Machining plastic

[Dixon]

I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

[Half-nutz]

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

Can you attatch the shop vac near the cutting tool?

[tpow]

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It
gets about 25 deep "V" belt type grooves down the 40" length. This is done
on a manual lathe and it takes as much time to remove the wound-up chip,
that almost instantly winds around the part, as it take to cut it. It cuts
with a continous chip. Any good ideas here? Stopping the feed every .025"
to break the stringy chip sort of helps, but I'm looking for a cutting tool
geometry type trick if possible.
Dixon

we machine pu and as Half says have an industrial vac set up running through
a 205 litre drum to draw off the swarf.

[John R. Carroll]

Post by tpow

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long.
It gets about 25 deep "V" belt type grooves down the 40" length.
This is done on a manual lathe and it takes as much time to remove
the wound-up chip, that almost instantly winds around the part, as
it take to cut it. It cuts with a continous chip. Any good ideas
here? Stopping the feed every .025" to break the stringy chip sort
of helps, but I'm looking for a cutting tool geometry type trick if
possible.
Dixon

we machine pu and as Half says have an industrial vac set up running
through a 205 litre drum to draw off the swarf.

I'll bet you could break a chip by incorporating this idea.

https://www.exair.com/Cultures/en-US/Primary+Navigation/Products/Vortex+Tubes+and+Spot+Cooling/Component+Cooler

[BottleBob]

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.

Dixon:

I think anyone that's ever turned plastic has run into the same
problem. The backing off of the feed handle (like you're doing), is
usually what I do. Chip breakers don't work well on plastic since the
plastic chips just flow around them.
Here's an idea (a little too involved for your application - but might
be viable for someone doing long production runs), a device that moves
the tool bit in and out rapidly while cutting would tend to break the
chips into small pieces. A tool post adapter that could be operated by
an eccentric operated by an electric motor, or perhaps by an ultrasonic
vibration generator.
An tooling opportunity for someone that could make one cheap, easy to
setup, and adaptable for turning as well as plunging.

[Anthony]

BottleBob <***@earthlink.net> wrote in news:***@earthlink.com:



For me, a *slow* RPM and *heavy* feed works sometimes as the chip is thick
enough that it breaks. Depends on material though.

[Proctologically Violated®©]

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It
gets about 25 deep "V" belt type grooves down the 40" length. This is done
on a manual lathe and it takes as much time to remove the wound-up chip,
that almost instantly winds around the part, as it take to cut it. It cuts
with a continous chip. Any good ideas here? Stopping the feed every .025"
to break the stringy chip sort of helps, but I'm looking for a cutting tool
geometry type trick if possible.

In my own hack-machining operation, I sometimes stand at the lathe in
autofeed, with a pair of long-nose pliers or channellocks ripping the
ribbons off the work/tool as the cut proceeds. It is indeed a pita.

A reciprocating solenoid or air cylinder suitably mounted, with knife-edged
hook of some sort, could proly be rigged to go back/forth over the work to
pull/tear/cut these ribbons off the work.

I don't know exactly how this would be done, but I suspect a few electric
air valves could be hooked up with a limiting microswitch or two to make
this happen pretty straighforwardly. Ditto a solenoid.

Perhaps a spray coolant would help to keep the cut cooler, the chips more
brittle, ergo more breakable.
--
------
Mr. P.V.'d (formerly Droll Troll), Yonkers, NY

Sodomized by Congress, butt again...
But, Obama at least took me to the hospital!

entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie,
all d'numbuhs

Post by Dixon
Dixon

[Cliff]

On Fri, 6 Jun 2008 00:39:22 -0400, "Proctologically Violated®©"

Post by Proctologically Violated®©
In my own hack-machining operation, I sometimes stand at the lathe in
autofeed, with a pair of long-nose pliers or channellocks ripping the
ribbons off the work/tool as the cut proceeds. It is indeed a pita.

PV,
This is not very safe at all.
IF you must get a longish pole with a slight hook
on the end of it. Cut the stick almost thru in several
places so that it will break easily if much force is applied to
it.
Use that to remove chips from a live machine. And don't be
running at high RPMs.

