I remember a piston knurling lathe type machine but do not remember exactly
how the skirt was supported. The knurls were formed in several bands around
the piston but only on the working sides of the skirts (not on the pin
sides). I think you might be able to knurl them if you can support the
skirt adequately. It might be feasible to make a squeeze type knurler with
one smooth wheel to use up and down the skirt from the bottom or back and
forth around the piston between the pin bosses. I recall it did not seem to
matter if the knurl was a little high, it just wore down to a reasonable
clearance. I remember a machine which peened the skirt from the inside with
a long arm while the piston was supported along a V groove and even a tool
which expanded the skirt by pressure rolling vertical grooves inside the
piston. There also used to be "piston expanders", heavy bow shaped springs
to be fitted between the pin bosses and the skirts. So old engines did work
with "expanded" pistons of several types.
Don Young
"DE" wrote in message
...


I'm refreshing some lawn & garden small engines, and I am
wondering if it is possible/adviseable
to knurl the pistons on a lathe. I understand it was common practice
at one time but has gone
out of favor these days. Some of these small engine parts
are obscenely expensive. I mean its just for mowing the lawn.

I've been honing out the taper with a rigid hone and the pistons
have good grooves but are a little under sized after honing.
Just use a regular knurler under the pin hole maybe?? I know
it was done with a dedicated machine at one time but a knurl is
a knurl huh.? If it goes over sized just knock it back with a file??
Need a special chuck or go with 3/4 jaw??

Been grinding the valves on the lathe using a small router
(with the ways covered) fitted into the compound, not as nice as a
sioux but the final results are great.

Any advice/comments appreciated.

DE



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