Inside caliper vs telescoping gauges
Close
Login to Your Account
Results 1 to 15 of 15
  1. #1
    Join Date
    Oct 2018
    Country
    UNITED STATES
    State/Province
    Michigan
    Posts
    8
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Default Inside caliper vs telescoping gauges

    Hi,

    It seems that a good quality inside caliper should be capable of making the same measurements to the same type of accuracy as a set of good telescoping gauges. So - why would I buy a set of telescoping gauges instead of a good inside caliper that can handle all of the hole sizes the set would?

    Thanks!

  2. #2
    Join Date
    Aug 2015
    Country
    UNITED STATES
    State/Province
    Illinois
    Posts
    1,256
    Post Thanks / Like
    Likes (Given)
    895
    Likes (Received)
    526

    Default

    I have used both. With an inside mike you are feeling for the loosest position (diameter) in one direction and the tightest in the other (longitudinal). It takes practice to get the "feel" for getting the reading. With telescoping gauges the user just sweeps the gauge through the bore. The gauge picks up the diameter without the need for "feel". Telescoping gauges are a lot more convenient than inside mikes.

    That is probably not a clear expkanation. If you use the mike and then use telescoping gauge you will notice the difference.

  3. #3
    Join Date
    Sep 2009
    Location
    Apex, NC
    Posts
    1,405
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    701

    Default

    Calipers in general for linear measurements are only good for +/-.001 (if you're careful), when measuring an ID it becomes even less accurate because of variability of placement of the caliper. And you can't really place a caliper "in" the bore to take a measurement, just at the top of a bore. The width of the caliper blade has a large error as the holes get smaller. You can get about the accuracy of the caliper on larger holes (with care), with a telescoping gage and micrometers (not caliper), and care, you can get within approx +/- .0003 . I use them even with the calipers (versus micrometers) for any hole that requires better than +/- .005 or so, and use mics and the gages for less than .003 required.

  4. Likes kstarr215, EmilySue liked this post
  5. #4
    Join Date
    Jan 2002
    Location
    West Coast, USA
    Posts
    7,291
    Post Thanks / Like
    Likes (Given)
    435
    Likes (Received)
    4760

    Default

    Are we talking inside jaws of a digital caliper or an old school inside caliper?

    The former won't reach very far into a bore, are fragile, and don't have a good sense of feel. They are quick.

    The latter typically don't have well finished ends and are harder to "sweep" than a telescoping gage. The t-gage handle also helps with reach and perpendicularity. In addition, a telescoping gage locks for subsequent micrometer measurement, while the caliper needs to be sort of swept again against the mic anvils.

    That said, either type of calipers might get you within a couple thousandths.

  6. #5
    Join Date
    May 2010
    Country
    DENMARK
    Posts
    2,352
    Post Thanks / Like
    Likes (Given)
    3875
    Likes (Received)
    13341

    Default

    Quote Originally Posted by pugglewuggle View Post
    Hi,

    It seems that a good quality inside caliper should be capable of making the same measurements to the same type of accuracy as a set of good telescoping gauges. So - why would I buy a set of telescoping gauges instead of a good inside caliper that can handle all of the hole sizes the set would?

    Thanks!
    I think we all know what telescoping gauges are but not so sure about inside calipers. The picture is what I call an inside caliper.

    Which is better/more accurate? It all depends on use. To use telescoping gauges you also need a micrometer, in fact 6 if you want to cover the range up to 6"/150mm. Takes longer time too to measure with telescoping gauges.

    Personally, when I use a caliper (inside or standard) to measure internally, the first thing I do is to calibrate it against a ring with a known ID. Closing it and zeroing it just isn't good enough. I zero on the known hole diameter and add that onto the measurement result I get from the hole measurement. I'd feel confident of getting a result within 0.02mm/0.001". Maybe even less.

    As to telescoping gauges then it'll very much depend on who's using them and their experience with them.

    Now if what I've shown isn't what you mean by "inside caliper" then you'd better tell us what you do mean.

    ic.jpg
    Last edited by Gordon B. Clarke; 12-09-2018 at 04:49 AM.

