Milling Cutter Run-out - advice needed

>> Thanks Keith, much appreciated. Good of you to carry out these tests.
>>
>> Having spent some more time checking my set up, I've convinced myself
>> that the axis of the morse taper in my machine spindle is slightly
>> tilted with respect to the axis of the spindle. This error adds or
>> subtracts to the errors in the chuck and cutter, resulting in the
>> variation I'm seeing.
>>
>> So the question now is whether to live with the run-out of up to 3
>> thou, or to attempt to re-machine the spindle to improve the Morse
>> taper accuracy.
>>
>> Thanks again
>>
>> Mike

>
>Mike, many (many) years ago I attempted to make a small bench top mill
>using various parts I had about. Having machined the spindle on an old
>Colchester Student I had trouble getting a decent internal finish on
>the 2MT socket. Although as far as I could measure it ran true I just
>couldn't settle with the awfull looking finish. Someone lent me a 2MT
>reamer "just to clean it up" and assured me it would follow the bored
>taper. I attacked the spindle with that and it never ran true again, I
>eventually remade the spindle and learnt to live with the internal
>finish.
>
>These days and assuming the spindle outer diameter is true and the
>spindle is not bent I might be tempted to set up a small grinder in the
>tool post and grind the internal taper. Run the lathe at top speed and
>use the top slide if it has sufficient travel to get the correct taper.
>It takes a little trial and error to set the top slide "just so" but
>I've done it on a small 1MT spindle for a high speed drilling machine
>and after a couple of attempts I got good coverage when tested with a
>1MT drill and engineers blue. The machine is not finished so I can't
>tell you if it has been completely satisfactory. I spent a lot of time
>setting the spindle up in the 4 jaw to run "spot on" and I bet I didn't
>remove more than a couple of thou in total. While I was lucky that my
>lathe spindle was large enough to take the drill spindle I suppose if
>it isn't you could always set it up with the fixed steady and do the
>same thing, just a bit more fiddly.
>
>As Andrew says and Adrian shows, there will always be a little run out,
>If the machine is doing what you need I'd be tempted to carry on using
>it. Of course this a case of "do as I say not as I do" with me because
>if I've spotted something that I'm not happy with I just have to get it
>right. I can't help myself even though I have a pile of experiences
>where the trouble to fix something was far worse than the perceived
>problem. Anyway, good luck whatever you decide to do.
>
>Best regards
>
>Keith