[How do I?] Restore Morse taper in lathe spindle

[Bob Korves]

Another approach to true running centers in the headstock is to use a soft center that can be trued up in place and stamping a match mark on the spindle end and the center so that it goes in to the same location when it is used; this usually ensures that the center will run very close to true. I think that careful use of a morse taper reamer is the practical way to deburr the spindle taper.

With a soft center you can simply make a new skim cut every time you install it, making it 'perfect' every time. That is good for work held between centers, but the internal spindle taper is also really convenient for many other types of tooling. A reasonably accurate spindle taper makes much work go faster.

 

[benmychree]

With a soft center you can simply make a new skim cut every time you install it, making it 'perfect' every time. That is good for work held between centers, but the internal spindle taper is also really convenient for many other types of tooling. A reasonably accurate spindle taper makes much work go faster.

On the other hand, perhaps using the spindle taper for other tooling is what messed up the spindle taper to begin with. On my 19" Regal lathe, I have match marks on the spindle, the spindle sleeve, and the center itself; I used a small "0" steel stamp to do the marking. I generally do not worry about a very small amount of runout on the headstock center, as I mainly turn between centers such work as I plan to finish grind later.

 

[Bob Korves]

On the other hand, perhaps using the spindle taper for other tooling is what messed up the spindle taper to begin with. On my 19" Regal lathe, I have match marks on the spindle, the spindle sleeve, and the center itself; I used a small "0" steel stamp to do the marking. I generally do not worry about a very small amount of runout on the headstock center, as I mainly turn between centers such work as I plan to finish grind later.

I have semi-permanently marked the spindle on my lathe so I know where the bore high spot is. It is about .0008" out. That can be dealt with, or ignored for some jobs. When I get the right size wheel for my tool post grinder I may fix it. In the meantime, it serves to offset the errors of other inserted tooling, which are also marked for high spot.

 

[gasengin]

Here is an update to this point. Using my dial indicator, I checked the spindle bore about 1/4 inch in and found almost no run out. I then used the flashlight idea that someone suggested. I could see two spots about 90 degrees apart that were a point touch on the MT adapter. These were likely from someone bumping the spindle nose when inserting stock in the chuck. I then took a real light cut from the spindle nose that would be like a small chamfer. This took my run out from .005 to .002. Not perfect, but a big improvement. I have a MT#3 reamer coming (not here yet) that I will use to try to improve on there I am now.

 

[Sblack]

There are grinding shops out there that will take your spindle and regrind the taper for you. It is not cheap, but the end results are a nicely ground tapered bore to your needs.

That's what I did with an old Burke mill. I took the spindle out and the machinist indicated on the bearing journals. It cost me $80. Somebody once said that no machine shop foreman ever turned down cold hard cash. I just walked in with my spindle and said " can you do this?". they had a lathe with a huge scale on the compound that allowed precise angles and a tool post grinder. I could see that internal grinding was all this machine did. It worked out very well.