Micrometer

[Tar Heel]

After finally purchasing a precision micrometer which reads to .0001, I have had a new world open up for me with the associated "epiphanies" thereof. One of those is that my cast bullets from a SSK (NEI) mold for the 45 heavy bullets which I was sizing to .451 were not getting sized to .451 on the front driving band. This was preventing the chambering of this bullet into a Freedom Arms 454 Casull.

Using my RCBS plastic dial calipers, I had determined that this bullet was sized correctly to .45..ish but now I know that the darn front driving band is .4532 while the lower portion of the bullet is .4514".

What a difference a good tool makes. If you are casting, sizing and loading and do not have a good micrometer, go get one off eBay. You can find a nice $150 micrometer for about 20 bucks.

[1hole]

"Using my RCBS plastic dial calipers, "

And some people blast Lee for selling "cheap" junk! RCBS has sure come up with a list of their own losers over the years. ??

[Pigslayer]

Just recieved my Starrett 1" micrometer. I got it on Ebay for $17.50 plus a few dollars shipping.
Yes I have a cheap caliper & a cheap 1" micrometer & they were surprisingly close. But the Starrett now . . . that seperates the men from the boys.It's a #436-1in. Still in the original box w/padding & oilpaper along with the wrench in it's own sleeve. Original instructions too.

[machinisttx]

Brand new Starrett tenth reading, carbide faced mics are almost always under $100 brand new. Brown & Sharpe and Mitutoyo are as well. If you're not accustomed to using micrometers, I'd suggest friction thimble versions rather than ratchet or solid(definitely stay away from solid thimble if you're not used to them).

[dragonrider]

" front driving band is .4532 while the lower portion of the bullet is .4514"

How are you sizing, Lyman, RCBS, Star, Lee?????

[Pigslayer]

" front driving band is .4532 while the lower portion of the bullet is .4514"

How are you sizing, Lyman, RCBS, Star, Lee?????

Hmmmmmmm. If he was sizing with Lyman it would indicate that the boolit was not being pushed into the die far enough. But . . . it looks like he has the problem solved.

[Tar Heel]

" front driving band is .4532 while the lower portion of the bullet is .4514"

How are you sizing, Lyman, RCBS, Star, Lee?????

It's an RCBS but in fairness, it's also a BAB (Big As.. Bullet) for a revolver with no lube in the crimp groove. For as few of these as I load, I'll live with running them in tip down first then the other way with lube.

I was surprised to see the difference and glad that it also explained why they just would not seat that last little bit in the cylinder. Now I know. The FA Casull has TIGHT chambers anyway and perhaps the other guns now chambered for the 454 Casull have sloppier chambers.

It is really nice to get a good measurement tool. Agree with the other posts too about a friction thimble on the device.

[Reverend Recoil]

eBay also has some good deals on precision gage blocks. The shop grade gage blocks are precision ground to 0.000050". Only three or four is needed to wring together for calibrating a 1.000" micrometer.

[Tar Heel]

"Using my RCBS plastic dial calipers, "

And some people blast Lee for selling "cheap" junk! RCBS has sure come up with a list of their own losers over the years. ??

Really now.....it's not a bad tool, it just has limits. These are great for COAL measurements and case trimming but certainly not for gas check ID verification. I was pushing the tool beyond it's capabilities and the capabilities of my 55 year old eyes.

Tell me you have NEVER used a $1.99 hardware store screwdriver with a beveled tip to tighten one of your revolver frame screws?? Sometimes you pull it off......and then you get screwed when that tool slips.

[atr]

Starrett and Lufkin have served me well over the years. Add a jo-block to check calibration.

[Tar Heel]

Just recieved my Starrett 1" micrometer. I got it on Ebay for $17.50 plus a few dollars shipping.
Yes I have a cheap caliper & a cheap 1" micrometer & they were surprisingly close. But the Starrett now . . . that seperates the men from the boys.It's a #436-1in. Still in the original box w/padding & oilpaper along with the wrench in it's own sleeve. Original instructions too.

This is my first good micrometer and you just know I'm measuring everything I can. Did you know that ........yup....I'll bet you did!

