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  • DRO

    Is it my imagination, or on the Oriental lathes, do they fudge on the screws in order to be able to mark the hand dials in both metric and inch? The biggest problem I have with my lathe, is that without an indicator I have no idea what a cut will actually be. When I drug the B'port home, it had a DRO on it. What a joy. I intend to stick one on the lathe in the not to distant future. So, when someone asks about an Asian lathe, would it make sense to bring up the relative inaccuracies of the dials, and suggest they look into a DRO? Mike

  • #2
    The problem is, there are no made in China DRO to match the price of the made in China machine. Price of a decent 3 axis DRO can be more than half the cost of the import machine. My home built DRO is taking forever. Someone say that the hardest part of a project is the start, and I seem to be suffering from this all too freqeuntly. I'm sure I'm not alone.

    Albert

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    • #3
      We have this new asian made thing at work, I'm glad it has a DRO on it. If it wasn't for the DRO a person would have to use this machine with an indicator. Cross slide jumps every time you start spindle.

      I've had gib tight and loose, doesn't seem to matter. Jumps whether spindle at high or low speed. I've fiddled with motor mounting, I don't like the tightener and where it's located in relationship with base and levelers. It might be causing a twist to base when starting up. I've tried rubber under the washers, etc.

      I know another guy who had a heavy 14" Enco with this same problem, he had to use an indicator.

      I tried my best to get the boss to get an old LeBlond, Monarch or such, but it had to be new you know. Kinda wish they had got a TOS.

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      • #4
        Albert, but what about the Canadian made DRO. 2 axis for about $600 including shipping. This is what I have been considering for myself. Specificaly though, I was thinking of the packages, lathe and dro for less than the price of each separate. Would it be wise to tell the inquiring, "Hey this might be a good idea, save you a lot of future problems."
        Halfnut, I think on mine they rounded off when marking the thing. It seems to be incremental, that is 20 thou is so much off and 40 is about twice that. But who wants to constanly do the math in the old noggin while playing. Mike

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        • #5
          I looked at the Canadian unit for my lathe - they were extremely helpfull but I still can't put their damn encoder on the cross slide. The Heineman and Mitutoyo work (just because they cost twice as much no doubt). So I are waiting to score the one I need on eBay.

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          • #6
            The "fudged" calibrations are pretty standard, don't appear to be inch or metric. The dials never seem to come out to an even number either.
            How much money must you save on the purchase of a machine to justify the cost of a DRO to make it useable?
            Jim H.

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            • #7
              Mike, The reason why I didn't consider the $600 DRO is that it uses rack and pionion with shaft encoder. Not only will this impede the movement, but I can't image that it will hold it's accuracy over time and temperature range. For smoothness and long term accuracy I believe optical encoders are still the best solution, which is what I plan to build. Unfortunately, the operative word there is "plan".

              Albert


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              • #8
                Check out the DROs carried by JTS machinery, (800) 321-3566. They range from 6" ($36) to 40" ($259). A 1-axis remote read-out is $103.

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                • #9
                  JC, that is a good question. Until I started playing with the DRO on the mill, I thought they were for sissies. I still ride a ridgid Harley, shoot a stick bow, favor Mausers, carry a pocket watch, have a '68 for a family car, and refuse to use a 4 wheeler as long as my legs work. If my appreciation of the DRO changes my outlook on a lot of things, I am going to be in trouble. The plan when I bought this lathe, was to use it until I came across an older US built that fit in with my other junk, and perhaps use it to rebuild/repair the US. I'm thinking the DRO would be transferable if the machines are relatively the same size.
                  However, your point fits very well with my question. If this problem I live with is indicative of Asian lathes, should we not point it out when discussing Jet, Birmingham, Grizzly? It might save someone a lot of grief. Mike

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                  • #10
                    Yup.
                    Jim H.

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                    • #11
                      Hi all, My Emco (not Enco) Compact 8 lathe is as accurate as I need. My Jet JVM-626 mill has both inch & metric on the handwheel collars and any inaccuracy from that is the result of the Asian import quality and not fugging of any measurements. I use an indicator because the entire machine is not as rigid as a B'port. Anyone else have a Jet mill assessment of accuracy?
                      John
                      interested in Di-Acro equipment, classic jukeboxes, 1967 T-Bird, oscilloscopes, locksmithing
                      [email protected]

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                      • #12
                        John, Are the marks for inch and metric the same. I mean, are there separate marks/divisions for each method of measuring. My lathe has one set of marks on the handwheel, and there is a one index mark labled for inch and metric. However, the math does not work out for either the conversion or measurements. That is why I also suspect the screws. Mike

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                        • #13
                          I have a couple of East European lathes that have dual dials. Because there is no direct comparison between english and metric measurements one or the other is bound to get fudged.
                          There three ways of doing this, We will take imperial here:-

                          [1] Imperial pitch screw and divisions in imperial - OK every thing matches. The metric divisions are calibrated to be accurate but at the end of a turn there is a gap becuse of the don't line up error.
                          The way to use these in metric is to rough to near final size, zero the dial and then work to the metric divisions. Do not go more than one turn or you will have to re zero.

                          [2] Same description as [1] above but they make the metric divisions line up at the end of a turn. This doesn't work and you will have to check to see if the metric divisions are accurate with a clock or just cosmetic.
                          I have seen machines like this, they do exist.

                          [3] Last and best are the seprate twin dial machines, usually in the high end range.
                          These work by having one dial, in our example the imperial dial connected direct to the screw. The metric dial is driven from this by internal epicyclic gearing with a ratio of 50 / 127 This will give an accurate conversion between imperial and metric as 50 / 127 is the same as 100 / 254 and as we all know 25.4 is the correct conversion factor.

                          The same applies to machines with metric screws, in this case it's the imperial divisions that get altered.
                          Provided you never go more than a turn this setup can be used quite accurately.

                          John S.
                          .

                          Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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