  7. #6
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    23,871
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    7505

    Default

    Quote Originally Posted by pugglewuggle View Post
    Hi,

    It seems that a good quality inside caliper should be capable of making the same measurements to the same type of accuracy as a set of good telescoping gauges. So - why would I buy a set of telescoping gauges instead of a good inside caliper that can handle all of the hole sizes the set would?

    Thanks!
    First reason: "reach". Second reason: "minimum size". Third reason: "accuracy". Fourth reason: Odd shape of a bore and/or its SUB features to be measured.

    One has to have "all of".. gage pins, telescoping gages, inside mics, inside calipers, bore gages, and now and then even spring calipers to get around obstructions or Indicals or similar goods for internal grooves.

    Each have advantages and disadvantages.

    Like it or not, if you can only have ONE, it would be the ancient spring caliper.. and good OUTSIDE mics with reliable setting standards to transfer to/from. PITA, but the most universally usable.

    Tedious - DAMHIKT! It is actually all I DID have for a short while.

    But VERY short, that while was to be .... before I started adding.. "all of the above".

    Inside thread mics still "to do", but not much else has been missed-out.

  8. #7
    Join Date
    Oct 2018
    Country
    UNITED STATES
    State/Province
    Michigan
    Posts
    8
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Default

    I mean an old school inside spring caliper that looks like dividers. Starrett 274-6, for example.

  9. #8
    Join Date
    Dec 2008
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    9,693
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    2544

    Default

    Quote Originally Posted by pugglewuggle View Post
    Hi,

    It seems that a good quality inside caliper should be capable of making the same measurements to the same type of accuracy as a set of good telescoping gauges. So - why would I buy a set of telescoping gauges instead of a good inside caliper that can handle all of the hole sizes the set would?

    Thanks!
    .
    usually use neither. a bore indicator gage can reach in much farther and easily detect bore taper and out of round (if bore is vertical)
    .
    usually set to a ring gage, or to gage blocks

  10. #9
    Join Date
    Jan 2003
    Location
    Columbia Missouri
    Posts
    789
    Post Thanks / Like
    Likes (Given)
    35
    Likes (Received)
    117

    Default

    The design of the spring calipers goes back to when a shaft and bore were made to fit each other- not made to any measured standard. If you have enough time to make repeated adjustments and measurements, and develop a good "feel" for them I suspect you could get by with them in a home shop. But getting by is all you will be doing, and wasting time doing it.

    Measuring tools is not the place to try and save money. They will cost you in time and material, lead to frustration, and suck the joy out of you.
    Last edited by J_R_Thiele; 12-15-2018 at 09:33 PM. Reason: corrected link

  11. #10
    Join Date
    Mar 2012
    Location
    Geilenkirchen, Germany
    Posts
    2,193
    Post Thanks / Like
    Likes (Given)
    1350
    Likes (Received)
    1117

    Default

    Rather than answer your question directly. I'll tell you how to measure anything. Never do it once. Always do it multiple times until your repeatability gives you confidence that your reading is correct. That is the ONLY correct procedure. Now, whatever tool provides you with that level of confidence is the right one. The rest is personal preference. Remember, these tools were made to satisfy a requirement. Just because you have not found the need for the tool does not mean the requirement doesn't exist. It just means you have not been in the trade long enough.

  12. Likes tdmidget liked this post
  13. #11
    Join Date
    May 2010
    Country
    DENMARK
    Posts
    2,352
    Post Thanks / Like
    Likes (Given)
    3875
    Likes (Received)
    13341

    Default

    Quote Originally Posted by steve-l View Post
    Rather than answer your question directly. I'll tell you how to measure anything. Never do it once. Always do it multiple times until your repeatability gives you confidence that your reading is correct. That is the ONLY correct procedure. Now, whatever tool provides you with that level of confidence is the right one. The rest is personal preference. Remember, these tools were made to satisfy a requirement. Just because you have not found the need for the tool does not mean the requirement doesn't exist. It just means you have not been in the trade long enough.
    It's not that I disagree with you so much as I'd probably express it differently.

    Measuring multiple times and getting the same result only means you are consistent. It doesn't mean you are getting a correct measurement result.

