spindle bore size is very important. Modern lathes do not usually have long beds and a long bed
is especially difficult to have on a conventional MultiMachine since the vertical slide would have
to be deep (long) enough to support the bed. A long bed like this could be difficult to raise
evenly. Modern lathes feed the work through large (or giant) spindle bores like one on our
largest MultiMachine designs. Strangely enough the 100 year old Lindsay book "Practical Metal
Turning" talks about just this as the "modern" way!
I would choose one of the common Chevrolet, Jeep or similar straight 6 cylinder engines with a 3
7/8" bore. I would use 100 mm OD bearings and bore the block to that size. (3.937"). For a
spindle I would use a 20" piece of 2 1/2" xxhy pipe (a pipe size chart is at the end of the book)
that has an OD of 2.875" and an ID of 1.771. This would allow plenty of room for a 2 1/4" 8
thread and the shoulder and register that the chuck "centers" on when it is mounted.
Simple so far. The reason for the metric bearing size is because they seem to cost a lot less. I
used 4 1/8" OD Timken bearings in my 6 cylinder Ford 300 cubic inch pickup block and the
cheapest roller bearings I could find were $75 ea, I later found metric 100mm 32013x and 32011
bearings for $22 to $32 (probably different quality). These bearings have an ID of 65mm and
55mm respectively which is perfect for this size pipe. It also means that the spindle can be
threaded (use a dial indicator to center the spindle thread on the bore) and room left for the
"register", shoulder and bearings. The #1 cylinder can be bored to the size of a "cleaned up"
piece of 4" OD pipe or tubing that is used for the overarm.
Like everywhere, there are trade offs here, and in this case it is that "x" at the end of the
32013x bearing number. This is not a heavy duty bearing even though it is supposedly rated for
automotive use. If we would go to a heavier duty bearing (32011) with a 55mm or 2.165" ID
then the spindle wall is just .2" thick which seems thin but will probably work fine. Nothing is
written in stone in this project, a clean 100mm cylinder bore gives you many choices in spindles
that use single or double ball bearings, tapered roller bearings (like mine) or cast aluminum alloy
bushings. If you spend a nice afternoon at your NAPA dealer, you will probably be able to find
inexpensive bearings to fit almost any block within a 3.75" to 4.25" range of bore sizes.
So what to use if you are totally broke or stuck a hundred miles from nowhere in Kenya? No
problem! Just build our ratchet drill and one of the "temporary" lathes described at the end of this
booklet, cast bushings or take apart every front and back axle that you can find to harvest the
bearings, pile these and whatever pipe pieces that you can find under a good shade tree and sit
down and think! MultiMachines are thinking peoples tools. I guarantee you will find a way since
there are dozens of ways to build the spindle (and almost everything else here)!
Lets start from the front end of the spindle to keep things in some kind of
I am going to assume that you have a way to thread the spindle but if you don't, no
problem again! You will soon learn about our "miracle" device that can cure almost every
problem! It can mount a big chuck on one end of an un-threaded spindle, be a roller
bearing adjuster, a thrust bearing, a pulley mount or a mounted pulley and also clamp all
kinds of attachments to the back end of the spindle.
But first, what size pipe to use for the spindle? It could be almost any size! But since we have to