Heald Red Head 405 Rode hard and put away wet
Heald Red Head 405, 25,000 RPM, oil mist lubrication, belt driven
This vintage ID grinding spindle was still spinning freely when it arrived at our facility, but our comprehensive dimensional evaluation disclosed the extremely poor condition of nearly all critical surfaces of the major components. We measured runout of >20µm in the ID of the quill pilot, and >15µm on the pilot face. Both the front and rear 25mm bearing journals were worn undersized two to three times the ISO specification. The pulley journal had a whopping 60µm runout when measured on the bare shaft. Not surprisingly, the 52mm rear housing bore was also severely fretted, out of round and worn oversized up to 5x ISO. One could assume that the excessive vibration during operation would have precluded this spindle’s use for any sort of precision ID grinding application.
The shaft and housing made the short trip to our in-house machining & grinding section, where we ground the pilot ID, bearing journals, pulley journal and rear housing bore to prepare them for plating with hard chromium. When the components were returned to us by our plating vendor, we put them back on our in-house cylindrical grinding machines to finish to size. While the shaft was up on one of our Kellenbergers, we also kissed the pilot face to reduce the runout. All of the shaft surfaces were finished to 1-2µm runout with the exception of the pulley journal where runout was reduced to 4µm. The rear housing bore was tightened up to the middle of ISO spec. We rebuilt the spindle with all new bearings, seals and assembly screws. We finished this rebuild with our final test run, break-in, trim balance and final QC. Now our customer is able to use this spindle for any appropriate precision ID grinding application they choose.