According to :
DoN. Nichols wrote:
[ ... ]
Hmm ... how big is the Delrin to start? Anyway, if you are
turning a length down to 1/8", and the length is something like 9/16" or
so, it *will* bend as you try to turn it. The way to accomplish the
task is:
I have Delrin of Different shapes, but I'd use the scraps which are
basically about 1-1/2" x 2.00" X 12". I'd take it to a band saw first
to make it manageable for the lathe to turn down.
You are going to be making a lot more chips than parts, starting
from that size. A serious bit of waste in my book. And, you *will*
need the 4-jaw independent chuck to hold those rectangular pieces.
Hmm ... look at the MSC web site:
http://www1.mscdirect.com/CGI/NNSRIT...PMT4NO=4749765
which shows 1/8" Delrin (acetal) rod, 1 foot long, for 98 cents each.
Your choice of black, or natural (fairly white). Hmm ... that looks
like Teflon (PTFE), not Delrin (acetyl).
[ ... ]
Thanks. from what I've read, I should treat Delrin like Stainless steel
as far as the sharp tool and cutting speeds.
I also have several 4" diameter Delrin cylinders that are about a foot
long, I'll be slicing them into 3/16" or 1/4" thick disks that I'll
need to do six plunging operations involving making different sized
holes/slots in each of six equal "pie" slices.
O.K.
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.
What if I used a sharp punch of some sort to start, followed by a
center drill in the lathe, and then drill after that? since the 1/8"
hole is only 1/8" from the bottom I'd probably have to balance things
by using a tube with a 7/16" I.D. to fit over the rod/sleeve,
effectively lengthen it so it would slip out of the chuck.
Hmm ... how do you plan to use the lathe for this? I thought
that the hole was from one side to the other, not into the center of the
end.
I think my wording int hat last paragraph was bad, because a chuck
couldn't be used.
First I wanted to be clear that the purpose of the S.S. sleeve situated
around the turned down portion of the S.S. rod would be to keep three
1/16" plates(Delrin/stainless/Delrin) from sliding off.
O.K.
Now. yes, the 11/16" long(7/16" diameter) sleeve will have the turned
down end of the rod already inserted into it so I can drill the 1/8"
diameter hole all the way through *both* at the same time. That 1/8"
diameter hole will be located only 1/8" from the end, so gripping it so
it could be drilled would pose a problem.
Hmm ... I would not bother with the center punch given that
setup, as long as the holder (fixture) which you describe below remains
fixed in position between workpieces.
My idea is to make a "holder" out of a 5-1/2" long, (perhaps 1"
diameter) steel rod. I'd mill a 7/16" wide slot(1/2" deep)down about
half of it's length, so I can place the work(S.S. rod/sleeve)inside it.
The un-slotted end of this "holder" would be bolted to a face plate,
and the threaded end of the work(opposite the sleeve) would be screwed
into a 1" square block which would also be bolted to the face plate.
This would keep the work(S.S.rod/sleeve) from turning in the "holder".
After it is secure to the faceplate, drilling all the way through it
would entail a tool steel punch, followed by a center drill, followed
by a drill bit to get the 1/8" diameter hole(all the way through).
As I say -- the punch probably is not necessary. Just start the
hole with the center drill. (You can get them down to 1/8" diameter,
which would make a great start for the hole.
Now of course I'd have to slot and drill through the "holder" first.
:-)
If the holes must *all* be the same distance from the end, you
will want a V-block clamped to the drill press table, with a stop to
keep you from sliding the workpiece in too far.
Ok. If a $50 drill press would be easier then I will get one.(Hopefully
better than my last one).
Your setup on the faceplate would work. But you would need to
add a counterweight on the faceplate to allow it to balance properly so
you could run at reasonable speeds for a 1/8" drill bit.
P.S: I'd like to point out that I discovered that the 5/8" thru-hole in
my lathe was not a reference to the spindle bore. The spindle bore is
.787".
O.K. That is better.
This is the part that I misinterpreted: "3-jaw self-centering chuck
(bolts to spindle: 2-3/4 inch capacity, approx. 5/8 inch dia.
thru-hole)."
So -- holding workpieces with that chuck will still limit you to
the 5/8" diameter which will fit through that chuck. Other chucks may
allow larger diameters.
Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. |
http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---