Cleaning up the gear reduction stage

This is the only part of the head I haven't overhauled yet. Once the pulley housing had come off, there was a circular cover over the gear housing.

This revealed the gears that I removed yesterday.

The output gear is captive, presumably held in place by a bearing housing that is in turn held in place by bolts hidden under all this nasty grease:

So I need to clean all of them up - and scoop out all of the grease from the gear housing. Most of it doesn't actually do anything. It's clearly been sitting there for decades and there's no means for it to magically migrate to where it's needed.

There's nothing complicated about this. You put on some heavy duty disposable gloves, then scrape and wipe off the bulk of the gunge using kitchen paper or heavy duty tissue, then use WD40 or workshop wet wipes to remove the last traces.

Here we go.....

Getting that bearing housing off was a complete bugger. Once the 3 bolts were out, I could turn it with a brass drift and mallet but it wouldn't magically lift itself out and there is no lip to get a lever under. Finally I realised I could remove the Z axis cover and knock it upwards through the Z axis yoke slot a few mm, then get a couple of levers under the rim. TFFT - it could have taken hours otherwise. 

Interestingly, I can now access the top of the spindle bore, where there is a rusty ridge around the top. That's an area of the cylindrical bore that I wasn't able to access and clean when I was trying to fix the backlash and friction on the Z axis. I packed the bore with tissue to prevent debris getting down near the quill, then tried to scrape it away with a razor blade. That didn't work out so well but at least I didn't draw any blood. Instead I used wet and dry paper with WD40 to stop any abrasive debris from falling into the quill past the tissue. That did the trick - here's the final result, which is a significant improvement. It will be interesting to see if the quill moves more easily at the top of travel.

This looks pretty good. I wouldn't eat my dinner of it but it's not far off.

The outer race of the taper bearing remains in the bore, not surprisingly. 

That wasn't so bad, although it took me a couple of hours and several sets of gloves.

For the 2 large gears, I also soaked them in Gunk and rinsed them in hot water. Looks good!

Here we are - all parts clean:

I assembled the large output gear into the bearing housing but I wasn't completely happy with the noise. This pair of bearings spins with the spindle, so any noise will be pretty evident. Sure enough, the spindle isn't entirely quiet and this bearing is in an area where there has been a fair bit of rust damage. I don't plan to go back in here any time soon, so I may as well replace them if they aren't expensive. Note they are open on one side, so it's not surprising that one of the bearings is looking a bit rusty.

These are 6009 sized bearings (75 x 45 x 16mm) and I'll replace them with double sealed equivalents from a decent manufacturer. The bearingboys.co.uk site has some FAG brand (German) for just under £4 each, so Bob's your aunty. Should have them by the end of the week.

There.