According to :
Don,

Since we had gotten more and more off the original topic of "Mills and
Drills" I didn't want to irritate anyone further and so started this
thread to address what you told me.

And -- I'm starting to burn out. You are adding an extra hour
or more of typing to my evening newsreading time. (And, I'm going to be
quite busy for the next two days, so I might not be able to answer much
of anything during that time.

And -- it is still not at all clear that you *can* do SS --
depending on your choice of *which* of many Stainless Steels. Some of
those are very nasty to work.

I originally wanted to go with 316L stainless steel when I was
considering a larger lathe, but I'm now thinking more in terms of
Aluminum and 303 stainless steel. But the following are details of the
part of this project that *must* be made of 316L.S.S.

I still fail to see what gives the "must" for these.

1.00" of a 2-1/2" long, 7/16" diameter rod must be turned down to 1/4"
diameter.

O.K. As long as your lathe can handle 7/16" diameter though the
spindle, this should work reasonably. Much beyond 1" length at 1/4"
diameter would be a different matter.

The 7/16" diameter end will be threaded so it can be screwed
into a 316L stainless steel ball-knob.

Unless you can get the balls pre-threaded, this will call for
rather high quality taps, and you will need to replace them fairly
often, unless you are willing to use one until it breaks off in a
workpiece, thus junking the workpiece before switching to a new tap.

And -- you'll need a proper tapping fluid when tapping those
balls. I don't know what is the best fluid for that, so I'll let others
suggest for that. I don't work 316 SS.

The 1/4" diameter end will fit
into a 316L S.S. sleeve that will be 5/8" long, leaving a 3/8" area in
the assembly that is 1/4" diameter. To keep this sleeve on the main rod
I will need to drill a 1/8" hole all the way through the sleeve *and*
the rod inside so I can slide a tight fitting 1/8" Delrin rod to lock
them in place.

Why not something like Locktite to fixture it in place without
needing the drill and pin.

And why Delrin? If people are getting frantic and applying a
lot of force to this (it is sounding like the knob to a joystick), they
may well shear the Delrin at only 1/8" diameter. I would suggest a roll
pin instead, if you have room to drive it through when you need to
remove it.

I don't know what the milling attachment for the lathe will allow me to
do,

Not much, in SS. SS needs lots of rigidity, and a milling
attachment in a lathe normally lacks a lot of rigidity compared to a
true milling machine.

Even though it's a "baby-step" I'm considering the Micro-Mark mini-mill
to compliment the lathe.(Perhaps there will be compatible tooling
between the two).

Some -- mostly between the milling attachment for the lathe and
the real (but small) milling machine.

I'm just wondering if the milling attachment for the
lathe would make this unnecessary.(At least at this low level).

That depends on the size of your workpieces, among other things.

but some things below may require totally different tools.
Nevertheless, I still want to see how much I can get done on a lathe
before I really need a dedicated milling machine.

I will need to: Bore 1/4" wide, 1/4" deep circular grooves in S.S.

In flat SS, or in round stock? It sounds as though you are
planning to do this in flat workpieces (races for balls, I suspect, from
earlier postings you have made). And I presume that this means round
profiles to the groove as well as a circle form to the groove.

Actually, this would be a "trench" with a square profile.(But it's one
job I mentioned that I may not have to do).

O.K. Easier to do on the milling machine with a rotary table to
rotate the workpiece around the center of the circle formed by the trough.

To do this on a lathe, you will need a form tool corresponding
to the shape you need to produce, and that is going to be nasty to use.
A quick calculation says that a 1/4" wide groove will need the tool
cutting on a 0.3927" wide surface. I would not really like to do this
on my 12" lathe, let alone your little 7" (IIRC) lathe. Most of my
tools cut on (at most) a 1/8" (0.125") long edge before the power of my
1-1/2 HP motor gets to struggling.

Then I definitely wouldn't try it on the Microlux lathe. :-)

If it is a square bottomed trough, you could turn it, using a
tool ground as a trepaning tool (and with the workpiece held in a 4-jaw
chuck, if it is small enough to be rotated around the center of the
trough circle above the bed without hitting the bed.

You cut a fairly narrow groove, them move out and plunge again
until you get the full width. Then you move the tool sideways to smooth
out the bottom of the groove.

And you've been talking (in another thread) about rigidity not
mattering as much on a small lathe. When you do something like this in
Stainless Steel, you're going to need every bit of rigidity you can
find. If you don't have the rigidity to take a reasonable cut, and the
power to keep it going, the SS is going to work harden and then fight
you all the way.

Yes. But just to reiterate, stainless steel is the extreme. And thanks
to your advice I'm using it as a yardstick to determine what is and
isn't plausible with the MM lathe.

No -- SS is *an* extreme. There are other things which are more
difficult to machine -- though you have not yet mentioned wanting to
machine them. These include hardened tool steel. (Better done with a
toolpost grinder than a turning tool.)

On a *mill*, you would want a 1/4" ball-end mill, and a rotary
table to turn the workpiece under the mill.

And -- your talk of 1/4" deep as well as 1/4" wide says that the
top of the balls will not show above the surface, so it will offer no
bearing operation -- even if by some miracle you get a smooth enough
finish to have the groove act as a reasonable bearing race. Your groove
should not be that deep.

If I did end up doing this I would place a 1/16" Delrin "floor" inside
the groove.(But as it stands now, I'm going with he Delrin "cup" idea
so the bearings will touch only Delrin and not metal).

O.K. How much force per ball? How long will it set in one
place with the full load? That might cause the balls to indent the
Delrin, making bumps as it moves later.

Turn down 7/16" diameter S.S. rods to 1/4".

