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Myford ML7 Headstock Project

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  • Myford ML7 Headstock Project

    I just picked up a Myford ML7 but it has a few issues, headstock bearings are bad, back gears all have broken teeth and change gears are missing. I don't want to put the money into buying gears and bearings for a lathe that is limited by a too small spindle bore so I am looking at other options. I am thinking of a project and looking for opinions so here is the first question. Would needle roller bearings work on the spindle? If that can work, I will look at step 2 which is making a new spindle with a little bigger bore. I was thinking to use the lathe as it is to make a new spindle from thick walled stainless pipe or solid stock. I will not be using the lathe for cutting threads so I could also add electric power to the lead screw, this will eliminate the need for change gears.

  • #2
    I had an ML7 for a while. My advice would be to sell it to someone that would like the challenge of refurbishing the machine since you clearly feel that it is not what you want to end up with even before you start using it. I don't mean this harshly either. You seem to already know that it would be too limiting so you may as well move on and get a machine you can grow with instead of putting a lot of time into a stop gap solution.

    My thought would be to either do a babbit bearing to replace the existing bad bearing or to consider getting a big piece of bearing bronze and turn a tapered main bearing and a matching tapered press fit cone for the head stock shaft to upgrade at least this portion to be more like a Super 7. That way the play can be easily tuned out of the lathe.

    If I had kept mine that was on the list as the one I had suffered from a slight beaten up and looser than idea main bearing too.

    But of course all this requires a lathe to do the modifications/repairs

    I suppose a first step would be to take the machine apart and start by seeing what the sizes are. And how far the caps would need to be shimmed to be truly round in all ways. Then shop for suitable bearings.
    Chilliwack BC, Canada

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    • #3
      If you make a new spindle, I don't know how you will avoid cutting threads unless Myfords are a LOT different from other machines I have seen.
      CNC machines only go through the motions.

      Ideas expressed may be mine, or from anyone else in the universe.
      Not responsible for clerical errors. Or those made by lay people either.
      Number formats and units may be chosen at random depending on what day it is.
      I reserve the right to use a number system with any integer base without prior notice.
      Generalizations are understood to be "often" true, but not true in every case.

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      • #4
        Older ML7's had sleeve bearings, newer ones had angular contact bearings I believe. Here's someone selling the angular contacts: https://www.ebay.co.uk/itm/New-Myfor...UAAOSwfQVdDNQ0

        And here's the bush version: https://www.ebay.co.uk/itm/New-Myfor...8AAOSw8BNdCMLX

        You can also find replacement back gear parts: https://www.ebay.co.uk/itm/MYFORD-SU...kAAOSwbb5eOYJA

        Ian
        All of the gear, no idea...

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        • #5

          Click image for larger version  Name:	IMG_1732.JPG Views:	0 Size:	146.0 KB ID:	1868825
          I tried this a few years ago with a "spare" spindle (previous owner had forgotten to stop boring so the MT2 taper was mostly missing!). Used a Koyo HJ- 202820 Needle roller bearing (1.75" OD and 1.25" ID) and made two Delrin oil seals as shown.

          It was an abject failure because there is too much play in this type of bearing. One would need to have an ID about 0.002" larger (or a little more) to eliminate play.

          I currently have twin thin wall bearings in a cartridge that are preloaded. Had to turn the spindle down a bit and I fitted an MT2 sleeve into the bore after boring it out. Much better performance.

          Geoff
          Last edited by ammcoman2; 04-15-2020, 10:21 AM.

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          • #6
            Hi Gremlin have a look at this link https://www.model-engineer.co.uk/for....asp?th=127838 there are some internal links there as well. It is rare that your white metal bearings are completely shot unless they have been run dry and melted ! on these machines there is usually a shim pack under the bearing cap so that you peal off a shim and re-scrape the bearing to fit [from and rear of course] There has just been an article in a UK magazine about doing this, if you want a copy message me with your email and I will scan and send it.

            Conversions have been done fitting angular contact bearings, I don't think needle roller bearings would work at all -- the wrong type of bearing for this application.
            The backgears are another story, plenty available this side of the pond in good used condition if you check out ebay -- if you bought the machine at the right price it may be worth fixing it and then sell on ???
            Regards John
            Knowledge withheld is knowledge lost

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