On 2008-08-31, Michael Koblic wrote:
----- Original Message -----
From: "DoN. Nichols"
Newsgroups: rec.crafts.metalworking
Sent: Saturday, August 30, 2008 1:47 PM
Subject: Red-neck lathe v2.0
O.K. The v-groove in the vise (likely not a very deep one, but
something to help) is a start. Ideal depth of V-groove would be such
that the two sides of the 'V' are tangent to the diameter of the thing
being held. If it is shallow enough so the tops of the V touch the
circumference of the workpiece it will cut grooves into the workpiece
and will not be as good a grip. Of course, some vises (e.g. toolmakers
vises) have deeper grooves than others do.
So far so good, but I have also a couple of bigger v-blocks if need be.
Good.
[ ... ]
For that you need a wiggler?
Well ... actually a "wiggler" is an indicator used for moving
centers of the workpiece over/under the axis of the lathe, mill, or
drill press spindles.
That was supposed to be a joke...
O.K. No smiley, so I wasn't sure.
Good -- pictures do help a lot. You know -- there are
downloadable PDF files of various old books (out of copyright) which are
very good things to have for what you are trying to do -- or for anyone
with an old manual lathe, mill, and other such tools.
I am beginning to find them. It seems tricky. You do the search one way and
nothing happens, you do it another and out they pop..
Try to find "Modern Machine Shop Practice" (I forget whether
that last word should have an 's' on the end. :-) Don't confuse it with
"Machine Shop Practice" by Moultrecht which is a two-volume set. It is
a good book set to have, but you won't find it for free.
[ ... ]
O.K. Yes, that would want to run fairly fast. 2000 RPM would
be only slightly over 65 SFM (Surface Feet per Minute -- the measure
used for determining the speed of the workpiece/tool interface. (take
the diameter in inches, multiply by Pi, divide by 12 to give the
circumference in feet, and divide that into the RPM. That is a fairly
conservative speed for HSS (High Speed Steel) in brass.
I run most of my drills slower than the book speed. I have not find a
convincing argument that it is harmful to the tools.
It typically puts more stress on the flutes of bits.
The centre drills seem
to be an exception - they snap at lower speeds.
Hmm ... check your drill press. Put a round tip piece of stock
in the drill chuck, put a flat piece of metal on the table, and bring
the round end of the rod down on the piece of metal. Look carefully at
the point of contact as you apply pressure. A lot of relatively
inexpensive drill presses flex -- both the arm supporting the table and
the head. This results in the contact point skidding towards you. This
applies lateral force to the point -- and with the skinny point of a
1/8" center drill and it *will* break. A higher speed means that you
are less likely to apply as much force to the spindle feed levers.
I swear the first one snapped just by me looking at it...
It feels like that sometimes. Were you using it in a drill
press, or in a hand drill? The drill press is the better bet. And
don't just keep pushing it in -- go a little way in, then back the
spindle up to let chips clear, then in again, etc. Normally you don't
need cutting fluids on a free-machining brass, but I don't know what the
characteristics of the cast brass which you are working with might be.
I wonder whether it could be a bronze? Not likely, as those are more
expensive, but they are tougher alloys.
Garage sale candlesticks - generic brass all the way. Very soft.
Very soft can be a problem -- it gums up the flutes of the bit.
360L brass has lead in it and is a bit harder than normal brass, but the
lead lubricates the cuts, so it is a very nice machining material. Cast
brass is more likely to be too soft to machine well.
I just took apart a very old Sears cordless drill and liberated a 12V
motor
as well as a 3/8" chuck and a whole bunch of cool little gears. Also I
found
an old 12V motor with some strange reduction gear which, many years ago
was
going to be a pottery wheel for kids. Some of this stuff has got to be
useful even though 12V is not exactly ideal.
An old automobile battery and a battery charger to keep it near
full charge and you should be fine. And that would be a lot cheaper
than a lab power supply of sufficient capacity to handle your tools.
(Hmm ... if it is small enough, perhaps a motorcycle battery would be
sufficient.
I have a couple of power supplies - one should give steady 5 amps which as
it turns out may not be enough. The other one should give 20 amps. I have
not tried that one yet.
But with an automotive battery, it would keep the battery
charged, and the battery would handle the current to start the motor.
(Of course, it really needs to be something like 14.4V to fully charge
the battery.
Note to self: Do not take motors apart without securing the brushes first! A
good way to avoid doing anything productive for an hour...
:-)
Enjoy,
DoN.
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