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  1. #1
    Join Date
    Nov 2010
    Location
    Frankston south
    Posts
    102

    Default Headstock replacement

    Hi, I've been lurking for a while now, reading post's getting the feel of the place, trying to figure out stuff.....So I guess it's time to say G'day and get some opinions (always interesting) and or advise.
    I own a couple of Hercus's, one is a 1945 thereabouts VB that has been upgraded to A spec's and a 1963 ish model A. The latter machine is a fairly recent acquisition and in surprisingly good nic except for the Headstock. Please bear in mind that I have not pulled the headstock down for inspection yet, the story so far is that there is no play and all looks good except that it looks as thought the front bearing cap is sans shim and closed up tight . So speculating the worst the headstock may need line boring and bushing or do I replace the assembly with a roller bearing number (I posses)?
    What sort of issues or actions need to be done if the headstock is replaced? Are there alignment issues? Would it have to be scraped in or do you just bolt it on and check the Lathes alignment and shim to suit?
    Yeah I know lots of questions but it's all new territory for me.
    I haven't as yet had this machine going, so far it has just been given a good clean, disassembled the slides cleaned, lubed and adjusted where necessary, I particularly want to do this one right as the ways and everything else are pretty good, running a test indicator along the bed revealed less than 0.0015" variation over it's length.
    Anyway I've prattled on enough, hopefully someone will take the time to offer an opinion.

    Cheers
    Wayne

  2. #2
    Join Date
    Oct 2004
    Location
    Southern Highlands NSW
    Posts
    1,894

    Default

    Hi Wayne,
    I've never done it so it's just armchair speculation, but my thinking is that it's practical to change a headstock, but not to shim it. It'd be very difficult and untidy because of the mix of flat and V ways, and not necessary. The headstock fixes the spindle position so make that your starting point. The other things guided on the bedways are the saddle and tailstock. The saddle is no problem I think, because whatever variation there is, the normal tool movement controls compensate. It might be an issue if you changed the saddle to a different bed, because the front slide fitting thickness might differ slightly, but we're not talking about that in your case. The tailstock can be adjusted by the setover screws in one direction, and by either shimming or machining in the other, at the horizontal joint faces.
    I've never heard of a plain headstock modified to fit roller bearings, don't like your chances but it's probably not hard to find a roller bearing headstock. Unless you want the higher speed capability of frictionless bearings, getting a plain headstock in better condition than yours is a good option. My 1947 plain bearing model has no spindle play, and lots of adjustment left. Amazing that the shim gap on yours has been closed up - sure it's not got some shims stuck in place that you can pry loose?

    Jordan

  3. #3
    Join Date
    Oct 2007
    Location
    Sydney
    Posts
    3,112

    Default

    Wayne, I feel if your spindle has no play in it the best solution is simply to leave it as is. If/when the play becomes excessive then it may be time to search for solutions as you suggest.

    Pete

  4. #4
    Join Date
    Aug 2007
    Location
    Melbourne
    Age
    68
    Posts
    1,410

    Default

    > What sort of issues or actions need to be done if the headstock is replaced? Are
    > there alignment issues? Would it have to be scraped in or do you just bolt it on and > check the Lathes alignment and shim to suit?

    Wayne, I am not sure about Hercus, but usually first the bed is perfectly levelled to have a reference surface to work from.

    Then the headstock gets scraped to the bed to ensure spindle centerline is parallel to the bed. The tolerance for this is extremely small, because any error would result in turning taper.

    Once the headstock is parallel to the ways, its center height is measured and a Tailstock selected that matches this. Easy enough at the factory where a few dozen tailstock ready for assembly can be tried and matched. If you have unly the one tailstock, if it is high you can grind it between the upper and lower casting. But if it low its not a nice job to shim.

    Trying to scrape the headstock to be parallel in x and y plane to the bed AND to additionally match center height of an existing tailstock, is quite a challenge with unsure outcome.

    Given all this work, it is best to avoid changing headstock if any posssible. If it still works, why fix it?

  5. #5
    Join Date
    Nov 2010
    Location
    Frankston south
    Posts
    102

    Default

    Ok, thanks for the reply's.
    I have had a better look at the headstock and have decided I need new glasses the front cap's shim is hidden by the factory paint, so it's still there and going strong, yippee.
    So without the Lathe bolted down I gave it a test cut and it appears to be cutting a slight taper, 1 thou over 4" distance. I wont worry about that until it is mounted and leveled which is after I put a VFD on it and source a 1 horse motor that can be wired for 230.

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