The next step was rebuilding the failing spindle. I've been uncomfortable working on the spindle in the past as it requires a lot of care and precision as well as some tools that I don't have (arbor press, bearing pullers, etc.). That being said, my current setup has significant notching to the bearings and runs very hot and loud. They need to be replaced.
Prior to starting work, I made a set of tools to disassemble the spindle, press the bearings on and off, and get things adjusted correctly. If anyone wants a rough set of drawings for their own use, I'd be more than happy to make them up. I think the job was much easier with these.
Pin spanner for removing the lower bearing retainer
Deep pin spanner for adjusting and removing the spindle locknut (sometimes called an adjuster nut)
Various rings to press bearings
Tool to knock out the upper quill tube assembly
I began by removing my old AC servo, belt, and pulleys. From there, the drawbar could be removed and the entire lower section of the spindle drops out. There was a touch of surface oxidation on the spindle housing, but otherwise it looked really good. At this point I could tell that the angular contact bearing pair on the spindle itself was the source of the notching, and the upper quill tube bearings spun smoothly (I still replaced them since I had purchased new bearings). I used an aluminum disc and a deadblow to knock out the quill tube.
I removed the spindle head casting to fill a few holes with epoxy. I have designed the new belt drive to be "air-tight" to reduce the audible noise from the system.
There was a little porosity due to using JB Kwik, but it won't affect the final product.
Next I worked on removing the quill tube bearings. Many youtube videos show people popping these off with a pair of screwdrivers no problem, but my experience was different. After an hour of getting nowhere, I put it away for the night and went to Harbor Freight to get a 3 jaw gear and bearing puller. I made a quick tool to go on the end of the quill tube so the bearing puller had something to push against, and viola, the bearings came right off. I highly recommend the $20 to have one of these in your tool box for times in need.
Quick tools don't have to be pretty.
Since I don't have any kind of press, I use my lathe to apply pressure to press parts together (pressing against the side of my toolpost). Pressing the bearings for this project is about the most force I'm comfortable applying with this method. Using a machined aluminum disc and a piece of scrap tubing, I was able to carefully press on the new bearings and reseat the snap ring.
I'll save my angular contact bearing woes for the next post.