RobCox
Member
- Messages
- 391
- Location
- Cambridge, UK
A few weeks ago I pulled the spindle out of my M300 to enable me to fix an oil leak from the feed reversing lever. Whilst cleaning up the front bearing shell for re-installation, I came across this delightful sight (pic taken after the bearing was changed):
This patch was at the bottom of the bearing and appears to be coolant damage. It's bad enough that you can feel it gently wiping your finger over it. A new bearing is around £1200 and this 1973 lathe probably doesn't justify such expenditure. By a stroke of good fortune, @Brad93 put me in touch with someone who could obtain a good used one for a fraction of the price, so I went for it.
The first job was to make all of the fixtures to pull the old bearing parts off the spindle and headstock. To remove the cone from the spindle, I came across a youtube channel who suggested pushing it off using rods through the D1-4 chuck fixing holes. If you look down these holes the inner half is obstructed by the spindle body but the outside half reveals the labyrinth seal casing. Pushing through these holes avoids risking cracking the casing. This is the view down these holes:
Three lengths of 20mm rod were turned down (while the lathe was still operational) to 5/8" then milled to half thickness for a length of 2 1/2". The round end was threaded M8 so they could be bolted to a disc for convenience:
I ended up with two rings of 3 holes so the same rods could be used to pull the bearing cup out of the headstock. Additional discs were turned to fit inside the headstock to push the cup out and another for the back end of the spindle.
Onto the process of changing the bearings. First port of call was to give the workshop a thorough clean as you dont want swarf finding its way into the headstock. Then my toolboxes had to move to access the back of the lathe - an area seldom visited. This leaves next to no room to manoeuvre:
Then the headstock oil was drained. I changed it when I got the lathe 5 yrs ago and it needed doing. The drain plug has an integral magnet which had collected plenty of debris. The tray below is balanced on two bits of wood wedged under the motor. The funnel guided (most) of the oil from the drain hole to the tray.
I then filled up the sump with paraffin, ran the lathe briefly to spread it around then left it overnight to mix with the remaining goo to make it easier to clean out.
This patch was at the bottom of the bearing and appears to be coolant damage. It's bad enough that you can feel it gently wiping your finger over it. A new bearing is around £1200 and this 1973 lathe probably doesn't justify such expenditure. By a stroke of good fortune, @Brad93 put me in touch with someone who could obtain a good used one for a fraction of the price, so I went for it.
The first job was to make all of the fixtures to pull the old bearing parts off the spindle and headstock. To remove the cone from the spindle, I came across a youtube channel who suggested pushing it off using rods through the D1-4 chuck fixing holes. If you look down these holes the inner half is obstructed by the spindle body but the outside half reveals the labyrinth seal casing. Pushing through these holes avoids risking cracking the casing. This is the view down these holes:
Three lengths of 20mm rod were turned down (while the lathe was still operational) to 5/8" then milled to half thickness for a length of 2 1/2". The round end was threaded M8 so they could be bolted to a disc for convenience:
I ended up with two rings of 3 holes so the same rods could be used to pull the bearing cup out of the headstock. Additional discs were turned to fit inside the headstock to push the cup out and another for the back end of the spindle.
Onto the process of changing the bearings. First port of call was to give the workshop a thorough clean as you dont want swarf finding its way into the headstock. Then my toolboxes had to move to access the back of the lathe - an area seldom visited. This leaves next to no room to manoeuvre:
Then the headstock oil was drained. I changed it when I got the lathe 5 yrs ago and it needed doing. The drain plug has an integral magnet which had collected plenty of debris. The tray below is balanced on two bits of wood wedged under the motor. The funnel guided (most) of the oil from the drain hole to the tray.
I then filled up the sump with paraffin, ran the lathe briefly to spread it around then left it overnight to mix with the remaining goo to make it easier to clean out.