According to :

What is wrong with the black Bakelite knobs which are also
available with cast-in brass inserts with female threads for screwing
onto your shaft? They are a bit lighter than the stainless steel, and
certainly a lot less expensive.

Yes, but they wouldn't give it that solid, heavy, durable, quality look
and feel that a stainless steel ball-top would. :-)

The Bakelite ball is pretty solid, so it may work well.

O.K. Loctite can be unscrewed -- if you heat it up with a torch
first.

That would be a pain. And since this sleeve will be wedged against a
(3" diameter)Delrin plate I don't think that'll work.

O.K.

You are obviously not familiar with a roll pin. Picture a
length of flat spring steel stock which has been rolled into a two-turn
roll. The ends are tapered a bit to make them easy to start, and they
are driven into the mating holes, with the spring expanding to grip both
the parts. They can be driven out as long as the hole goes all the way
through. They are available for relatively little money for large
quantities. With blind holes, people have managed to use a tap to
thread the ID and give a grip with a screw to pull them out.

It would seem to be more reliable(though not easier or cheaper) than
using Delrin rods.

It may well be cheaper than using Delrin rods. After all, these
are mass produced to standard diameters and lengths. Delrin tends to be
rather expensive (though something like 1/8" diameter rods would not be
that expensive, and you would simply have to turn them to the desired
final diameter and cut them to length.

So I'll look that up. (Tapping is going to be a
subject unto itself that I'll have to study).

Indeed so.

The largest workpieces will be A) 4-1/2" square(6" diagonal), 3/16"
thick, and B) 4" square, 1/4" thick.

O.K. It could require somewhat over that 6" diagonal, if the
groove has to be around a point other than the center, because it *must*
rotate around the center of the groove to be.

The groove(which would have a 3" O.D.) would actually have to be made
in the 4" square piece.

But -- the groove could be off towards one corner, so it is just
barely grazing two sides, and that would result in the other sides
extending 1" beyond what would be the case with a centered plate. And
that would be 1.414" beyond at the corner. So -- what would have been a
5.65" diameter if centered would be closer to an 8.48" effective
diameter. This is why I specified the center point of the groove being
important.

Granted, I suspect that the groove *will* be centered, but I
want to point out the problems you can have if you make that assumption
blindly.

I'm actually *considering* using
5052 Aluminum.(6061 would be my second choice).

Given the size of the workpiece, I don't expect too much flex
from 1/4" thick aluminum, let alone SS. :-)

Well, if I go with Aluminum, most of it would be turned/milled down to
1/16" thick. Only a ring(with an O.D. of 2-5/8") would be left. (And a
3/8" Delrin ring(with "cups" drilled into it for the bearings) would
fit around this.

In fact the above may just be the best idea.

O.K.

What you are looking at are designed to hold flat workpieces and
feed the tap in truly square to the surface. Your rod, with a hole in
the end, would be difficult to mount truly vertically so the tap is
guided in square.

Let me try an ASCII drawing of the kind of tap wrench that I'm
talking about. You'll need to set your screen to a fixed pitch font
like Courier to keep the drawing from being distorted.
___________
___________________/ ________ \_____________________
(___________________ |__ __| _____________________)
\___________/

I clicked "Fixed Font" on this Google page and it was no better than
proportionate. But when I clicked print to bring up the printer
friendly page your ASCII drawing came out perfect.

Ouch! -- You are using *Google* for this? I'm glad that you
found a way to get it to display properly. And I had to re-adjust the
tap wrench to correct for whatever Google did to it when you quoted it
in your followup.

I was looking at those tap wrenches on the Grizzly catalog, so I'll
have to investigate further what I'll need to drill that 1/8" diameter
hole through rod and sleeve.

For that -- I would suggest that you look for a bench block
(Starrett makes two sizes, and you would want the smaller of the two.)
Check out eBay auctions 7587959068 and 7587168821 to see what they look
like. The first auction has only eight minutes left as I type, so you
are unlikely to get it.

But -- the V-groove supports the shaft (and the sleeve), and
there is a small hole at the bottom of the V-groove to clear the drill
(or to clear a pin when it is being driven out).

The second one is being sold from the UK, and who knows who
really made it. It looks nice, at least.

The last one is also a Starrett, but is the larger one, and I
think that it would be less satisfactory.

BTW. I suspect that the 11/16" long sleeve(tube) would be easier to buy
than to attempt to drill a rod that length end to end.

Perhaps -- if you can find the right size. Or, you might be
able to buy it as a long sleeving, and part it off to length.

[ ... MSC catalog ... ]

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).

[ ... ]

I'll try again.

You might mention that you tried before, and never got a
catalog.

[ ... ]

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

Nope -- though they do on ones like my Cameron Micro Precision
sensitive drill press. It is a maximum chuck capacity of 1/8" with the
Albrecht chuck, though a small Jacobs 3/16" chuck can be fitted to the
drill press. It is precise enough so it handles #80 drill bits (Hard to
see, even in the drill index) with no problems.

I believe I'v seen simular drill presses go for $400+ on eBay.

Mine was $150.00 new -- but that was back around 1972 or so, and
prices have increased since then. :-)

Anyway,
I can only hope that one of the $50 bench tops will allow enough
accuracy for my needs. I suppose I'll need it to be pretty accurate if
I go with the roll pin.

The roll pin expands to fit the hole, within reason. But
without special fixturing (other than the V on the top of a bench
block), I would suggest that you drill through both the sleeve and the
rod at the same time. The hole may wind up a bit off center, but it
will be the same for both parts, so the roll pin should fit through it
easily enough.

Now -- if you were using a dowel pin, you would need a very
precise hole diameter. Drill it a bit undersized, and then use a hand
reamer to take it to the proper size.

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.

Hmm ... Do they need to be a full 180 degrees of rounding, or
just a gentle curve. The latter can be turned in the lathe. The former
will take either a rotary table, or a larger mill with a corner rounding
end mill.

Technically, I can leave this piece pointed at all four ends, but I
just wanted to clean things up. I'm flexible, so I'll see what can be
done.

O.K. So just chuck it in the 4-jaw, as well centered as you can
manage, and then turn the OD to produce the curved ends, which may well
be enough.

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.

I've never seen such a combination. It is something which you
will have to make up out of parts which you can find and combine
together. A lot of machining is making special combinations of existing
tools. So -- you are highly unlikely to find such a visual. This is
one of those "figure it out for yourself" tasks.

Yes. That is why I joned a Yahoo Group "mlathemods - Mini Lathe
Modifications". Perhaps there will be some ideas there.

O.K. Good luck there. There will be things which you will have
to design for yourself.

BTW. I have a line on an Enco lathe that is supposed to have a lot of
tooling for $550. The seller says he thinks is a 9" by 16", but I don't
know if that even exists. I've only been able to find references to a 9
X 20(#308-0338).

Since I don't have an Enco catalog on hand, I've no idea whether
they currently have (or ever had) a 9x16". The shorter it is, the
lighter, as the bed adds significant weight.

Good Luck,
DoN.

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