In article ,
says...

ok, guys, thanks one and all.

more info: tightwad here hoping to drill a .177 or .178 sized hole
without reaming to size, centered in end of a .250 OD piece of cold
rolled mild steel round, in my lathe (this will result in sort of
'thin wall pipe' of sorts) withOUT 'springing for' a reamer. mid-term
goal being to silver solder into this (drilled) hole the 'head' end of
a (for all practical purposes) round brass pilot jet, OD of jet .177
inch, or maybe two ten-thou's over that. final intent being, to place
a 'hex head' on other end of this same very short steel jet
'extension', to make it 'real world adjustable' (using a small
quarter-inch drive socket) WITHOUT having to 'spring for' the special
"single D" tool required, ordinarily, to turn (adjust) these same two
jets (one per carb). that tool's a 50-buck item...

1) you don't need to get a 0.0001 tolerance hole to silver
solder the brass part into the steel part. You could have
a thou of clearance and it will work find.

2) if you absolutely feel that you need to manufacture the
hole better than that, simply bore it to size using your
lathe and a small boring bar. You can size it will within
a thou that way. As mentioned you don't really want a
press-in fit for silver soldering.

3) what kind of carb has an adjustable pilot fuel jet that
is manipulated with a D-shaped tool? Most pilot fuel jets
simply screw into the carb body and are swapped out if
the size of the jet is not right.

4) the D-shaped adjusting tools are available for about
ten bucks in most auto parts stores.

Jim

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