Wire Nichrome

Hey guys,

Heres a website for cheap nichrome wire only $5.80 for 4m 

http://www.surplustronics.co.nz/shop/product-EWW4040.html

Also:

Tomorrow (1st of June) Would like to extrude some plastic through the screw extruder and see if it has any issues.

In manufacture they use a screw with a variable thread and spacing to increase pressure, move material in different states and maintain temperature within the chamber.

Ive had a really good look around in town and the hutt for a screw or orger, at any place I could think of, as well the ideas of every business i walked into. I couldn't find exactly what would be used and it seems they are usually custom made for their purpose.

The screws were either far too large, thread depth was too small or angle of thread was too large and would require a high pressure to move.

And so far the best suited is a 8mm wood orger for drilling holes - run in reverse.

If this does not work a 10-15mm Coach Screw may be a good replacement.

I also think Ive underestimated the amount of pressure that can be required within the chamber to extrude the plastic, in a few different machines they use COOLING only because the large pressure causes over heating of the plastic within.

If it requires heating it is usually done at the chamber close to the die and uses the radiating heat along the chamber to melt the plastic at a slower rate making it mix better. As the plastic moves along the chamber it will absorb heat from the outside and help to stop overheating towards the hopper.

Hopefully, at the moment the steel chamber will give us enough control over the temperature along it.

On the extrusion side with our current screw configuration, some upgrades might be

*A heat separation section between the start and end of the die to help cool and keep the plastic in the die shape (high temp plastic, brass,copper which is 5 times less thermally conductive as steel or ceramic - i haven't check its thermal capacity yet)

*A vent to reduce air within the melt section(a vertical metal tube with a plate at the top that has tiny holes or a porous material)

*A screen inside part way down the melt section to help clean the Plastic as it moves along the chamber (Metal Plate with holes in it)

This also helps with re-aligning the chemical bonds within the plastic and a possible avenue to make re-melting easier within the makerbot and the recyclebot process

*Change of material for the Chamber to better control temperatures.

*Screw Replacement.

And further down the track and easy way to assemble/clean/clear material and replace parts within the extrusion chamber and screw assembly.

Have been looking at the variable temperature melting points and has something to do with re-melt and amount of moisture within the plastic during flake to melt stage.

If the plastic is not kept below a certain Moisture content the water has a chemical reaction within the plastic and causes it to break down back into its primary elements causing a higher temperature to re-melt again.

"Ideally the reground pet should be dried to below 0.025% moisture content before extrusion"

Seems there are generally two methods. Drying the pre-grind and then flakes, or a Vacuum in the melt and flak chamber(Seems a little intense).

hopefully we can get the extrusion and heating a little tuned and see if we really need to go down the "drying" track before investigating further.

To make our job easier we really need to keep as much moister away from pre-melted and melting pet as possible.

Got the coffee grinder, so far it just jams it up. Hand grinder may be the way to go. I'll keep on working on it though.

Meeting

Meeting at 9-10am Friday 28th

Circuit Diagram

Just been working on a circuit for the heating component of the extruder with help from Tiago.

Jamie and I bought a couple of things from Jaycar and will grab a couple more things tomorrow.

The best material to make the barrel out of is brass but we need some kind of heat insulator between the barrel and the electronics. Apparently wood is good. Its easier to explain it in person some other time though.

http://www.plastics.org.nz/page.asp?id=585

good plastic info

do we want to go visit wellington plastic extruders for more info and ideas?
check the list out at:

http://nz.vicdir.com/dir-w10015s24347-plastic-goods-manufacturers.htm

will call Leda industrial as sugested by Ross

to talk about if they do extrusion...e t c

Meeting 8am Wednesday morning

PET Melting Temperature

• Maximum Temperature: 248°F 120°C
• Minimum Temperature: -148°F -100°C
• Autoclavable: No
• Melting Point: 266°F 130°C
• Tensile Strength: 4550 psi 

Plastic Melting Tempertures

Swiped the following table from Nasa:

HDPE about 130 ºC
LDPE about 110 ºC
PET 250—260 ºC
PP 160—170 ºC
PS 70—115 ºC
PVC 75—90 ºC

Grinding mechanism

COFFEE GRINDERS!

