Are These Rods Good?

[digger]

i've heard of guys measuring to a tenth for bearings on one of the HPF videos. i don't have the right equipment to know if this is realistic and repeatable in practice.

[EatsHondas]

.0001, you can't even measure that accuratley. Thermal growth from holding the mic in your hand is probably more than that.

Aircraft parts are often to .001 or maybe .0005 at most...

M20 connecting rod specifications run out to 4 decimal places in the Bentley (with a tolerance of +/- .0002 being common), are you saying you can just throw out the last decimal for all rebuild/tolerance checking procedures? If that's true, it's news to me.

[EatsHondas]

i've heard of guys measuring to a tenth for bearings on one of the HPF videos. i don't have the right equipment to know if this is realistic and repeatable in practice.

http://www.mscdirect.com/product/det...&item=57480824

Guess it depends how much you're willing to spend. But the tools are out there.

[AndrewBird]

A dial or micrometer bore gauge can measure down to tenths no problem. Some can even measure down to .00001, but those are rarer and more specialized.

Pretty much any bore for a bearing will have at least a +/- .0005 tolerance. All depends on the application.

[LJ851]

M20 connecting rod specifications run out to 4 decimal places in the Bentley (with a tolerance of +/- .0002 being common), are you saying you can just throw out the last decimal for all rebuild/tolerance checking procedures? If that's true, it's news to me.

You don't throw out the fourth decimal place (in inches), it's just that ONE tenth is not really going to make a difference. A few tenths, yes in a few select parts on an engine. Crank journal taper and roundness for example.

[TobyB]

...and a .001 graduated mic can feel the difference of .0001 in the crank, certainly...

t