In article ,
"Michael Koblic" wrote:

Jim Wilkins wrote:
I started off by milling on the drill press with a cheap X-Y vise. It
worked as poorly as others have said on metal but was OK for making
plastic electrical connector housings. The vise as bought was a flock
of crudely machined parts flying in loose formation. The cast iron was
soft enough to file and stone smooth and carefully adjust to a better
fit without tight or loose spots. I "lapped" the slides with fine SiC
sandpaper.

For $9 I am expecting something very similar. As usual, it has to come from
Calgary...

One of the reasons I suggested Holtzapffel was to show you how
serviceable lathes were made without accurate machined ways in the
early 1800's. The cross slide was a bolt-on accessory that was aligned
to the spindle axis with a simple jig or test bar. For instance if you
want the vise jaw opening perpendicular to the spindle to hold a tool
bit, clamp a long straight bar and tap it parallel to the face plate,
or tram it like a mill. This should align the X and Y axis with the
spindle. You could make a sheet-metal gage that rests on the ways with
a shelf at center height to set tool bits easily.

Great minds (and mine, sometimes) think alike! That is the sort of thing I
am planning. The additional advantages I have over proper machinists are the
absence of necessity to do things to tight tolerances (BTW what are all
those zeros after the decimal point on my calipers for?) and sufficient time
to work on a piece.

BTW Holztapffel is a source of constant inspiration.

When I design a machine or a circuit or a program I break it up into
modules first and try to clearly define and minimize their
interaction, without too much concern for the internal details except
for any difficult ones, i.e. the critical path. For a machine I build
the frame and provide a nice flat solid mounting surface wherever I'll
need to add something later. Each module can be assembled and tested
in order of importance and any changes added to the spec list for the
next assembly.

I am trying to follow a similar path: However, one needs to keep in mind the
project as a whole, all aspects of it, physical, social and economical
included. As I mentioned I think the headstock concept is sorted *but* I do
not want to spend a lot of time and money on it if the concept of tool
application is vague. To exaggerate somewhat, it would make no sense to go
ahead and build the headstock for $100 only to realize that the crosslide
etc. will require additional $500 to complete. I might as well save me some
time and buy the whole thing ready made. Interestingly, I saw some economic
analysis of home-built machine tooling and the sums were more or less
identical to the cost of lower end commercially available machinery. I am
hoping to avoid that pitfall through my incredible ingenuity and foresight.
Failing that, denial.

Sometimes a wooden model helps. I made one for my front end loader's
frame to determine clearance for the front wheels and steering
linkage, and assembled the sawmill wheels on 2X4s first before welding
the steel frame.

The wooden version 1.01 is in operation, version 1.02 should be in progress
tomorrow depending on supplies delivery. BTW has anyone noticed lack of
scrap at local scrap yards? Ours was nearly empty today.

When your wife begins to scream at you: "For God's sake buy the bloody lathe
already!" you know you have become a bit of a bore on the subject (of course
the threat of being asked to turn various handles and her need for a new
iPod go some way to explain this laxity of fiscal policy). Still, I propose
to give it the last shot before I cave in.

The truth emerges at last - it's all a scheme to convince the CDFO to
allow the purchase.

Joe Gwinn