[40Super]

You just found out why I always kind of chuckle when someone says this or that measures to .0001" ,when they are using a caliper of sorts. Being a machinist ,I have some of the most expensive and highest quality calipers,and I still don't take the measurement reading as "exact" like some do. I guess if the readout goes to 4 numbers past the decimal,they think that it is truly that acurate. It is hard to explain the difference between the two measuring devices.
I've seen some new guys at work ,treating a micrometer like a "C"clamp.Then wondering why it keeps needing to be calibrated.

[WILCO]

I've seen some new guys at work ,treating a micrometer like a "C"clamp.Then wondering why it keeps needing to be calibrated.

It's all in the finger tips.

[Ziptar]

Unlike reloading equipment seems good micrometers can be had on eBay very inexpensively.

I've recently bought two Brown & Sharpe Micrometers on eBay both for the grand total of $23.32 with the shipping.

The first was a Brown & Sharpe model #1 for $4.92 with the shipping after a $5.00 eBay coupon I had to use as it was going to expire.
http://www.ziptar.com/reloading/brown_and_sharpe_model_1_micrometer.jpg

It's a carbide tipped ratchet type, is accurate and works great but was hard to read with my years of working in IT fried eyes.

About a week later I won a Brown & Sharpe Model #10 for $18.40 shipped. It's a carbide tipped friction thimble type and it came in a wooden case. I love it! It's like a Large Print edition! :-) It's dead nuts accurate and really easy to read, no more squinting. :-P.

http://www.ziptar.com/reloading/brown_and_sharpe_model_10_micrometer.jpg

I've also got a Brown & Sharpe 6 inch Dial Caliper in a wooden case on eBay for $15.50 shipped. It's like brand new.

[Char-Gar]

Nothing like a good 1" micrometer for the handloader. It was the first tool I acquired in 1959 after the press, dies, scale and power measure. It was a well used Starrett 436-1 and I still use it. I have added several more, but these things are everlasting if treated as intended.

We made case length guages from a piece of aluminum or brass. Using a new unfired case as a guage, we filed a slot so the case would be a slip fit and stamped the metal with the caliber. I still have some of those as well.

I was 35 years into handloading until I owned my first set of calipers. They proved to be much inferior to the micrometer, so have used them very little.

[machinisttx]

Starrett and Lufkin have served me well over the years. Add a jo-block to check calibration.

More than just a single gage block is needed to calibrate a micrometer. It should be checked at 1/4 and half rotations to verify that the spindle and anvil are parallel. Optical flats can be used to verify flatness of the anvil and spindle faces.

[nanuk]

More than just a single gage block is needed to calibrate a micrometer. It should be checked at 1/4 and half rotations to verify that the spindle and anvil are parallel. Optical flats can be used to verify flatness of the anvil and spindle faces.


eBay also has some good deals on precision gage blocks. The shop grade gage blocks are precision ground to 0.000050". Only three or four is needed to wring together for calibrating a 1.000" micrometer.

what ones do you guys suggest?

[jcwit]

If you're going out to 4 digits, are you working in a temp. controled room?

[btroj]

Man, are we going down this road again?
I own a micrometer. It will measure to 4 places, I am perfectly happy knowing to the 1/2 on the 4th place and can actually live with just a solid 3 places.

I don't own anything to check or calibrate my micrometer. May buy something at some point but am in no hurry.

If I measure a bore slug then a sized bullet I would imagine the error would be similar and offset itself. I am not a machinist and am not working with anything that critical. Heck, I got by for 25 years without a micrometer at all. Somehow I think I will get by even with a small amount of error.

[zuke]

what ones do you guys suggest?

Look on EBAY and see what's there.
Your measuring bullet's,not making part's for jet engine's.
Able to read 0.875 is good enough. 0.8753 is about all you'll ever need,and remember that last number is 1/10 of 0.001. That's fine enough .

[Buckshot]

..............Depends on what you're doing if that 4th digit is important or not, and if it IS important it's worth checking your mic's a couple times a year. I do it a the time change twice a year. However for sizing cast boolits if it's supposed to be .452" and the .002" hash mark is on, or just above the horizontal "Zero" line at 45 you're gold.

