I wanted to make some "outrigger pads", which are square pads
something like 24x24x3" thick. I have some scrap polyethylene cutoffs
and I was wondering, if I just melt and cast them, do I lose any
possible assurance of strength?

i

Ignoramus885 wrote:
I wanted to make some "outrigger pads", which are square pads
something like 24x24x3" thick. I have some scrap polyethylene cutoffs
and I was wondering, if I just melt and cast them, do I lose any
possible assurance of strength?

Just melting and casting scraps, void free, without starting a huge sticky
fire will be quite the project by itself.

Heat breaks down molecules so keep the heat low enough to melt
and merge all together and then pour (maybe trowel) the result into a
form. Nice thing, it is in the 300 some odd temp. Color might change
the melting temp.

Martin

On 11/12/2015 8:15 PM, Ignoramus885 wrote:
I wanted to make some "outrigger pads", which are square pads
something like 24x24x3" thick. I have some scrap polyethylene cutoffs
and I was wondering, if I just melt and cast them, do I lose any
possible assurance of strength?

i

In article ,
Ignoramus885 wrote:

I wanted to make some "outrigger pads", which are square pads
something like 24x24x3" thick. I have some scrap polyethylene cutoffs
and I was wondering, if I just melt and cast them, do I lose any
possible assurance of strength?

Well, with ordinary polyethylene, there isn't much assurance of
strength - it's polyethylene.

One can certainly melt ordinary low-density polyethylene, it's a bit
like sticky wax. But do it outside.

The higher the molecular weight, the harder to handle.

What is the purpose of these slabs?

Joe Gwinn

"Ignoramus885" wrote in message
...

I wanted to make some "outrigger pads", which are square pads
something like 24x24x3" thick. I have some scrap polyethylene cutoffs
and I was wondering, if I just melt and cast them, do I lose any
possible assurance of strength?

i
================================================== ==============

I've played a bit trying to melt very small pieces of PE, and I usually got
charring and smoke long before I got any kind of fluid state that I could
pour. I think there is a reason they use injection molding with PE and not
simple pouring - get it hot, pump it in so it doesn't need to have a very
low viscosity, and get it cooled before it can decompose. Guessing that you
only want two or four pads, I'd weld up a pan to use as the mold from mild
steel, maybe 1/4" thick or more on the bottom for decent temperature
uniformity and 1/8" or whatever on the sides with some angle for easy
release, and put it on a stove top with two or all four burners going. Put
in your chunks of PE and try to melt them in place, stirring as you go as
much as you can. Even if you don't get it all truly molten you might get
enough mixing to get a fairly cohesive mass. Then just turn off the
burners, cover it and let it cool slowly, and hope it doesn't crack too
badly. Do your pads have to be solid, or would high density foam work? You
can get some pretty thick foam from ULine for not that much $$.

-----
Regards,
Carl Ijames

On Thu, 12 Nov 2015 20:15:27 -0600, Ignoramus885
wrote:

I wanted to make some "outrigger pads", which are square pads
something like 24x24x3" thick. I have some scrap polyethylene cutoffs
and I was wondering, if I just melt and cast them, do I lose any
possible assurance of strength?

i
I think polyethylene would difficult to melt and fuse successfully.
It'd probably be heavier and less stiff than the traditional wood as
well. If you got it done, it'd certainly take a beating. I'd go for
bolted live oak or whatever you have of similar toughness up there.
I've had to drill a pilot hole to drive a nail in live oak.

Good luck.

Pete Keillor

On Fri, 13 Nov 2015 06:20:23 -0600, Pete Keillor
wrote:

On Thu, 12 Nov 2015 20:15:27 -0600, Ignoramus885
wrote:

I wanted to make some "outrigger pads", which are square pads
something like 24x24x3" thick. I have some scrap polyethylene cutoffs
and I was wondering, if I just melt and cast them, do I lose any
possible assurance of strength?

i
I think polyethylene would difficult to melt and fuse successfully.
It'd probably be heavier and less stiff than the traditional wood as
well. If you got it done, it'd certainly take a beating. I'd go for
bolted live oak or whatever you have of similar toughness up there.
I've had to drill a pilot hole to drive a nail in live oak.

I have success with HDPE welding with a 200 watt iron and the lock strip
from HDPE bucket lids. Flows well and very controllable.
I am not sure how a casting would work.

You might consider several yard sale/trash pile cutting boards
interlaced and bolted.
--
Mr.E

On Thu, 12 Nov 2015 20:15:27 -0600, Ignoramus885
wrote:

I wanted to make some "outrigger pads", which are square pads
something like 24x24x3" thick. I have some scrap polyethylene cutoffs
and I was wondering, if I just melt and cast them, do I lose any
possible assurance of strength?

i

POlyethylene comes in different densities and six or seven different
types. Also, consumber products often are made of hybrids and mixtures
(sometimes "alloys") and I've heard that they don't mix well. When the
scrap is re-melted, it's usually to make lower-grade products.

