Does anyone know how to machine polyurithane. I have to bore a tapered
hole in the subframe mounts for my car, (custom application). Using a
boring bar the material just flexes around the bar.

Any Ideas.
John Roncallo

freezer....

jremovespamblockroncallo wrote:
Does anyone know how to machine polyurithane. I have to bore a tapered
hole in the subframe mounts for my car, (custom application). Using a
boring bar the material just flexes around the bar.

Any Ideas.
John Roncallo

"jremovespamblockroncallo roncallo @snet.net" "jremovespamblock wrote
in message et...
Does anyone know how to machine polyurithane. I have to bore a tapered
hole in the subframe mounts for my car, (custom application). Using a
boring bar the material just flexes around the bar.

Any Ideas.
John Roncallo

I would make a external mandrel to hold the outside of the material and then
grind the desired internal dimention. Trying to single point something this
soft is going to be an exercise in futility.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

"jremovespamblockroncallo roncallo @snet.net" "jremovespamblock wrote
in message et...
Does anyone know how to machine polyurithane. I have to bore a tapered
hole in the subframe mounts for my car, (custom application). Using a
boring bar the material just flexes around the bar.

Any Ideas.
John Roncallo

It can be machined with success, assuming it's not too soft. It varies.
HSS tools with an absurd amount of positive rake, honed very sharp, will
work. The rake is best accomplished via chip breaker, which helps prevent
hogging. It doesn't cut clean, the way Delrin does, but it will cut size
when you have things right. Drilling is an excellent indicator. You
should get a reasonable hole, and chips. If the drill plunges but doesn't
cut well, most likely you won't have any luck machining the stuff you have.
Grinding, as has already been mentioned, will work. If you're trying to
use carbide insert tooling, I'm of the opinion you'll never achieve your
goal.

I made tapered bushings from urethane for the boat I used to own. It had a
Mercruiser I/O drive. The hydraulic arms came equipped with rubber bushings
that extruded regularly, and were a PITA to replace. The bushings I made
lasted years, and were still in the drive when the boat was sold. You're
making an excellent choice, assuming it's hard enough to machine.

Harold

jremovespamblockroncallo wrote:

Does anyone know how to machine polyurithane. I have to bore a tapered
hole in the subframe mounts for my car, (custom application). Using a
boring bar the material just flexes around the bar.

Any Ideas.
John Roncallo


These people give good advice that works:
http://www.redranger.com.au/docs/Page%208.pdf

Tom

Grinding works well even on things like sponge rubbers.

But it leaves one hullova mess!

DOC



On Jul 29, 12:11 am, "Roger Shoaf" wrote:
"jremovespamblockroncallo roncallo @snet.net" "jremovespamblock wrote
in odigy.net...

Does anyone know how to machine polyurithane. I have to bore a tapered
hole in the subframe mounts for my car, (custom application). Using a
boring bar the material just flexes around the bar.

Any Ideas.
John Roncallo

I would make a external mandrel to hold the outside of the material and then
grind the desired internal dimention. Trying to single point something this
soft is going to be an exercise in futility.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

On Sun, 29 Jul 2007 09:47:36 -0700, wrote:

Grinding works well even on things like sponge rubbers.

But it leaves one hullova mess!

DOC



On Jul 29, 12:11 am, "Roger Shoaf" wrote:
"jremovespamblockroncallo roncallo @snet.net" "jremovespamblock wrote
in odigy.net...

Does anyone know how to machine polyurithane. I have to bore a tapered
hole in the subframe mounts for my car, (custom application). Using a
boring bar the material just flexes around the bar.

Any Ideas.
John Roncallo

I would make a external mandrel to hold the outside of the material and then
grind the desired internal dimention. Trying to single point something this
soft is going to be an exercise in futility.

--

Roger Shoaf

Freeze the durn thing, and then work FAST.
About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.



--
Posted via a free Usenet account from http://www.teranews.com

According to Harold and Susan Vordos :

"jremovespamblockroncallo roncallo @snet.net" "jremovespamblock wrote
in message et...
Does anyone know how to machine polyurithane. I have to bore a tapered

[ ... ]

If you're trying to
use carbide insert tooling, I'm of the opinion you'll never achieve your
goal.

