Just thought I'd update, I have made more headway with wax forumulas, quite interesting actually. I repeated the above experiment with a a few variations on the prefered formula. I have found that 7.75 parts wax to 1 part polyethylene painter's drop cloth works well (the clear kind of plastic). I have also found that the oil based color dies used in candle making should not be added until AFTER the plastic is added. Adding it first causes the plastic to not dissolve properly.
I am trying to locate a viscosometer to measure the viscosity of the plastic/wax mix at temperature. The reason for this is that to much plastic makes a higher viscosity mix with the consistancy of pankake syrup. I fear that for lost wax process this is to thick to properly run out of the mold. SO I will try to get some readings on the viscosity at a given temperature and rate the wax based on that as well.
Here is my general reccomendation for wax mixes, note though that I used unrefined low grade paraffin bought at craft stores. This means I have not evaporated the wax "steam" which is the low grade wax, instead I have kept the melt temperature below 400 F (around 350 is my normal prefered temp). I advise caution at these temperatures as splashed wax will instantly burn the skin and eyes (saftey gear recommended). Additionally above 400 F pure Paraffin is flamable/combustable. As stated in my previous post I have had some burn. I am pretty sure however it was due to the fact that my heat source is an open source rather then hot plate. So I would say its ok to use a hot plate above 400 F but be very careful as I place no garantees on it. A tight sealing lid for the container should be sufficient to put any fire out. I also recommend not doing this in the kitchen but in a well vented open area, as it will avoid filling the area with fumes and any fire hazard can more easily be contained.
Also keep a good powder fire extringuishe around (or a gas type, but avoid a liquid type as liquid and hot wax are not a good combination).
Next I will try some high grade wax soon though. Note that all measurements are by weight not volume (this does matter), Additionally I used painters plastic drop clothes 0.7 mil thick (1 mil would also work). To more readily dissolve them I take the sheet and twist it into a rope and cut 1/8" slices off the rope with a good pair of scissors (Cutco brand works great for this). The result is a thin plastic strips that resemble the fake grass used for easter (which might be a good option for pre cut polyethylene, IF it is in fact made of polyethylene). I will try a blender soon to make it powdered, however I have yet to locate a Blendtec blender (
www.willitblend.com they blend almost anything its kinda scary).
For machining I recommend a higher plastic content as it delivers good hardness and a bit of flexibility, without sacraficing edge sharpness: mix 7.5 parts paraffin candle wax with 1 part Polyethylene sheet
For a bit harder wax try 8-8.5 parts wax with 1 part Polyethylene sheet
For a more flexible wax try 6-6.5 parts wax with 1 part Polyethylene sheet
For a durable wax that has less of a waxy feel, try 6.5 parts wax, 1 part polyetheylene sheet and 0.5-1 part low temp hot glue sticks (A.C. Moore Craft store brand melts at 230 degrees F and easily dissolves) the downside of this wax is it doesn't hold an edge quite as well but would be great as a prototyping wax as its reusable and flexible to a degree. However I wouldn't recommend burning this wax as a cande.
For even more flexibility (but less tensile strength) try the following:
7 parts wax, 1.5 part hot glue, 0 parts plastic. It produces a rather unique plastic thats extremely flexible.
Also of note is that none of this batch produced any cracking on cooling as previous low Polyethylene content batches have. I even tried feezing the waxes and then warming them in my hand (How I cracked a different batch) and these seem pretty stable. They do however contract quite a bit in the freezer, which I will be using to see how castings might shrink.
Now for something new: Molds!@!
I have been experimenting with low cost molding techniques to make billet wax. The cheapest I have found is duct tape lined cardboard boxes. I have tried the metal foil duct tape to seal the corners of the box (alternatively 3M trim adhesive spray would work to glue heavy duty aluminum foil to the cardboard and then use the tape to tape up any seams. It surprised me because I expected it to leak through and melt the adhesive, but all I did was press the seams as flat as possible and had no leaks. One thing that is important is that I poured the wax at about 230-260 F rather then the 350 F mix temperature, this keeps my mold boxes from being damaged. For sample pours I use bead storage containers (also found at AC Moore crafts) they look like stackable petri dishes found in my high school bio lab. The main difference is that the bottom of one dish is the lid for the next etc... I have found that these work for pouring paraffin, but I have also found that to high a pour temperature puts a hole in them (I suspect above 240 F is to high).
More to follow.
