Originally Posted by
maddog34
Two points to consider:
1- the largest seat post sold is 34.9mm.. the SECOND largest size sold is... 31.8mm
2- .05mm is... .002"...or one average human hair, roughly. most machined metal parts use +/-.002" as a mfg. Tolerance.. seat posts tend to run up to -.020" out of standard.
...
I don't know your experience in things like this, so I'll just state some of mine.
I ran a manufacturing business and many in the bikw industry are still using tools they bought from me almost 50 years ago. So, I know about manufacturing to tolerance.
Specific to this application, reamers can consistently produce round holes to tolerances nearer to 0.0002" (yes, a fraction of the thickness of hair) than to 0.002" so reaming a seat tube to the specs I referenced is very easy.
BTW - before retiring I sold various cutting tools to builders and shops, including BB taps, various mills and faces and SEAT TUBE REAMERS. I'd have been very upset to hear that one of my clients couldn't hold tolerance.