    Probably the same as calibrating anything and using something you know the exact measurement of. As long as there is user influence involved you'll go for the "desired" measurement.

    Rarely done but much better to measure an "unknown" dimension, write down what you get and then measure with something you know will give you an accurate result. First then will you know how good you are and how good what you intend using is.

    When I claim to measure this and that and state the accuracy I get it's never done based on using just one measuring device. When I read in PM now and then how accurately some say they measure I often wonder if it is accuracy or repeatability they've achieved. Of course without repeatability no accuracy.

    It might just be said I'm calibrating myself too

  14. Likes EmilySue liked this post
  15. #12
    Join Date
    Jul 2013
    Location
    Indiana
    Posts
    3,086
    Post Thanks / Like
    Likes (Given)
    4520
    Likes (Received)
    1570

    Default

    Quote Originally Posted by pugglewuggle View Post
    Hi,

    It seems that a good quality inside caliper should be capable of making the same measurements to the same type of accuracy as a set of good telescoping gauges. So - why would I buy a set of telescoping gauges instead of a good inside caliper that can handle all of the hole sizes the set would?

    Thanks!
    I don't think calipers are as accurate as telescoping gauges measured with a good set of mics. As with anything else using them takes practice. I took some master set rings and measured them over and over to have a comparison between what I measured them at to the actual size of the ring. It's how much you tighten the lock screw that causes the most variation in measurements. I think you should buy both, I did and haven't regretted it.

    Brent

  16. Likes EmilySue liked this post
  17. #13
    Join Date
    Dec 2008
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    9,693
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    2544

    Default

    Quote Originally Posted by yardbird View Post
    I don't think calipers are as accurate as telescoping gauges measured with a good set of mics. As with anything else using them takes practice. I took some master set rings and measured them over and over to have a comparison between what I measured them at to the actual size of the ring. It's how much you tighten the lock screw that causes the most variation in measurements. I think you should buy both, I did and haven't regretted it.

    Brent
    .
    40 years machining and maybe used telescoping gages for maybe 2 hours compared to using indicating bore gages maybe 2000 hours
    .
    just saying indicating bore gages will easy see taper and out of round literally in seconds. never seen a professional even bother with telescoping gages.
    .
    and obviously 99.999% of professional wouldnt bother with the caliper either unless tolerance was over .002" , sure you occasionally find the guy who says he can measure .001" with his $20. calipers....... obviously he aint making many expensive parts. if you got $20,000 part with a oversize bore it can be a very expensive rework job

  18. Likes EmilySue liked this post
  19. #14
    Join Date
    Jan 2009
    Country
    UNITED STATES
    State/Province
    Missouri
    Posts
    83
    Post Thanks / Like
    Likes (Given)
    122
    Likes (Received)
    22

    Default

    Quote Originally Posted by pugglewuggle View Post
    Hi,

    It seems that a good quality inside caliper should be capable of making the same measurements to the same type of accuracy as a set of good telescoping gauges. So - why would I buy a set of telescoping gauges instead of a good inside caliper that can handle all of the hole sizes the set would?

    Thanks!
    Simple mechanics.
    An inside mic, or telescope gauge detect contact in a single 'line' or axis of the item. That includes whatever tolerance or imperfections are contained in the tool. A good hand should/ could get near identical readings blindfolded.

    A caliper has contact points far from the frame they slide on, which requires clearance to move. The only plus to calipers is quickness, not accuracy, and can be compact compared to same size micrometer. Why digital calipers display .0005 is beyond me, other than interpreting something different than what they display seconds before. That is neither true resolution or accuracy. Regarding bores or OD's, those are always subject to interpreting squareness to axis being checked. Try that blindfolded?

  20. #15
    Join Date
    Dec 2014
    Country
    CANADA
    State/Province
    British Columbia
    Posts
    1,206
    Post Thanks / Like
    Likes (Given)
    347
    Likes (Received)
    563

    Default

    Since this got bumped. Ignoring bore depth and range how does something like a Starrett 700A compared to telescopic gages and tubular inside mics for accuracy? I don’t trust mine to less than a thou or two.


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •