Saturday, June 19, 2010

Nice Recipe for Machineable Wax

I have been working on the Xerox Mendel for a bit, and I keep running into issues with the wax shrinking too much. I found out that I need to let the Wax cool down slower, which makes it leak out more. I am going to have to find a good balance.

Found this website: they have a great description on how to make machinable wax at home. All you basically do is melt LDPE in a deep fat fryer full of paraffin wax. Basically you raise raise 4lb of paraffin wax to 95C for LDPE or 110C for HDPE. You then add 1 lb of LDPE or HDPE very slowly. Any amount can be made. Considering the limitations of a Maker bot drimel toolhead, this could be a great substrait.

The store this is from looks like it's dying, so I will quote it here:

"You may be looking for a cost effective solution for machinable wax.
One basic composition of machinable wax is simply standard parrafin wax, available at most craft stores, and polyethylene.
What is polyethylene? It’s most basic description is that it is a thermoplastic and it is derived from petroleum. The two main types are Low Density and High Density polyethylene, commonly referred to as LDPE and HDPE respectively. The following is a list of common LDPE/HDPE items:
* Grocery store bags
* Garbage Bags
* Paint drops (plastic sheets)
* Lawn Chairs
* Cutting Boards
* Plastic Lumber
* Milk Jugs
* Commercial Bathroom stalls
One of THE most common uses is in plastic grocery store bags. This is also probably the best source of LDPE/HPDE for use in making homemade machinable wax. It’s readily available as most people have 50 or so stuffed away in a pantry or cabinet. Perfect to make a little machinable wax with.
Alternate sources for use in a machinable wax recipe, would be plastic drop clothes used in painting. They can be purchased at most home improvement stores.
Most plastics are usually marked with LDPE or HDPE and have a number 4 or 2 (respectively) located on recyclable polyethylene.
In general it’s easier to melt down LDPE for use in machinable wax. LDPE has a lower melting point, and hence mixes better with the parrafin. LDPE’s melting point for continuous heat is 203F (95C). HDPE’s melting point with continuous heat is 230F(110C). It may be helpful to note that in general Target uses LDPE and Walmart uses HDPE.
What to use for melting??? You everyday kitchen cooker will work fine. It’s HIGHLY recommended that you dedicate a cooker to your machinable wax recipe. Temperature control that lists numbers is better than just lo/med/high. Do not use a double boiler, they generally only get up to 212F(97C). That’s only barely hot enough to melt LDPE, and it would take a lot longer.
So you have your block of candle wax, a few handfulls of grocery store bags, and a cooker. A METAL kitchen strainer will be very helpful as well. The large ones used for pasta noodles are best. You also need a mold to poor your machinable wax into. Use metal molds, plastic tupperware will melt or warp from the heat.
The general machinable wax recipe is a 4:1 ratio of parrafin wax to LDPE/HDPE. Your machinable wax recipe could vary depending on how hard or soft you want the wax to be. Obviously, the more plastic you add the harder it will get. But like sugar in a glass of tea, eventually the polyethylene will stop disolving and you will get large clumps of polyethylene form in the pot. If you poor it in a pan without straining it, it will look like goo in your wax and will not carve very well.
We will use a 4lb wax to 1lb LDPE in this machinable wax recipe example. So you will end up with about 5 lbs of machinable wax.
Start out by melting the wax in the pot. Get it good and hot, about 250-275F, max 275F.
Once you’ve reached temp, start feeding in small pieces of the plastic. If you can, cut up the plastic into small strips before feeding it in. It will melt better and more consistently than just dumping whole bags in. Stir constantly and use good ventilation.
You will know you’ve added enough because the plastic will stop melting as well. It will start balling up into clumps.
Now you can use the kitchen strainer, poor your wax through the strainer into your mold. This will remove any unwanted clumps from the mix.
For cooling, try to slow down the cooling as much as possible. You can wrap the mold with an old blanket, or use a small space heater to keep the area around the mold warm. Some warping is unavoidable. You can either plane the finished product, or use a CNC router to shave down the top.
You will be left with a good quality machinable wax. Refine your machinable wax recipe. You may try different types of wax, or different types of polyethylene in your recipe.
We also offer kits of shaved LDPE and HDPE. Our kits are sold by weight and use LDPE/HDPE shavings that will melt better than most types of plastic you may find."


  1. link is not working?

  2. Based on your formula, I would also recommend adding 10% by weight of ethylene/vinyl acetate to the LDPE. For example LDPE=1 lb. then add 1.6 ounces of EVA. By adding the EVA you add stress crack resistance and high gloss. Additionally, you will have less tooling marks as well as forgoing the tedious undertaking of cleaning out the plastic burrs.

    A cheap source of EVA can be obtained from:

    Regardless of where you purchase your EVA tubing just remember to purchase 1) Non-reinforced flexible construction 2) Non-medical use (who wants to pay more?)

    EVA has a strong order like vinegar, so cook outside and keep the Mrs. Happy!!!!


  3. Replies
    1. Poor people have to pour their own wax, LoL!!!!!

  4. One thing to keep in mind about LDPE and paraffin wax is you aren't actually "melting" LDPE into the hot wax, you're dissolving the polyethylene into it. You don't need to get the wax up to the melting point of LDPE for the plastic to go into solution.

  5. in case anyone is interested, a quick look at google patent search came up with the following for "machinable wax".
    (US 4518288 A)

    ...a block of machinable wax, the wax block comprising a mixture of:
    5 to 15 percent by volume paraffin wax having a melting point of substantially 150° F. to 152° F.,
    5 to 15 percent by volume microcrystalline wax,
    5 to 10 percent by volume ethylene/vinyl acetate copolymer,
    40 to 50 percent by volume nonemulsifiable polyethylene wax having a melting point of substantially 220° F., a hardness of generally 4 dmm., and a Brookfield viscosity at 302° F. of about 9400 cps,
    25 to 35 percent by volume nonemulsifiable polyethylene wax having a melting point of substantially 240° F., a hardness of generally 1 dmm., and a viscosity at 284° F. of about 350 cps;

  6. I tried and tried doing the same thing over and over but never able to have the plastic dissolved into the wax. I had the paraffin wax that I bought at Micheal melted into liquid and drop a small piece of ziplock bag and stirred it for 30 minutes with 300 degree on. The piece of plastic is still there. I tried with walmart bag.. still the same.. Please help.

    1. I had a similar experience. At 330 degrees F for an hour and mixing vigorously I still had globs of white shopping bag swirling around in the mix. I had better luck with freezer bags.

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  9. Really Nice one! fantastic and usefull post right infromation. Thanku for share this post.

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  11. Excellent! I am happy that we have the same concept on environmental protection, our company INTCO recycling waste styrofoam to reproduce beautiful frame or moulding to replace wood or marble.

  12. Hiii..

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  13. hot glue gun sticks instead of bags......contains eva and other goodies. Just sayin'.