Remember a sheet of common 20lb typing paper is .004" thick. In that thickness there are 40 of those lovely ten thousandths [smilie=l:

..............Buckshot

[Flinchrock]

..............Depends on what you're doing if that 4th digit is important or not, and if it IS important it's worth checking your mic's a couple times a year. I do it a the time change twice a year. However for sizing cast boolits if it's supposed to be .452" and the .002" hash mark is on, or just above the horizontal "Zero" line at 45 you're gold.

Remember a sheet of common 20lb typing paper is .004" thick. In that thickness there are 40 of those lovely ten thousandths [smilie=l:

..............Buckshot

Good idea,,That checking at the time changes...

[adrians]

morning ,, i have been using this Starrett for years and has given me all i need to measure my "stuff".
the reading on this boolit for me is good enough for my meager needs.
fleabay sellers offer these at reasonable prices..(so long as you don't get sniped:().
turning the thimble to get the most accurate reading is the trick ,just turn till you get a hit and no tighter,
i don't particually care for the ratchet types but that a personal choice i made.
and in the years iv'e had this mic not once have i had to replace the battery [smilie=1:
have a great 2012....:twisted::coffee::twisted:

[btroj]

Sizing bullets is pretty much all I use mine for Buckshot.

If I was doing machine work or something requiring greater precision I would certainly do what it takes to keep things calibrated.

I was mostly pointing out that we have periodic threads on what the "best" way to calibrate a micrometer is. What to use, how many, etc, etc, etc.

[Ziptar]

Buckshot. Sheet of paper comparison is perfect. Thats puts it in perspective I think.

I agree on the 4th digit, for bullets its not important for me. I just need to know how big my bores slug, what size are my boolits dropping at, and what size are they after they are sized. For all of that measuring out to the thousandths is all I need.

I know its not the "best" or proper method, I don't have any gauge blocks, when the two I bought on eBay arrived I checked them against random gauges in my feeler gauge set. That was good enough for me.

[Char-Gar]

It is very easy to split the lines on the micrometer with the eye and get .0005 accuracy and less with practice.

[uscra112]

In answer to what to buy - Mitutoyo is IMHO best value for money, Fowler's Japanese made models are also good (I've long suspect they are made by the same plants that make Mitutoyo). Yes, my "Lord Chancellor" is a WW2 vintage Brown & Sharpe, but that's just 'cause I like old stuff.

Just for giggles, buy one of those electronic mikes that resolves to 50 millionths, and then find out how much your technique affects the readings you get! A worthwhile learning experience.

Finally, speaking as a metrologist, (which I were one), more resolution is always better, so long as you have the means and the will to verify the accuracy you're getting, and the instrument isn't so delicate that you can't use it without fear of breaking it. I spent years tooling auto plants to measure engine blocks and heads - most tolerances were 2-3 thousandths, but our machines resolved to 20 millionths anyway, and were accurate to a less than a tenth per foot of linear distance, sometimes better. Man, what they learned, having such accurate and precise measurement capability!

I had a boss once (at a machine tool builder) who was unhappy with my new laser interferometer. "This damned thing tells us things we didn't know we didn't want to know!" said he. To their credit, I never heard that from any Ford/GM/Chrysler engineer. The machine tool builders, yes - they hated our machines, because we made 'em work for a living! The Japanese especially. Which is why so much of the new machinery in the D3 is German.

[MtGun44]

Many here will verify that I have expended a good bit of bandwidth trying to convince
some of the new casters to get a .0001" capable micrometer to replace their calipers.
Sometimes they listen, I think most of the time they blow it off.

I frequently recommend the Fowler mics that Enco has pretty often on sale for well under
$50.

Bill

[jcwit]

Truly asking a question here.

In our sport/hobby what is the purpose of measuring out to 4 digits?

Just wondering?

[Ziptar]

Many here will verify that I have expended a good bit of bandwidth trying to convince
some of the new casters to get a .0001" capable micrometer to replace their calipers.
Sometimes they listen, I think most of the time they blow it off.Bill

While I agree on the micrometer vs. calipers for checking bore slug and bullet diameter, measuring out to ten thousanths isn't required. Well maybe for a a bench rest or long distance competition shooter with OCD it might be. :)

[Reload3006]

its nice having a micrometer that can read to the 4th decimal place but honestly I would bet my arm and leg you aren't going to be able to measure that accurately with a micrometer. I used to think I could but was proven that I was mistaken give ten people the same mic and you will get ten different answers when you get into the ten-thousandth range. heat and feel play too big a role.

