Author Topic: Machinable wax  (Read 57203 times)

Offline PTsideshow

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Re: Machinable wax
« Reply #25 on: February 17, 2010, 10:49:40 AM »
Thanks,  :thumbup:


I still learn more every day on this and a number of other forums!  :dremel:

Yep I'm still working on the first two in my sig line and will never try the third  :bugeye:
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Offline AdeV

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Re: Machinable wax
« Reply #26 on: February 17, 2010, 07:12:19 PM »
A 25kg bag of paraffin wax beans turned up today (see BMW sump thread), I can turn approximately 2.25kg into machinable wax in 3 hours if tonight is anything to go by, so by this time next week, I should have tons of the stuff :)

Today, I moulded some in a cup; when it set I chucked it up in the lathe & did a few turning/facing/drilling/reaming operations on it. Again, it behaved impeccably. Only two issues, really: I didn't wait quite long enough for it to cool down. so it shrunk in the chuck & came loose (didn't go anywhere, luckily). And, because you can't hear a cut being taken, it's hard to plunge a drillbit into an existing hole, and be confident of knowing when it starts cutting...
Other than that, this stuff is a hoot. It's like plasticine for grownups :D
Cheers!
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Offline DMIOM

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Re: Machinable wax
« Reply #27 on: February 18, 2010, 04:10:30 AM »
A 25kg bag of paraffin wax beans turned up today (see BMW sump thread), I can turn approximately 2.25kg into machinable wax in 3 hours if tonight is anything to go by, so by this time next week, I should have tons of the stuff

Next experiment - what's the adhesion/cohesion like? if you can make a dozen 5lb blocks, then you could make a dozen micro-sumps - but unless you then remelt & cast via a 45 gallon drum, are you sure you can build up the layers OK with the modified wax as is done for candles?  or will you have to re-inforce it - concrete re-bar?
« Last Edit: February 18, 2010, 05:00:56 AM by DMIOM »

tumutbound

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Re: Machinable wax
« Reply #28 on: February 18, 2010, 04:30:13 AM »
Has anyone tried making up a machinable wax using a microcrystalline wax as the base?
It's supposed to be harder that standard paraffin wax.

Offline AdeV

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Re: Machinable wax
« Reply #29 on: February 18, 2010, 04:44:12 AM »
Next experiment - what's the adhesion like? if you can make a dozen 5lb blocks, then you could make a dozen micro-sumps - but unless you then remelt & cast via a 45 gallon drum, are you sure you can build up the layers OK with the modified wax as is done for candles?  or will you have to re-inforce it - concrete re-bar?

And that is the $64k question (well, £6.40 at least...).

My current plan is to try to re-melt the whole lot together and pour it in one go. I've yet to ascertain how I'll do that, but it will clearly involve some big pans, and probably an engine crane...

I did wonder about pouring in sections/layers, but I'm not sure what stresses that will set up in the wax. I'd hate to get half way through machining and the whole lot goes "pop" & breaks up...
Cheers!
Ade.
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Offline DMIOM

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Re: Machinable wax
« Reply #30 on: February 18, 2010, 06:13:55 AM »
....I did wonder about pouring in sections/layers, but I'm not sure what stresses that will set up in the wax. I'd hate to get half way through machining and the whole lot goes "pop" & breaks up...

If you do need to re-inforce it, instead of using discrete candle wicks, how about using something like Rab C. Nesbitt's string vests? would need a test first though - they may pull-out rather than cut when you come to machine them ...

Offline AdeV

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Re: Machinable wax
« Reply #31 on: February 18, 2010, 07:23:07 AM »
I'm going with Plan B instead....

 :proj:

I've just bought 2mtrs of nichrome wire, which I'll mount up on a wooden dowel framework; attach to a car battery, and I've got myself a nice big flat heater, capable of ~200 degrees C (a shade less, actually) - perfect for keeping the wax molten in the mould until I've added enough. Once the mould is full, I can just pull the heater out, and let the wax cool & set naturally.

Photos will be forthcoming when the wire arrives...
Cheers!
Ade.
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Offline andyf

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Re: Machinable wax
« Reply #32 on: February 18, 2010, 10:46:32 AM »
.... I've just bought 2mtrs of nichrome wire, which I'll mount up on a wooden dowel framework; attach to a car battery, and I've got myself a nice big flat heater........

..... and perhaps a nice big flat car battery, too -the heater might draw a lot of current. If you have a charger, it might be worth using it instead, or (if it won't cope with the load) use both by putting some charge back into the battery while you are discharging it.


Andy.
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline AdeV

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Re: Machinable wax
« Reply #33 on: February 18, 2010, 11:00:54 AM »
.... I've just bought 2mtrs of nichrome wire, which I'll mount up on a wooden dowel framework; attach to a car battery, and I've got myself a nice big flat heater........

..... and perhaps a nice big flat car battery, too -the heater might draw a lot of current. If you have a charger, it might be worth using it instead, or (if it won't cope with the load) use both by putting some charge back into the battery while you are discharging it.


Andy.

According to my calculations (and I've had them verified by someone who actually does know what he's talking about), it should draw just about 2.1amps.

