Allan Adler wrote in message ...
I've finished chapter VI of Gingery's book, The Metal Lathe. So far in the
book, I have been able to visualize details of the construction and to answer
most of my own questions about it. I do have a few questions about Ch.VI,
though, where I'm less certain.

(1) The frame assembly for the counter shaft can (p.70) be put together by
welding the parts. That sounds to me like a rigid assembly. On the other
hand, rivets are recommended as an alternative to welding. I don't know
anything about rivets or about the tools one would use with them in the
frame assembly. It does sound, however, as though they are also intended
for rigid construction. That seems to contradict the fact that some parts
of the frame assembly are supposed to be able to move when one pulls the
release handle. Apart from the bolts that are used to mount the motor,
I only noticed mention of rivets, so I'm unclear about how the parts
that are supposed to move are attached. And since I'm unclear about that,
I'm also confused about which parts are really supposed to move and which
are not.

(2) Gingery's design is for NEMA 48 frame (whatever that means). He emphasizes
that one will have to modify the design for other fractional horsepower
motors. Apparently, he is assuming that the reader is somewhat literate
about motors and about the frames one builds for working with them.
What is the book I need to read to get the necessary background in
fractional horsepower (and why only those?) motors and the frames they
need?

On to the headstock!

Ignorantly,
Allan Adler






I built a slightly larger version of the Gingery lathe and may be able
to help. The frame that carries the countershaft is pivoted at the
base on each side so that it can be moved back & forth when neccessary
to shift the belt to the different pulley diameters for changing
speeds, but the frame itself should be as stiff as possible so as not
to upset the alignment of the countershaft bearings. Think of it like
a door, you want the door to easily open and close but you wouldn't
want the door itself to bend or twist. A casting would be ideal for
this part from a stiffness standpoint but a good one would be harder
to make. Mine was welded up from 2" steel angle because that was the
easiest way for me, but rivets would do if you don't have welding
equipment. NEMA is a set of standards and specifications that the
National Electrical Manufacturers Association came up with for motors
so that, in theory, every #48 motor base will interchange with every
other #48 base, as far as hole diameters and spacing is concerned. My
motor was an ancient one built before the NEMA standards were thought
of but I just sized the countershaft frame to fit what I had. There
are motor handbooks that show base diagrams for the various NEMA frame
sizes ("frame" in this case referring to the motor's mounting base)
but it would be better to find the motor you are going to use first
and then use it as a guide for building the countershaft frame.
Mike.