How to repair a spindle taper that's too deep?

[Larry$]

What material would be best for the sleeve?

Something as close to original as possible.
Option G, make a MT3 sleeve that you use only when you need a MT3. Let it stick out. Knock it back out when you want to use the threaded spindle nose. That way it can be thicker and not need to thin the existing spindle more. My lathe came with a reducing sleeve so I can use MT3 accessories. Still have the larger bore to use W/O the sleeve in place.

 

[TorontoBuilder]

You could make a thin tapered sleeve and install it with bearing retaining compound, then bore to the final size/taper.

That way you wouldn't end up with the huge and troublesome #4mt hole...

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The problem with a thin tapered sleeve is potential deformation of the sleeve during machining...

Unless you're thinking to insert a thicker sleeve, bond it to the spindle and then machine a new MT3 taper inside that sleeve to result in a thin inserted section.

This is sort of how I plan to make a 5C adapter to fit a MT4.5 taper, except I will use an internal grinding wheel to bring the 5C taper section to
the finish dimension. If the OP really wants to make the spindle bore as precise as possible I'd say that making an insert and then internally grinding it to the final dimension is the best way to go.


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[Nutfarmer]

The Clausing 6300 lathe had a 4.5 Morse tapper. It had bushings for a 3 Morse taper and a 5 C collet. If I remember correctly it has just over an inch and a half spindle. You could bore it out and then make bushings to fit , but the spindle would be dead on.

 

[markba633csi]

Leave it alone is best I think. You did a good job on restoring it.
-Mark
9 thou to .3 is pretty darn good

 

[WobblyHand]

Leave it alone is best I think. You did a good job on restoring it.
-Mark
9 thou to .3 is pretty darn good

I agree. If you need a dead center to stick out more, can you make a custom one?

 

[strantor]

I agree. If you need a dead center to stick out more, can you make a custom one?

Yes I plan to

 

[redgrouse]

Hi, when i read your post my initial thoughts were the same as Weldinrod's except I would use a parallel bore rather than a tapered one, just max it as large as is practical at the front of the bore without compromising the thread. Fit with engineering adhesive then bore the internal in situ to ensure concentricity, maybe even bore to MT3 and use the reamer for finishing ?
As for material use as close to the original spindle as possible and from your stock probably the latter two would be the best choices, aka bison shaft or keyed shaft.

 

[Weldingrod1]

I agree, start with a tube, maybe 4140 commercial heat treat. Machine the outside taper. Clean both parts. Coat with retaining compound and smack it home. Wait a day or two. Machine/grind to final taper. Use cooling stuff and/or be gentle.

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