Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Posted to rec.crafts.metalworking
external usenet poster
 
Posts: 656
Default OT HDPE/UHMW polyethylene?


I'm looking at 3/16" thick polyethylene sheets. Can it be bent 180°
to an outer diameter of about 1 1/4"?

HDPE
http://www.smallparts.com/products/descriptions/283.cfm

UHMW
http://www.smallparts.com/products/descriptions/284.cfm

I suspect some form of HDPE if not UHMW is available at the local
hardware Borg. Will check tomorrow, but I'm not confident about
getting good information about what the material there really is.

Thanks.
  #2   Report Post  
Posted to rec.crafts.metalworking
external usenet poster
 
Posts: 879
Default OT HDPE/UHMW polyethylene?


"John Doe" wrote in message
...

I'm looking at 3/16" thick polyethylene sheets. Can it be bent 180°
to an outer diameter of about 1 1/4"?


This will require heat, but the good part about forming PE is that it melts
easy and doesnt require drying.

If you have a waffle iron with removable grids, you can make your self a
strip heater very easy. Lay out the iron flat on a surface that will not be
affectd by the heat, remove the waffle grids, and using foil make your self
some heat deflectors. (If using kitchen foil, fold it over several times.)

Position the foil so there is an open gap about an inch wide, and hold the
area you want to form over the gap in the foil about an inch or so above.
You may have to flip it a few times to heat it evenly.

In the natural state PE is sort of milky white. With the application of
heat, it turns clear and s then ready to form. To make the bend you
describe, get a length of rod about 1 inch in diameter. You can use wood,
copper or aluminum sucessfully but if yu use metal be sure to pre heat with
a torch or the metal will suck heat out of the plastic too fast. Polishing
helps also. If you use wood, sand it really smooth. If you decide to use
metal as a form heat it gently untill you can touch it but only for a short
time.

While heating the plastic, move it back and forth so the area you heat to
clear is about an inch and a half wide. When you have a clear spot in the
plastic an inch and a half wide lay the center of the clear spot over the
rod and fold it.

It will give you a better form if you have a 1 inch board under the rod and
some spring clanps to attach it too while the melted plastic cools.

It will deform aroung the edges so form a piece that is longer and wider
than you want to end up with.

It will probably be a little funky where the melted part meets with the part
that wasnt melted but for a skid plate this should not matter too much.

A fan will speed up the cooling process.

When the PE is cear it will burn your skin so be careful.

Once you have the plastic clear, that is the time to take it away from the
heat. If you continue to heat it will go from soft to liquid pretty quick.

I didnt meat to make this sound too tough, you might practice on some scrap
to get the hang of it before you do the full size piece.

You do not need to worry about the smell. It will not hurt you like other
stuff might.




I suspect some form of HDPE if not UHMW is available at the local
hardware Borg. Will check tomorrow, but I'm not confident about
getting good information about what the material there really is.


Look for milky white cutting boards that have a waxy feel to them. These
are usually UMHW PE. I have not seen PE as a raw product at the borgs.

--

Roger Shoaf

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


  #3   Report Post  
Posted to rec.crafts.metalworking
external usenet poster
 
Posts: 879
Default OT HDPE/UHMW polyethylene?


"John Doe" wrote in message
...

A second idea might be to get a 1/4 inch sheet larger than the whole board,
remove the axel trucks and form the PE over the bottom of the board. When
cool, trim the edge level with the top of the board, drill holes for the
trucks and screw them back on. This will make the whole bottom of the board
a skid plate. It will add some weight however so doing the board flipping
stuff will be a little trickier and when you bash your shins there will be
more mass to impart a bigger bruise.

Good luck.


--

Roger Shoaf

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


  #4   Report Post  
Posted to rec.crafts.metalworking
external usenet poster
 
Posts: 656
Default OT HDPE/UHMW polyethylene?

"Roger Shoaf" wrote:

Look for milky white cutting boards that have a waxy feel to them.
These are usually UMHW PE.


I've examined those for other purposes, didn't know what they're made
of, thanks.
  #5   Report Post  
Posted to rec.crafts.metalworking
external usenet poster
 
Posts: 656
Default OT HDPE/UHMW polyethylene?

