Instructables
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Featured on Hackaday.com!  Woohoo!  But for records sake, my name is Jake: http://hackaday.com/2012/12/29/make-your-own-machinable-wax
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A major issue that I ran into when I first started working with my new CNC machine was the cost of raw materials to machine. Sure, a block of plastic is not terribly expensive by itself – but figure in the cost after you mess something up and the cost becomes quite unreasonable. For this reason, I began looking into machinable wax.

Machinable wax is a very hard wax that won’t gum up a cutting tool, is soft enough to machine quickly and most importantly is completely reusable! Since I am cheap, I decided to make my own, which is actually quite simple and could be considered environmentally friendly since we use recycled plastic bags. Be aware that this Instructable is DANGEROUS! We will be melting wax
around 300* and this wax will be thick and sticky so it will literally burn your skin off faster than you can say “OUCH!”

(The basic recipe is 4 parts wax to 1 part plastic)

You will need:

- Paraffin Wax (Available at Hobby Lobby)
- Plastic Shopping Bags (HDPE or LDPE, Recycle symbol #2 or #4)
- Deep fryer WITH adjustable thermostat
- Candy Thermometer (to make sure your fryer thermostat is working correctly)
- Wood Spoon
- Leather Gloves
- Safety Glasses
- Molds (I’ve used Tins, Wood frames, and Cardboard)
- Strainer
- Wax paper is handy
- A scale to measure wax/plastic
 
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Step 1: Melting Wax

Set your deep fryer to the “Warm” setting or 100* if applicable and add the paraffin wax. Keep stirring the wax until it is completely liquid. Once melted, you could add a crayon for color if you would like. I recommend leaving the candy thermometer in the wax to keep a better eye on the temperature.
Paraffin ignites at around 400*F.

Don't forget that what your looking at is melted wax, not water.  Hot water will splash and drip off of you, hot wax will splash and STICK TO YOUR SKIN!  So be careful....

Step 2: Melting Bags

Set your deep fryer to 300*F and monitor the temperature with the thermometer. Make sure you continue to stir the wax because we do not want any hot spots that could cause the wax to ignite.

Once you hit 300*, begin adding the plastic bags, one at a time. It helps to cut them into strips so that they wont ball up, but I don’t have any data to support a specific way just yet. The more your stir this mixture, the faster the bags will dissolve (Just don't get too crazy, you could introduce a lot of air into the wax). Continue adding bags until they won’t dissolve any more.  Most of the plastic should have dissolved, leaving just a few chunks left.  With LDPE this is usually a 25% mixture, whereas HDPE bags are around 15%. Stay patient, this process can take a while.

Step 3: Casting the Wax

Once your bags are dissolved, it is almost time to pour the wax into molds.  You may have some small clumps of plastic at this point, and there are a few different ways to remove them.  The first option is to use a kitchen strainer to filter out the clumps as your pour the liquid goo into your molds.  This works very well, but I have yet to be able to re-use the kitchen strainer afterwards.  The second (and less effective) is to turn off your fryer and let the clumps float to the top.  The top of the liquid will start to solidify and make it easier to skim off the clumps with a spoon.  Either way, wear leather gloves!

If you chose option #2, turn your fryer back on and make sure your wax is liquid before pouring.  When pouring into molds, pour slowly but be committed as you do not want wax to drip down the side of your fryer.  Once poured, cover the molds with a towel so that they cool slowly.  The slower they cool, the more likely that air bubbles will escape before getting stuck in the wax.

Step 4: Machine that Wax!

Out of the mold, the wax will have a HUGE sink mark in the middle; I usually just clamp the sides of the block and face off about ¼” to get it flat.  Then I flip the block and machine to thickness.  If you are carful and clean your vacuum ahead of time, you can save the chips to re-melt later.  I keep a container nearby where I store my wax chips.

Recycle Your Wax

When recycling your wax, I recommend using no more than 50%-75% reground wax.  This is due to the fact that plastics degrade rapidly when heated (think compost) and can start to smoke/burn/ignite if you are not careful.  Therefore, start by melting paraffin wax, adding new bags and THEN adding your recycled wax.

