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Surface Gauge - What Makes One Good

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  • Surface Gauge - What Makes One Good

    Whelp, i need a better surface gauge. This is my current one:
    https://www.grizzly.com/products/Gri...ges-4-7-/H2712

    Its... functional, i guess? It holds my indicator, sits on my surface plate. The fine adjustment is fine in name only, its pretty jerky and likes jumping a few thousandths. Makes setting a test indicator a bit of an exercise in frustration, i shudder to think of how a tenths indicator would work with it. The base is on the small side too, not the most stable thing and im pretty sure its not completely flat either. To replace it, ive been thinking about making one, but i dont have much to work off on what makes a surface gauge good. Smooth fine-adjustment is a must id imagine, as is a stable base with a decent bit of mass to reduce any movement. Most of the gauges ive seen use the same spring-loaded lever arrangement to manage the fine adjustment, frankly though that seems a little... inelegant i guess? Youve got the potential for slop in the pivot of the lever, slop in the slot that part of the lever runs in depending on the design. I think my current gauge has kinda soured me on the design. I stumbled across this design earlier:
    https://www.hschmidt.com/wp-content/...-List-2015.jpg

    Gotta say, that strikes me as being a lot more stable, as well as being easier to make. No pivots or separate springs to deal with, and the flexure being a wide piece of spring steel seems to me that it would resist twisting or side to side movement during fine adjustments, plus the adjustment itself should be dependent entirely on the fit of the screw since thats the only actual contact point. A fine thread screw set back a few inches from the flex point should give a pretty good adjustment, yes?

    Before i talk myself too far into this design, i was hoping to poll for opinions on what makes a good surface gauge actually good. Like i said, my hands-on is pretty limited, so im hoping that someone whos been around more can chime in and school me

  • #2
    Well, the requirements are pretty universal -- stability, repeatability, ease of adjustment, etc. My best surface gauge is an old Lufkin model 520 similar to this one: https://www.ebay.com/itm/LUFKIN-No-5...wAAOSw4yJdTC5X

    Incredibly stable and smooth, works OK with a tenths indicator (still have to be a bit careful though). The base of it is so flat that it starts to wring to the surface plate. When I got it, I didn't have to do anything other than disassemble and clean with a light scrubbing in kerosene.

    Hermann Schmidt makes nice stuff but I'm sure you've noticed the price.... it's definitely top of the line... much like expensive liquor and pretty girls in church. If you have to ask, you can't afford it.
    Last edited by nickel-city-fab; 04-03-2020, 11:54 AM.
    25 miles north of Buffalo NY, USA

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    • #3
      Those Hermann Schmidt surface gages work as good as they look. Very solid and the adjustments are smooth as silk. Worked with a lot of guys who had them but never could bring myself to part with the money when my Starrett did the job. If I ever had to pick up another the HS would be my choice, budget be damned.
      George
      Traverse City, MI

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      • #4
        Its not clear to me how the adjustment device works on the HS, but I'd prefer a used Starrett or Lufkin over either of those. The HS doesn't have the ball on the post or the retractable stops. I've used those enough that missing those functions rules it out. The HF well its HF, not the place to go to for precision devices.....especially given about every machinist in NA for the last 100 years had one in their box so they abound used for small dollars.
        Last edited by Mcgyver; 04-03-2020, 11:54 AM.
        in Toronto Ontario - where are you?

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        • #5
          The nice thing about making your own is that you can get the fancy one with just your own time invested. Cost of materials is always going to be pretty minor.

          If you're going to look at a version with a sturdy main staff and larger sort of block that holds the more slender arm for the gauge itself to fit you might also look at the squareness comparator that Stefan G made. It could easily double as a surface gauge. All it would need would be a second main block that is patterned after the HSCO style

          A bit of a hint if you make the HSCO style you found. One end of the lower or upper base should be just very slightly angled so that when assembled it wedges the gap closed at the knob end. The idea is that you want the flexure spring to always be flexed at least a little even when it's in the neutral (parallel) position shown in the pictures. So the end of either the base or upper should be angled very slightly to ensure that this is the case.

