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Lathe DRO

Discussion in 'JIM DAWSON' started by JimDawson, Apr 14, 2017.

  1. JimDawson

    JimDawson Global Moderator Staff Member Director

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    Last weekend my son informed me that it is time to put a DRO on the lathe. I guess he hasn't figured out what all those little numbers are for on the dials. :rolleyes: He has a short production run for a product he is developing so figured it would be easier to do it with a DRO. I suggested we just CNC the lathe, but he thought that would be overkill and make the lathe less useful. Mmmm OK. :confused: He's buying the DRO so we'll do it his way, I'll just spec it so it will be CNC compatible later.:p

    So this is the starting point. A basic Jet 1340GH.
    upload_2017-4-14_18-20-24.png


    Since I have been experimenting Ditron products, I ordered one of their D100-2V readouts
    upload_2017-4-14_18-23-6.png


    And 2 of their DMR-200, 1um read heads, and 2 meters of magnetic tape. Should have all the pieces by Wednesday of next week.

    See the test results of the DMR-200 read head here http://www.hobby-machinist.com/thre...le-replacement-vendor-spec.49299/#post-475210

    Hmmm, does this mean that I can have 1 micron accuracy on my lathe now?;) Nah, I suppose not. Durn.:(

    I have never liked the idea of scales being exposed on a lathe, especially the cross slide scale, but have never seen a better way of doing it. Can't put it on the headstock side, it would be destroyed by something in no time. If you put the scale on the tailstock side of the cross slide, you lose some working clearance. Not acceptable in my book. I want the scale tape and read heads well protected and out of the way.

    There is a better way.....I just haven't designed it yet.:grin: Stay Tuned..........
     

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  2. BGHansen

    BGHansen United States H-M Supporter - Premium Content H-M Supporter-Premium

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    You'll like the DRO on your lathe, not as "essential" as one on a mill, but still nice to have. Have one on my Grizzly G0709 lathe and turn it on maybe 10% of the time; obviously depends on the work being done. I use the DRO on my tail stock quill all the time, easier than doing the math.

    Bruce
     
  3. rwm

    rwm Active User H-M Supporter-Premium

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    I don't understand why the scales need to be so large in general. You would think someone could produce a very small dimension scale that could mount on the cross slide and take up minimal space.
    Robert
     
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  4. RJSakowski

    RJSakowski H-M Supporter - Premium Content H-M Supporter-Premium

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    Deciding on the least obtrusive mount for the cross feed scale was my problem too.

    I had considered mounting the scale to the rear of the cross slide but that would have meant losing the back splash. Another idea was to use a spring steel tape riding on a ball bearing guide to turn the direction of motion parallel to the ways. The steel tape concept has been used effectively for precision positioning requirements such as hard drives. You could use a tension spring to keep the tape taut or run it around in a loop. I would think that spring from a small pocket tape rule would work.

    In the end, I decided to go with the more compact iGaging scales and mounted the scale on the tail stock side of the cross slide with the pickup mounted below and between the ways. I lost about an inch of travel on the tailstock but felt that it was the best compromise.

    The write up on my DRO install is here: http://www.hobby-machinist.com/threads/another-lathe-dro-install.34106/
     
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  5. RJSakowski

    RJSakowski H-M Supporter - Premium Content H-M Supporter-Premium

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    You would think so, Robert. Unfortunately, the industrial side of their business has larger machines where mounting is a problem. The smaller hobby type machines just aren't a big enough market to mess with, IMO. iGaging has made an effort in that regard but their pickup could be smaller too. Their scales have 10 micron resolution. I'm not sure that their pickup would be robust enough to be able to resolve 5 microns, let alone 1 micron.

    There are other technologies that would be amenable to small scales with higher accuracy. An interferometer comes to mind. It uses a beam of light and can resolve to better than .1 micron. Sounds like a good project for some entrepreneur.
     