"Roger Shoaf" wrote:

A second idea might be to get a 1/4 inch sheet larger than the
whole board, remove the axel trucks and form the PE over the
bottom of the board. When cool, trim the edge level with the top
of the board, drill holes for the trucks and screw them back on.
This will make the whole bottom of the board a skid plate. It
will add some weight however so doing the board flipping stuff
will be a little trickier and when you bash your shins there will
be more mass to impart a bigger bruise.


I'd probably wear shin guards.

Not that it matters, but I'm making a very small skid plate for
in-line skates, not for a skateboard. The front 80 mm wheel will be
replaced with a 125 mm wheel. That leaves a little more distance
between the front wheel and the second wheel, and I want a stopgap
between those two wheels so the second wheel doesn't get caught up
on stuff the big first wheel rolls over. After an obstruction gets
beyond the first two or three wheels, it's no longer a major hazard.


Without the skid plate, it will look like this but with a bigger
front wheel.

Subject: in-line skate big front wheel
Newsgroups: alt.binaries.phish













Good luck.





  #6   Report Post  
Posted to rec.crafts.metalworking
external usenet poster
 
Posts: 71
Default OT HDPE/UHMW polyethylene?

On Mar 18, 1:25 am, "Roger Shoaf" wrote:
"John Doe" wrote in message

...



I'm looking at 3/16" thick polyethylene sheets. Can it be bent 180°
to an outer diameter of about 1 1/4"?


This will require heat, but the good part about forming PE is that it melts
easy and doesnt require drying.

If you have a waffle iron with removable grids, you can make your self a
strip heater very easy. Lay out the iron flat on a surface that will not be
affectd by the heat, remove the waffle grids, and using foil make your self
some heat deflectors. (If using kitchen foil, fold it over several times.)

Position the foil so there is an open gap about an inch wide, and hold the
area you want to form over the gap in the foil about an inch or so above.
You may have to flip it a few times to heat it evenly.

In the natural state PE is sort of milky white. With the application of
heat, it turns clear and s then ready to form. To make the bend you
describe, get a length of rod about 1 inch in diameter. You can use wood,
copper or aluminum sucessfully but if yu use metal be sure to pre heat with
a torch or the metal will suck heat out of the plastic too fast. Polishing
helps also. If you use wood, sand it really smooth. If you decide to use
metal as a form heat it gently untill you can touch it but only for a short
time.

While heating the plastic, move it back and forth so the area you heat to
clear is about an inch and a half wide. When you have a clear spot in the
plastic an inch and a half wide lay the center of the clear spot over the
rod and fold it.

It will give you a better form if you have a 1 inch board under the rod and
some spring clanps to attach it too while the melted plastic cools.

It will deform aroung the edges so form a piece that is longer and wider
than you want to end up with.

It will probably be a little funky where the melted part meets with the part
that wasnt melted but for a skid plate this should not matter too much.

A fan will speed up the cooling process.

When the PE is cear it will burn your skin so be careful.

Once you have the plastic clear, that is the time to take it away from the
heat. If you continue to heat it will go from soft to liquid pretty quick..

I didnt meat to make this sound too tough, you might practice on some scrap
to get the hang of it before you do the full size piece.

You do not need to worry about the smell. It will not hurt you like other
stuff might.

I suspect some form of HDPE if notUHMWis available at the local
hardware Borg. Will check tomorrow, but I'm not confident about
getting good information about what the material there really is.


Look for milky white cutting boards that have a waxy feel to them. These
are usually UMHW PE. I have not seen PE as a raw product at the borgs.

--

Roger Shoaf

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


The only problem with what you're suggesting, Roger, is that the
plastic won't be UHMW when it cools.

UHMW requires heat and pressure to form. Heating it without pressure
turns it into something different ( not sure WHAT it is, but it's not
UHMW.)

As for differentiating it, cutting boards are usually made of UHMW or
HDPE. HDPE is usually high gloss in finish and a solid white - UHMW
is a semi-transparent while and semi-gloss at best.

If you really need the material to remain UHMW, I'd suggest cutting it
out of a suitably-sized block and drilling out the center.