          I've seen a couple of the squareness comparator projects on YT where the maker used pressed in bearing balls as the feet. The balls were pressed in then rough ground and finally you could lap or surface grind them for three points of hard steel in contact with the plate. This produces an inherently non rocking fit. It also avoids the need to use a heat treatable steel for the base and find a way to heat treat something that big.
          Chilliwack BC, Canada

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          • #6

            Originally posted by George Bulliss View Post
            Those Hermann Schmidt surface gages work as good as they look. Very solid and the adjustments are smooth as silk. Worked with a lot of guys who had them but never could bring myself to part with the money when my Starrett did the job. If I ever had to pick up another the HS would be my choice, budget be damned.
            Funny thing, i didnt actually check the maker or the price of that surface gauge i used as an example... Sure are proud of those things, aint they? Then again, seems like most places are pretty proud of their metrology gear. The more i look at it though, the more i like the design, least for one that id be making


            Originally posted by Mcgyver View Post
            Its not clear to me how the adjustment device works on the HS, but I'd prefer a used Starrett or Lufkin over either of those. The HS doesn't have the ball on the post or the retractable stops. I've used those enough that missing those functions rules it out. The HF well its HF, not the place to go to for precision devices.....especially given about every machinist in NA for the last 100 years had one in their box so they abound used for small dollars.
            The base is 2 seperate pieces, connected by the bit of spring steel bolted on. The adjustment screw forces the 2 base pieces apart and the spring steel acts as a pivot, changing the angle of the post and pushing the indicator up or down. Pretty cool low-tech way of giving the adjustment i feel, theres no pivots to interfere with the motion, just the flex of the steel. Ill confess that ive never used the ball on the end of the rod or the retractable stops, in fact i didnt even know that they had a purpose. What are those for?

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            • #7
              Oh OK, You want to make one? Cool! Here's something similar to look at, notice they give you the dimensions...

              https://www.judgetool.com/products/t...arator-square/

              The retractable stops are so you can make it follow a straight edge, such as the side of your surface plate, or some part of a big machine.
              25 miles north of Buffalo NY, USA

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              • #8
                Originally posted by epicfail48 View Post
                . Ill confess that ive never used the ball on the end of the rod or the retractable stops, in fact i didnt even know that they had a purpose. What are those for?
                checking squareness....and the parallelism between two vertical surfaces. They're repeats...but a picture is worth a thousand words.










                Last edited by Mcgyver; 04-03-2020, 12:30 PM.
                in Toronto Ontario - where are you?

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                • #9

                  Originally posted by nickel-city-fab View Post
                  Oh OK, You want to make one? Cool! Here's something similar to look at, notice they give you the dimensions...

                  https://www.judgetool.com/products/t...arator-square/
                  I think that indicator stand costs more than my entire shop...

                  Making one is just to save a few bucks without sacrificing quality. Ill be keeping an eye out, to see if i can score a good deal on something good from the usual suspects, but if it comes out to be cheaper to make one, well, gotta justify having the tools somehow.

                  Originally posted by Mcgyver View Post
                  checking squareness....and the parallelism between two vertical surfaces. for both of these....they're repeats...but a picture is worth a thousand words.
                  Much obliged! Id always seen squareness measurement done with a radiused front on the gauge, i didnt know that the ball on the bar could be used to the same effect. As for the stops, taking a measurement like that never even occurred to me, though i understand now how its useful. Just isnt a measurement that ive yet to go up against. Still, feature to add to the list, if i do end up making a knockoff HS gauge i can always add a few reamed holes to the base portion to allow for the insertion of a few gauge pins

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                  • #10
                    Originally posted by epicfail48 View Post

                    I think that indicator stand costs more than my entire shop...