Well ... that depends. With *most* carbide insert tooling, I
totally agree. However, I do have some nicely sharp *uncoated* carbide
insert tooling in 55 degree diamond shape which fit the shanks for my
Compact-5/CNC. Any time you get a coated insert, you can bet that it is
not particularlys sharp, but some uncoated can be sharp enough. (I
often use these even on the much larger 12x24" Clausing when I want a
particularly sharp tool.)

These show signs of being ground to finish after being formed,
which probably accounts for the major part of the difference.

I have no idea how to duplicate this set. There was someone
perhaps five to eight years ago here in this newsgroup who was offering
to give away a few to anyone who was interested. I turned out to be the
only one interested (perhaps the only one here with the holders), and
they were superior to any that came with the lathe, so when he offered
to sell me the whole batch of what was left, I took him up on it. Some
are ground for left-hand cutting only, some for right-hand cutting only,
and some for both. Of course the "both" is the smallest number, and the
"right-hand" is the next smallest, but I still have enough to keep me
happy.

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 ---

jremovespamblockroncallo wrote:
Does anyone know how to machine polyurithane. I have to bore a tapered
hole in the subframe mounts for my car, (custom application). Using a
boring bar the material just flexes around the bar.

Any Ideas.
John Roncallo

Gentelmen

Thank you for all the help. From most of the posts here it kind of
pointed me in the right direction. Get some tool with a high rake in
there. I made a tool out of a piece of 1/2" tubing. I ground down 90 %
of the cross section from one side and sharpend it to effectively make a
boaring bar with a very high rake angle. I did forget to mension that
the bore was not required to be precise, so eyeball round was fine.

I also liked the idea of frezzing but anything below houshold frezer
temperature was unavailable (Except for the last 5 LB of Freon 12 I have)

http://www.mercedesshop.com/shopforu...4&postcount=68

"DoN. Nichols" wrote in message
...
According to Harold and Susan Vordos :

"jremovespamblockroncallo roncallo @snet.net" "jremovespamblock
wrote
in message et...
Does anyone know how to machine polyurithane. I have to bore a tapered

[ ... ]

If you're trying to
use carbide insert tooling, I'm of the opinion you'll never achieve your
goal.

Well ... that depends. With *most* carbide insert tooling, I
totally agree. However, I do have some nicely sharp *uncoated* carbide
insert tooling in 55 degree diamond shape which fit the shanks for my
Compact-5/CNC. Any time you get a coated insert, you can bet that it is
not particularlys sharp, but some uncoated can be sharp enough. (I
often use these even on the much larger 12x24" Clausing when I want a
particularly sharp tool.)

These show signs of being ground to finish after being formed,
which probably accounts for the major part of the difference.

I use a diamond ground insert (RB), too, which would be sharp enough, but
sharp isn't enough for this material. If you haven't attempted to machine
it, it's hard to understand. It machines much like rubber. It requires
considerably more positive rake than is available from insert tooling, plus
a broad, deep chip breaker (if desired), thus my comment. I have no doubt
that a successful tool could be ground in carbide if one cared to spend the
time.

Harold

According to Harold and Susan Vordos :

"DoN. Nichols" wrote in message
...
According to Harold and Susan Vordos :

[ ... ]

use carbide insert tooling, I'm of the opinion you'll never achieve your
goal.

Well ... that depends. With *most* carbide insert tooling, I
totally agree. However, I do have some nicely sharp *uncoated* carbide
insert tooling in 55 degree diamond shape which fit the shanks for my
Compact-5/CNC. Any time you get a coated insert, you can bet that it is

[ ... ]

These show signs of being ground to finish after being formed,
which probably accounts for the major part of the difference.

I use a diamond ground insert (RB), too, which would be sharp enough, but
sharp isn't enough for this material. If you haven't attempted to machine
it, it's hard to understand. It machines much like rubber. It requires
considerably more positive rake than is available from insert tooling, plus
a broad, deep chip breaker (if desired), thus my comment. I have no doubt
that a successful tool could be ground in carbide if one cared to spend the
time.

O.K. I'll take your word on that.

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 ---