Ben and I have been looking at grinding mechs, real expensive to buy new but I've found some on trade me, probably end up costing about $60-80. orrr we could get a cheap old skool hand coffee grinder (might have to attach a motor to it) for about $20.

The electric ones would keep everything automated but may not have enough torque to grind the PET, where as the hand grinder should be fine. as long as it doesn't break.

Chur

Teflon Bra and concept

http://www.youtube.com/watch?v=pu44qf8eetY

pet experiments

Pet, melting at home mmm

http://www.goedjn.com/essays/botplas.html

Here's a slightly less beefy shredder.

Due for Thursday, May 20th

Come up with three concepts in terms of how we will create the process of melting and extruding the plastic bottles. Focus on how we will shred, melt, create a dye cast, and turn it into a spool.

Notes:
Melting Point is 120-130 Celcius for high density PET

sketch concepts and we will present them to each other and find the best techniques.

It would be good to do some experimentation as well!

Just SHREDDING it up

Check out these industo shredders, needa get one

http://www.youtube.com/watch?v=Qedfz8nTHO8&feature=related

how can we shred our plastic efficently?

Hey,

Sorry i had to leave today.

Jeon bin has been researching with extruding a few different types of plastics and heaps of colours for the maker bot up at kelburn . He said he had some PET extruded and it could be a good insight into the process and see whats really required for us.

I'm not sure what was talked about but i will just put my two cents in.

For initial trials any PET will work - and then extruded, but re-use of the PET from bottles could be more challenging. They need to cleaned, washed and de-labeled and possibly flaked. It could be a good idea if people bring down a couple of bottles for tue's and see if we can start the re-use process soon. I assume different colors wont mix in recycling clear might be easier for a start.

A quick experiment could be to use the press in the workshop and see if we can extrude some plastic through a pipe and a die, Pet melting point is around 250 ish and shouldn't be hard to do.

An iron might just have enough heat for we need but it could be easier to have indirect heat such as a microwave oven or ..an oven so we can heat the die, hopper...ect all at once and cool individually as needed either outside or inside the "heater"

Contact Information

Hey Guys,

I have changed the settings for the Google Document so that you do not have to be signed into a google account to edit documents/etc, and I invited the rest of you to see the document. It doesn't matter to me how much we use it, I just wanted to make sure you knew that we have it as a resource.

--Jenny

Here is the link: https://spreadsheets0.google.com/ccc?key=t6PM1O7ZYj4IAQmdqGOJMEA&hl=en

And here is the updated Group Member Contact list from the spreadsheet...

Name Number E-mail J-Drink 2102550592 jenny.drinkard@gmail.com uke devail 272009071 lukedevil@slingshot.co.nz Lou-sh 212350423 lou.francism@gmail.com avid vivid 273,571,599 avid_1989@hotmail.com j-wat 272228665 jonofordwatkins@gmail.com dc collindani@myvuw.ac.nz jamie yau jamie.yau@hotmail.com jason mac-attack hotcrap@msn.com P-diggle a.diggle@hotmail.com KITCHEN 273232586 ben.kitchin@hotmail.com

RECYCLE BOT is alive

Hey guys,

recycle bot is underway,

we have research groups :

Plastics research group: Avivid , Jonono, Yauu

( melting point, how to crush it, cooling times, blend? sticky? And what you think you should do)

Heating Research group: Louie, D.Cmassive, Mack-attack hot crap.

( Irons, teflon coating, Cooling how to? talk to Jen about Recycling research and how they doit. )

Precedent recearch group? : P-diggle, Lukass, Bennie

Research how plastic is actually extruded, the ins and outs and how we can apply to our project.

recycling research: Jen

(you know what to do)

Put all that you find online and bring on tuesday!!!