Question about Run-out.

[ddickey]

Question. If I have a MT3 stub arbor and turn the stub down should I have the same run-out as my spindle? The spindle has ~.0005" run-out.
The reason I ask is that I made an MT3 stub arbor and got .008" run-out on the stub.
I don't understand where this is coming from.

 

[JR49]

Question. If I have a MT3 stub arbor and turn the stub down should I have the same run-out as my spindle? The spindle has ~.0005" run-out.
The reason I ask is that I made an MT3 stub arbor and got .008" run-out on the stub.
I don't understand where this is coming from.

I'm assuming the MT3 part of the arbor fits directly into your spindle. If you had a good fit with the arbor in the spindle taper, and you turned the stub correctly, it should be perfectly (or close to) concentric with the spindle axis. Something else must be wrong. After turning the stub down, did you remove the arbor from the spindle? If so, and the MT3 taper you cut isn't perfect, then when you put the arbor back in, all bets are off as to concentricity. You need to give us more info, for us to help you. Or, possibly someone else more experienced, will answer. Good luck, JR49

 

[David S]

I would carry on with JRs thought and repeat the runout check with the arbor placed into the spindle at different positions. Mark the spindle and the arbor and then check it. Remove, rotate arbor 90degrees and repeat.

David

 

[Billh50]

Mark the arbor with a magic marker or scribe line. Check the run out. Then remove the arbor and turn it 180 degrees. Put it back in and check run out again. You may be able to find a spot where the arbor runs perfect. If so just put an alignment mark on both the spindle and arbor. That way it should run true every time you put it in aligned.

 

[4GSR]

Are you sure both tapers were perfectly clean and no burrs? All it takes is a minute size chip get caught in the tapers and will throw you off by .008". The two tapers should wrung together smoothly with no gritty feeling.

 

[willthedancer]

You may need to check your taper with some spotting dye (high spot blue). To wring the tapers true means they both need to be perfectly clean and free of dings, dents, chips, pet fur, and any other unmentionable obscenities. If the spindle taper runs true, and the tapers are clean and in perfect condition, then the runout is a concentricity error on the stub.

 

[ddickey]

I will continue with this at a later date. Had some issues with the lathe cutting a taper so it is unleveled now and trying to figure out what to do next.
I have a quite unleveled garage floor.