I don't know if you can just melt it and cast it. When they make
products from recycled poly, it's usually pelletized and then
injection-molded. You'd have to see if you can get it to flow with
just gravity alone.

--
Ed Huntress

On 11/13/2015 9:50 AM, Mr.E wrote:
....
You might consider several yard sale/trash pile cutting boards
interlaced and bolted.


Several? If a cutting board is 12 x 16 x 1/2 (WAG), it would take 18 of
them to make 24 x 24 x 3.

On Thu, 12 Nov 2015 20:15:27 -0600, Ignoramus885
wrote:

I wanted to make some "outrigger pads", which are square pads
something like 24x24x3" thick. I have some scrap polyethylene cutoffs
and I was wondering, if I just melt and cast them, do I lose any
possible assurance of strength?

i
The PE will probably be prone to cracking if you do this.
Eric

On Thursday, November 12, 2015 at 6:15:30 PM UTC-8, Ignoramus885 wrote:
I wanted to make some "outrigger pads", which are square pads
something like 24x24x3" thick. I have some scrap polyethylene cutoffs

Yeah, melting polyethylene was the basis of toy-soldier home kits some
years ago. It's do-able. The problem is, you need low-density polyethylene
or the temperature/pressure requirements will be a nuisance.
Some (very cheap) hotmelt glues, and P-tex candles (for ski repairs)
are melt-friendly (more 'soften', really) polyethylene.

Outrigger ground pads - sounds like you want some tough stuff
lifting up the crane with them. I would think you might squish them
out from under the feet. 1/2" steel plate would be nice, I see a
lot of large lam blocks or log cabin cutoffs.

I saw the guys here in town - they have some neat cranes! - They
use counter balance weights. They move them with the crane while
setting up - boom not extended... light enough to use tires...

I would think plate weights would be in the scrap line of yours.

Martin

On 11/12/2015 10:30 PM, Carl Ijames wrote:
"Ignoramus885" wrote in message
...

I wanted to make some "outrigger pads", which are square pads
something like 24x24x3" thick. I have some scrap polyethylene cutoffs
and I was wondering, if I just melt and cast them, do I lose any
possible assurance of strength?

i
================================================== ==============

I've played a bit trying to melt very small pieces of PE, and I usually got
charring and smoke long before I got any kind of fluid state that I could
pour. I think there is a reason they use injection molding with PE and not
simple pouring - get it hot, pump it in so it doesn't need to have a very
low viscosity, and get it cooled before it can decompose. Guessing that you
only want two or four pads, I'd weld up a pan to use as the mold from mild
steel, maybe 1/4" thick or more on the bottom for decent temperature
uniformity and 1/8" or whatever on the sides with some angle for easy
release, and put it on a stove top with two or all four burners going. Put
in your chunks of PE and try to melt them in place, stirring as you go as
much as you can. Even if you don't get it all truly molten you might get
enough mixing to get a fairly cohesive mass. Then just turn off the
burners, cover it and let it cool slowly, and hope it doesn't crack too
badly. Do your pads have to be solid, or would high density foam work? You
can get some pretty thick foam from ULine for not that much $$.

-----
Regards,
Carl Ijames

On Fri, 13 Nov 2015 11:03:02 -0500, Ed Huntress
wrote:

I don't know if you can just melt it and cast it.

Nope, will not work.

When they make
products from recycled poly, it's usually pelletized and then
injection-molded.

Or granulated, which is a crude approximated pellet. Many products have
a percentage regrind added back. Sprues, risers (injection) tops, tails
(blow molding) and reject parts are ground and added back to the virgin
pellets. Even baby bottles! Of which I had my grubby fingers in hundreds
of thousands of back when I was a blow molding operator. (Someone had to
give the inspectors / packers breaks and lunches) Almost identical with
injection molding and similar with roto molding other than the regrind
has to be turned to powder first and is sometimes 100% recycled which
was never the case when I worked with blow or injection molding. (Shift
supervisor and then maintenance there)

You'd have to see if you can get it to flow with
just gravity alone.

Nope, will not work.
--
William

William Bagwell fired this volley in
:


Nope, will not work.
--
William

Agree,
I managed a lancet injection line for a time. The temperatures NEVER got
high enough to liquify PE at atmospheric pressure. The screws were
delivering it at about 150 atmospheres.

Lloyd

On Sat, 14 Nov 2015 21:15:54 -0500, William Bagwell
wrote:

On Fri, 13 Nov 2015 11:03:02 -0500, Ed Huntress
wrote:

I don't know if you can just melt it and cast it.

Nope, will not work.

When they make
products from recycled poly, it's usually pelletized and then
injection-molded.

Or granulated, which is a crude approximated pellet. Many products have
a percentage regrind added back. Sprues, risers (injection) tops, tails
(blow molding) and reject parts are ground and added back to the virgin
pellets. Even baby bottles! Of which I had my grubby fingers in hundreds
of thousands of back when I was a blow molding operator. (Someone had to
give the inspectors / packers breaks and lunches) Almost identical with
injection molding and similar with roto molding other than the regrind
has to be turned to powder first and is sometimes 100% recycled which
was never the case when I worked with blow or injection molding. (Shift
supervisor and then maintenance there)

You'd have to see if you can get it to flow with
just gravity alone.

