Well i guess everyone is entitled to thier opinion,,, am just relaying what i read from RR on the subject of turning the DB crank, as to a print, i dont recall ever quoting from a print. From my limited machining experience, i was making a small part for personal use with a tolerance of plus or minus .0002″, using a fairly old, but tight lathe. My reject rate was 10 to 15 out of 100 pieces made, which i didnt think was too bad, so going to 5 decimal points may not be as big a deal as initially thought.
As an owner of a Tool & Die shop, 32 year exp. working to “tight” tolerances, & 20 years of racing engine builds…..here’s my 02:
There is no problem reproducing the engines in question, it amounts to how much $$ someone is willing to throw @ it.
The existing technology far exceeds what was required @ the time of the orig. design/build(s).
Yes, the O.A. level of skill which a “modern day” tradesmen possess IS substantially lower than his/her predecessor as it’s simply not required due to the lessening # of manual operations now required.
Vega is correct, the crank tolerances prev. posted are ridicules, & would require a totally temp. controlled environment to be achieved.
I’m sorry but, achieving a “grinding or lapping” tolerance of +/- .0002″ (two tenths of a thou!!) on a manual engine lathe is also completely ridicules.
I’d be tempted to believe that you’ve added a decimal place as .002″ is more like it?
Cheers!
PAul
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