1. Most likely taper in your spindle is not made correctly – will need reboring. This is to address horrible runout of dead center. If it is really 3mm spindle may actually need *remaking*.

2. Bearings will need replacement and/or rescraping. Installation of chuck increases runout – worn out bearings.

Bent spindles are very rare and 3mm runout on dead center in the spindle taper combined with relatively slight runout on spindle nose suggests something else.

Martin

Something silly has happened. If it was running well before and doesn't now, by what is obviously a gross degree of error then it cannot be a fault with the spindle which will have been set aside while painting took place.

You have forgotten to fit something perhaps, Can you shake the spindle about or has it collected some foreign object in the bore in the interim? Common sense says it has to be something of that kind, major faults just don't happen in this way

I would definitely hold off on reaming or anything drastic, I'm sure such work is completely unnecessary

Brian

Edited By Brian Wood on 24/03/2018 19:20:49

If you have not missed anything during re-assembly and it's set up correctly maybe the question is have you included something that shouldn't be there like a bit of swarf or some other foreign matter? As Brian suggests.

Edited By Martin W on 24/03/2018 23:21:21

If everything was running true before disassembly obviously something has gone awry on reassembly .

Are you 100% certain the bearings went back in exactly same way / orientation they came out ? Was there any operations on the spindle that required a press like having to press a pulley off or on etc ? Did you use any substantial amount of heat on anything ? I would set the spindle up on some v blocks and check it for straightness and if the bore is running out .

Before you go machining anything double check everything as machining the spindle bore should be a last resort .

Is there any tight spots when you rotate the spindle by hand ? If it were bent i would think there would be one hell of a tight spot !

When you indicate the taper in the spindle bore push the spindle back towards the rear of the headstock with with your hand as you rotate the spindle to ensure any endfloat is taken out of the equation .

Lastly the centre you used have you used it before ? If not is there the possibility that it came of a different lathe and may have been machined to run true on that machine ?

Is your Grayson one of the models where the headstock is held by three bolts and detachable from the base?

If it is, and you dismantled it, are you sure the spindle is on the centreline of the lathe when you put it back together?

Have you cross-checked with a different centre?

Shafts can bend spontaneously due release of stress's. I worked for a large sugar mill and we removed a very large old lathe, which twisted to hell when we undid all the bed bolts. Also long carnakshafts have to be stored vertically to stop them twisting.

No problem Brian, I probably didn't make myself clear anyway

Set your spindle carefully in another lathe and make sure it turns true on external diameter close to chuck, in the middle and far away.

If you succeed then spindle is true. It is impossible to achieve it with a bent one.

Once done insert test bar into taper socket and check with DTI both ends of the test bar.

If the bar "wiggles" then your taper socket is surely misalligned. If it doesnt then you are not reasembling your spindle correctly.

Another approach is to install a chuck in your existing spindle mounted in the lathe.

Then grab test bar, eg 1 inch diameter linear bearing bar in the chuck and allign it true (make sure chuck grabs it straight). Make DTI readings on both ends of bar, close to chuck and close to far end.

If you get the same readings your spindle must be straight. Now insert test bar with tapered end into Morse socket of the spindle.

If wiggling increases with distance (towards end of test bar) *and* your initial test with test bar was OK then tapered socket is *definitely* misalligned and need correcting.

Martin