Re: ATM and lathes - Al on a wood lathe ???

["Peter John Smith" <pjifl@bigpond.com.au>]

Tom and Beth Simmons wrote,

>   This list has discussed several times that some wood tools (saws,
routers)
> could be used for Aluminum cutting. Could someone expound on why a wood
> lathe could or could not be used for the generally small aluminum items
> normally turned into telescope parts, for example, a crayford focuser,
> knobs, truss tube ends? For the sake of this conversation, let's say the
> largest Aluminum part would be cut from a 4 by 4 inch block.  I've seen a
12
> x 36 inch lathe at Home Depot for about $350.00. I believe that someone
here
> said that this is obviously a wood lathe (based on cost??). If this is
> possible, would the table need to be re-inforced? Should I buy tools
> designed more for the "beefy" metal working lathe?

he main difference between a wood and metal lathe is that in a wood lathe

1.  The cutting tool has to be guided by hand using a rigid rest and a LONG
handle for control.  They are not cheap.  You will probably have to make
some of your own for metal work.  The most basic safety thing is to always
set the rest as close to the work as possible.  Especially for metal.

2.  There will be no means to clamp the work in a chuck unless bought and
fitted seperately so work will be confined between centres.  This will rule
out much of what you want to do.  So more money needs to be spent on what
are really basic equipment for metal work.

3.  The wood lathe will spin faster - far too fast for larger diameter metal
work unless it is slowed down.

4.  There will probably be no provision for drilling from the tailstock
which in metal work you will often find important.

Because the cutting tool is not guided as in a metal lathe, one has to
concentrate and look very carefully at the cut.  This means the head will be
closer to the work and any foul up with the tool or loosening of the work is
potentially more serious.

All this means that it is probably more important for the wood lathe to be
heavy and rigid than a metal lathe.  Paradoxical .  Many of the pressed tin
ones in hardware stores are not really up to the job except for very small
work between centres.

It is not really difficult to make a good wood lathe - out of wood of
course.  Seriously, two heavy hardwood members of about 3 x 6 mounted around
blocks of wood at each end make a bed for a wood lathe that will leave small
pressed metal ones for dead.  They do not have to be particularly accurate.
There has been talk of weight in machine tools recently as being important
and I agree.  Especially in a wood lathe.  By the way, I do have a quite
small metal lathe - but also a larger one and both are used seriously.  The
wood bed, or a cast iron bed, will dampen vibrations far better than a tin
one.  It depends on your siruation, but people with plenty of room and some
ability to work wood and simple steel work should consider this.

Watch what second hand prices really good solid cast iron wood lathes bring
and ask yourself why ?

Of course, in principle, small work could be done.  In fact, metal work was
done on jewellers lathes and brass finishers lathes in much the same way
that a wood lathe is used.  The brass finishers of 100 + years ago would
take the small brass castings and turn and thread then by hand - faster than
a metal lathe.  And even today, Aluminium spinning is often done by hand
tools.

But they had heavy rigid equipment and the operators had a LOT of bitter
experience.

I think 4 inch of Al way too much for a small wood lathe.  Maybe 2 inch ?
To make matters worse, the common Al you will purchase often does not turn
well.

Now for the crunch.  If you really want to do a lot of smallish wood turning
maybe look seriously at this and then try it out on smaller Al and Brass
parts. (watch your eyes with brass.  It turns easily but small chips spray
everywhere.)

If you really want to do metal work I would think even the cheapest Asian
import will be far better and come with a chuck.  Probably also a chuck for
the tailstock as well.  And a few pieces of high speed steel tooling will
not cost much and go a long way.

>   If this is a really stupid question...I'd rather that than a stupid
> mistake. I'm kinda "attached" to my fingers.

And your eyes too.

Hope this helps.

Peter Smith.