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.

No problem. I'm just trying to address all the loose ends, so my goals
are clear. No need to spend so much of your time typing. You've helped
me out a lot already. Not just with your direct responses(which have
been pretty fast), but also with your archived posts I've spent hours
reading.

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.

A gamer's hands can get pretty sweaty in the heat of battle.(But I'll
have to settle for 303, since no one makes 316* 1-3/8" diameter ball
knobs).

O.K. As long as your lathe can handle 7/16" diameter though the
spindle, this should work reasonably.

The site page for my lathe makes reference to a 5/8" dia. thru-hole, so
that may be it.

Much beyond 1" length at 1/4"
diameter would be a different matter.

Well, the rod will still be 2-1/2"(to 2-3/4") long. only 1" of it will
be turned down to 1/4" from 7/16".

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 ball-knobs from McMaster Carr are pre-threaded. I just have to
decide on which of the following eight threads to get.(Though I suspect
that it'll make no difference).

1) 1/4" - 20
2) 5/16" - 18
3) 5/16" - 24
4) 3/8" - 16
5) 3/8" - 24
6) 7/16" - 20
7) 1/2" - 13
8) 1/2" - 20

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.

Because I want the option of taking it apart in the future for part
replacement. I was however thinking of using Locktite where the rod
screws into the ball knob. That is the fit that needs to be permanent.

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.


There will be no room for protrusions, so the length of the 1/8"
diameter Delrin rod will equal the diameter it is placed in(which is
7/16"). I figure that Delrin(or nylon) in the proper size would make
for a tighter fit than a metal pin. And I can just punch it out when I
need to.

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.

Of course the work envelope(whatever that will be) will be the big
difference, but outside of that I'll need to determine how big a
difference there would be in other ways between this lathe(with
attachment) and a mini-mill.

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.

The largest workpieces will be A) 4-1/2" square(6" diagonal), 3/16"
thick, and B) 4" square, 1/4" thick. I'm actually *considering* using
5052 Aluminum.(6061 would be my second choice). The reason is because
I'm concerned about the possibility that the stiffness of S.S. steel
may cause the assembly to lock, and aluminum's flex may prevent that.
I'm probably worried about nothing, because this part is basically a
flat Delrin surface that will be sliding(a half inch in any direction)
between upper and lower bearings situated inside Delrin cups.

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.)

Actually, what I meant was that S.S. is the most estreme material *I*
will be working with. :-)

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.

That's the reason for the *replaceable* Delrin ring(floor) idea. :-)
But the downward force will for the most part be insignificant, since
the push of the "race face" will tend to be horizontal. It's still
smart to assume the occasional downward push(though there is no point
to doing that), but again, these are prototypes and I will be getting
feedback so I can determine where the weak links are.

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.

My intentions exactly.

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.

Ok. "Collet block". I'm on it.

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.

Yes, I know. I was just trying to indicate that that was all M.M.
had(since I already had M.M. open in a browser window as I was typing).
But if the "T-bar" is what you turn, then I'm confused, because the E-Z
tappers and Encos I see have that.

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.

:-) I tried getting a catalog from them a couple of months ago with no
luck. Even though they advertsie the catalog, there are no options for
getting it.(My Grizzly catalog just arrived though).

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

Ok, I guess I have to get the two I mentioned on the M.M. lathe page.

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.

Obviously "small" and "accurate" don't go together on any of these
machines.

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.

My wording probably wasn't clear enough. Basically, I'll need to turn a
4-1/2" square(1/16" thick) plate into a 3" disk that has four 1/2" wide
arms that are rounded at the ends.

I'll still need to get a rotary table, so I'll be searching the
internet for a visual on anything relating to a rotary table on a lathe
that has a milling attachment.

Thanks a lot.

Darren Harris
Staten Island, New York.