[R-390] Resistor Tolerances

Mon, 29 Jul 2002 11:56:24 -0500

OK.  I suppose gasoline engines are different.

My experience comes from the manufacturing process for high-speed, precision punch presses.  There, you grind the shaft to a tolerance and bore the bushing to a tolerance for the necessary fit.  I suppose a gasoline engine may run with even tighter tolerances for the crankshaft, but we held some pretty tight ones for our presses.  Many of the bearing surfaces were hand scraped for fit as well as oil pockets.  It required quite some skill to do that right.  I ran the jig-borer before becoming an NC programmer.  Sometimes I miss those days...

Oh well, off-topic enough from me for one day.

Barry(III) - N4BUQ

(EMERSON)

> -----Original Message-----
> From: Thomas W Leiper [mailto:[email protected]]
> Sent: Monday, July 29, 2002 11:44 AM
> To: [email protected]
> Subject: Re: [R-390] Resistor Tolerances
> 
> 
> On Mon, 29 Jul 2002 11:27:21 -0500 "Scott, Barry (Clyde B)"
> <[email protected]> writes:
> > Just curious:  How do you make a bearing clearance tighter 
> once it's 
> > bored too big (or the race is ground too small)?
> 
> We're talking about crank and rod bearings which consist
> of half-shell inserts. Bearing inserts are designed to deliver
> a certain clearance at a certain torque on the bearing cap
> bolts, in other words they "squeeze" down to the tolerance.
> You order undersized inserts (which are thicker) and then
> reduce their length so they don't crush as much when you
> torque down the bearing cap. If you are having your crank
> turned (I recommend this treatment every night), you can
> have the shop turn an "over"-undersize to tighten things up
> as well if the availability of custom bearing inserts is poor.
> 
> Or, you can pick what's behind Door#3 ...A New Car !!
> 
> Hammarlund
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