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Thread: Lathe alignment

  1. #16
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    Quote Originally Posted by jack620 View Post
    Isn't the common way of aligning the spindle axis with the ways to adjust it out using the levelling feet (or shims)?
    Thereby inducing a slight twist in the bed. At the end of the day, it doesn't really matter if the lathe bed is dead level or not. What matters is that the spindle axis is parallel with the bed in the vertical and horizontal planes. Or is this only done on small lathes? It's certainly how Hercus recommends doing it.

    Steve,
    I wouldn't be adjusting the headstock until I'd tried adjusting/shimming the feet.
    The headstock on the hercus is mounted on the vee's of the bed so the only way to get alignment is scraping or twisting the bed. on a larger lathe, the headstock normally has provision for adjustment.

  2. #17
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    Quote Originally Posted by OxxAndBert View Post
    Thanks Chris. Adjusting the feet was the first thing I tried.
    I can pretty much jack the intermediate feet off the ground by adjusting one of the headstock end corners without seeing any significant change on an indicator against the side of the test bar. The lathe construction is pretty solid - headstock/bed are bolted to a monolithic casting comprising the headstock pedestal, chip pan and tailstock end pedestals - so I'm not surprised that it doesn't move much.

    I faffed around a bit more with it last night. Fitted the 4 jaw chuck, got inconsistent results, then finally realised that the chuck is probably classified as "pretty flogged" condition with quite a lot of play between the jaws and the body. Particularly at the smaller diameter.

    Put the 3 jaw back on (which is "tight as bro"), much more consistent results - same as what I got earlier - but even though its set up as a "knock-tru" chuck I couldn't get the bar running perfectly concentric at both ends so either the bar or the chuck is out of whack.

    At that point I decided to cut my losses, be aware that the headstock is likely slightly out of alignment and just work around it.
    I'll come back to it at some point when I've got more time.
    Probably the bigger issue is the worn 4-jaw, and that might help explain some of the random weird behaviour I've had on occasions with chatter and jobs walking in the chuck etc when using it. I should have picked it up before now.
    Anyone got a great condition 10" D1-6 4 jaw chuck lying around gathering dust

    Steve

    Use some thin aluminium between the part and the jaws, 1-2mm is good 3mm max. the aluminium will deform and take up some of the wear in the jaws and give better contact on the part.

  3. #18
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    Quote Originally Posted by OxxAndBert View Post
    Thanks Chris. Adjusting the feet was the first thing I tried.
    I can pretty much jack the intermediate feet off the ground by adjusting one of the headstock end corners without seeing any significant change on an indicator against the side of the test bar. The lathe construction is pretty solid - headstock/bed are bolted to a monolithic casting comprising the headstock pedestal, chip pan and tailstock end pedestals - so I'm not surprised that it doesn't move much.
    Steve
    I had a similar experience with my Taiwan lathe, using a precision level and making 'adjustments' with shims under the bed feet made no difference to the way it turned, I eventually made some adjustments to the head stock positioning in relation to the bed using the 'rollies dad' method to check my progress - I have adjusters at the rear of the headstock and I found them to be very touchy needing only the smallest fraction of a turn, my initial thoughts with this were "I should have left it alone" as I seemed to be going around in circles and over correcting, but as with a lot a things you learn as you go, using a home brew extended T bar allen key to make micro adjustments easier, and after each adjustment tightening the headstock hold down bolts gradually and always in the same in order - much the same way as a cylinder head is tightened down - I eventually settled on less than 0.5 thou over 12 inches. As a final check I made up up a test bar - an old piece of 1.25" diam shafting with a pair of 1.5" diam dounuts welded to it about 30cm apart, a test cut showed the error with this was just under 1 thou over the 12 inches - I put this down to tool and/or work spring and decided leave it at that point.

  4. #19
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    Hi there,

    Out of interest, what is the sensitivity of your level? Is it 1 thou/foot? on the graduations?

    Also how did you level your lathe across the bed, just sitting the level on time of the Vs at each end?

    If so then sometimes the top of the Vs are not necessarily super precision. I would use a set of precision parallels sitting on each side of the flats and put the level on them.

    Do this at both headstock end and TS end. Use the same parallels for both ends.

    Simon

    Sent from a galaxy far far away
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  5. #20
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    Thanks Simon.
    I just looked it up and the Starrett 98 is 5 thou per foot.
    I was sitting on the flat part of the ways using some 123 blocks, and making sure I kept the blocks on the same orientation etc.

    It’s by no means a perfect setup, but the best I could do with what I’ve got at hand.
    A more sensitive level would be nice, and slightly longer.
    I’ll need to pull my finger soon and finish scraping my straightedge so I’ve got something long enough to span the ways on the DSG. I’ll re-check this one at the same time.

    Steve

  6. #21
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    I have always just put the level on the top of the carriage and moved the carriage along the lathe. That's how all the techs that have done installs at work have done too.

  7. #22
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    Quote Originally Posted by snapatap View Post
    I have always just put the level on the top of the carriage and moved the carriage along the lathe. That's how all the techs that have done installs at work have done too.
    Never tried it that way. I'll try it next time.

    Simon

    Sent from a galaxy far far away
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  8. #23
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    Thanks Snapatap. Putting the level on the carriage is so logical - but I've never come across that method in any of the lathe leveling videos online etc or what I'd read. I wonder if its less applicable on smaller lathes for some reason.

    Out of interest I checked both the Takisawa and DSG manuals for leveling procedure. The Takisawa one basically says "level the ways" but doesn't give any method, but the DSG is quite detailed and specifically says to put the level on the carriage.

    Steve

  9. #24
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    Steve, when you are happy the lathe is level, if it's still measuring a taper, you may have to adjust the headstock. I had to on my Nuttall lathe. It's design has the right hand back bolt as a dowel bolt, so it pivots on that one. Under guidance of a real machinist I loosened all four bolts and used the device as you pictured to adjust the headstock. It's a slow process, just creeping up on it and rechecking the test bar many, many times, but I got it right.
    Also when you get it right, you then have to check the tailstock alignment as well.
    Good luck,
    Rgds,
    Crocy.

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