Spindle runout - what to do next

[Ben17484]

Hi All,

Some of you may have seen my other threads that identified that my lathe has some pretty bad spindle runout - 0.08mm / 0.003inch. This runout can be measured inside and outside of the spindle.

It was suggested that if I were to make my own chuck back plate on the lathe itself, the backplate runout would mean that the only runout measurable would be down to the chuck itself. If my understanding of that is true, my question is this: if I make my own chuck backplate for my 3 jaw chuck and make my own ER32 collet chuck (that fits directly to the spindle) - will the spindle runout become a non concern? Or will I go through this effort of creating these back plates to find out that I’ve another issue further down the line? Like if there’s wear now, will the wear get worse and I’ll start seeing more runout.

Sorry for the vagueness of the question, but I don’t feel I have enough knowledge to ask the question in a more constructive way.

Thanks In advance.


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[mickri]

Even though I have had my lathe for a while I am still pretty new to machining. My understanding is that run out is only a problem if you have to remove the work from a 3 jaw chuck to do something and then when you put it back in the 3 jaw chuck you loose concentricity. If you are using a 4 jaw chuck you can dial the work in to maintain concentricity. Spindle runout is not a problem.

I have never measured the runout on the spindle of my lathe or any of my chucks. Why bother. Even if there is runout in the spindle or the 3 jaw chuck when you turn the work it will be round with no runout. As a test turn something in your lathe. There will be runout before you start but there shouldn't be any runout in the finished part.

 

[Ben17484]

Even though I have had my lathe for a while I am still pretty new to machining. My understanding is that run out is only a problem if you have to remove the work from a 3 jaw chuck to do something and then when you put it back in the 3 jaw chuck you loose concentricity. If you are using a 4 jaw chuck you can dial the work in to maintain concentricity. Spindle runout is not a problem.

I have never measured the runout on the spindle of my lathe or any of my chucks. Why bother. Even if there is runout in the spindle or the 3 jaw chuck when you turn the work it will be round with no runout. As a test turn something in your lathe. There will be runout before you start but there shouldn't be any runout in the finished part.

Thanks Mickri.

It my understanding as well that the issue is only when taking work out and putting it back in. I thought there must be something more to it than that, as when googling, in different forums I’ve seen people say that any lathe with more than .002 inch runout is junk. So this made me think there must be more to it than I know.

I’ve a good 4 jaw chuck, so I can dial the work in ok if I need to take it out and remount it.

I guess making an ER32 collet holder than is concentric with the spindle would still be a good idea though as my understanding of collets and their advantage is repeatability?


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[jwmelvin]

It depends on the runout source. A bent spindle, for example, isn’t an issue if you true the work first and keep it mounted. That’s because the runout repeats each revolution.

Rolling-element bearings, however, can (often?) have runout related to the rolling elements, which will not repeat every revolution. That kind of runout will not allow precise work, even with a single setup.

You should be able to determine if your spindle runout correlates with rotation.

 

[mickri]

Do a test like I suggested. Turn a short piece of steal and measure the runout.

 

[Huub Buis]

Not only measure the runout but mark the chuck for the high point of the runout. Than measure if the part turned is round.
Remove the part and place is back in the chuck rotated 90° and repeat above 3 times.

If the parts turned are round, the runout is always at the "same" and always at the "same position", than making a backplate will decrease the runout of the chuck.

When in doubt, take a thick piece of aluminum and make the backplate. It will not last forever but you get a pretty good idea of the result and it is a good turning exercise. Once it is worn or damaged, make a new one from steel.
My aluminum backplates for my collet holders of my mini lathe are still OK even after 10 years of (hobby) use.

 

[mikey]

Hi All,

Some of you may have seen my other threads that identified that my lathe has some pretty bad spindle runout - 0.08mm / 0.003inch. This runout can be measured inside and outside of the spindle.

Ben, you will save yourself a lot of grief by making sure you measured what you thought you measured, meaning the amount of spindle runout is really what you think it is and that it is coming from where you think its coming from. Try taking a look at post #8 in this thread and see if it helps you. Then go from there.