Good luck and be safe!
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kwhitacre1 year ago
Oh, I almost forgot. If you recycle a clean pair of panty hose or knee-high hose you can vacuum up the pieces without it going into your vacuum. Place the nylon over the hose. Tape or clamp it to the side of the hose so it cannot be sucked up. When you vacuum it will catch the small items and you can reclaim them easily. I use this to clean up spilled beads and sewing pins. Works like a charm. But before you turn off the suction be sure to hold the end of the hose up, as everything may fall out again when the air isn't sucking it into the foot of the hose.

theres an idea

mcottew4 months ago

Can this wax be used for the lost wax method of casting aluminum? also, since I intend to use it for a DIY cnc mill, how hard is it? i'll be using 5v stepper motors and a cheap rotary tool, so it will be a fairly weak machine. I just need to know if this is best, or if just regular paraffin would work best. Incidentally, excellent instructable. Many props!

Machine5 months ago

That's a very nice instructable and thanks for all the sensible cautions and it is easy to see that you have thought carefully about the text of this instructable.

stevfuri1 year ago
What CNC machine are you using in these photos?
haven't got a clue...sorry...if you describe it, maybe i can find one around here?
*sigh* Guys in the kitchen! LOL!!!!!

To avoid someones wife getting opinionated about where HER deep fryer has gone off to---git yer own! Try the thrift stores and Sal Army or Goodwill first or go directly to Craigslist. This also avoids having to sneak the thing back into the kitchen after use---and how exactly ARE you goin' to 'splain any drips????

To strain a simple and cheap solution might be to use a Chinese wok skimmer/strainer---these have a bamboo handle with a brass "mesh" (some have better mesh than others!) attached in a shallow bowl shape; These are a very few bucks and being that they are metal with a fairly wide space between could be useful for those chunks but not clog. They come in several lengths and bowl sizes. Try an Asian market for the best selection and pricing. You can also buy regular stainless strainer spoons at thrifts or other sources or even new for a few bucks---if you really want a custom size buy a large cooking serving spoon with a long handle to avoid getting burned and then drill or make "slices" across the bowl to the size you need. Polish. Done!

Great idea by the way---remember how spendy hard dopping wax was back when I used to do gems---and sealing wax the same! Prob could use your formula for these uses and carving as a to-be-cast project in addition. Thanks!
beware. of buying stainless steel utensils at wall-mart. they are chromed up normal steel. try bringing in a small hard drive magnet with you. then bring it to the mangers knowledge that their breaking the law. no false advertizing, false truths, and misleading the consumers.

Perhaps you are unaware but there are different kinds of stainless steel, some of them magnetic.

rawkstar320 (author)  stevfuri1 year ago
Zen Toolworks 7x7 with a Dremel 4000. Very nice little kit machine, but I highly recomend getting the 12x12. The 7x7 bed is awkwardly small.
Baughb6 months ago

I didn't see it elsewhere, so I'll mention it: Please do your heating and pouring outdoors. This is similar to deep frying a turkey, and if you haven't heard stories about that....

afaul7 months ago

LOL Ok, I will admit right off, I did this the ghetto way. I knew it was ghetto, and although I didn't have a fire it was freaky.

What I used:

  1. Soup pan on gas stove.
  2. 2 boxes of Gulf Wax (paraffin wax for canning)
  3. some grocery bags. #2 typ
  4. Food thermometer (yes at least I was that smart)

I made the HUGE mistake of being scared, because I knew better but did it anyway, of having the wax directly on the pan bottom in the very beginning, so I put in like 1TBSP of water to keep the touching surfaces below 212F

This was ok for that, but after I hit 212F melting the wax the water wanted to boil and I had to continually stir it and keep it around 212F until the water was mostly evaporated. It kept wanting to "burp" and splash wax! (duh, looking back at it)

This made me scared of the process as I worked the temp up higher. I ended up putting a bag in well below 300 just to help contain the bubble bursts from splashing all over the stove, which they did anyway.

