much about creating a high pressure neck tension situation unless you do not trim your brass.