Thread: lathe spindle runout

Ouch! Thats something I would do Andre!

Simon

OUCH, hope it doesn't hinder you in sorting the lathe out. How loose was the nut?.
Kryn

So this weekend I put an indicator on the spindle and I have 0.02 mm on the chuck on mounting and it seems to no repeat. I then used my newly acquired MT5 test bar and I have the 0.03 and the chuck end and .26 mm at the tailstock end but oddly the runout is 90° from the chuck side. Do you think it may be the bearing causing this problem or is it something more simple?

Originally Posted by KBs PensNmore

OUCH, hope it doesn't hinder you in sorting the lathe out. How loose was the nut?.
Kryn

It was fairly tight but after I tightened down the nut the noisy gear quieted right down and the vibration level halved.

Originally Posted by welder

So this weekend I put an indicator on the spindle and I have 0.02 mm on the chuck on mounting and it seems to no repeat. I then used my newly acquired MT5 test bar and I have the 0.03 and the chuck end and .26 mm at the tailstock end but oddly the runout is 90° from the chuck side. Do you think it may be the bearing causing this problem or is it something more simple?

Is there a small ding/burr on the inside? Something that small an amount you possibly wouldn't see or feel it, try putting the test bar 90 deg and see if the reading comes at the same place or moves, just as a test?
Kryn

Isnt there 2 locking nuts,didnt you use 2 C spanners.

Originally Posted by pipeclay

Isnt there 2 locking nuts,didnt you use 2 C spanners.

No one lock nut held on with grubscrews. The smart man would have put a spanner on the chuck

Originally Posted by welder

So this weekend I put an indicator on the spindle and I have 0.02 mm on the chuck on mounting and it seems to no repeat. I then used my newly acquired MT5 test bar and I have the 0.03 and the chuck end and .26 mm at the tailstock end but oddly the runout is 90° from the chuck side. Do you think it may be the bearing causing this problem or is it something more simple?

You should have push/pull adjusting bolts for the whole head of the machine. Lathe heads have a tendency to move after accidental tools hitting chucks and so forth. As for the vibration, the issue may be the main head bearing if you already have taken up all the thrust

Originally Posted by welder

The smart man would have put a spanner on the chuck

Or selected a low speed gear. Yes, I am talking from experience here too buddy. Gears are not very forgiving. Then again not much is in our sheds. I'm almost too embarrised to mention this but since we are on the topic of smart things to do, I was fooling around adjusting the wheel height on the surface grinder, spinning the wheel by hand in an attempt to find the height just as it touches the surface, when the momentum of the wheel and spindle grabed my finger and tried to squash it between the wheel and mag chuck. I am idiot! A smart person would just use a feeler gauge or some paper!

Now, wrt your runout. I would be marking with a texta on the chuck where the runout is and then taking it off and placing it in another position. Is it a D1-4? try all 3 locations and see if the runout is the same on the chuck or same location on the spindle. Look for swarf or other "stuff" that shouldn't be on the taper on the spindle and chuck. Don't forget, chuck runout does not necessarily mean it's caused by spindle runout. Also, Remove the test bar and re-position to see if the runout moves.

Have you measured the runout just on the front of the spindle or inside the taper? That is what ultimately counts I would have thought.

Try putting a piece of bar in the chuck say 30mm diameter and 200mm sticking out. Put a DI on the chuck and see how much it moves when grabbing the bar with your hands and puting some upward & downward force on it.

Hope I have helped but I think your level of expertise exceeds mine anyway.

Edit: ignor half my post as I just re-read your post! I smart person would have remembered what you already tried!

Simon

Andre,

there sometimes is a little brass piece between the grub screw and the spindle, to avoid the grub screw marring the spindle thread. Do not loose that brass piece. Sometimes the grub screw is secured with paint. Sometimes there are two grub screws in tandem.

As someone said before, the slightest dent or dirt betwen test bar and spindle taper can cause very false runout readings.

Under NO circumstances touch the bolts that hold down the headstock!!! Not until you have verified several times over and are 100% sure that the headstock alignment is off. On low cost lathes it can be a nightmare and very very time consuming to realign the headstock!!!! It can be a can of worms that ends at having to shim or scrape the tailstock to match the new headstock height after touching the headstock hold down bolts. Do NOT assume the headstock is scraped to the bed ways like on 5 times more expensive lathes. It most likely is not scraped, but instead only torque shimmed.

You can slowly increase bearing preload, but watch carefully headstock temperature. As you increase preload, there is a point when suddenly bearing temperature runs away and keeps rising and rising. The ideal preload is just before this condition occurs, at maximum rpm and good lubrication. The headstock should get quite warm after running 1/2h at full speed, but not hot to touch.

Interested in this thread... So what is the acceptable tolerance here? I also purchased an AL-960B (albeit 6mths ago...) and just came across this thread and wanted to test mine.. I have a manual and I know the it states we should pre-load the spindle until the dial indicator stops moving on the face of the spindle, however I'm getting approx 0.0015" runout on my chuck circumference with no lateral movement at all without resetting the pre-load. It runs loud as hell and I've been under the impression I should be saving up for a set of new bearings for the spindle as that seems to be where the bulk of the noise is.
My other problem is my lathe is in the garage next to where my daughter and wife sleep, so I can't go running it at all at night... Might get an hour or two on the weekend if I'm lucky.
How did the OP go with fixing the runout on his machine?

Hi MOA,
Welcome
I wouldnt be worried about 0.0015" run out on the chuck just yet. Have you move the chuck to all three positions? does the run out move with the chuck or stay in the same place relative to the spindle? If it moves with the chuck I'd say you have nothing to worry about. If says with the spindle you'll need to look a little deeper.
Are the bearings getting hot?

As far as noise goes, I doubt its from the bearings(unless they aren't getting any oil) move like just gear noise, do you have the change gear train disengaged when you're listening?

Stuart

Thanks for the advice Stuart.

Looks like the high and low points follow the chuck positions. Lucky me
I haven't noticed the bearings getting hot at all, but I really haven't spent as much time as I'd like working on it. I'll have to run it tomorrow after work to see how hot it gets.
The bearings are getting plenty of oil (don't ask how I know lol) I have already thought of that. I think you're right though, it's probably just standard noise, nothing sounds out of place, I just wish it were quieter so I could run it all night.... No. Gear train's not been disengaged. I'll compare the noise levels tomorrow.
Cheers

You may also find that your geared head lathe will have less gear noise when it is driven under load.

Simon