I never got it all the way to 300, but was close. Probably about 265F. The bags began melting in but never really totally did so. I have a lot of particles in there now. This would be fine for milling, but I am injecting this stuff with a food syringe into silicone jewelers molds I have made. I'm going to use the wax casts to make plaster casts and melt the wax out and pour aluminum in. I have already done this before, but didn't do the wax step in between and had a lot of problems because my parts are irregular and it's pretty much impossible to make a two part plaster mold.

So anyway, since the plastic didn't totally liquefy I'm not sure it will melt out of the plaster molds once they are hardened and I heat them to creat the void for the molten aluminum. I may have to burn away the plastic bits and it may contaminate my casts. We will see.

If it does I'll have to remelt this and strain it really well. Then it should be fine.

So, what did I learn from this kids? No water, don't use a pan because it's too hot right at the bottom.

I'm lucky I did this really slowly or I know I would have had a splash and a fire. I probably won't do the bag thing again and just use paraffin wax for my casting. I just thought the plastic would strengthen the wax so it wouldn't be so easy to break the piece when I take it out of the silicone mold.

Speaking of which, it should be cooled off by now. Time to see if it worked!

inciteman8 months ago

I used the fiberglass mesh for windows screens and it worked fine! About $7 for a roll! 36" x 84"

Good Instructable. You can also get paraffin from almost any grocery store in food canning section. How well does it match your expectations for clean cutting? Does it leave any significant residue on the cutter?
rawkstar320 (author)  AndyInAnnArbor1 year ago
It cuts very cleanly, the only problem to watch out for is swarf sticking to the part. The cutter stays nice and clean, much more so than cutting UHMW PE actually.

You can buy paraffin at the grocery store, but it is about 50% cheaper at hobby stores....strangely enough.
grocers buy it in bigger bulk than the hobby stores will ever get it.
It's really not a food/non food grade issue as much as the way the market works in the distribution/consumer interaction. Anyway, you should that there are multiple formulations of paraffin wax differentiated by the hardness, melting point, narrowness of the cut (how much of the block is X type of paraffin versus Y type of paraffin), and so forth. You can buy paraffin wax that melts at 125F (for containers) and wax that melts at 180F (for hurricane shells and embeds). You can even modify the melting points through the use of additives (microwax - which is essentially plastic) etc etc etc... In the application you are talking about here I'd try to make sure you are using a relatively high melt point wax suitable for pillars/hurricanes. If you get into this you can buy wax in 50# boxes for around $80.

Oh, as for the melting pot - it's a good idea. When I first started candlemaking I bought a presto pot ($25), tapped a hole near the base, and installed a spigot. Made it a lot easier to transfer the wax into a pour pot.
Not so strange...the paraffin sold in grocery stores is food-grade, (it's found in the canning section) whereas the wax sold in hobby stores is for candle making.
rawkstar320 (author)  bruce.desertrat1 year ago
Good point.
n1cod3mus1 year ago
shame paraffin wax is so hard to get hold of here in the UK and if you can get it, its massivly expensive.

still a good instructable, would be great for lost wax casting of metals.
try using beeswax instead. pafafin wax is a oil based product . if u used beeswax instead u'd have a better made block.
You can get 1kg of pelleted paraffin wax on ebay for £5.95 inc. P&P - that's not too expensive.
every time i have gone looking its always expensive, prehaps i wasnt lucky enough to come across a good price when ever I have looked on ebay. I'll keep my eye out
jmpg n1cod3mus1 year ago
most candles are paraffin wax as beeswax is far to expensive. If the candles contain carnuaba wax or some other nut derivatives it will be harder than paraffin wax, which will be a benefit in this manner.

When you melt the candles just pull the string/wick out of the molten wax.

I've also used electric frypans to melt wax as they have a thermostat also.
Thats exactly what i was thinking.
Pjstone1 year ago
If I could offer a suggestion! When you pour a liquid from one container to another the pour creates air bubbles....so...I would like to suggest that you use a cook secret (I am a cook by trade) of pouring the melted wax over the back of a wide spoon or a wide piece of wood that is held on a slant or just leaned into the container you are pouring into. This reduces splashing and possible burns...and less air bubbles should give you a really good product!
try using a vibrator off some kind as well. too get the air bubbles out as well.
veeguy1 year ago
Fantastic Idea! I have both a CNC router and a milling machine. I had a quantity of machinable plastic, foam and wax free samples I have gone through. I was *shocked* by the prices of machinable waxes and plastics. I needed some 4" X 4" X 6" blocks, and they wanted $65.- each!