[badgeredd]

As a retired tool maker, my opinion is that when one buys a measuring device, one should get the best he can afford. Being able to read tenths is not necessary for the vast majority of our needs in our sport BUT one can buy a good to excellent quality micrometer for almost the same price as a intermediate mic. Why not buy one with tenths? :-P

I'd opt for carbide faces and a friction thimble with tenths if I had need for another mic. I definitely prefer good old American made Starrett but that is just my obsession. I don't care at all for the angle line Brown & Sharps but the vertical line ones are ok. I also have used Mitsys and with carbide faces on the anvils and tenths, they are definitely serviceable. I personally don't care for digital mics as that's one more thing to mess up and battery operated readouts need batteries. Japanese tools seem to be of good to excellent quality. I'd stay away from ANYTHING made in China...the quality just isn't there.

Now that is my opinion and it's probably worth what you paid for it. [smilie=l:

Edd

[nanuk]

Look on EBAY and see what's there.
Your measuring bullet's,not making part's for jet engine's.
Able to read 0.875 is good enough. 0.8753 is about all you'll ever need,and remember that last number is 1/10 of 0.001. That's fine enough .


But isn't boolit casting Likened to Rocket Science?

and what does Geargnashers sig say about precision?

[nanuk]

I got lucky at an auction sale
bought a Mitutoyu for $10... cause it was in metric.

took it to the local machine shop so he could see if it was in spec and it was spot on with his technique, and another thing he pointed out... it is graduated 2/3 more fine than an SAE one...

[Silver Eagle]

A key thing in Metrology is not the resolution of the device. It is repeatability and reproducibility.
I worked in Metrology for 5+ years measuring to Tenths and 20 Millionths on optical measuring microscopes. We proved that we could hit these numbers and repeat them by doing blind checks using 2 techs on the same piece of equipment with the same parts. This is also how we got rid of the complaints from the engineers that according to their .001 dial caliper (uncalibrated) that the part was out of spec and they had to fix the tooling.
We had our equipment calibrated every 6 months by an outside traceable company. And also performed in house self checks on a regular basis
As for home use equipment, get something you are comfortable using and that can measure to the accuracy you need. Best bet is to practice with it. Get something to measure with it and measure it 5 to 10 times and see if you hit the same number each time.
For home calibration find a couple of items that span the range of your tool and measure and record the numbers. Then, every so often check these same items and see if you get the same numbers. A slightly better option would be to get some jo-blocks, plug gauges or other precision part that you are given the measurements of.

Silver Eagle

[Sonnypie]

Truly asking a question here.

In our sport/hobby what is the purpose of measuring out to 4 digits?

Just wondering?

Because it's a damn site closer than that Stanley Tape measure on your pocket. :bigsmyl2:
Some of us can understand trying to be as precise as we can.
OK, you can go back to your yardstick now. [smilie=s:


I have 2 Starrett micrometers, and 1 odd-ball, I refer with.
And a factory certified Starrett digital caliper.
It's nice to be precise. ;)
Don't always have to be. But it's nice to have when you really want to check a red hair... :lol:

http://i1195.photobucket.com/albums/aa382/Sonnypie/P1050201.jpg

The older Starrett was used by my Grandma at the Douglas Aircraft plant during WWII.

[WILCO]

Here's what I use around the house:

[uscra112]

Old rule of thumb was to have the measuring instrument be ten times as accurate as the units you are measuring to. Thus, if you want to measure thousandths with a high confidence level, use a micrometer that is repeatable and accurate to a "tenth". This is almost a law of the universe in process control.

Silver Eagle touched on a process that I had to do with wearisome regularity when I was with Zeiss. Called a Gage Repeatability and Reproducibility study, acronym GR&R. Every system we delivered had to pass this test before it could be accepted. Basic protocol is take ten parts, measure each characteristic of each feature on each part ten times, and do it all again for five different operators. (It can take days to do a full GR&R on a complex part like a cylinder head.) There's a detailed statistical reduction you do on that mountain of data, which tells you how much variability you have for each characteristic as a percentage of each tolerance. GM/Ford/Chrysler would accept an uncertainty of five percent of tolerance. That was it. On the particularly tough ones we might negotiate ten percent, but they didn't like it.

