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  • #31
    Originally posted by oldtiffie
    I realise that many like to work to that order of accuracy most if not all of the time - but is it really needed or justified in terms of what the part has to do?
    That "justification" does not really apply in many cases*.....

    Most folks here need to do very close work maybe 5 or 10 times per year..... the rest of the time "welder's tolerances" are more like what is heeded.

    but there is such a thing as "practice"..... you know, "that which makes perfect".

    if you reserve your efforts at very precise work for strictly and only those cases where you absolutely need it, guess what? You may not do so well, as you are out of practice.... or maybe never DID any "practice".

    So many, myself included, do things to precise tolerances when "not justified", so that when we NEED TO, we have confidence that we CAN.

    You, with 40+ years in the trade, can afford to take it easy when you can, it's old hat to you.

    Originally posted by oldtiffie
    I can't get too excited about "indicators".

    Loss/replacement of them is regarded as a consumable item and is all part of running the shop.
    Not everyone can afford to regard a $300 or even $30 measuring tool as "consumable". It can be a bit different when running a big shop.... stuff is gonna happen, and tools will need replaced. But there you have "cash flow" and a 'tooling budget".


    *
    In my case, I DO use 0.0001" indicators, not so much in machining, but in scraping..... For instance when scraping the top guiding surface and the bottom guiding surface of a mill crosslide.... it wants to be precisely parallel, so a flat and a good indicator are "indicated" for testing. Same for ensuring that "parallels" are scraped to BE "parallel".....
    CNC machines only go through the motions

    Comment


    • #32
      I'll give that last word DTI a good home..

      Comment


      • #33
        Originally posted by macona
        Interapid, Compac, B & S, anything but a last word.
        +1 (or whatever we're up to) Fowler, SPI, Phase II, ... are all the same rebranded Chinese DTI.

        The good news is that, like Punkinhead says, the Swiss DTI's are dirt cheap on Ebay. Highly recommend spending a couple of extra $$ and buy new in box. I've had mixed luck buying used metrology gear on Ebay.

        I was the lucky buyer of the infamous "excellent condition" B&S DTI on PracticalMachist, that showed up with a bent dial.

        Edit: also concur with Jerry's assertion that DTI's are not a wear item - LOL! If you take care of a fine DTI, it will last a lifetime.
        Last edited by lazlo; 11-16-2011, 03:59 PM.
        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

        Comment


        • #34
          Limits and Fits

          Thanks JT.

          Good sensible reasoned reply - as usual (mostly).

          I sometimes give myselt a "practice run-through" just to keep my skill-set up either because I feel its time to or the the job in hand warrants it.

          I break jobs and tools and methods/sequencing down to their basic or fundamental needs for the job in hand and if necesary work my way up from there.

          It is surprising how often the "basics" will do and how often some of the "better" tools (including machines and processes) are rarely needed.

          Needless to say a lot of my "stuff" (indicators etc.) are rarely needed or used - but they are there on or for the odd occassions when they are needed.

          Screw threading is far too much worried about and given unrealistic tolerances. Here is a sample. Note the limits for OD and "over the wires"!!

          http://i200.photobucket.com/albums/a...ThreadPal1.jpg

          http://i200.photobucket.com/albums/a...ThreadPal2.jpg


          and pitch diameter limits - and clearances etc:
          http://i200.photobucket.com/albums/a...n_P72-73_1.jpg

          some should get aquainted with classes of finish and limits and fits:
          http://i200.photobucket.com/albums/a...and_Fits14.jpg

          http://i200.photobucket.com/albums/a..._and_Fits1.jpg

          http://i200.photobucket.com/albums/a..._and_Fits2.jpg

          None - or very few - require much better than a 0.001" resolution indicator (use carefully to interpolate) and a bog-standard 0>1" micrometer.

          I would be very disappointed if those who are srarting out and/or have limited budgets were to think that the standard cheap tools in these cases will not do the job.

