View Full Version : correcting mill spindle runout

18-01-2009, 03:57 PM
The run-out on my mill is measuring about 0.1 mm, I've checked it with a few other tools I think I've narrowed it down to the taper inside the spindle.

I've cleaned out the spindle bearings and this improved things a tiny amount, but this is really stopping me from squaring the machine / head properly; this is also evident in the poor finish Im getting.

I've also found that the taper is only in contact with the lower 50% of the tool, is this going to be a contributing factor?

As I only have the Mill, my options are a bit limited, but Im currently thinking of getting a MT3 reamer to centre things up a bit, are there any other idas/ways to approach this problem?

Thanks in advance,

18-01-2009, 04:08 PM

What type/brand of mill are we talking about?

18-01-2009, 04:16 PM
Its an XJ20, I've had it for 2-3 months, and so far spent most of my time cleaning and adjusting it :)

18-01-2009, 04:26 PM
Its an XJ20, I've had it for 2-3 months, and so far spent most of my time cleaning and adjusting it :)Personally if its only 2- 3 months old and you bought it new I'd get the vendor to deal with it - it shouldn't have a problem of that nature.

It could be a bit of dirt in the taper tho. What you could do is get some engineers blue and put a very fine coating on a taper then draw it into the spindle. Carefully drop it out again and see if there's any obvious marking where the blue has been rubbed off... 0.1mm is 4thou and you should be able to do better than 1/2 of that at least.

I'm assuming here that the tooling is pulled in by a drawbar? If so, how tight do you go?

18-01-2009, 06:43 PM
Yes, I'll try the vendor; As its a budget machine, I was kind of expecting a few inaccuracies.

I will try you suggestions with the blue to see if there are any patches inside the taper - Thanks.
Yes this is with a draw bar, I tighten it as much as possible - it will only come back out with a few taps with the hammer.