[digits]

Hi guys, just thought I'd share this with you lot - I am trying to make a rather large (230x140x55mm) part on my mill, and making prototypes out of aluminium was getting rather expensive in terms of metal and tooling, so I decided to have a go at making and mahcining some machinable wax.

I got the idea from this amazing thread: BMW V8 dry sump from billet

and duely bought some candles, plastic bags and a cheapo deep-fat-fryer to melt them all in. I then cast some 'billets' in silicone cake-moulds which are great as you can simply peel the moulds off once the wax has cooled.

I started off by cutting my very rough block to size in my bandsaw. It cuts very quickly and cleanly in the saw, but as you can seem my block is full of impurities!



I popped it into my vice with the softjaws I need for a block of this size, and gently clamped it in place. Unlike metal, there doesn't seem to be an obvious point where it feels clamped - I guess it just starts to squish...

I'd been too lazy to mill any of the faces flat, so I indicated the y-zero off the inside of the vice jaws using my 3D-taster. This is a great bit of kit!



I started off milling it with the same parameters as I was planning to use on aluminium -12mm 3-flute rougher 1mm DOC, 5mm WOC and 540mm/min and ~1600 rpm. This was way, way too gentle for the wax, which is practically effortless to cut. So I redid the toolpaths with 2mm DOC, 8.4mm WOC and 1000mm/min feed.

Here's a pic of one end after roughing. Looks like there's something wrong with the toolpath as that post in the foreground shouldn't be there.


The roughing produced a shed load of chips - and the best thing about that is that I can simply pop them in the fryer and melt them back down I could really do with a furnace for my ally chips, but the idea a bucket of molten ally scares the hell out of me!

After roughing, I cracked on with the finishing pass using a 10mm ball-nose mill. I used a 0.5mm stepover and you can see the scallops in the finish in the wax. I should probably have run a full waterline pass over it to clean it up, but my mill-computer locked up mid way




There also seems to be quite a lot of bubbles and other gunk in my wax block - I did try pushing a previously cast block into the pour as it was setting - looks like it bonded ok, but wasn't nearly hot enough to mix properly. I also think I'm going to buy some proper candle making dye to give the block a much darker and hopefully uniform colour.

[pete from TN]

That looks pretty close to what it should be man, I suppose with some tinkering with materials you should be onto a good mixture. It sure seems to machine well and the chips look about right. I had ONE piece of machinable wax I got from a friends machine shop and I played with it but I got some oil and grease in it and it was not too pretty after that. It is a very good way to test run expensive parts and whatnot. Good luck with it and keep up the good work...peace

Pete

[rwskinner]

Cool. Isn't the store bought machine wax much harder than candle wax? I dunno I hadn't messed with any.

Richard

[gd.marsh]

It sure is .. went that route before I started cutting aluminum with my machine & I was surprised at how hard that stuff is for being wax. By comparison, the blue stuff I used could be clamped firmly in a vise & you could feel it when tight.

Gotta give you kudos though .. pretty darn good for a home-brew attempt. It certainly seems to accomplish it's intended purpose.

[Geof]

You didn't nee to go somewhere else for homemade machinable wax. A custom search for 'machinable wax' here on CNCzone turns up many pages of results. Here are a couple:

http://www.cnczone.com/forums/teache...nable_wax.html

http://www.cnczone.com/forums/hobby_...nable_wax.html

[digits]

Thanks for the comments and the links guys. I would however really recommend buying a dedicated electric fryer for this - heating candle wax to 170C over an open flame seems like a recipe for a chip-pan fire to me! Also, it doesn't smell that nice (think candle that's just been put out), and the electric fryers have lids and filters which help keep the fumes in.

I did consider just buying some commercial wax, but the UK suppliers seem to want more per kilo of wax than I pay for aluminium!

My wax probably is a bit soft - you can scratch it with a fingernail, but I was surprised at how thin you could machine it before bits cracked and fell off. I guess I can always add another load of plastic bags to the mix when I remelt this lot - I guess it's a trade off between machining time/tool wear and duribility of the wax.

[Smertrios]

Parafin wax shrinks as it cools I dont think beeswax will do that at least not near as much *and* beeswax is hard.

[fragger6662000]

no wonder you have issues cutting ally at 540mm/min at 1600 with a 3 flute all it is going to do is jam up.

[digits]

no wonder you have issues cutting ally at 540mm/min at 1600 with a 3 flute all it is going to do is jam up.

I don't actually have a rpm gauge on my mill at the moment, but with my 3 and 4 flute roughers, and my mill's 2000-2500 odd max rpm, I have no trouble cutting way faster than that. Roughers make absolute mince meat of ally, the only thing I have trouble with is deep slotting with slot-drills.

[neilw20]

Beeswax is nice, and remember, years back, melting a pot full on the stove in the mess at work, just before meal break..

Worked fine, but the FIERCE SWARM OF BEES THAT CAME to the pot became a real problem !!!!

Keep the flyscreens on the doors and windows, or wear a head net. :idea:
Was still good fun, all the same. Something new for the workers to discuss.