Nope, will not work.

That's what I thought. We needed the voice of experience in there.
Thanks for contributing it.

--
Ed Huntress

On Sat, 14 Nov 2015 20:23:46 -0600, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

William Bagwell fired this volley in
:


Nope, will not work.
--
William

Agree,
I managed a lancet injection line for a time. The temperatures NEVER got
high enough to liquify PE at atmospheric pressure. The screws were
delivering it at about 150 atmospheres.

Lloyd

Powdered PE will melt / fuse at atmospheric or very slightly above if
the vent tubes are partially plugged. But hollow pads are not what Iggy
needs.

When I started there (roto) ten years ago they were running mostly low
density PE but had a second silo of high density for the few customers
who wanted it. After a powder mill was added to save the ten cent per
pound difference (~three million pounds per year, it adds up!) we
switched to medium density PE for every one. One silo for pellets and
one for powder.

Been gone four years now and miss that place like a stubbed toe!
--
William

"William Bagwell" wrote in message
...
On Sat, 14 Nov 2015 20:23:46 -0600, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

William Bagwell fired this volley in
m:


Nope, will not work.
--
William

Agree,
I managed a lancet injection line for a time. The temperatures
NEVER got
high enough to liquify PE at atmospheric pressure. The screws were
delivering it at about 150 atmospheres.

Lloyd

Powdered PE will melt / fuse at atmospheric or very slightly above
if
the vent tubes are partially plugged. But hollow pads are not what
Iggy
needs.

When I started there (roto) ten years ago they were running mostly
low
density PE but had a second silo of high density for the few
customers
who wanted it. After a powder mill was added to save the ten cent
per
pound difference (~three million pounds per year, it adds up!) we
switched to medium density PE for every one. One silo for pellets
and
one for powder.

Been gone four years now and miss that place like a stubbed toe!
--
William

Is there a material and method suitable for amateurs with some
machining capability?

I've molded rubber in a simple brass mold compressed in a bench vise
and heated with a propane torch until a drop of solder on it melted.

-jsw

On Sun, 15 Nov 2015 07:03:25 -0500, "Jim Wilkins"
wrote:

"William Bagwell" wrote in message
.. .

Powdered PE will melt / fuse at atmospheric or very slightly above
if
the vent tubes are partially plugged. But hollow pads are not what
Iggy
needs.

When I started there (roto) ten years ago they were running mostly
low
density PE but had a second silo of high density for the few
customers
who wanted it. After a powder mill was added to save the ten cent
per
pound difference (~three million pounds per year, it adds up!) we
switched to medium density PE for every one. One silo for pellets
and
one for powder.

Been gone four years now and miss that place like a stubbed toe!
--
William

Is there a material and method suitable for amateurs with some
machining capability?

I've molded rubber in a simple brass mold compressed in a bench vise
and heated with a propane torch until a drop of solder on it melted.

-jsw

What are you trying to make? After thermoforming roto molding is
probably the easiest for an amateur to try. Lots of videos on
Youtube showing DIY rotomolding 'contraptions'. Most using compounds
which do not require heat. So if you want to melt powdered plastic
use metal where they use wood.

Finished part must be hollow, very simple shapes do not always
require draft though it helps. Complex shapes must have ample draft
or you will never get the part out. 1 to 1 ratio will only work for
very simple shapes, 4 to 1 is better for complex parts. 4 to 1 and
the faster 8 to 2 were about all we used when I worked there.

If you want to build a mold and have it run by a commercial shop
this page may be of help.
http://www.mysecondbathouse.com/firstmold.html
Place I worked at was always slow around the holidays even during
busy years. Much more receptive to small runs when things are slow.
--
William

William Bagwell fired this volley in
:

Much more receptive to small runs when things are slow.

Maybe "more receptive", but what would be the cost of a custom mold?

Don't kid me! I was IN that business. I know what (domestically-made)
molds cost! G

Lloyd

On Sun, 15 Nov 2015 19:21:02 -0600, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

William Bagwell fired this volley in
:

Much more receptive to small runs when things are slow.

Maybe "more receptive", but what would be the cost of a custom mold?

Don't kid me! I was IN that business. I know what (domestically-made)
molds cost! G

Lloyd

Yes, injection (and blow) molds are very expensive. When I worked at
Evenflo was told one of my two cavity bottle molds was probably the
least expensive mold in the plant at $20,000! Multi (24 - 36) cavity
injection mold that could mold threads and 'unscrew' before ejecting
might be a quarter million. Pretty sure this included the
thermolator which could send coolant at different temperatures to
various places in the mold. In some cases the mold cost twice what
the machine it ran on cost.

Rotomolding tooling is an order of magnitude cheaper since there is
little or no pressure involved. Cast aluminum and weldments, steel
or aluminum are the norm. Only seen one machined from solid rotomold
and it was extremely small. Out of time...
--
William