  6. JimDawson

    JimDawson Global Moderator Staff Member Director

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    They don't have to be.

    That is one of the reasons I went the way I did on this install. The mag tape is only 0.063 thick, and the read head is 1.2 x 0.95 x 0.39 inches. All you need is a surface to stick the tape to, and a place to mount the read head. I have 1 micron mag readers on 3 machines (soon to be 4) in my shop, and am very happy with the performance. I nearly have the read head mounting design complete and it will not be visible on the lathe at all. I may get it built this weekend.

    What I would really like is a heads up display. The problem with a DRO on anything is you normally have a choice of looking at the DRO or the work. I want to see both at the same time.:grin: Time to start thinking about that one. Ideas anyone????? :eagerness:
     
    Last edited: Apr 15, 2017
  7. RJSakowski

    RJSakowski H-M Supporter - Premium Content H-M Supporter-Premium

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    +1 big time on the heads up display!
     
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  8. RJSakowski

    RJSakowski H-M Supporter - Premium Content H-M Supporter-Premium

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    The Touch DRO comes a little closer to the heads up as I can place my smartphone anywhere. If I make a mount for a Noga system, I could put the display wherever is convenient.
     
  9. JimDawson

    JimDawson Global Moderator Staff Member Director

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    I know how to build the HUD, but not how to do it in the hobby class price range. But, I haven't researched all of the new hardware available, some of the stuff out there is pretty cheap.
     
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  10. rwm

    rwm Active User H-M Supporter-Premium

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    Jim- I missed that about the tape thickness. Yes, that would help a lot. I wish the read head wasn't .095" That is the issue on my machine.
    Where would you ideally project the HUD image? I guess just above the work piece?
    Robert
     
  11. JimDawson

    JimDawson Global Moderator Staff Member Director

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    Either just above or maybe actually on the workpiece just above the tool bit.
     
  12. middle.road

    middle.road Active User Active Member

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    Jim, can you post some prices on the ditron parts?
    I'm curious to see if going with TouchDRO on a 10" tablet is cheaper than a 3-Axis display for the mill.
    I'm also curious to see if I could do up this mag system compared to a glass scale setup.

    Thx.
     
  13. JimDawson

    JimDawson Global Moderator Staff Member Director

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    1)D100-2V 2axis 70USD
    2)DMR200 1um 90USD X 2
    3)MS200-2M 2+2 56USD (2 meters tape)
    Shipping cost By FedEx 65USD

    Amount 371USD

    I can't see any reason to buy all that extra aluminum housing that you have with most scale systems. All you need is a flat surface to stick the mag tape to. Alignment is pretty forgiving. The sticky on the tape is pretty much impervious to normal coolants, including petroleum products. Mine have been continuously soaked in coolant (kerosene, WD40) and way oil for 3 years with no sign of coming loose. Keep acetone, MEK, and lacquer thinner away.
     
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  14. StepSide 88

    StepSide 88 United States Iron Registered Member

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  15. JimDawson

    JimDawson Global Moderator Staff Member Director

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  16. JimDawson

    JimDawson Global Moderator Staff Member Director

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    An interesting development in the DRO delivery. The DRO was shipped as one package, but the tracking is currently showing the package(s) as being in both Japan and Memphis, Tn. Also, the expected delivery date is now showing Pending, as opposed to Wed, Apr 19. I hope I get all the pieces.:cautious:

    Also currently waiting on a tool bit for the cross slide mag reader install. I thought I had one that would work, but I should have measured before making an assumption. Poor planning on my part. :( So the lathe carriage is currently clamped to my mill table and taking up space waiting for the next operation. The tool bit is somewhere between Salt Lake City, and Sandy, Or. Maybe I'll get it Thursday or Friday. :rolleyes:

    BTW, I'm purposely not publishing the installation steps and build yet, you'll see why later. Going for the dramatic presentation later :grin:
     