If you need small blocks of UHMW, you can get them online at;

http://stores.ebay.ca/The-Great-Indu...eNameZl2QQtZkm
  #7   Report Post  
Posted to rec.crafts.metalworking
external usenet poster
 
Posts: 1,803
Default OT HDPE/UHMW polyethylene?

On Tue, 18 Mar 2008 06:45:40 -0700 (PDT), eric h
wrote:




The only problem with what you're suggesting, Roger, is that the
plastic won't be UHMW when it cools.

UHMW requires heat and pressure to form. Heating it without pressure
turns it into something different ( not sure WHAT it is, but it's not
UHMW.)


I've been working with UHMW for 25 years and have never heard this. Do
you have a source?

http://www.garlandmfg.com/plastics/h...mingparts.html

--
Ned Simmons
  #8   Report Post  
Posted to rec.crafts.metalworking
external usenet poster
 
Posts: 4,632
Default OT HDPE/UHMW polyethylene?

eric h fired this volley in news:990dff51-3c37-
:

It weighed less afterwards.


And it took over forty thousand years to cool, too!

LLoyd

  #9   Report Post  
Posted to rec.crafts.metalworking
external usenet poster
 
Posts: 47
Default OT HDPE/UHMW polyethylene?

On Wed, 19 Mar 2008 07:06:43 -0700 (PDT), eric h
wrote:

On Mar 18, 10:14 am, Ned Simmons wrote:
On Tue, 18 Mar 2008 06:45:40 -0700 (PDT), eric h

wrote:

The only problem with what you're suggesting, Roger, is that the
plastic won't beUHMWwhen it cools.


UHMWrequires heat and pressure to form. Heating it without pressure
turns it into something different ( not sure WHAT it is, but it's not
UHMW.)


I've been working withUHMWfor 25 years and have never heard this. Do
you have a source?

http://www.garlandmfg.com/plastics/h...mingparts.html

--
Ned Simmons


I don't have a source for it, ned, but I do remember reading it - I
believe it has something to do with the difficulties you encounter
when UHMW is extruded.

I did experiment with UHMW myself to find out more about what I was
selling (I sell it on ebay as surplusdealdude), and I do remember
weighing a piece, heating it up and re-weighing it after it had been
pressed and cooled. It weighed less afterwards.


I worked for a company that had the capability of injection molding
UHMW. Lots of folks said it couldn't be UHMW but a major chemical
company that makes the resin tested it and said it had all the
properties of UHMW. If it looks like a duck and quacks like a duck
.......
  #10   Report Post  
Posted to rec.crafts.metalworking
external usenet poster
 
Posts: 879
Default OT HDPE/UHMW polyethylene?


"tom (REMOVE) (Tom)" wrote in message
t...
I don't have a source for it, ned, but I do remember reading it - I
believe it has something to do with the difficulties you encounter
when UHMW is extruded.

I did experiment with UHMW myself to find out more about what I was
selling (I sell it on ebay as surplusdealdude), and I do remember
weighing a piece, heating it up and re-weighing it after it had been
pressed and cooled. It weighed less afterwards.


I worked for a company that had the capability of injection molding
UHMW. Lots of folks said it couldn't be UHMW but a major chemical
company that makes the resin tested it and said it had all the
properties of UHMW. If it looks like a duck and quacks like a duck
......


I don't think there is a problem injection molding UHMW any more than there
is HDPE. If I understand my plastic chemistry, (As a non chemist.) the
heaver density varieties of PE just have longer molecular chains. Soda
bottles are the same stuff where the molecules are crosslinked so they will
hold higher pressure without bulging.

--

Roger Shoaf

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


Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
New Help center for UHMW Polyethylene users (jig material) [email protected] UK diy 1 January 8th 07 10:20 PM
New Help center for UHMW POLYETHYLENE (jig making material) [email protected] Woodturning 1 January 8th 07 10:12 PM
Sources for UHMW or HDPE Rob V Woodworking 8 September 15th 05 04:21 AM
Source for 3" thick HDPE sheet or bar? DeepDiver Metalworking 4 June 4th 05 11:54 PM


All times are GMT +1. The time now is 10:12 AM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"