                    Making one is just to save a few bucks without sacrificing quality. Ill be keeping an eye out, to see if i can score a good deal on something good from the usual suspects, but if it comes out to be cheaper to make one, well, gotta justify having the tools somehow.
                    Pretty much in the same boat myself, I've been spending the last 7 yrs slowly accumulating stuff. Mostly used, and some home made. I'll be watching this because its something I'd like to do someday myself!
                    25 miles north of Buffalo NY, USA

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                    • #11
                      making one is I think a common apprentice type project and there are drawings on the internet you can find. My view is it would be tough to justify on the basis of cost savings, but certainly worthy for the learning and pride in making a using a nice tool. I guess it depends on where you are at in the hobby, I sure learned a lot making tools in the earlier days but now buying them (used for small dollars) feels like what I'm really buying is time.

                      Much obliged! Id always seen squareness measurement done with a radiused front on the gauge, i didn't know that the ball on the bar could be used to the same effect.
                      you are welcome, afaik, that's the sole single purpose of the balls existence. Those pins have to be a very careful fit, the magical balance just between sliding and interference. Any wobble would mess up their usefulness.
                      Last edited by Mcgyver; 04-03-2020, 01:02 PM.
                      in Toronto Ontario - where are you?

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                      • #12
                        MacGyver thanx for that , don't remember seeing it before, and I did not get to work with many other machinists.
                        That is not what I use mine for. I have around 5 guages. I used one A lot.
                        The ball on mine was up top, I use it for parking the curved tip in the groove, when putting tool away or bringing it over to use. And I keep a short cork on the other end. Very easy to spear yourself with a proper scribe, notice how the good ones have a gracefull curve and long taper to the points easier to see when picking up a line.
                        A few uses for the pins, often laying out you want lines parallel to other lines, if piece is laid flat and held in place, you lay out a line using the pins, adjust to next measurement, lay out it and other lines, all parallel.
                        But what I use it for the most. I have a scribed edge, I set the piece in the milling vice. Now with pins retracted I use the point on the scribe to get my layout line the same both side of vice.. tap tap. If it's under say 1.25, I often use dividers against the vice jaw, same deal.
                        Now say you are making a piece that won't fit in the vise, it's on the table. Now put spacers under the work and slightly snug your hold down clamps. Now you slide the gauge with the pins against edge of mill table, and scribe positioned near your line, fine adjust to get tip near the line, use the tap tap tap, then clamp, check and you are done.
                        I am not sure how others do it.. sometimes I use a tooth on end mill , but its hard to get it good, I use it to get in the ballpark.

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                        • #13
                          I think cheap gauges use a coarser thread adjuster screw, not a snug fit to nut.. cheating out.
                          Length of the arm the adjuster is on makes a difference too. ..

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                          • #14
                            Well, the ball on top can be easily enough shifted to the bottom just by pushing the staff through the knuckle of the base.

                            We had a long discussion on squareness comparators in another thread recently and Mcgyver showed that picture there. It was an eye opener for me too. But while it would work just fine it needs a bit more care to set up so that the ball for the DTI is above and will be within the circumference of the ball of the staff. It's a lot less fussy to set up a workable alignment on a dedicated comparator where the toe is a far larger radius. Or to use a large loose bearing ball in the V of the surface gauge. However it's nice and opens up options knowing there is one right at hand.

                            On the HSCO gauge there's no ball because the fixed vertical shaft can't be set down low to be used the same way. Which is why I think that a rounded toe on the other end and a second holder to hold a DTI in the same way as Stefan did in his comparator could give us a project that does it all very neatly.

                            I forgot the link to Stefan's video. And while looking up that one I saw that he did a related video on indicator stands that should add some interesting ideas to any sort of surface gauge project. Here's the two links...

                            Squareness comparator

                            Indicator stand with focus on DTI holder
                            Chilliwack BC, Canada

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                            • #15
                              Originally posted by BCRider View Post
                              We had a long discussion on squareness comparators in another thread recently and Mcgyver showed that picture there. It was an eye opener for me too. But while it would work just fine it needs a bit more care to set up so that the ball for the DTI is above and will be within the circumference of the ball of the staff. It's a lot less fussy to set up a workable alignment on a dedicated comparator where the toe is a far larger radius.
                              Have you tried it? Its very easy, fuss free. I'd say what constitutes a major bit of fuss is having to buy or make something else to do this job.
                              in Toronto Ontario - where are you?

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