RobCox
Member
- Messages
- 507
- Location
- Cambridge, UK
I got a bit fed up of oil dribbling out of the feed reversing shaft, puddling on top of the QCGB and continually lowering the headstock oil level, so I finally cracked and decided to do something about it.
To get at the feed direction shaft, the spindle has to come out. I did this once before when the lever came loose, so no stress. Firstly the changewheel banjo needs to come off:
At this point another oil leak is revealed, out of the rear spindle bearing cover. So, off with the rear cover, put a pop mark on the spindle to show the position of the split locknut that sets the bearing preload, then undo the locking grubscrew and take the split locknut off. The worst bit is trying to get the circlip which holds the feed drive gear an bull gear onto the spindle splines, but after a few minutes colourful language we have the spindle out:
There are two other gears that restrict access to the feed reverse lever - these are the reversing gears:
The pictures aren't very good, neither are there that many of them as I spent a fair while sloshing around in the oil to get the circlips off. Probably only the one directly under the spindle needs its circlip removed, then the detent screw for the reversing knob needs backing out, the knob is turned clockwise and the gear at the bottom comes off and its posible then to get an allen key to remove the shifter bar off the splined shaft.
I took the shaft out, prised off the O ring and measured the groove, which was 12mm dia and about 86 thou wide. The O ring I got to fit on the 3rd try was nominally 7mm ID, 2mm thick. It was a tight fit into the sleeve despite being stretched, so hopefully will fix that leak.
Then for the AAAHH! moment. I took a look at the bearing cups as I was cleaning up gunge (it needs an oil change):
Those marks are little dents in the bearing cup caused by water damage from coolant, judging by the staining on the outside of the bottom of the cup. Now here's the dilemma: it's been like this since I've had the lathe I imagine, as I've never run coolant, and it's been useable, so do I replace the bearing or not? I've asked for a quote from Simply Bearings and I'll make sure I'm sitting down when I open the reply, as it's likely to be £800+. So I could run the lathe like it is, replace the bearing or scrap the lathe and buy another. If it runs OK thats obviously the cheapest option, if not, despite the cost of the bearing its going to be cheaper than trying to find another M300 or similar, in good nick (I've renovated this one so it all works fine). Parting off has always been sketchy on this lathe, would this be the cause?
Anyhow, for now I've put it back together and made new gaskets for the bearing covers:
And it's due an oil change, judging from the state of the oil (last changed 5 yrs ago when I did the lathe up). I'm thinking of draining it and filling it with paraffin to clean out the muck, before draining and refilling with clean oil.
To get at the feed direction shaft, the spindle has to come out. I did this once before when the lever came loose, so no stress. Firstly the changewheel banjo needs to come off:
At this point another oil leak is revealed, out of the rear spindle bearing cover. So, off with the rear cover, put a pop mark on the spindle to show the position of the split locknut that sets the bearing preload, then undo the locking grubscrew and take the split locknut off. The worst bit is trying to get the circlip which holds the feed drive gear an bull gear onto the spindle splines, but after a few minutes colourful language we have the spindle out:
There are two other gears that restrict access to the feed reverse lever - these are the reversing gears:
The pictures aren't very good, neither are there that many of them as I spent a fair while sloshing around in the oil to get the circlips off. Probably only the one directly under the spindle needs its circlip removed, then the detent screw for the reversing knob needs backing out, the knob is turned clockwise and the gear at the bottom comes off and its posible then to get an allen key to remove the shifter bar off the splined shaft.
I took the shaft out, prised off the O ring and measured the groove, which was 12mm dia and about 86 thou wide. The O ring I got to fit on the 3rd try was nominally 7mm ID, 2mm thick. It was a tight fit into the sleeve despite being stretched, so hopefully will fix that leak.
Then for the AAAHH! moment. I took a look at the bearing cups as I was cleaning up gunge (it needs an oil change):
Those marks are little dents in the bearing cup caused by water damage from coolant, judging by the staining on the outside of the bottom of the cup. Now here's the dilemma: it's been like this since I've had the lathe I imagine, as I've never run coolant, and it's been useable, so do I replace the bearing or not? I've asked for a quote from Simply Bearings and I'll make sure I'm sitting down when I open the reply, as it's likely to be £800+. So I could run the lathe like it is, replace the bearing or scrap the lathe and buy another. If it runs OK thats obviously the cheapest option, if not, despite the cost of the bearing its going to be cheaper than trying to find another M300 or similar, in good nick (I've renovated this one so it all works fine). Parting off has always been sketchy on this lathe, would this be the cause?
Anyhow, for now I've put it back together and made new gaskets for the bearing covers:
And it's due an oil change, judging from the state of the oil (last changed 5 yrs ago when I did the lathe up). I'm thinking of draining it and filling it with paraffin to clean out the muck, before draining and refilling with clean oil.