So if we were measuring a tolerance of .001", our gage system had to repeat and be accurate to fifty millionths, all day, every day, three shifts. Amazingly, it can be done, and that's why American engines are better made today than Japanese. The Japanese factories won't buy Zeiss gaging; they buy only Japanese gages, which are 2x to 4x worse than Zeiss. This is a case of what you don't know can hurt you.

[Sonnypie]

Old rule of thumb was to have the measuring instrument be ten times as accurate as the units you are measuring to. Thus, if you want to measure thousandths with a high confidence level, use a micrometer that is repeatable and accurate to a "tenth". This is almost a law of the universe in process control.

Silver Eagle touched on a process that I had to do with wearisome regularity when I was with Zeiss. Called a Gage Repeatability and Reproducibility study, acronym GR&R. Every system we delivered had to pass this test before it could be accepted. Basic protocol is take ten parts, measure each characteristic of each feature on each part ten times, and do it all again for five different operators. (It can take days to do a full GR&R on a complex part like a cylinder head.) There's a detailed statistical reduction you do on that mountain of data, which tells you how much variability you have for each characteristic as a percentage of each tolerance. GM/Ford/Chrysler would accept an uncertainty of five percent of tolerance. That was it. On the particularly tough ones we might negotiate ten percent, but they didn't like it.

So if we were measuring a tolerance of .001", our gage system had to repeat and be accurate to fifty millionths, all day, every day, three shifts. Amazingly, it can be done, and that's why American engines are better made today than Japanese. The Japanese factories won't buy Zeiss gaging; they buy only Japanese gages, which are 2x to 4x worse than Zeiss. This is a case of what you don't know can hurt you.

BINGO!

That right there was worth the price of admission!

But what chaps my butt is American Manufacturers contracting out, and buying furrin plants, to make stuff for American Made (HA!) cars.
And this chutney has been going on for decades and decades.

Measure with a rope, Cut with an axe, Beat it to fit, Paint it to match.

And with enough powder, you could send a rock down the bore.
I'm sure glad I'm not a boolit.
Blam! Oh! That's got to hurt! (http://youtu.be/Z33L8XcwrJY)

[Moonman]

YUUUUP! Some are Carpenters, Some are Machinists, and Some are Tool and Die Makers. They work to different Tolerances/Allowances and achieve different results as to the final end products precision and repeatability.[smilie=l:

[jcwit]

Posts # 30, 31 & 32 nailed it.

[uscra112]

That right there was worth the price of admission!

But what chaps my butt is American Manufacturers contracting out, and buying furrin plants, to make stuff for American Made (HA!) cars.
And this chutney has been going on for decades and decades.

This is OT by more than a little, but . . . .
The American machine tool builders were ruined by a combination of unions and bad management. This all started in the '70s, BTW. At Zeiss alone I participated in three of the last attempts by an American MTB to supply the auto plants with what they needed. Indeed, my (German) Zeiss equipment stood as judge and jury on whether the MTB systems would be accepted. They fought like lawyers - rather than make their systems work right, they too often spent their energy trying to discredit Zeiss. No arguing with me on this. To quote Elmer, "Hell I was THERE!"

To their credit, the Big 3 did not do what the Japanese do - they went to the best possible sources for their new engine and transmission plants, anywhere, at any price. (Including the gaging, obviously) I was in the MT industry for forty years, (fifteen with Zeiss), and I am still in awe of what the German machine tool builders can do.

Now to get back on topic - - - The reason they do so well is that they can measure with such precision and accuracy, (thank you Zeiss). They found out the stuff that they didn't know that they didn't know, and fixed it. And THAT's why you need the a "tenths" micrometer, even of you're only measuring thousandths.

[Sonnypie]

I like it for those times when I wonder....
Now is that a tight .XXX?....
Or is it more like a .xxxy?, or xxxz?

Because you zee a z is closer to the next → X, than it is to a y ↔, or the preceding ← X... :shock:

And then the temperature changes hotter and things get fatter.... DARN! :bigsmyl2: