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  1. #31
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    Jun 2007
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    Have you centred the bar at the outer end or just at the chuck end.

    If just the chuck end then do it at the outer,then check the chuck end then the outer, you may find that you may have to tap the outer slightly to get it running true without touch the chuck jaws.

    Any job hanging out of the chuck of any length will generally require a bit of mucking around to get it running true.

  2. #32
    Join Date
    Sep 2008
    Location
    Sydney
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    27

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    I centred it at the chuck end and also tried to centre it at the other end, by tapping and tightening it, but it wouldn't move. I have the, very little used 4 jaw, on. The 3 jaw, which I use most of the time, does allow me to move and tighten. After I had ground the jaws on the 3 jaw I couldn't get the work to move as much, by tapping etc.
    If I centre at the end of the work then measure at the chuck end, wouldn't I get the same differential measurements.

  3. #33
    Join Date
    Apr 2008
    Location
    NSW
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    537

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    The full weight pressing on maybe three rollers in the bearing and it's not going to crush even a few thou into the bearing race surface . Could easily cause a slight mark that eventually trashes the bearing some years later .
    I do agree that it could damage the whole head stock and or put it out of alignment . Just not a away I ever want my lathe to be lifted .
    The volume of a pizza of thickness 'a' and radius 'z' is given by pi z z a.

  4. #34
    Join Date
    Jan 2011
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    Far West Wimmera
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    63
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    What exactly are you trying to measure? There are a number of reasons this could happen. If you are measuring how true the lathe is cutting, put a steel bar in the chuck (any chuck), turn the bar down leaving a short section near the chuck and another at the end, just cleaned up with the rest 3mm smaller diam. Do a light cut on these 2 bigger sections in one run without touching anything. Measure them. That is how your lathe is cutting. The bar obviously needs to be big enough to avoid deflection.

    Dean

  5. #35
    Join Date
    Sep 2008
    Location
    Sydney
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    27

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    I think it was just a coincidence that after centering my peice of 45mm near the chuck with the dialguage on the toolpost, l then wound down to the end and the reading was the same, zero. I was very happy until I turned the chuck 180 degrees and the dialguage read 0.015". When I turn the bar down as you have said shouldn't I get a reading of a touch under 45mm near the chuck and 45mm less whatever it takes to get the concentricity out of the other end.
    I also have some bigger chrome bar that I can use 50, 60, 70, or 90. But I'm thinking that the 45 will not flex over that distance.
    I will check it tomorrow.
    Thanks again

  6. #36
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    Jan 2011
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    When I turn the bar down as you have said shouldn't I get a reading of a touch under 45mm near the chuck and 45mm less whatever it takes to get the concentricity out of the other end.
    What this is doing is taking a cut along a length of bar so you can check measurement at the chuck and further out, so these 2 can be compared. Removing the material between the 2 positions reduces the wear on the cutting tool so you get 2 cuts (one at each end) as close to identical as possible. Both sections should be cut to clean up totally first, then take a light cut to equalise the diameter and then the measurement cut. Cut end to end in one continuous run with power feed. Don't touch the lathe.

    As Pipeclay said you need to adjust a long work piece in 2 places to get it to run concentric and this negates any measurement you may wish to take to determine how parallel the lathe is cutting.

    Dean

  7. #37
    Join Date
    Jul 2008
    Location
    near Warragul, Victoria
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    3,718

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    hi Slim I wish you the best of luck with your Aussie built Nuttall lathe . I am not a lathe expert in any sense but I'm a little confused about what you are trying to measure . If I did a static test like you did i.e. used a 4 jaw chuck and a ground bar and a dial indicator, I would be amazed if I got those results you did, chucks are not the ideal holding method for doing a static test , they are OK for the dynamic tests i.e. turning a bar down at each end and measuring the two diameters for taper .

  8. #38
    Join Date
    Sep 2008
    Location
    Sydney
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    27

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    Quote Originally Posted by Oldneweng View Post
    What exactly are you trying to measure? There are a number of reasons this could happen. If you are measuring how true the lathe is cutting, put a steel bar in the chuck (any chuck), turn the bar down leaving a short section near the chuck and another at the end, just cleaned up with the rest 3mm smaller diam. Do a light cut on these 2 bigger sections in one run without touching anything. Measure them. That is how your lathe is cutting. The bar obviously needs to be big enough to avoid deflection.

    Dean
    4jaw (5).jpg
    So here are the results, 44.420mm at the chuck and 43.985mm at the end (220mm apart). That's 0.435mm
    What now? Do I tackle the headstock?
    Slim

  9. #39
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    Jan 2011
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    Quote Originally Posted by slim View Post
    So here are the results, 44.420mm at the chuck and 43.985mm at the end (220mm apart). That's 0.435mm
    What now? Do I tackle the headstock?
    Slim
    First raise the rear tailstock end floor mount a little. Put a shim under it if you don't have adjusting screws. I would be trying 1mm to start. It is a solid lathe and it may take some time to settle into the new position. If another floor mount lifts off the floor, wait for a day and see what happens. Try doing the cut again. You may need to do this quite a bit. A machinists level will help to tell if the lathe is going to respond to this or not.

    I am no expert at this. I have read about it a lot, but I have yet to do it for my lathe. Another job is to make some adjusting screws so I can.

    Dean

  10. #40
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    Jul 2008
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    near Warragul, Victoria
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    Slim, people have heart attacks and mental breakdowns when somebody mentions they are about to move the headstock on a lathe If your Nuttall is as bad as your test indicates then you might have to twiddle the adjusting screws . Deans advice is good but the beds on these Nuttall's are very solid with very heavy cross bracing . I don't know if the bed would twist ?

  11. #41
    Join Date
    Jun 2005
    Location
    Townsville, Tropical Nth Qld.
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    225

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    Quote Originally Posted by Oldneweng View Post
    No doubt there are some members tearing their hair out right now. There have been a number of threads where people have written about doing this and the general reply is NO, NO, NO. What have you done! This is a very last resort after everything else has been adjusted. 0.005" over 18 inches can be caused by the bed not being correctly leveled and by that I don't mean with a machinist level, I mean adjusting for the taper. Adjusting the bed (removing the twist) to remove or reduce taper is done a long long time before touching the headstock.

    I am not saying not to touch the headstock, but do not encourage people to do this unless they have eliminated every other option. This is a very touchy subject in almost any metalwork forum and don't even think about mentioning "Rollies someones dad".

    I agree with the clutch being a boon. I swapped the 3hp 3ph motor for a 2hp 1ph motor. If it wasn't for the clutch I would not have been able to do this and the 2 top gears needed to slip the clutch to get the chuck rotating a bit first.

    Dean
    Hi Dean, I am going to politely disagree with you on this. I am an electrician, not a machinist so after I moved the lathe from dad's old shop to mine I got a very respected turner come and set it up and test run it for me. He brought his machinist level and parallel set and after he shimmed it up, we did a test cut and it was cutting a slight taper. He said I needed the experience of adjusting the headstock and believe me it was. He said it was a common problem with
    Nuttals.
    This may not be Slims problem, but at least he now knows that they are adjustable.
    Rgds,
    Crocy.

  12. #42
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    Jan 2011
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    Quote Originally Posted by Old Croc View Post
    Hi Dean, I am going to politely disagree with you on this. I am an electrician, not a machinist so after I moved the lathe from dad's old shop to mine I got a very respected turner come and set it up and test run it for me. He brought his machinist level and parallel set and after he shimmed it up, we did a test cut and it was cutting a slight taper. He said I needed the experience of adjusting the headstock and believe me it was. He said it was a common problem with
    Nuttals.
    This may not be Slims problem, but at least he now knows that they are adjustable.
    Rgds,
    Crocy.
    What is it that you disagree about? Are you saying that because it is a Nuttall you should just jump in and adjust the headstock? All I am saying is check first, because if the headstock does not need adjusting then you have just let yourself in for a lot of unecessary trouble. It is far easier to remove a shim that realign a headstock. Did you read Mikes post just before yours.

    PS I would like to politely suggest that you check my spelling for Nuttall.

    Dean

  13. #43
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    Sep 2008
    Location
    Sydney
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    I did lift the foot/tailstock end, previously and set a couple of dialguages up on the bar in the chuck. The lathe was off the ground and both dialguages did not measure any movement. I have to agree with old croc, these old Nuttalls are built like the proverbial ****house.
    The lathe isn't bolted to the concrete and probably would need to be so that it could be twisted (maybe)
    Big job?

  14. #44
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    The lathe isn't bolted to the concrete and probably would need to be so that it could be twisted (maybe)
    Big job?
    I have heard that sometimes it is necessary to bolt them down, but you would really need to have a better idea of the level of the bed. If at some previous location the lathe had been sitting in a twisted state then it may have taken a set, so to speak. This would require either bolting or waiting to see if it will return to level over time. The bed would need to be checked for level so you can tell whether this is the case or not. Considering the amount of taper that your lathe is cutting, if the bed is twisted it should be pretty obvious with a level. When I say level, I mean level in a "plane". Using the level to check for twist.

    I have owned a Nuttall and I know how solid they are. It is my understanding that even the most solid lathe can twist if sitting unevenly. This is why proper setting up is recommended for all lathes.

    Remember I am no expert.

    Dean

  15. #45
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    Apr 2008
    Location
    NSW
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    All lathe beds can twist from their own weight the more solid the more weight so that cancels the thickness and bracing somewhat . If they never twisted and never bent slightly then no precision levelling would be required . No one is having any heart attacks over anything . Moving the head at this stage is stupid as the lathe could still be out of level , the chuck or jaws could be the problem a number of things could be out . Is the test bar even straight ?
    The volume of a pizza of thickness 'a' and radius 'z' is given by pi z z a.

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