    Last edited: Apr 18, 2017
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  17. coolidge

    coolidge United States Active User Active Member

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    Remote camera on the DRO read out plumbed to a big 60 inch flat screen mounted on the wall behind the lathe :big grin:
     
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  18. JimDawson

    JimDawson Global Moderator Staff Member Director

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    This is what I want to see. I like the 60'' flat screen idea, maybe my poor old eyes could actually see it. :cool:
    upload_2017-4-18_11-48-33.png
     
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  19. coolidge

    coolidge United States Active User Active Member

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    Jim you can probably buy an older 60 inch flat screen for under $100, I was only half joking.
     
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  20. JimDawson

    JimDawson Global Moderator Staff Member Director

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  21. Charles Spencer

    Charles Spencer Active User H-M Supporter-Premium

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    Contact the Air Force. They can probably tell you how to do it for a reasonable price.


    $3 million is reasonable, right?
     
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  22. sanddan

    sanddan Active User H-M Supporter-Premium

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    Just saw on TV, the F35 headsup helmet the pilot uses cost $400,000 ea!

    That's reasonable, right?
     
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  23. StepSide 88

    StepSide 88 United States Iron Registered Member

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    Well since the display in the ski goggles is so much more affordable the reason the helmut costs 400k must be something to do with the 'special foam padding' ... no?
     
  24. fradish

    fradish United States Active Member Active Member

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    Frank Hoose has a video of a camera he has setup on the tailstock to help
    him see when doing boring or internal threading operations. He has that
    hooked up to a monitor next to the lathe. Not a heads up display, but
    something to help with our old eyes... :D



    My only concern (and maybe that is where a heads up display would help) is
    I would be concerned that I would be too busy watching the screen and miss out
    on something dangerous going on in front of me...
     
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  25. JimDawson

    JimDawson Global Moderator Staff Member Director

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    OK, it's not quite done, but time to post anyway.

    First the before picture.
    upload_2017-4-23_19-58-27.png

    And the after installation picture. Still not quite back together, but I'm tired and need a break. :faint:
    upload_2017-4-23_19-59-51.png


    And the Readout.
    upload_2017-4-23_20-0-48.png

    OK, now for the fun stuff. The goal was to mount the scales so that they would not be in the path of flying chips, dropped objects, and not interfere with any operation. I don't like the normal mounting systems for most DROs. So this means burying the the scales and read heads inside the works.

    One of the magnetic read heads, 1 micron resolution.
    upload_2017-4-23_20-7-52.png

    The before picture of the cross slide. The area above the dovetails is just clearance, not a bearing surface.
    upload_2017-4-23_20-9-30.png

    So milling a slot for the magnetic tape to sit in on the back of the cross slide. 1.6mm deep (mag tape thickness), 11 mm wide.
    upload_2017-4-23_20-13-2.png

    There were also no oil grooves on the cross slide, so I added some. 1/4 ball end mill, 0.015 deep. Whoever designed the oiling system on this lathe did not think it through very well, there was really no way for oil to get on the cross slide ways.
    upload_2017-4-23_20-16-41.png

    So now we have a slot for the mag tape.
    upload_2017-4-23_20-18-9.png

    The next step is to mount the mag read head inside the carriage to line up with the mag tape. It needs to sit about here, more or less.
    upload_2017-4-23_20-20-45.png

    and another view
    upload_2017-4-23_20-21-39.png

    So clamping the carriage into the mill and locating the edges off of the cross slide, tells me where the mag read head needs to locate,
    and that is about here
    upload_2017-4-23_20-25-19.png

    So chew out a pocket in the casting to mount the read head
    upload_2017-4-23_20-27-35.png


    But we still have a little cable clearance problem. I can fix that ;)

    upload_2017-4-23_20-27-49.png

    One 3/16 convex radius router bit. One minor problem, I need to go deeper than the bearing will allow.
    upload_2017-4-23_20-29-8.png