The main problem I can foresee is sneaking the french fryer out of the kitchen and into my basement "Little Shop of Horrors".

-And your spelling and grammer is OK by me. The complainer is obviously a frustrated English teacher.
i dislike (pc correctors) they dont like when other pple mispell.
rawkstar320 (author)  veeguy1 year ago
That price is unreasonable, look into machinablewax.com if you want to buy it. Amazon and eBay dont have any good deals on machinable wax for some reason.
cjs12981 year ago
Hello, I am only 14 and in need of cheap material. Unfortunatly I do not have a deep frier. Is there an alternitave to a deep frier? My best guess is a camping stove and an old pot. I have a candy thermometer, so is there some possible way that I could measure the inital temp of the propane stove?
try to experiment first. try getting a dutch oven. and the propane stove part 4 a turkey fryer. that should help u out. by the way u should also have safety gear on hand as well as using it. face shield (full) respirator of some kind, to block the wax / plastic fumes from entering yr lungs. gloves (work gloves, welding gloves are better. long sleeve style excellent, to protect yr arms.) long pants that cover yr work boots. god forbid please dont wear any thing thats made from plastic type materials. unless u wanna go to the emergency room, and explain to them how you tried to remove 1 - 3 layers of yr own skin. other than that happy smelting. if u like that u can do the same thing with aluminum soda cans, pie tins, empty beer can (that yr parents have emptied (or better yet pick them up off the street youill help yr help city out as well.
they also sell plastic meltars that you could probably use
It's simple...

1. If it catches fire, it's too hot.

2. If the plastic fails to melt, it's not hot enough.

3. Once it's up to heat, turn your cooking gas, right down to almost nothing.

5. There is no 4.
rawkstar320 (author)  cjs12981 year ago
do NOT use a camp stove. Check out Goodwill/salvation army for a deep fryer WITH thermostat.

The deep fryer I use is only $20 at walmart, I convinced my wife to let me getting it by selling her on the idea of making her own candles. :-)
Go to a thrift store and get a used deep fryer. Go to several. Check back every week until you find one.

Avoid open flames around boiling oil.

I have had success with a new hot plate I bought at Walgreens for $10. I opened it up and bypassed the temp switch, and now I use it to melt lead. If you keep the temp switch working, it should be able to melt plastic well.

For low temp melting, electric is WAY easier to work.
Awesome writeup. Ive done this before with an electric hotplate and an old soup pot, but the electric fryer with a thermostat seems waaay better. One piece of advice, keep a lid nearby that will seal tightly to the pot on the fryer - you can put out an accidental fire with the lid if a hot spot occurs and you get an ignited pot of wax. Dont ask me how I know...
we all know now. u accidentally let it heat up too high.
BMcDanel11 months ago
HDPE melts at 266F LDPE melts at 248F. Running it at 300F is a bit hot for these materials. You may be able to reuse this more if you melt it at a lower temperature.

You can get HDPE or LDPE pellets for about $5/pound. These are used in injection molding as well as making your own filament for 3d FDM printers.

Investment casting is another option for this, you would mill your shape then coat with a 50/50 sand and plaster of paris mixture. Multiple light coats bring out more detail. Invert your mold and heat to its melting point and everything will go out the sprue (you did make a sprue right?). pour in your molten metal and let cool. Smack with a hammer and the plaster breaks off (which can also be reused if you grind it back into powder). You now have a metal object cast from the wax one.

This can save on milling time since you can run higher feed rates, save on bits, etc. You do lose the temper so you would want to investigate how to restore that if its important (each alloy is a little different).
jeiclin1 year ago
Thanks so much for this - very interesting!

Do you think this wax would be suitable for hand carving? I'm looking for something like jewelry wax (although I don't need quite the same level of fine detail), which is prohibitively expensive.

Would this melt if held in the hand too long or get sticky? How brittle is it? Any help would be very, very appreciated!
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