Model Engineers’ Workshop – July 2019

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were clear. I had chosen a scrap piece of
aluminium which had been centre drilled
leaving an almost sharp edge at the end.
My frustrated striking of the shaft trying
the hydraulic solution had resulted in the
shaft bottoming and then peening over to
eff ectively form a rivet head on the end of
the shaft. Shaft removal took a matter of
seconds aft er a brief introduction to Mr. Belt
Sander. Photograph 3 shows the end of the
shaft aft er the bulge had been ground away,
some remaining grease still visible.
I am aware it is not an ideal method to
remove a bearing by tugging at the centre
but in the absence of any other means to
remove it, this method at least is better
than none.
If I needed something more solid or I was
looking for perhaps a more refi ned solution,
I would machine up a small cone shaped
piece of steel to drop into the end of the
shaft to help peen it over – rather in the
manner of the brake pipe fl aring tools that
used to be available for cars.
The second bearing extraction was a
rather more brutal aff air. We had been lent
the use of a professional quality concrete
mixer so that our occasional gardener
could build some small walls. However, two
weeks into the loan, it started to make very
unhappy noises and eventually stopped
functioning altogether. My examination
revealed that the motor pinion was no
longer engaging with the ring gear around
the outside of the drum. This was because
one of the two bearings supporting
the drum was no longer in existence.
Photograph 4 shows the drum once it
had been removed from the remainder of
the mixer. Aft er dismantling the machine,
it became clear that there are two chunky
bearings supporting the entire weight of
the loaded drum which had probably never
seen any form of lubrication in their entire
lives. The outer bearing had disintegrated
into an inner quasi-welded to the shaft ,
some non-spherical balls and the remains
of the cage and shields. Moreover, the outer
track had broken into two, having split
along the bearing track, presumably as a

Mixer drum – the entire weight is born by 2

bearings about 70mm or so apart

Less than simple access – the out of focus

ring is the edge of the remains of the

bearing outer

Crude and roughly applied but with maximum current for deep penetration

Equally noxious welding of the studding – but it held! The bead is clearly seen here as well as the point where the track split
into two

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