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Thread: micrometers

  1. #1
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    Default micrometers

    I'm looking to purchase a new micrometer and was wondering what brand(s) folks might recommend? Are the digital readouts worth the additional cost?

  2. #2
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    Default

    I have a lyman and an RCBS digital and use both really. The digital is very nice but not really needed if your good with numbers. Also the battery thing can be annoying and I like to have "power outage" backup hehe.

  3. #3

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    starrett, mititoyo, browne&sharpe, NSK, older lufkin those are the best central is also not too bad. as for digital, I dunno I use good old fashioned mics and standards to set em'

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    The main thing to remember is that the the most expensive digital calipers for reloading from RCBS, Lyman, etc., allow you to measure accurately to plus/minus .0001", which is excellent for reloading. A good quality dial caliper does the same, but most cheaper digital and dial calipers only get you down to plus/minus .001" accuracy, which is OK, but not the best for accurate work.

    For example, the RCBS mechanical Dial caliper (fiberglass-reinforced) measures down to .001" You can use this caliper for reloading, but the same one in digital form is even better for checking case-head expansion, because it is accurate to plus/minus .0001" The dial caliper costs around $39.00, while the digital version costs around $10.00 more. A micrometer is even more accurate, to at least .00005", but most of the ones for reloading have narrow jaw-openings to measure not too much over an inch. These are great for measuring case diameters.

    Bottom line: buy either a dial or digital caliper that is accurate to plus or minus .0001"

  5. #5
    New member reuben_j_cogburn's Avatar
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    Default accuracy

    Any of the major recognized brands will give you enough accuracy. Most the error you will find is in your abilities not the caliper.
    I own 2 Mitutoyu calipers. One is perfect the other is a lemon... gave up sending it in..
    You can find really good deals on ebay.... there always seem to be about a billion of them up for auction...


    reuben...

    p.s. don't care for digital because when the battery goes... there ya are..

  6. #6

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    I recently purchased a Starrett 734XFL-1, which is a digital micrometer. I haven't used it enough yet to give it an honest review, but so far I really like it. It comes with two batteries, and I have no idea how long they last since I haven't had long. The major PLUS is quickness to read it. That is why I bought it to use over the old style. I never did like reading them and always wanted digital.

    Keep your eye out because micrometers do go on sale, so if you have time you can get a good deal on new or used if you are patient.

    Personally I like the non-digital dial calipers and I have used both of those for a long time. I can use those as quickly as digital and just feel more comfortable with it for some reason.

    Also, I will add I only use the mic's and dial calipers for reloading and gunsmithing tasks which is a hobby, I'm not a machinist.

    Good luck!

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    Member AKBighorn's Avatar
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    And any machinist will tell you your fooling yourself if you think you are going to measure within .00001. Matter of fact Machinists will vary .0001 to .0002 from one another. If you think your going to measure within .0005 you should think twice. As a hobbyist you should not expect to measure any more accurate than .001 with practice. Just my .02 and I make a living using micrometers.

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    Default good info

    Thanks for the feedback. I already have a caliper so the micrometer is the next step up in measuring precision for me. It will be used primarily for reloading duties (case head expansion & bullet diameter). I got on to the Midway website and read some of the product reviews which was also helpful. Like many things, it appears that you get what you pay for.

  9. #9
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    Quote Originally Posted by AKBighorn View Post
    And any machinist will tell you your fooling yourself if you think you are going to measure within .00001. Matter of fact Machinists will vary .0001 to .0002 from one another. If you think your going to measure within .0005 you should think twice. As a hobbyist you should not expect to measure any more accurate than .001 with practice. Just my .02 and I make a living using micrometers.
    AKBighorn:

    Thet's thuh way it's been workin out fer me.

    I'm glad to hear that I'm not necessarily just incompetent.

    Smitty of the North

  10. #10

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    Quote Originally Posted by AKBighorn View Post
    And any machinist will tell you your fooling yourself if you think you are going to measure within .00001. Matter of fact Machinists will vary .0001 to .0002 from one another. If you think your going to measure within .0005 you should think twice. As a hobbyist you should not expect to measure any more accurate than .001 with practice. Just my .02 and I make a living using micrometers.

    a 50* temp swing could change the measurement that much for the same machinist.

  11. #11
    Member AKBighorn's Avatar
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    A 50 degree temperature difference will not simply change the measurement for said machininst, it can in fact change the dimension of the part due to thermal expansion. Just FYI a part measured at 70 degrees and then measured at 280 degrees may grow .015. This however depends on the geometry and material of the part. I know most of you may not see the exact value in this but look at how much the measurement changed by quadrupling the temperature. I didn't mention any of this to step on toes but wanted to offer a realistic point of view to the average guy and his hobby. The temperature variance info. is more food for thought then anything.

