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  • How do you like to measure holes?

    How do you like to measure bores? There are telescoping and small hole gages, which are cheap if you already have the mike, and there are such things as caliper style bore mikes. What do you find to be the best system for an HSM to use>

    I currently lack any and all bore measurement methods.

  • #2
    Measuring holes

    If you do much work in the shop you will need at leat 1" & 2" mics, and a set of telescope gages will do a good job fo precision measurements. I use my digital or dial calipers for measurements that don't need better than plus or minus 0.005 but when it gets closer i tend towards my telescope gages. I have ID mics and rarely use them because the telecsope gages are easier to use.

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    • #3
      For rough work, I use my dial calipers. For larger diameters that are deeper and may have a taper or egg shape, I measure with a mic and a set of telescoping gauges. Takes a bit of practice to get accurate readings with the telescoping gauges.

      Then there are the bore gauges. Too expensive for me to afford! And, of course, plug gauges for small sizes. Those can sometimes be had for a very reasonable amount at auction.

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      • #4
        If you use a ring gauge of a known demension the ID jaws of your calipers can be plenty accurate for most things.

        An example of cheap accurate ring guages are new un-used ball bearing inner races.

        Lets say you need to bore a 25mm hole,if you have a 25mm bore ball bearing handy just feel in the calipers to the bearing bore and set the dial/display to zero.Bore the hole until the calipers read zero and your there.

        This method will get you as close if not closer than a set of telescope gauges and a mic.

        For work I have a set of hole micometers for bores up to 3",then a set of inside mics for 3" up to 30"

        The mics are Polish made and run $80-90 each and the inside mics I picked up used for $75.

        An assorment of even Chinese ball bearings can be had for $30 or less and even they are held to +.00015 -.0000"
        I just need one more tool,just one!

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        • #5
          if you get telescoping gages, get starrett. don't waste your money on cheap ones. You'll hate them.

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          • #6
            I bought some Brown & Sharpe telescoping gauges.
            I thought I was buying good ones.
            Nope. Turned out to be junk.
            Grind the ends of the binding rods, as they
            looked like they were nipped off with a pair
            of pliers!?! Inexcusable for B&S.
            I inherited a set of Lufkins. Very nice.
            Also get some split-balls for measuring
            the small stuff.

            --Doozer
            DZER

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            • #7
              It all depends on the tolerance, speed, number of parts, and number of different size bores. One part, one hole, and brick tolerance (length of a brick close enough) go ahead and use calipers or telescopic gauges. One hole in 40 parts with + or - .00025, set the price high enough to recoup partial cost of a Fowler bore mike.

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              • #8
                Originally posted by rbregn
                if you get telescoping gages, get starrett. don't waste your money on cheap ones. You'll hate them.
                Mitutoyo are nice as well.

                Comment


                • #9
                  The innards of the innards

                  For "small stuff" (less than say 1/2" or so), use the "expanding ball" type. They are cheap, very accurate and very reliable. For the "medium-larger" stuff, try a set of "old-fashioned" spring calipers. They too are very cheap, very reliable and very accurate.

                  I can hold 0.01mm (0.0004") easily and down to 0.005mm (0.0002") with a bit more effort and with a bit of practice and a lot of effort and concentration, I can hold 0.0025mm (0.0001").

                  For larger stuff, just make a "length guage" - a rod with tapered ends and a small hemisphere on the end. It costs nothing as it can be made from scrap. All I need is an outside micrometer. I have full range of 0-150mm (0 - 6") outside micrometers, and until a week or so ago, I never had a digital inside micrometer (see later).

                  Here is a pic of the "ball type", (top left, which I like), the "telescopic" type (top right, which I don't like under 1/2" but need to be careful with, so generally OK) and the internal spring caliper which I really do like (bottom left).



                  Here is the math for the "length guage" and the internal spring calipers:
                  http://i200.photobucket.com/albums/a...tickgauge1.jpg

                  If you have the mating part (shaft) for the bore you want to do, you can use a digital caliper (no need to turn it on as I am only using the blades - not the screen - as a gauge) to accurate "span" (but NOT measure) the shaft so that the gap between the blades matches the diameter of the shaft. Now by using the "expanding ball" (WITHOUT the "stick" math/chart) you can very accurately measure the bore.

