Calling all turners: question on acceptable degree of runout

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  • #743499
    Matt Mahan
    Participant

    Hello out there and wishing the community the happiest of New Years. I’m really hoping to collect some opinions from turners more experienced than myself on this issue. I’ve had a Jet midi lathe for a couple of years and have done a handful of spindle turnings with it. Right off the bat, I noticed that there’s a visible degree of runout on the spindle (see video attached with spindle turning in relation to the tail stock live center). I know that not even the most expensive lathes could fully avoid this, but I’m wondering if what I’m seeing is “normal” or if it could be problematic/affect my turnings. I really try not to obsess over the engineering of tools, but this is out of my wheelhouse. The net at the end of the day is that I can turn knobs and pens, but I do have to fuss a lot to get rid of ridges – could that be a symptom or am I being paranoid? Bringing it up now because I want to try to do some small bowls and am feeling underinformed at this point. All the best! Matt

    #743536
    YrHenSaer
    Participant

    Working logically from the head-stock outwards, it’s could be the Morse drive on the head-stock is running off centre – so,remove the spindle and check that the insides of the taper run true and centred…. no debris inside etc..
    If it’s out, check the bearings for side-play. I don’t know if the bearings are adjustable on this lathe or sealed.

    Otherwise substitute the drive spindle and spot any difference…..
    Good luck..

    #743610
    Larry Geib
    Participant

    I turn a little but I am by no means an accomplished Turner. I buy way more sandpaper than a Turner does. .

    It’s hard to tell without using a micrometer to check headstock runout, but it doesn’t look like the headstock is the issue from your little video. I don’t see the same runout apparent there. If @YrHenSaer ‘s suggestions are sound and obvious.
    Morse taper connections need to be spotless to work properly. Even old packing grease that wasn’t cleaned out of the taper can introduce error. A bottle brush and some mineral spirits will clean out the headstock taper.

    Is that a MT1 to MT2 adapter in the middle? If so, get rid of it and get a proper MT2 drive center. You are compounding the chance for error.
    You should be able to get within .001” or ..002” (.025 to .05 mm ) without much trouble with a proper setup.. That won’t be noticeable.
    I suppose its possible the headstock shaft or bearings are bad, but I’d try the other things first.

    But part of your your question was whether it would affect bowl turning. With proper steps, it won’t unless it isn’t runout but a worn out shaft or bearings .( not likely if you bought the lathe new) You will be able to rattle the headstock by hand in that case. Some lathes have adjustments that allow you to preload the bearings to eliminate slop. Check your owner’s manual.
    Keep in mind that if you are thinking of bowl turning, you won’t be using the drive center, but rather a faceplate or a chuck. A faceplate,will be better if you do have issues with concenticity.
    You can cancel out any errors with a faceplate that has a sacrificial wooden plate on it. You true up the wooden bit before you attach your bowl stock to it.

    True up the edge , then the face of the sacrificial wooden faceplate with a stiff sanding block on the lathe and then either glue using the paper trick or screw your bowl blank to the trued up piece.

    #743622
    Matt Mahan
    Participant

    Thanks Larry and YrHenSaer – great advice. Very happy to know about the paper joint as I’d not seen that. I have a 4-jaw chuck for spigot turning (that’s actually where I saw the runout first because the chuck really exaggerates it) but I truly may just be over-obsessing. I can turn a fair knob etc off of that, and should be able to do a bowl as well, or using the faceplate. Larry that’s not an adapter – it’s a neat little drive center from OneWay that I really like (they may call it a safety driver, but mine is slightly modified a la the instructional videos from Alan Lacer). Basically it has much less kick when you mess up as compared to a spur driver. But, the tiny runout is evident with my spur as well (although less so).

    Although I cleaned the MT way back, I went ahead and ran a bit of mineral spirits in there and am telling myself it made a difference mostly to feel better 🙂 thanks both!

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