    Imho there is not necessarily a need for any hobbyist to expect to measure to such tolerances. It takes practice. If you are going to purchase any measuring tool, you will get what you are paying for. By this I mean, buy one of the better brands and it will last you a lifetime. Most micrometers will measure to .0001 and calipers usually to .0005 but the accuracy depends on the operators experience. Remember, they are not a C-clamp. I have had a set of Mitutoyo calipers for probably 14 yrs and I don't think I have replaced the batteries but a couple of times. They just don't die that fast unless you choose to leave them on when your done working.
    Last edited by AKBighorn; 03-04-2007 at 15:07. Reason: addition

  12. #12

    Default Micrometer

    IMO and for what it's worth,( I spent 17 years in a machine shop, as a second class machinist). If you buy a micrometer it should have a calibration rod with it. If you don't know how to check-calibrate your mic get a machinist or tool man to show you how( they can get out of tolerance). Unless you plan on making a living useing your new aqusition you won't need a Top-line Micrometer (Browne-Sharpe). Try something mid level, like a Starrett or Mitutoyo. If you buy a used one make sure it's repeatable and in good shape ( measure a couple of objects , open it up wide and then close it back down on the same items, the readings should be the same). Run the barrel all the way out and in check for rough threads and tight spots ( if someone drops a Mic it can bend or damage a spot in the barrel,or threads), check the adjustment end and make sure it's not damaged (showing tool marks other than the proper spanner wrench adjustments). Hope this helps, GOOD LUCK
    Last edited by brav01; 03-04-2007 at 20:13. Reason: spelling
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  13. #13

    Default Micrometer

    Hope this helps, GOOD LUCK
    Last edited by brav01; 03-04-2007 at 20:14. Reason: spellng
    " Americans will never need the 2nd Amendment, until the government tries to take it away."

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  14. #14
    Member akndres's Avatar
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    Default a machinist's opinion

    I am by no means an expert, but I do have ten years aircraft experience being a machinist. Bushings, bearings, mating parts, etc. rebuilding landing gears, flight controls, etc. all with closer tolerances than you are going to find in most reloading applications.

    so my .02

    You have a dial caliper... great. Acceptable accuracy is .001". Any claims that are tighter are false. These are for quick referencing and should not be used for close tolerance applications.

    Micrometers. Most reputable manufacturers will have a 0-1" micrometer calibrated to +-.0001 from factory. This can (and will) change with time, usage, climate, abuse, etc. The only way to maintain this calibration is to have it calibrated regularly by a qualified individual.... They should be accompanied in the case by a calibration rod... this is to check repeatability and rule out defects and questioned accuracy.

    Do you need +-.0001" for reloading? I can't see where a reloading/hobbyist would need such accuracy. Sure some will want that, and I'm not going to start stepping on toes. The "average to above average" reloader i don't feel needs this accuracy. Remember a human hair is roughly .003" in diameter. Now split is 30 times...see my point

    Digital micrometers/dial calipers. This is a personal choice. I personally don't like any of the digital tooling. Repeatability is harder with digital tooling because of the "feel" involved. "Feel" is what a poster said earlier about two machinists getting different measurements. The feel is based on torque. Feel differs from person to person. Some micrometers have ratchet stops on the thimble ends to help with feel. People develop their own "feel" and go with that. As long as you have consistent "feel" you will be fine. You also get the "flickering" number thing... if you know what I mean... with digital tooling. Digital tooling is more expensive, and I don't see the advantages besides the read out.

    When I buy tooling for my worksection, it is non-digital. Brown and Sharpe, Starret, and Mitutoyo top the list in that order. Once again, personal preferences. When buying, buy new. I wouldn't trust used tools. These aren't hammers, and you never know what someone has used theirs for.

    Climate. As mentioned earlier, room temperature has a lot to do with precision measureing. As long as you are in the 50-80 degree range, you should be good for realistic repeatable accuracy. Metal will shrink/expand, and thin metal moreso. So don't reload outside at -20

    If you have a quality dial caliper, it should be sufficient for measureing overall case/case length. Checking bullet diameter consistency should be done with a quality micrometer not a dial caliper. As long as you are realistic (i.e. mass reloading with acceptable tolerances) a quality micrometer is all you need.

    Remember you get what you pay for. If it sounds too good to be true, it usually isn't true.

    One last tip. Buy your tooling from Industial Suppliers (i.e. www.mcmaster.com, www.mscdirect.com,, www.grainger.com ) They have more selection and the prices are vey competitive. You don't need an RCBS micrometer because RCBS says so
    "The rich... who are content to buy what they have not the skill to get by their own excellence, these are the real enemies of game".... Theodore Roosevelt's A Principle of the Hunt

  15. #15
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    Starrett. 'Nuff said.

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