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Thread: Tuning a Lathe

  1. #1

    Tuning a Lathe

    OK, first a little background...

    I am finally back in woodworking after a 25 year hiatus that ended roughly 2 years ago when LOML and I built a new house and she let me design most of the basement as a shop. Bought a lot of tools in a 6 month period including an old Delta Rockwell VS lathe. The lathe became available at a great price so I grabbed it as I knew, eventually, I would go down that slope again.

    Well, I finally did last week doing a few quick pens for a special occasion. What became apparent is that the lathe is not spinning things smoothly. Now I'm not talking the type of wobble that happens with out of balance pieces of wood before you have trued them up a bit. This is when you are done to the final wood removal. It's not a huge wobble (I think you would call it runout but I'm still learning the technical terms ) but things were not turning true and, with pens, there's not a lot of reason for wobble other than the mandrel not being true (which is not the case). Thankfully things are close enough that sandpaper still produced a quality finish to the pens despite the tearout from the tools 'bouncing' on the surface.

    Which all leads to my question. I have a mag base and dial caliper for measuring/adjusting TS, jointer, etc. But how would I go about using it to test a lathe? Or should I even bother and just jump right to disassembly and replacement of the bearings which I suspect are the culprit? Or am I just being overly sensitive? The 'wobble' is very small but it is noticeable.

    I'm reasonably comfortable with most WW tools but I never did a lot of lathe work before now and I can't say I feel very comfortable at the moment.

    Thanks in advance for any advice.

  2. #2
    Join Date
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    Chip, welcome back to the abyss of turning. I had the same problem on my homemade lathe and the problem was the bearings. I still haven't had time to replace them, but when I check them out, one was shot and the other will go soon. How old is the lathe? A replacement of bearings may be a good idea either way?

  3. #3
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    Hey Chip, welcome back to the dark side!

    Put the mag base on the ways of the lathe, and then arrange things to the dial indicator touches the side of the spindle, in a place without threads, set the dial indicator to zero, and then turn the lathe by hand.

    Could you post the model of the lathe, and a pic?

    I do not know, but there may be a way to snug up your bearings somehow...

    Your lathe should not have run out that you can notice like you are saying, I would imagine a bit, on the dial indicator might be within specs, but not what you are talking about, that doe sound like a lot.

    I'm sure you can get it running true again.

    Cheers!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  4. #4
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    Chip, are you only seeing the wobble on pens? Even with a perfectly straight mandrel, if you overtighten the tailstock it can flex the mandrel enough to cause some wobble. (DAMHIKT) Just something else you might check before performing major surgery.
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

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  5. #5
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    Welcome back to the black hole of turning. Enjoy.
    Bernie W.

    Retirement: Thats when you return from work one day
    and say, Hi, Honey, Im home forever.

    To succeed in life, you need three things: a wishbone, a backbone and a funnybone.

  6. #6
    Quote Originally Posted by Stuart Ablett View Post
    Could you post the model of the lathe, and a pic?
    When I get home I'll get the model at least. Haven't warmed up the camera in a while so we'll see on the pic.

  7. #7
    Quote Originally Posted by Vaughn McMillan View Post
    Chip, are you only seeing the wobble on pens? Even with a perfectly straight mandrel, if you overtighten the tailstock it can flex the mandrel enough to cause some wobble. (DAMHIKT) Just something else you might check before performing major surgery.
    Yeh, I considered this but I don't think that's it. I did 10 pens (got eight good ones. *I* screwed up one in assembly and one chipped out really bad at the end)> The point is I experienced this on all of them and, at least on the last 6, I was beign careful about the tailstock.

  8. #8
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    Tuning a Lathe

    Welcome Chip,

    What Stu and Vaughn said, and, is your mandrel one with a morse taper shank? It is possible there is something inside your taper bore in the lathe spindle that is seating the mandrel shank off center. Take a good look inside and if you have a round wire brush (the kind you use for cleaning copper fittings for soldering), run that inside to see if it helps. Also take an indicator readings along the mandrel shaft with the tail stock tightened as it would be for turning. See if you get any runout there.

    Also a possibility of a bent pulley, or "lumpy" belt bouncing enough to flex the spindle shaft which would be amplified further out from the headstock.

    Just MNSHO. Your instructions Mr. Charnley, if you should choose to take this assignment, are to return a full report complete with pictures.

    Aloha, Tony
    "You got to learn from the mistakes of others. You won't live long enough to make them all yourself". (Author unknown)

    "Time flies like..... an arrow,,,Fruit flies like..... a banana." Groucho Marx

    Ah,,,to live in Paradise!

    Registered voting member

    Fighting for all I am worth, and praying every day.

  9. #9
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    Using just some pens as your test for the lathe can't be definitive. The mandrel, even if true, can, and will, flex. IMHO, you can't get a perfect pen using a full length mandrel. Try turning someting 1" in diameter, or thicker on centers and test again. Do the centers meet?
    "Folks is funny critters."

    Think for yourselves and let others enjoy the privilege to do so, too. ~Voltaire

  10. #10
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    Chip, do you have a chuck that can be fitted to the lathe?
    If so get a length of reasonably straight steel bar stock or metal pipe about 1" dia and clamp it in the chuck.
    Put you mag base on the bed and place the dial caliper against the bar some way from the chuck and pull and push the chuck*, if the bearings are worn or loose in the case of a plain tapered sleeve bearing you will see movement on you gage.

    *A length of 3x3 timber levered between bed and chuck maybe.
    Chas. just a traveller on the road of time.

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