          Comment


          • #35
            All squared (screwed??) up

            Originally posted by philbur
            The photos show that the scale value is 0.02mm/metre, it doesn't say what the precision of the square is?

            Phil

            PS: Also the calculation is a bit iffie!
            Originally Posted by oldtiffie
            A very good, honest and practical reply lbhsbz as to "how it really is all" too often.

            A framing square level is very accurate at 0.02mm/metre = 0.02mm/1,000mm = 1 : 0.000002mm is 0.0003146 degrees = 4.125 minutes of arc.

            It is also very accurate as regards the 90 degree sides.

            It beats machinists squares (all grades) hands down as regards checking verticality to the base (mill table?) reference that the framing square rests on. A great check for X:Y squareness too.

            http://i200.photobucket.com/albums/a...st_Square1.jpg

            http://i200.photobucket.com/albums/a...st_Square2.jpg
            I did side-track myself a bit there Phil, but that framing square comes up very well against my cylinder squares and my granite square on my granite surface plate as I had the same concerns as you did.

            http://i200.photobucket.com/albums/a...30SPandsq1.jpg

            http://i200.photobucket.com/albums/a...ansqsheet1.jpg

            http://i200.photobucket.com/albums/a...latesheet1.jpg

            Comment


            • #36
              In 35 years in the trade I have used many indicators, and always favored the Brown and Sharp Bestest indicators.

              I used the first one for over a decade, actually wore flat spots and had to replace the points. Then left it in the spindle of a mill (brain freeze, meant to engage the brake) and started it. I have to say it had a spectacular end (they don't make good bullets)!

              I have several indicators now, got a Federal .0001" indicator if that kind of resolution ever comes up. Several others- can't seem to pass them up at a flea market. The Bestest gets used most often, and I have a back up in case anything happens to it. Part of the preference is probably that I have used them so much I am very comfortable with them.

              Comment


              • #37
                I realize this is an old thread, but it contains a lot of good info. I'd just like to add:

                If you read Long Island Indicator's review of DTIs carefully, you'll see that they rate the Chinese test indicators very highly in their objective tests. They listed the Chinese models as more repeatable than Interapid, and faster acting. They panned them for accuracy and repairability, neither of which are important to me. I use DTI's as a comparative tool, not a quantitative one, so dimensional accuracy is irrelevent to me.

                I was also turned off by the ethnic jokes (take out food and chicken feet). The owners of LII are of Swiss descent and seem to prefer Swiss tools. That said, while their humor may be un PC, I think their analysis is probably correct.

                BY FAR, the biggest complaint I have with my $20 DT from LMS (and strangley not mentioned) is that its dovetails don't fit my Noga arms or ANY standard indicator studs. The Chinese DTs are wider. The studs my DTI came with were metric and also non-standard. In my shop, I need tools to work together so this has prooved the deciding factor against the Chinese DTIs (or at least mine). Before I bought a Fowler Xtest (which is made in China), I'd want to know about the dovetails.

                Currently, I'm using Fowler branded Giordtast (Swiss) DTIs (highly rated by LII and cheap on ebay). I also have a pair of Fowler Quadratest digital DTIs whose button push zeroing and graphical scale are handy features.

                Just for ergonomics, I like the slanted head of the Interapid. Had I to do it all over again, I think I would be happy with that one DTI alone.

                I use my DTI to straighten my mill vise, check runout on tools and round stock, and center the mill to holes in the workpiece. (For this I use a vertical faced DTI). I also use DTIs as inspection tools attached to my surface gage as a sort of make shift comparator.

