Forwarded for archives purposes:

For those on a beer budget......   I've been stuck for taps too, this
trick only works if cutting threads into aluminium, and really only if you
are partly started already (ie. it's perfect for stripped out head/exhausts)

Take an extra bolt with the correct threads you want to produce, and using a
bench grinder with a decent clean corner on the grinding wheel grind out 1/4
of the bolt (ie. a pie slice from 9:00 to 12:00 o'clock)  about 3/4" along
the bolt. This will produce a cheapo homebrew tap!  See ASCII.  Use it for
about 2-3 turns in, then back out, WD-40 blast out shavings and go again.
It clogs more quickly than a real tap, but will cut aluminium fine, not steel.

        |   | <--- bolt
  ______|_  |
 |     -->| |
 |   flat | |
 |        |_|
 |        |
 |        | < ----  wheel
 |        |
- - - - - - -

DO NOT grind 1/2 of the bolt away! You want a shallow 'scallop' that removes
only about 1/4 of the cross section.  Also  you want to make sure that the
'flat' surface is the one that is doing the thread cutting. So look at the
end of the bolt away from the head and imagine the flat (flank) the grinding
wheel coming down directly towards 12:00, the curved face cutting away until
you get down to 9:00 position (ie. the upper left pie quarter goes)

... bye, Tim

_____________________________________________________
Derek Drew                           New York, NY & Washington DC
ConsumerSearch
drew@interport.net
212-580-6486 (W)
212-580-4459 (H)