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 -- 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.
1.00" of a 2-1/2" long, 7/16" diameter rod must be turned down to 1/4"
diameter. The 7/16" diameter end will be threaded so it can be screwed
into a 316L stainless steel ball-knob. 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.
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). I'm just wondering if the milling attachment for the
lathe would make this unnecessary.(At least at this low level).
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).
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. :-)
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.
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).
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). 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".
And again -- which alloy of SS?
316L
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.
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.(A 1/4" thick disk with a square hole in the center will fit on
the end of the rod).
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).
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.
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).
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.
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.
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.
Thanks a lot.
Darren Harris
Staten Island, New York.