                IMO, if you buy cheap tools or second hand tools as I do, you need to have a way to inspect them and determine their strengths and weakness. Most important tools for the beginning machinist are inspection tools (mics, dial and test indicators, and good squares- all of which are available on ebay cheap).

                adamc

                Comment


                • #38
                  Originally posted by adamc
                  If you read Long Island Indicator's review of DTIs carefully, you'll see that they rate the Chinese test indicators very highly in their objective tests.
                  Really? I'm reading something completely different:

                  http://longislandindicator.com/p37.html
                  "China If you're buying indicators made in China, you're scraping the bottom of the barrel. You can't get any worse. Some years ago we were hired to evaluate these indicators for MSC (Manhattan Tool Supply) who wanted to know if they were worth importing. Apparently they didn't listen to our advise. "


                  BY FAR, the biggest complaint I have with my $20 DT from LMS (and strangley not mentioned) is that its dovetails don't fit my Noga arms or ANY standard indicator studs.
                  That is mentioned:
                  "Dovetails didn't fit and brand new .0001" indicators wouldn't calibrate. It turned out that dovetails didn't accept anyone else's attachments because they were oversized. Pass on these and order some Take-Out instead (but skip the chicken feet).
                  "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                  Comment


                  • #39
                    100% The damn dovetails don't fit. It is very annoying. Too wide to fit my Noga. No problem with the genuine articles. Yes, this has nothing to do with measurement, repeatability or comparative measurement, but it is a frustrating fact that you can't do any of those things unless you can mount the thing. They could be the best indicator in the world, but if they don't adhere to the standard mounting dimensions then I wouldn't give a damn.

                    Comment


                    • #40
                      Odd that.

                      I have several of those indicators with the 3-position dove-tail mount - from Little Machine Shop and possibly CDCO tools (USA) as well as some
                      here in Australia. Every dove-tail fitted perfectly.

                      Comment


                      • #41
                        Originally posted by lazlo
                        Really? I'm reading something completely different:

                        http://longislandindicator.com/p37.html
                        Check out their colored chart below.

                        Adam

                        Comment


                        • #42
                          I had a Starrett dial that the crystal fell out of too. I think after sevdral years the plastic shrunk.

                          JL.............................

                          Comment


                          • #43
                            Originally posted by oldtiffie
                            Odd that.

                            I have several of those indicators with the 3-position dove-tail mount - from Little Machine Shop and possibly CDCO tools (USA) as well as some
                            here in Australia. Every dove-tail fitted perfectly.
                            The problem stated seems to be that :

                            They fit THEMSELVES...... but they fit nobody else's attachments....

                            So it's fine if you only need what attachments they came with, but if you have any other holders, arms, etc, you may be out of luck, and have to buy or make an entirely separate set to keep set aside ONLY for the chinese ones.

                            Nobody seems to be complaining that they don't fit THEIR OWN attachments. (Although I HAVE seen that with other chinese stuff)
                            CNC machines only go through the motions

                            Comment


                            • #44
                              Originally posted by J Tiers
                              The problem stated seems to be that :

                              So it's fine if you only need what attachments they came with, but if you have any other holders, arms, etc, you may be out of luck, and have to buy or make an entirely separate set to keep set aside ONLY for the chinese ones.
                              +1 That's exactly where I was. Details: My Little Machine Shop DTI shipped with 10mm and 4mm studs. 8mm (5/16") is really the standard.

                              The Noga fine adjusting head (FA1500 - an option on most Noga mag base arms) has 6, 8, and 10mm holes. I WAS able to mount my DTI to my Noga mag base arm using the 10mm stud.

                              The Noga centering arm (NF1015) has only 8mm or DT, neither of which fit the studs that came with my indicator. This head is also standard on Noga mag bases without the FA head option.

                              I also mount my test indicators to my Starrett surface gage to check parallels, vise jaws, and the like. My Starrett #57 has a 5/16" mast. You can get snugs that attach 3/8" to the 5/16" mast, but my (admittedly older) snug won't accept 10mm.

                              The solution is really to get an 8mm stud. I purchased one from MSC and filed its dovetail to make it fit the wider dts on my DTI. And while this solved the problem, I was never able to attach using the DTs.

                              Comment

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