How to Make Machinable Wax at Home!

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Introduction: How to Make Machinable Wax at Home!

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

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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108 Comments

Is it durable enough to use for an outdoor waterproof enclosure? I know it's wax but the melting point is over 200F which is far more than experienced in the sun (right?)

"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."

With that in mind, maybe you should try putting the molds in the oven. All that insulation has to be good.

Amazing idea!! one question? can this wax be used in "Lost-Wax Casting"? thanks in advance for such great job!

How did this work out for you? I have a bag of those standing around.
And what grade parrafine did you use it with?

So i was trying to machine some very thin aluminium part and i was looking for some support material to reduce vibration, i tought of buying some machinable wax but for a fraction of the price a manage to make my own machinable wax.

I've prepare the wax with some of my friend for a school project, we were very doubtful about this instructables.... so we just tried it. the preparation of this thing was very long and a bit sketchy, since we had 4.4 kilograms of parafine. ( I would totaly recommand doing it outside or with gas mask...

In the end, i was very scares that the wax wouldn't stick enough to the aluminium but it worked way better than expected... No vibration at all during the machining ( it was somme very smooth cnc maching with nice and sharp tools, I think it helped.

So, in conclusion this wax is easy and clean to cut and it can also be use a support material, but it shrink a lot during cooling.

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.

3 replies

Or, for larger amounts, you could use a home-made cyclone between your vacuum and the hose. There's plenty of instructables on that topic.

Amazing idea. Thanks!

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.

I got the 12x12, but I still need to learn the software. They released $60 aluminum uprights recently to help rigidity.

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!

Just FYI: The Chinese wok skimmer is sometimes called a "spider" or "spider strainer".

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.

I have a container of paraffin wax in the freezer. I'm guessing that it will harden and be machinable long enough to make a test cut of a CNC file. What am I missing?

I needed some sealing wax, so I decided to try this to make it, but it didn't work. I found a large plastic bag marked as #2 HDPE, and it didn't melt in the wax even when it was boiling. I don't know what temperature it was at, since I don't have a thermometer. It just got really soft at best. Is there any other way to do this? Perhaps by mixing hot melt glue into the wax?