Problems with the grinding spindle

After I had the machine back together, I realized two problems with the grinding spindle:
  • I had only one hub for the grinding wheels that was in very bad shape
  • The spindle taper had a total runout of about 2/10mm
  • The machine is designed to take grinding wheels from 100 to 125mm diameter, thats also the size of wheels I can use on my tool and cutter grinder. So I decided to remachine the taper on the end of the spindle to be the same as on the t&c grinder.
    I chucked the spindleshaft in the lathe, machined down the bent taper end and glued on a steel bushing with Loctite 648. After the Loctite had cured I machined the taper to fit the wheel hub of my t&c grinder.
    To get perfect runout on the taper, I put the spindle back together and set the compound slide of my lathe up on the magnetic chuck. After everything was aligned properly, I did a final finishing cut on the taper, with the spindle running in its own bearings:

    Thats the finish I got on the taper. The steel I used for the repair bushing was 42CrMoS4, a pretty tough steel, even without additional heat treating:

    Now I can use the wheels and hubs from my t&c grinder on both machines: