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The MultiMachine is extremely simple - basically 6 unusual construction techniques that
we call "secrets" and 5 very simple "modules" that bolt to an engine block.
Using engine blocks as building blocks is the first MultiMachine "secret." Since cylinder bores
are bored parallel to each other and at exact right angles to the cylinder head surface,
MultiMachine accuracy begins at the factory where the engine block was built.
The second MultiMachine secret! In the most common version of the MultiMachine, one that
has a roller bearing spindle (the kind I built), this precision is maintained during construction
with simple cylinder re-boring of the #3 cylinder to the size of the roller bearing outside diameter
(OD) and re-boring the #1 cylinder to fit the overarm OD.
The best part is that the cylinder-boring operations will probably cost less than $50. An engine
machine shop provides the most inexpensive and accurate (.0005" on a 4" cylinder!) machine
work commonly done anywhere and guarantees you that the spindle and overarm will be both
aligned and at an exact right angle to the face (head surface) of the main engine block that serves
as the base of the machine.
The third MultiMachine "secret!" The spindle can be as simple as a piece of pipe machined to
fit the inner diameter of the bearings.
The fourth "secret" is the addition of a third bearing to the spindle. The three-bearing spindle
is necessary because the "main" spindle bearings just "float" in the cylinder bore so that the third
bearing is needed to "locate" the spindle, act as a thrust bearing, and support the heavy pulley.
The fifth MultiMachine secret! The main engine block and the vertical-slide engine block fit
together with the help of two 1/2" x 12" steel plates, along with my unique way of clamping the
plates together. It's easily built, easily adjusted, and easily clamped into position without the
workpiece moving. Far superior (I think!) to a homemade attempt at a four-foot-long dovetail.
Long, angled cuts similar to this
commercial dovetail assembly on the cross
slide shown below would be far more
difficult to build than the MultiMachine's
simple, square sections that are bolted
together. While the MultiMachine vertical
slide requires only a drill to build, a long
dovetail requires a very large milling
machine. A hugely important difference!