From me2576
Home made roller bearing from 40cc petrol engine
crankpin
Made from silver-steel, this was screwed into
the web with a fine thread. Before finally
pegging into position it was hardened and
tempered to a deep straw colour and lapped to
size. Two thous. were allowed for this operation
and no appreciable distortion occurred through
the hardening process.
Rollers
A few preliminary trials showed that unless
the rollers were constrained, serious distortion
would occur through hardening. Thirty-seven
1/2 in full lengths of 1/16 in. diameter silver-steel
were cut off and pressed into a mild-steel tube of
the same length and lapped in the bore to a
diameter of 7/16 in., or more exactly, 0.4375 in.
This number was selected because it is the
nearest number of 1/16 in. diameter circles to the
required number which lie geometrically in
contact. (It provided a goodly munber of
spares.) With one at the centre, successive
layers were 6, 12, and I8. They were secured
against movement by a spot of soft solder for
facing to length on the emery wheel. The
solder was cleaned off, the rollers replaced into
the tube, and the whole brought to a dull red
heat and quenched in oil. No discernible
distortion occurred in any of the rollers. They
were polished by rolling a few at a time between
two pieces of flat brass sheet smeared with a
touch of fine lapping paste.
Outer Sleeve
Cast steel was used for this and the inside
and outside diameters were machined with
0.002 in. allowance on each for final lapping.
A mild-steel plug having a nice push it was
inserted in the bore as a safeguard against
distortion during hardening. The heat treatment
consisted of quenching in oil from a cherry-rred
heat and tempering to a dark straw, evenly heating
in hot sand.- The sleeve was then lapped to
size, internally and externally, the first dimension
being checked by a plug gauge lapped to size
also (0.545 in. diameter)
Conclusion
On assembling the parts, the results were
extremely gratifying. The 24 rollers fitted
around the crankpin to a nicety ; there was no
lateral shake in the assembled bearing and it
worked with a pleasing ease and smoothness,
each roller turning evenly.
Edited By Ady1 on 16/04/2014 10:24:28