In a message dated 9/15/1999 1:03:02 PM, dmoon@METZ.UNE.EDU.AU writes:

<< There is nothing wrong with a portable boring rig. When set up by a VW
specialist they are quite often more accurate than an average industrial
mill.  I have seen these setups used for boring VW cases for aircraft.
Usually as well, the cam is bored at the same time as the mainshaft. Don't
be worrying about what is used to turn the bore, as long as it has the power
to do the job its just an electronic motor like any other. What is of
primary concern is the quality of engineering and experience which has gone
into the design, construction and set up of the rig itself
 >>
dmoon:
Thanks for your reply.  I have had a variety of experiences with field
machining and cannot fault the results of the most unlikely rigs when set up
by a true master.  I had a friend (God rest your soul, Tom) who would
routinely rebore 10-ft diameter steam cylinders in place(obviously).  And I
certainly don't doubt the capabilities of any prime mover, especially if its
a 1" Ingersoll-Rand air drill backed up by a deadman.  Whereas, the only VW
case prep I have seen was featured in a VW rag and according to the text and
photos the operator simply used the existing bore to pilot his cutting tool.
While I agree, the C/L of the opened-up holes probably coincided, I saw
nothing done to assure perpendicularity to the cylinders.  What is done to
provide for this important geometric relationship?
Richard