                  Next up, you can use the telescopic guages or the "stick" guage (WITH the "stick" math/chart) you can very accurately measure the bore.

                  For diameters over 6" up to 12" I use my digital height guage on any convenient flat surface to set my "caliper/s".

                  http://i200.photobucket.com/albums/a...Dig_Ht_Gg1.jpg

                  http://i200.photobucket.com/albums/a...Dig_Ht_Gg2.jpg

                  This is the digital 10 -30mm (~0.400" - 1.200") caliper I referred to previously. It is NOT cheap (AU$340 x 0.7 ~ AU$240).
                  https://www.machineryhouse.com.au/Pr...stockCode=Q244

                  It is accurate to 0.01mm/0.0005" but must be set for each reading/diameter. I find it easier to set with an outside micrometer than with slip-guages. I use the slip guages to check the micrometer.

                  Here are the pics:






                  Here are the instructions etc.
                  http://measumax.com/InstruSheets/33-239_33-246.pdf

                  They are pretty convoluted at best - a lot of "Chingle-ish" - but as usual when you need them they are hard to follow and when you master it, it all makes sense and you (I) don't need the instructions etc.

                  It is as good as it says - 0.01mm/0.0005" - every time. Setting is a bit of a PITA and frankly, I can do better quicker with mt spring calipers and a micrometer. I bought it to "see what it was like" and it did what I wanted and despite the price, I am happy with it.

                  This applies to most "internal" mearurements - which includes widths of slots, spaces between parallel faces etc.

                  So, all-in-all you can do very with little cost and a bit of ingenuity and lateral thinking.
                  Last edited by oldtiffie; 01-04-2009, 02:50 AM.

                  Comment


                  • #10
                    I bought a set if expanding piston calipers and have been fine tuning the ends and de-burring them. They are junk as they sit on the shelf but are rhinestones in the rough. The mechanisms are adequate and when the ends are polished they're acceptable.

                    I also use dial calipers for inside dimensions and often do so as Tiffie suggests, using them as a dimension capturing tool that is later measured with a good micrometer.

                    Comment


                    • #11
                      Wow, checking holes is a subject unto itself.

                      "How do I like to measure holes?" Not very much thank you. If I must, then how about a scale, or just a pair of calipers?

                      In truth, as stated, it all depends on your needs, your access to tools, and the physical realities of the hole in question. Not only accuracy required (hand held scale, or calibrated air gage in temp controlled room?), but absolute size as well. Measuring a 0.030 hole is a completely different thing from measuring a 1" hole, which is still different than measuring a 10" hole. How deep is the hole, and what is it's aspect ratio? Chamfered? Tapered? Finish? Accessibility? And so on...

                      If it's a deep or through hole, it's hard to beat a "quick check" cones or the Starrett long taper scales. Accurate and couldn't be easier, if it is in range and accessibility/depth is not a problem.

                      Very small holes, almost exclusively the domain of pins.

                      Smallish holes, then Quick Check cones or "small hole gages" or perhaps precision balls?

                      More moderately sized holes, Split Ball bore gages (Mahr), finger bore gages (Federal or Standard), "T" gages, inside mics, some tube/bar mics, Tri-Mics. Perhaps comparator gages like Tiffie shows (but dial, not digital). Pin/Plug gages can still be used if you have them. Calipers of course, both sliding and classic spring or even firm joint. Perhaps even a scale is "good enough"? Might even use an adjustable parallel if the chord of the flats is not an issue.

                      Large holes, there are some common, and some very different options. Calipers in various flavors of course. Or tube mics (or anything similar) in direct reading if you have the length, or chordal calculation if you don't.
                      Russ
                      Master Floor Sweeper

                      Comment


                      • #12
                        How do I measure holes??? Not very easily when you want it measured accurately....

                        I generally use a set of mitutoyo telescopic gauges and can try to get to 0.01mm but lets be realistic here, when someone comes along and says they can measure a bore to microns in a general workshop they are talking out their arse...The smallest temperature change will totally stuff up any measurement they have...Take yesterday for example...I was machining down some steel using carbide and when I finished it was over 100C..I measured it and then measured it when it was room temperature...The difference was in the order of 0.1mm..