[Cliff]

On Fri, 6 Jun 2008 00:39:22 -0400, "Proctologically Violated®©"

Post by Proctologically Violated®©
In my own hack-machining operation, I sometimes stand at the lathe in
autofeed, with a pair of long-nose pliers or channellocks ripping the
ribbons off the work/tool as the cut proceeds. It is indeed a pita.

PV,
This is not very safe at all.
IF you must get a longish pole with a slight hook
on the end of it. Cut the stick almost thru in several
places so that it will break easily if much force is applied to
it.
Use that to remove chips from a live machine. And don't be
running at high RPMs.

BE PREPARED TO LET GO OF THE STICK. Don't
wear clothes it might catch on either.
Perhaps a half inch wooden dowel ... sand off splithers ...
wear gloves ...

[Proctologically Violated®©]

Post by Cliff
On Fri, 6 Jun 2008 00:39:22 -0400, "Proctologically Violated®©"

Post by Proctologically Violated®©
In my own hack-machining operation, I sometimes stand at the lathe in
autofeed, with a pair of long-nose pliers or channellocks ripping the
ribbons off the work/tool as the cut proceeds. It is indeed a pita.

PV,
This is not very safe at all.
IF you must get a longish pole with a slight hook
on the end of it. Cut the stick almost thru in several
places so that it will break easily if much force is applied to
it.
Use that to remove chips from a live machine. And don't be
running at high RPMs.
BE PREPARED TO LET GO OF THE STICK. Don't
wear clothes it might catch on either.

Not really a problem, as I machine mostly butt-necked in the summertime.
I have, however, taken to wearing a sheetmetal codpiece--esp. when welding.
--
------
Mr. P.V.'d (formerly Droll Troll), Yonkers, NY

Sodomized by Congress, butt again...
But, Obama at least took me to the hospital!

entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie,
all d'numbuhs

Post by Cliff
Perhaps a half inch wooden dowel ... sand off splithers ...
wear gloves ...
--
Cliff

[Gunner]

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

Good strong shop vac attached to the cutting tool


Gunner

[Dixon]

Post by Gunner

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

Good strong shop vac attached to the cutting tool
Gunner

Thanks everyone, the next time I will try a strong vac. I'm hopeful, but I
"almost" see the continous chip as having a evil mind of it's own when it
comes to causing greif. I've even seen plastic continuous chips wrap around
the lead screw until it was completly covered.
Dixon

[Jon]

Post by Dixon

Post by Gunner

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

Good strong shop vac attached to the cutting tool
Gunner

Thanks everyone, the next time I will try a strong vac. I'm hopeful, but I
"almost" see the continous chip as having a evil mind of it's own when it
comes to causing greif. I've even seen plastic continuous chips wrap
around the lead screw until it was completly covered.
Dixon

I can't share my best suggestion, but here's another...

Milling cutters have multiple cuting edges and make chips in pieces instead
of long strands.
(are the gears turning yet?)

Also consider different tool shapes. You could rough plunge the grooove
first. You still get stringy chips, but it changes the nature of them.

We used the vacuum cleaner trick on a recent production job, and it worked
great!

We machine LOTS of plastics and urethanes.
Whenever I see someone say you can't machine this or that, I snicker.

[tpow]

Post by Dixon

Post by Gunner

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

Good strong shop vac attached to the cutting tool
Gunner

Thanks everyone, the next time I will try a strong vac. I'm hopeful, but I
"almost" see the continous chip as having a evil mind of it's own when it
comes to causing greif. I've even seen plastic continuous chips wrap
around the lead screw until it was completly covered.
Dixon

forget all the suggestions about chip breakers and freezers, we turned a
load of this stuff a few years back and the Hoover was the very best. Start
the cut and guide the first tail of swarf down the nozzle and the rest will
follow.

[Proctologically Violated®©]

Post by tpow

Post by Dixon

Post by Gunner

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

Good strong shop vac attached to the cutting tool
Gunner

Thanks everyone, the next time I will try a strong vac. I'm hopeful, but
I "almost" see the continous chip as having a evil mind of it's own when
it comes to causing greif. I've even seen plastic continuous chips wrap
around the lead screw until it was completly covered.
Dixon

forget all the suggestions about chip breakers and freezers, we turned a
load of this stuff a few years back and the Hoover was the very best.
Start the cut and guide the first tail of swarf down the nozzle and the
rest will follow.

How elegant!
I didn't initially envision exactly how a vacuum cleaner would help, but
this is Da Bomb!!
Also keeps the place clean!

I would imagine, tho, that at high enough rpm this might be a little touch
and go, but still a great solution.
Would be good for *any* ribbon-like chip, I would imagine, assuming suff.
diam hose/nozzle.

[Gary H. Lucas]

Post by tpow

Post by Dixon

Post by Gunner

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

Good strong shop vac attached to the cutting tool
Gunner

Thanks everyone, the next time I will try a strong vac. I'm hopeful, but
I "almost" see the continous chip as having a evil mind of it's own when
it comes to causing greif. I've even seen plastic continuous chips wrap
around the lead screw until it was completly covered.
Dixon

forget all the suggestions about chip breakers and freezers, we turned a
load of this stuff a few years back and the Hoover was the very best.
Start the cut and guide the first tail of swarf down the nozzle and the
rest will follow.

One thing, when you go to pull the chips out of the steel vacuum drum wear
rubber gloves. The damn static charge HURTS!

Gary H. Lucas

[Gunner]

Post by Dixon

Post by Gunner

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

Good strong shop vac attached to the cutting tool
Gunner

Thanks everyone, the next time I will try a strong vac. I'm hopeful, but I
"almost" see the continous chip as having a evil mind of it's own when it
comes to causing greif. I've even seen plastic continuous chips wrap around
the lead screw until it was completly covered.
Dixon

One thing you can do, depending on depth of cut etc etc..is to use a
razor sharp 2 flute endmill as your cutting tool. One flute to be the
cutting edge and oriented to be horizontal. Thats a positive rake
with a polished "guide" for the chip string to travel along, away from
the cut, and into the vacuum.

Standard right hand twist for a plunge (turned appropriately),
lefthand twist for a longitudnal cut. (angled into the work on the
right flute

I ground one flute back for clearence and had a newbie try it on some
nasty nasty red plastic he was trying to cut..after he called me to
take his manual lathe apart to get out all the red stringers. He
called me back the next day and blessed me, my family and all my
ancestors back to Hardimus the Horny because it was working so well.

If you take a 3/8 HSS tool and grind it way positive rake, with a deep
deep front relief...like a trepanning tool, and a smooth curved gullet
behind the cutting edge, the chip string flies out of the gullet and
up into the air. Ive seen guys have arcs of plastic flying up over
their heads and down into a garbage can to the side and behind them.
Running 3000 rpm plus and feeding balls to the wall with their razor
sharp tool, ground as I described.



Gunner

[Jon]

Post by Gunner

Post by Dixon

Post by Gunner

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts
with
a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

Good strong shop vac attached to the cutting tool
Gunner

Thanks everyone, the next time I will try a strong vac. I'm hopeful, but I
"almost" see the continous chip as having a evil mind of it's own when it
comes to causing greif. I've even seen plastic continuous chips wrap around
the lead screw until it was completly covered.
Dixon

One thing you can do, depending on depth of cut etc etc..is to use a
razor sharp 2 flute endmill as your cutting tool. One flute to be the
cutting edge and oriented to be horizontal. Thats a positive rake
with a polished "guide" for the chip string to travel along, away from
the cut, and into the vacuum.
Standard right hand twist for a plunge (turned appropriately),
lefthand twist for a longitudnal cut. (angled into the work on the
right flute
I ground one flute back for clearence and had a newbie try it on some
nasty nasty red plastic he was trying to cut..after he called me to
take his manual lathe apart to get out all the red stringers. He
called me back the next day and blessed me, my family and all my
ancestors back to Hardimus the Horny because it was working so well.
If you take a 3/8 HSS tool and grind it way positive rake, with a deep
deep front relief...like a trepanning tool, and a smooth curved gullet
behind the cutting edge, the chip string flies out of the gullet and
up into the air. Ive seen guys have arcs of plastic flying up over
their heads and down into a garbage can to the side and behind them.
Running 3000 rpm plus and feeding balls to the wall with their razor
sharp tool, ground as I described.
Gunner

We remove urethane from steel wheel cores exactly as Gunner described

My brother took it step further, he scores the tire first, and gets pieces
flying thru the air

[Cliff]

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

It's too bad that you cannot just wind the chip up on a driven roller ....