    No lathe to make new spacers, so just break the bearings. Wrap in a heavy towel, and smack with a large hammer on a suitable solid surface. Forklift forks work well for this.:) Now you have a suitable spacer with a much smaller diameter.
    upload_2017-4-23_20-30-41.png

    upload_2017-4-23_20-33-21.png

    Now just carve out cable clearance. 500 RPM, 7 IPM, 0.010 step over.
    upload_2017-4-23_20-34-10.png

    Now it fits properly.

    upload_2017-4-23_20-35-51.png


    Then locate, drill & counterbore for the two M3 x 30mm mounting screws. I had to use a 1/4, 2 flute router bit to counterbore, the only thing I had that was the right size, and with enough length to counterbore 0.875 deep. I normally don't recommend an endmill in a drill chuck, but in this case I already had a 0.125 pilot hole through, and was very careful in my feeding.
    upload_2017-4-23_20-39-19.png

    And there it is, mounted in place. You see why it is buried in the casting, not a heck of a lot of room between the nut and the read head.

    upload_2017-4-23_20-45-24.png

    OK, the X axis is done, now on to the Z axis :)
     
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  26. JimDawson

    JimDawson Global Moderator Staff Member Director

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    The Z axis

    The back way is machined top, bottom and side. The top and bottom are bearing surfaces, but the side is not a bearing surface, and has clearance. A perfect place for the mag tape. The Z axis read head needs to mount in the back of the carriage to match up with the back way. So a little surgery is required on the back of the carriage. I also added oil grooves.

    upload_2017-4-23_20-59-52.png

    The read head is a bit wider than the back of the carriage, so a mounting tab was needed. I also needed to chew out cable clearance as I did on the X axis in the previous post. In addition, I needed to take out a bit more material to get tool clearance for the convex radius cutter because I had to go a bit deeper with the cut.
    upload_2017-4-23_21-5-7.png

    There wasn't quite enough clearance for the mag tape, so a T-slot cutter made quick work of adding a bit more clearance in the proper location. Normally I would not have this much stick out on the tool, but the shank had been turned down for clearance on another project and that's all I had to hang on to.
    upload_2017-4-23_21-7-17.png

    And there is the read head mounted in it's new home.
    upload_2017-4-23_21-10-51.png

    And a shot from the back showing the read head and tape installation. With the clearance slot cut in the carriage, it was pretty simple to get the tape to line up properly, just keep it in the slot.;)
    upload_2017-4-23_21-13-41.png

    So next is some cable management, and finish assembly. Should have that done in the morning. :)
     

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  27. JimDawson

    JimDawson Global Moderator Staff Member Director

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    A little update.

    I have to say that when I opened the manual for the Ditron D100-2V DRO I was pleasantly surprised. It is well documented, and in readable English. Unexpected from a China manufacturer. It was written/translated by a native English speaker, and quite possibly someone with a machining background.:encourage:

    The system works fine. I had to calibrate the DRO to match the read heads, took all of about 5 minutes. Seems to be very accurate and repeatable. The 1 micron scales are a little overkill, I probably don't need to read to 0.000039 inches. But who knows, maybe I'll get a job from NASA :grin:

    Overall I'm very satisfied, and the lathe is ready to make chips again. :) On to the next project...............
     
  28. Silverbullet

    Silverbullet Active Member Active Member

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    Wow, next will be remote heads with solar power lithium . No cables to mess with. I like the route you took mounting and fixing the oiling problem , maybe its a good thing it made ya fix the lathe while upgrading. Nice job very nice.
     
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  29. JimDawson

    JimDawson Global Moderator Staff Member Director

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    Thank you for the kind words. :)
     
  30. rwm

    rwm Active User H-M Supporter-Premium

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    You make it look so easy! I would like to try one of those DROs. Please keep us posted on your experiences with it. Can it be ordered online?
    Robert
     
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