Model Engineers’ Workshop – July 2019

July 2019 29

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Bearing Removal

Out, Out Damned

Bearing

I

n the recent past, I have had to remove

three bearings from blind holes, none

of which was easy to extract. I hope the

following may be of assistance to anyone

else in a similar position in the future.

I discovered this fi rst method by pure

chance and although I have not seen it

published elsewhere, I cannot imagine that

it is unknown, but I hope to bring it to a

wider audience.

I had a need to replace a small shielded

bearing, shaft size 5mm, that was fi rmly

located in a blind hole. Although the

bearing was un an unhappy condition, I was

hoping to recover it for the short term until

a replacement could be found. The problem

of course was fi nding a means of removing

the 12mm diameter race which was fi rmly

fi xed in a blind hole. Photographs 1

and 2 show the object with the bearing

partly replaced for these photos, I had no

intention of returning the bearing properly

into the hole just for this article!

Aft er various fumblings all of which

risked damaging the shields, I decided to

apply a method that I had read about but

never successfully applied. In this method,

the void behind the bearing is packed with

grease and a tight fi tting shaft inserted into

the bearing to act as a piston. This is then

fi rmly struck, and, in theory, the bearing is

then hydraulically ejected from the hole.

As is all too common the case, theory and

practise departed on diverging paths and a

lot of grease seemed to appear everywhere

whilst the bearing remained fi rmly in place.

The next step aft er removing the

larger globs of grease was to remove the

aluminium shaft I had used as the piston

which immediately presented a new

problem. The shaft would slide out until

a certain point whereupon it stuck in the

bearing. Major cursing followed until light

dawned that this was maybe my salvation.

I then gripped the aluminium shaft in a vice

and proceeded to pull it out on the slide

hammer principle.

This removed the bearing from the hole

with no further damage. Once removed,

the reasons for the shaft getting stuck

With apologies to the Bard, Simon Davies shows his powers of perseverance

1

The shaft aft er being cleaned up. The thin walls

around the centre drilling are clearly visible

Bearing partly returned to blind hole

This shot shows some evidence of trying to remove the bearing by

other means

2

3