How long? If the length is more than four times the diameter
(final diameter, not starting diameter) and you are turning in a chuck,
you will need a "traveling steady rest" (also called a "follower rest").
If it is more than double that, you will need the traveling steady even
for workpieces turned between centers. (And you will need a ball
bearing "live" center in the tailstock.)

MM sells a live center set for $92.65(#83185), and a live ball bearing
center for $12.95(#82509).

The set probably includes several special points for handling
strange shaped workpieces, and you probably don't need that at present.
Wait until you get a project needing that before ordering.

I'm also looking at that steady rest for
$31.45(#82503) and the follower rest (#82504) on the Micro-Mark
mini-lathe page, but it doesn't say "traveling".

"Traveling rest" is a UK way of saying "follower rest" --
different terms, same item.

And again -- which alloy of SS?

316L

Which I have not used.

Thread S.S. rods to fit rod-ends, knobs, ect.

This also calls for a lot of rigidity. You will need either HSS
toolbits ground to the proper angles for the threading (60 degrees for
most threads these days), or insert threading tooling. I tend to use
the latter most of the time. Your SS is going to make this more
difficult, too.

After more reading here I've decided to drop the idea of getting the
grinder attachment for the lathe. I want to make some of my own tools,
so I'm studying up on bench grinders.

Far better. A grinder on the lathe leaves abrasive compounds on
the ways, and leads to rapid bed wear. You have to jump through hoops
to protect the bed and other parts of the lathe.

Mill round S.S. rods into square rods.

This, you could do in the milling adaptor on the lathe, with
either some form of index head for the lathe's milling adaptor (probably
difficult to find), or a collet block which will hold the workpiece.
And how long do these square parts need to be? A milling adaptor in a
lathe is not good for very long cuts.

I'm flexible on this at this point, but these rods will be about 1/2"
in diameter, and I'll only need to mill 1/4" of the rod's end into a
square.

O.K. That should be doable on the milling attachment. The main
trick (solved by the collet block) is having a way to turn the workpiece
precisely 90 degrees for the next cut.

(A 1/4" thick disk with a square hole in the center will fit on
the end of the rod).

O.K.

Tap 1/4" diameter holes into 7/16" diameter
S.S.rods.

Here, you can drill the tap holes in the lathe. You will then
probably start the tap in the lathe, but will then need to move the rod
to a vise, and use a hand tap holder to turn the tap.

All I could find at Micro-Mark is the following:
http://www.ares-server.com/Ares/Ares...oduct&ID=83146

But there is somethng called an E-Z hand tapper on eBay.(I've also seen
Enco tappers on eBay).

Neither of these are what I was talking about. Those are for
tapping holes properly vertical in plates of material. And it might be
difficult to hold the workpiece properly vertical, even with the vise
shown as an accessory.

What I am talking about are tapping *wrenches*, which form a
T-bar around the end of the tap, and are turned by hand. The knob on
the top of that tool you've ponted to will be too small for driving a
1/4" tap into stainless steel.

Micro-Mark is *not* the be-all and end-all of machining
supplies. Call up MSC, and register with them. They will send you a
4000+ page catalog, which can show you more than you ever imagined in
the way of tools. And -- you can take it with you to the john, to learn
more about what is available, which you can't do with a web page,
unless you use a laptop and a wireless net connection. :-)

But be careful to not loose circulation in your legs with that
big catalog on your lap.

If the rods are too large to fit through the spindle, you will
need a fixed steady rest to support the rod out near the end where you
are drilling.

I'll keep an eye on eBay.

The steady rests should be ordered *with* the lathe, as they are
specific to the lathe's design. Many other things are more adaptable.

Drill 1/8" diameter holes through 1/4" S.S. rods.

Drill press -- unless you are drilling from one end to another.
And if so, how long is the rod? Drill bits tend to walk from a dead
on-center position, so you need to come up with another means to drill
it if the concentricity matters and the length is more than perhaps 1/2"
(with a 1/8" drill bit.)

The diameter that I'll have to drill through is 7/16"(which would
actually be the total of the rod inside the sleeve together).

O.K. A small benchtop drill press (perhaps $50.00 or less from
eBay to get a junky one, but one which you can carry upstairs in one
hand. It may be sloppy, however.

Mill 3/4" wide, 1/8" deep grooves in S.S. plates.

Straight lines? Two flute end mills will work -- as long as the
grooves are not longer than the travel on your cross slide (for doing it
on a lathe).

I'll add those to my shopping list.

The two-flute ones are the best for milling slots. In England,
they are called "slot drills" for that reason.

Radius corners to 1/2" in 1/16" thick S.S. plates.

For this, you will need some kind of tiny rotary table on the
milling attachment in the lathe. You would need one in a milling
machine as well, unless you have a CNC milling machine, which can simply
be told to cut the radius.

And -- of course, this depends on how large the workpiece is,
since it has to rotate above the bed of the lathe without hitting it.

I'm going to have to search the internet for visual aids. Project sites
are difficult to come by, and Yahoop Groups is a pain.(BTW. I do know
that I'll also need some sort of indexing tool for making gears).

Mill out 1/4" diameter, 1/4" deep "cups" in S.S.

Round cups? For this, you will also need 1/4" ball end mills.
This is closer to drilling than to milling, as it is just a plunge
operation.

And this may be done in Delrin instead if it comes to that.

All of this is guesses based on what I remember of what you have
said in the past. I really think that you will need a capable machinist
to teach you how to do a lot of this, and to explain (and demonstrate)
why some of the things you want to do are beyond the capability of
anything that you can get up the stairs into your apartment.

I don't have a schooling option, so I'll have to wing it. But you've
given me a good idea of where to start.

Good Luck,
DoN.

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