How to accurately bore a milling spindle on an old lathe

[Roger HartParticipant @rogerhart88496]

I am making a milling spindle (2 inch block+2 taper rollers+centre-turned shaft) and wish to bore the shaft Morse Taper 2.  My lathe is a pretty old flat-belt job and I want the taper as true to the taper roller CL as possible (and not wobbly either).

 

Am I better off boring the taper in the 4 jaw (set true as well as possible) or would I be better off setting up the roughly bored M2 taper in the milling spindle as a sort of pseudo-chuck using its own block and taper roller bearings and pulley and then finish boring it??

 

Oh,  and not spending money either!

 

Roger H

[Roger HartParticipant @rogerhart88496]

[Peter TuckerParticipant @petertucker86088]

Hi Roger,

 

I would suggest boring the spindle in its own housing and bearings

 

Good luck.

 

Peter.

[jomacParticipant @jomac]

Hi Roger.

What if you brought a set of morse taper reamers, they are cheap on E/bay,  and ream the shaft   insitu using a properly aligned holder.  And then check with a good dead centre that you know is accurate. or if you have them, a  set of collets, fitted with an accurate point, or clock a piece of drill steel while this is set up in position. It probably means making some sort of jig to get everthing in line, Best of luck.

John Holloway

[John HaineParticipant @johnhaine32865]

Another way to do this is to make a double-ended MT2 arbor – ie 2 make tapers back-to-back (assuming your lathe h/s is MT2 as well). It may be possible to do this by joining two off-the-shelf MT2 arbor blanks, but I made mine from scratch.  You first chuck some 3/4 free-cutting and turn the best MT2 taper you can; then remove it from the chuck, remove the chuck, and mount the workpiece in the h/s socket by the taper, holding it with a drawbar.  Now turn the second taper MT2 and also drill and tap for a drawbar.

 

Then bore an MT2 hole in the spindle stock material and ream it to size/finish.  You then fit the double-ended arbor in the h/s, and mount your blank spindle on the end sticking out, hold it by a drawbar (ie.a bolt) and turn the outside to be concentric with the MT2 socket you just made. Sounds long-winded but it didn’t take me too long and it all worked.  If I can find it I could lend you the double-ended arbor I made?

 

John.

[Roger HartParticipant @rogerhart88496]

Thanks to all.  Clamped block to lathe bed and did final cut using the spindle’s own bearings then used taper reamer pressed in by a flat-ended tailstock.  Worked very well,  max runout about 0.5 thou.  One problem.  Found taper reamer had cut a little too deep and had to machine 1/4 inch off the nose – lucky I had made this a bit long anyway.  I have used John’s technique in past and that can work well too.

 

Roger

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