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Acceptable runout from lathe spindle adapter?

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  • Acceptable runout from lathe spindle adapter?

    My L00 spindle has, what in my shop passes for zero run out. When I insert the 5MT to 5c adapter I have, the runout measures .003

    This is a ground adapter from a reputable company. I bought it new. Changing it's orientation in the spindle does not affect the runout.

    Par for the course?

  • #2
    No. Return it. Runout should be under 0.001 inches.

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    • #3
      wow, I think that is a terrible amount of runout. between centres should be the most accurate approach. You've measure runout in the spindle and checked for burrs and bruises etc?

      I'd return the adapter (assuming you just bought it) and go with the centre in the three jaw turned in situ trick. The runout is always that of that of the spindle bearing, can't get any better than that. I never set up a centre in the adapter for that reason....although I can see where a very large work piece would need it and the drive plate
      .

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      • #4
        Not unheard of lathe spindle bore morse taper to have dings and burrs... so thats what I would be checking first.

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        • #5
          Before you return it, check the spindle bore carefully for swarf.

          Thin aluminum swarf sticks easily to the inside of the bore and is nearly invisible, especially if it's been smashed flat by a morse taper being seated.

          I have a nicely ground 3/4 inch square x 6 inch lathe tool bit that is great to feel for high spots when swept across a flat surface. It works for tapers too. It bumps into raised areas but does not mar the surface.

          Dan
          At the end of the project, there is a profound difference between spare parts and extra parts.

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          • #6
            Does your indicator it give you a reading of .006" out?

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            • #7
              Spindle is clean, adapter is clean and smooth. Changing the adapter location in the spindle and getting exact same reading at the same place on adapter clears the spindle of suspicion to my thinking.

              digr I am just placing a dti on the inside of spindle and also adapter and rotating spindle. There's a spot on the adapter that reads .0035 regardless of how the adapter is oriented to spindle. Moving indicator fore/aft has no affect. So I guess I muddled my terminology and the runout is half that..

              It's very precise in it's inaccuracy. A bit unnerving to have a spindle measure out so well, then add something and have it go to pot.

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              • #8
                If you're also checking your MT bore 'fore and aft' and it reads as good as the front, then I'm with those who say 'send it back'. I don't know what you consider a reputable company, but if the adapter is of US or European manufacture (and usually Taiwan too) then you should expect much better.

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                • #9
                  Originally posted by softtail View Post
                  Spindle is clean, adapter is clean and smooth. Changing the adapter location in the spindle and getting exact same reading at the same place on adapter clears the spindle of suspicion to my thinking.

                  digr I am just placing a dti on the inside of spindle and also adapter and rotating spindle. There's a spot on the adapter that reads .0035 regardless of how the adapter is oriented to spindle. Moving indicator fore/aft has no affect. So I guess I muddled my terminology and the runout is half that..

                  It's very precise in it's inaccuracy. A bit unnerving to have a spindle measure out so well, then add something and have it go to pot.
                  I was going to ask about how the runout moves around but you covered it with this post. And that pretty much seals the deal on it being a bad adapter.

                  Ideally you can return it for a replacement. But if that isn't an option then you may as well see if it is tempered back far enough that you can skim the 5C cone to true it up. And at the same time reach in with some manner of extension for the indicator to see if the parallel section deeper in is running true or if it has the same runout. Skimming the cone true is one thing. But if the parallel rear portion needs to be opened up that's a bit of a deal killer.

                  If it's too hard to use a cutting tool then do you have a tool post grinder or could you rig up such a thing?

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                  • #10
                    I'm with BCRider. The .003 is way too much. If the back end is within a thou. or less, you can just set the compound slide to the front angle and clean it up with a carbide boring bar. I've done similar several times. For best results, take several spring passes. Then you will have very nearly zero runout.

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                    • #11
                      ...on the other hand if the 5C is out by the same .0035" at the rear portion as it is at the conical part indicating that the axes are shifted but parallel I'm thinking that by the time it's cleaned up it'll be too wobbly for good work anyway. In that case it's not bad as a paper weight......

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                      • #12
                        Thanks for opinions guys.. I'll contact the manufacturer before I try to monkey with it.

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                        • #13
                          Mark the adapter, stick it in the taper, and turn it some to see how many areas are contacting. Might find something.
                          Andy

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                          • #14
                            Originally posted by vpt View Post
                            Mark the adapter, stick it in the taper, and turn it some to see how many areas are contacting. Might find something.
                            Yes, planning on doing that.. has to wait till monday. Will also mic it and see if I can detect an increased thickness where my dti was reading high.

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                            • #15
                              Just thinking on this a bit more....

                              Naturally the first plan of attack is a replacement.

                              But if that does not work I'm now thinking that you would want to true it up on the outer MT5 portion instead of skimming the 5C side of things. My reasoning is that if the parallel portion inside the adapter for the tail of the collet is out then skimming it true will result in too much play and make the adapter useless. But if you can turn a stub of metal in your lathe to a nice true 1" diameter and slip a 1" 5C collet over that and then the adapter over that and lock it all or use the tail stock with a bullnose live center or some other method to lock it all together then you could skim cut or skim grind the MT5 taper into true and you'd be off to the races.

                              Otherwise if they won't take it back I'd say you've got yerself a paper weight as I suggested above....

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