c3 mini lathe bearing change - freeremi.antoine.free.fr/...mini_lathe_bearing_change.pdf · re-fit...
TRANSCRIPT
C3 Mini Lathe Bearing Change
1.Start by disconnecting the machine from the mains supply. Remove chuck
guard, chuck, gear cover and gear train.
(Note: It is not necessary to remove the leadscrew as shown in the picture -
these photos were taken during a complete strip-down of the machine during it's
initial preparation for a customer)
2.Remove belt and layshaft gear
3.Remove the two C-nuts, gear, key, plastic spacer and plastic bearing cover
from spindle.
4.Remove the gear cover support bracket and undo the control box but don't
disconnect it
5. Undo the two screws holding the spindle speed sensor and note how the
timing wheel fits between the forks of the sensor (some C3 variants are not
fitted with a spindle speed display)
6. Working through the holes in the spindle flange, remove the 3 screws from
the front bearing cover
7. Remove the spindle from the headstock using a puller. The diagram shows a
simple to construct puller made with bits from the scrap box.
8. Remove the plastic spacer and key then extract the front bearing from the
spindle using a press/mallet
9. Clean everything thoroughly, replace the bearing cover on the spindle and
press on the new bearing inner being careful to press on the bearing race and
not the cage! An 8" length of steel tube is handy here but ensure the bore is greater than 30mm to clear the spindle and the O.D. no more than 40mm to
clear the bearing cage.
10. Refit the spacer and key to the spindle
11. Extract the rear bearing from the case
12. Press or tap into place the new front and rear bearing outer races
13. To compensate for the wider taper roller bearings it is necessary to make a
new plastic spacer (approx. 0.105" wide) with keyway to fit the spindle between
the timing wheel and gears.
Trial fit the new spacer and adjust as required - the spindle speed timing disk
must not foul the pickup and the gears must mesh correctly
14. Grease front bearing and insert spindle into headstock locating keyed disk,
spacers and gears on the key
15. Fit the rear plastic spacer having first modified it by turning a smaller
diameter step at one end so it clears the bearing cage
16. Grease the new rear bearing and pull it into place using the C-nut, gear and
plastic spacer
17. Temporarily fit the belt cover and check tumbler reverse gear alignment -
they probably won't align because the black plastic spacer is now too long
18. Shorten the black plastic spacer as required
19. Final adjust the C-nuts using two C-spanners to remove free play and pre-
load the bearings
20. Re-fit the drive pulley, belt and belt cover complete with tumbler reverse
21. Re-fit gear train, gear cover and chuck.
22. Re-fit the spindle speed sensor (checking again that it clears the timing
disk!) and re-fit the control box.
Providing you have no bits left over (except the old ball bearings!) and
everything is tightened and adjusted correctly, your lathe is now ready to use.