                        Sorry but it irks me when people make outlandish claims about what they can measure...(or when their radial arm saw come surface grinder can hold tolerances of 0.0000001mm)
                        Precision takes time.

                        Comment


                        • #13
                          Originally posted by Ringer
                          Sorry but it irks me when people make outlandish claims about what they can measure...(or when their radial arm saw come surface grinder can hold tolerances of 0.0000001mm)
                          I made no such claim of tolerances regarding my grinder - I said it suited me for the purpose. If that purpose was a tolerance of 0.125 that is a figger I'll take to my grave

                          It does much better than that, though, and produces a nice flat finish I can't achieve with any of my other tools.

                          Comment


                          • #14
                            heh heh don't worry I was only taking the piss with the radial arm saw statement...
                            Precision takes time.

                            Comment


                            • #15
                              Radius/hole measurement

                              Originally posted by BadDog
                              Wow, checking holes is a subject unto itself.

                              "How do I like to measure holes?" Not very much thank you. If I must, then how about a scale, or just a pair of calipers?

                              In truth, as stated, it all depends on your needs, your access to tools, and the physical realities of the hole in question. Not only accuracy required (hand held scale, or calibrated air gage in temp controlled room?), but absolute size as well. Measuring a 0.030 hole is a completely different thing from measuring a 1" hole, which is still different than measuring a 10" hole. How deep is the hole, and what is it's aspect ratio? Chamfered? Tapered? Finish? Accessibility? And so on...

                              If it's a deep or through hole, it's hard to beat a "quick check" cones or the Starrett long taper scales. Accurate and couldn't be easier, if it is in range and accessibility/depth is not a problem.

                              Very small holes, almost exclusively the domain of pins.

                              Smallish holes, then Quick Check cones or "small hole gages" or perhaps precision balls?

                              More moderately sized holes, Split Ball bore gages (Mahr), finger bore gages (Federal or Standard), "T" gages, inside mics, some tube/bar mics, Tri-Mics. Perhaps comparator gages like Tiffie shows (but dial, not digital). Pin/Plug gages can still be used if you have them. Calipers of course, both sliding and classic spring or even firm joint. Perhaps even a scale is "good enough"? Might even use an adjustable parallel if the chord of the flats is not an issue.

                              Large holes, there are some common, and some very different options. Calipers in various flavors of course. Or tube mics (or anything similar) in direct reading if you have the length, or chordal calculation if you don't.
                              Thanks BD - I agree with everything you say - its "horses for courses" - depends on what tolls etc. you have to measure what-ever hole to what-ever accuracy for what-ever purpose.

                              Might even use an adjustable parallel if the chord of the flats is not an issue.
                              I presume that this is what you mean:
                              http://www.cdcotools.com/item.php?itemid=14

                              I have a set of those and have contemplated the diagonals, corner radius as well as the diagonals etc. with regard to using them for measuring the diameters of holes.

                              There is a fair bit of math to it - but that should not be insurmountable - its on my "get around tuit" list.

                              I intend to get another set and to grind a convex radius on each measuring face of each pair with the radius being jut a bit less than half the distance across the measuring faces. I had them when I was an Apprentice and later as they were standard tool in the shops and Tool-room. Just slide them in, get them snug, measure with an outside micrometer - job done - almost. They could only detect "taper" by the/any "swing" that remained at one end. We had "rules of thumb" for evaluating that too - not too unlike the "stick" method I posted earlier.

                              I have to get a radius profile wheel-dresser for my grinders - but they are expensive.

                              This should do the job:
                              http://www.cdcotools.com/item.php?itemid=32

                              This one is a bit small:
                              http://www.cdcotools.com/item.php?itemid=284

                              This one is WAY too expensive. ~AUD1,300 x 0.70 ~ USD900!!!:
                              https://www.machineryhouse.com.au/Pr...stockCode=P360

                              Precision is everything in this job - or perhaps its just a good excuse to buy a new tool without having a good reason!!

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