Homemade plastic recycling?

[Davidh]

Originally Posted by Geof Here is an idea, which is probably already lurking in your mind, prepare this hot mixture and then devise a way to vacuum impregnate low density MDF. I can imagine having the MDF in a shallow bath with a vacuum being pulled from below. You flood the top surface with the molten wax/PE mix, possible after preheating the MDF, and then shut off the vacuum pump. The resulting material could be quite durable and very machinable. A drawback would be that it would probably be impossible to paint but the wax mixture could be dyed almost any color.

@Geof

Here is how to do it
1 put MDF into a pot

2 cover with liquid (GRP resin is an option)

3 put on the lid and draw vacuum. Here the porus MDF is evacuated of air.

4 admit air. Now the evacuated MDF will suck in the liquid

5 lift it out for to dry/set and do another

6 machine a nicenameplate


It works

[diarmaid]

Something I've wondered for a while. Will a standard welding PAPR respirator protect your from toxic vapours/fumes released when melting quantities of plastic?

[graemeian]

I took 460 grams of paraffin and heated it to melt. I then slowly added about 115 grams of cleaned and cut up milk jugs. All I got was some gooey polyethylene. I then increased the temperature and the paraffin smoked but the polyethylene only remained clear. WHen I poured the mixture into a mold, It looked as if only the paraffin poured into the mold and the Polyethylene remained in the melting pot. What did I do wrong?

Doug

[sailandoar]

graemeian,
Thanks for experimenting and saving me the mess. I will be watching to see what develops with this. Machinable wax from FreemanSupply is quoting at $260_US for 40lbs (2"x24"x24"). So, I would like to see a DIY M_wax formula that works. http://www.freemansupply.com/MachinableWax.htm

This link is for an interesting project and toward the end of the page he does some DIY machinable wax with paraffin and polyethylene powder ??? http://www.submarineboat.com/sub/helm.html#Fly-By-Wire


UPDATE:
DIY M_Wax: http://www.cnczone.com/forums/showth...threadid=26351

[beone]

Guys, I put in one of the posts about making you r own machinable wax. I have been experimenting and have tried the stuff they sell for making candles harder. It dosn't seem to be as good. The best formula still seems to be 1 part polyetheline sheet to 3 or 4 parts paraffin by weight. Use fairly thin sheet so it will disolve. I thinkl the problem with the milk jugs is they are too thick. they sould eventually disolve but the whole time the paraffin is smoking and outgassing(I feel like it coats the inside of my nose) I usually use some of the candle colorant,I hae a nice purple now. Now if I can just figure out a good way to get sheets. I currently pour onto a plywood sheet and then machine it flat to the thickness I want but this leads to a lot of waste. I am thinking of trying to "roll" the wax just before it gets really solid. Any Ideas?
Dave

[coltons customs]

Originally Posted by beone Guys, I put in one of the posts about making you r own machinable wax. I have been experimenting and have tried the stuff they sell for making candles harder. It dosn't seem to be as good. The best formula still seems to be 1 part polyetheline sheet to 3 or 4 parts paraffin by weight. Use fairly thin sheet so it will disolve. I thinkl the problem with the milk jugs is they are too thick. they sould eventually disolve but the whole time the paraffin is smoking and outgassing(I feel like it coats the inside of my nose) I usually use some of the candle colorant,I hae a nice purple now. Now if I can just figure out a good way to get sheets. I currently pour onto a plywood sheet and then machine it flat to the thickness I want but this leads to a lot of waste. I am thinking of trying to "roll" the wax just before it gets really solid. Any Ideas? Dave

i have used a releasing agent in a old cookie sheet to get flat sheets i simply coat the inside of one sheet and the bottom of another pour the hot wax in the bottom and place the other on top with some bricks added for weight it presses down and leaves a sheet of machinable wax, you can control the thickness by how much wax you use , just my way might work for you

[FieroNate]

Last night I experimented with making my own Machinist wax. Worked out fairly well. However I have not yet tried to machine it. I tried three different materials: hot glue, PE and HDPE. Of the three the PE mix worked the best, with the hot glue and PE mix working the second best. The HDPE worked ok but I don't think it would be suitable for use as a wax casting core after machining as the melt temperature is above 200 F.

What I did was checked the MSDS sheets on all the materials first to see what their flamability was. None of them have a flash point below about 400 F (450 F I think). And none of them have an Auto ignition point below @800 F.

I bought the wax from a craft store (in granulated form) and the PE was bought in sheet form from Sears as a painters drop cloth. It was about a dollar for half a pound of the drop cloth and it was only 1 mil thick so it disolved fairly easily. I then heated the wax to 300 F as recommended, and the PE dissolved ok. I tried the hot glue and HDPE on various batches and ended up taking the wax to almost 480 F (with no incident). I adivse extreme caution with this. I was working with only a few ounces of wax as a trial and found that increasing the temperature does not much change the solubility of HDPE or Hot glue. Both of which acted similarly in the mix, they globbed up and only part of them dissolved. I suspect what happens is the shorter polymer chains dissolve and the longer ones are left behind, as when I fished them out the resulting plastic was fairly brittle compared to the initial plastic. In any case the results were interesting, I'm thinking about casting a few round bars and having them tested locally to see what the properties are like. The PE definatly works and if i had to do it again I'd order bulk wax granuals and then order the PE in granular form. Though the method I used is probably the cheapest. I also added blue die just to make it look like the real machinist wax (that I have seen). Hope this helps.

As a last note I tried variations of the ratios... 4 parts wax to 1 part PE seems to give a nice material.

[s-paine]

I have made a pneumatic injection molder and , I am using plastic bottles and such to familarize myself with different tyes of plastics.

My big question is, what is an easy way to grind up plastic bottles into small pieces to feed into the injection molder?

I cant seem to find any info on this. Does anyone have any advise or direction to point me.

I dont want to buy bulk material yet, since I am still experimenting.

Thanks!

[Paulwano]

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