[Cliff]

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

Have you tried first "freezing" it in a bucket of dry ice for a few hours?

[Cliff]

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

Programming lots of in & out moves to break up the chips
as the stock rotates ... just don't do it exactly once per rev
or anything similar (exactly N times per rev or every M revs) <g>.

[D Murphy]

Post by Cliff

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long.
It gets about 25 deep "V" belt type grooves down the 40" length. This
is done on a manual lathe and it takes as much time to remove the
wound-up chip, that almost instantly winds around the part, as it take
to cut it. It cuts with a continous chip. Any good ideas here?
Stopping the feed every .025" to break the stringy chip sort of helps,
but I'm looking for a cutting tool geometry type trick if possible.
Dixon

Programming lots of in & out moves to break up the chips
as the stock rotates ... just don't do it exactly once per rev
or anything similar (exactly N times per rev or every M revs) <g>.

So Cliff, what CAM system do you use to program a manual lathe?

[John R. Carroll]

Post by D Murphy

Post by Cliff

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long.
It gets about 25 deep "V" belt type grooves down the 40" length.
This is done on a manual lathe and it takes as much time to remove
the wound-up chip, that almost instantly winds around the part, as
it take to cut it. It cuts with a continous chip. Any good ideas
here? Stopping the feed every .025" to break the stringy chip sort
of helps, but I'm looking for a cutting tool geometry type trick if
possible. Dixon

Programming lots of in & out moves to break up the chips
as the stock rotates ... just don't do it exactly once per rev
or anything similar (exactly N times per rev or every M revs) <g>.

So Cliff, what CAM system do you use to program a manual lathe?

C-something wasn't it?
LOL

[D Murphy]

Post by John R. Carroll

Post by D Murphy

Post by Cliff

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long.
It gets about 25 deep "V" belt type grooves down the 40" length.
This is done on a manual lathe and it takes as much time to remove
the wound-up chip, that almost instantly winds around the part, as
it take to cut it. It cuts with a continous chip. Any good ideas
here? Stopping the feed every .025" to break the stringy chip sort
of helps, but I'm looking for a cutting tool geometry type trick if
possible. Dixon

Programming lots of in & out moves to break up the chips
as the stock rotates ... just don't do it exactly once per rev
or anything similar (exactly N times per rev or every M revs) <g>.

So Cliff, what CAM system do you use to program a manual lathe?

C-something wasn't it?
LOL

I'm convinced he can't comprehend what he reads.

I wonder if we can get him to post some code for the manual lathe?

[Cliff]

Post by D Murphy
So Cliff, what CAM system do you use to program a manual lathe?

Sorry, I just skimmed the content & came back later.
How about a geared/driven cam? Seems I sort of recall such
lathe attachments from way back?

[u***@earthlink.net]

Post by Dixon
I occasionally turn a large polyurethane roller. 12" dia X 40" long. It gets
about 25 deep "V" belt type grooves down the 40" length. This is done on a
manual lathe and it takes as much time to remove the wound-up chip, that
almost instantly winds around the part, as it take to cut it. It cuts with a
continous chip. Any good ideas here? Stopping the feed every .025" to break
the stringy chip sort of helps, but I'm looking for a cutting tool geometry
type trick if possible.
Dixon

Drill a hole every 180 degrees or so in the center of where the
grooves are going to go (perpendicular to centerline obviously). That
will give you an interrupted cut breaking most of the rough chip. Use
the biggest drill you can afford a margin of error in Z. Make a depth
jig to not exceed the minor diameter. You will still have to deal with
stringy finish chips though.