Unfortunately, that equates to just 25 watts.... I'm not sure if that'll be enough to keep the wax liquid while I frantically melt & add fresh wax... Only time will tell...
Cheers!
Ade.
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Offline No1_sonuk

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Re: Machinable wax
« Reply #34 on: February 18, 2010, 11:28:07 AM »
Might be ok - yo just need to delay one layer setting until the next is poured.

Offline andyf

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Re: Machinable wax
« Reply #35 on: February 18, 2010, 12:43:49 PM »
Only 25 watts, Ade? The battery should last for hours, but as you say, there might not be enough heat. I think you said you want to end up with a block of wax 22x10x2.5" = 550 cu inches. As a cube, that would only be a little over 8" each side. Could you find a container(s) of somewhat larger volume to allow for shrinkage and machining, and simply keep the stuff warm and liquid in the oven on a low setting (100C would probably suffice) as you fill up the container with successive dollops of the mix? As a cube, 9x9x9" would be ample at 729 cu ins. Some cut down old gallon oilcans might get you there.  Then, pour the whole lot into your mould.

Andy 
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline AdeV

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Re: Machinable wax
« Reply #36 on: February 18, 2010, 06:45:54 PM »
Only 25 watts, Ade? The battery should last for hours, but as you say, there might not be enough heat.

Yep, only 25 watts. Slightly less, in fact... The resistance is 5.6 ohms, voltage is 12v, giving 2.14 amps; amps * volts = watts. I was a bit surprised myself, I thought it'd be more than that. But, there you go...

Quote
I think you said you want to end up with a block of wax 22x10x2.5" = 550 cu inches. As a cube, that would only be a little over 8" each side. Could you find a container(s) of somewhat larger volume to allow for shrinkage and machining, and simply keep the stuff warm and liquid in the oven on a low setting (100C would probably suffice) as you fill up the container with successive dollops of the mix? As a cube, 9x9x9" would be ample at 729 cu ins. Some cut down old gallon oilcans might get you there.  Then, pour the whole lot into your mould.

Good thinking, using a cube form hadn't occurred to me. Probably a couple of those "vintage car oil" metal cans from Halfords would easily fit the bill. I'm pretty sure I've got one of those knocking about somewhere, maybe 2. I don't think I'd want to risk using a plastic oil can, though!   :bugeye:

[calculators out]

Just under 12 ltrs (9"x9"x9" cube), so 2 oil cans should do the job nicely :) Anyone got any old metal oil cans lying around, by any chance?


Might be ok - yo just need to delay one layer setting until the next is poured.

Indeed, it may be; especially if I keep the mould covered between applications. Even if I can only find 1 oil can, I can use my little toaster oven to melt 1st batch in that; the sheer volume of that + the nichrome heater + a cover, should keep the wax liquid long enough to melt the 2nd batch.


Also, it turns out that new wax poured onto old (cold) wax, does "glue" itself into the old wax quite satisfactorily - or, so one experiment has shown. I took the round piece, which I'd drilled out to various diameters, filled the hole with new wax. It shrunk quite considerably, leaving a void; which I then filled again. A facing cut showed that the new wax (which was a slightly different colour) didn't form a sharp divide, but quite a blurred join. The only concern is the huge shrinkage may have left voids deeper in the material.... I'll find out tomorrow when I cut it open.
Cheers!
Ade.
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Offline John Stevenson

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Re: Machinable wax
« Reply #37 on: February 18, 2010, 07:15:52 PM »
Get an ten quid immersion heater element and bypass the thermostat and keep an eye on the temp and melt the lot in one go.

Previous to this melt in stages from raw materiel as as this takes longer, the remelt stage takes less time.

John S.
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Offline AdeV

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Re: Machinable wax
« Reply #38 on: February 18, 2010, 07:29:46 PM »
Get an ten quid immersion heater element and bypass the thermostat and keep an eye on the temp and melt the lot in one go.

Previous to this melt in stages from raw materiel as as this takes longer, the remelt stage takes less time.

The nichrome wire cost £2 (delivered), and the car battery is free (already got it)... Of course, if it proves to be unsatisfactory....  :doh:

I'm up to around 9kgs of wax made & cast so far, which probably equates to about 8 litres. So, 2 more days of stirring should do it... which reminds me, I need more freezer bags - but, as a bonus, I can take some candles back to Tesco for a refund. As they say, every little helps!
Cheers!
Ade.
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Offline AdeV

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Re: Machinable wax
« Reply #39 on: February 21, 2010, 03:53:28 PM »
Update

Today was, mainly, about experimenting - as well as finishing up the last packet of bags...

On John's suggestion, I bought a £10 fryer from Argos (it's £13.97 in the catalogue, but £9.99 in the shop) - in fact, I bought two. These worked as well as the saucepan, only with less mess and more convenience. And I didn't need to worry about the temperature, it maxes out at 190.



Simply wait for the wax to melt, add the bags, give it 5-10 mins to get the bags nice & soft; stir/poke/prod/scrape the bags about a bit until they break up. Wait 5 mins, repeat; etc. until dissolved.

For what it's worth, here's what I've discovered:

  • Get the candle wax good & hot before you add the bags. 160 degrees is good, 180 is better
  • Dump all the bags in, as 2 or 3 handfuls. Poke/push each bunch of bags under the wax (it will shrivel up a lot) to make room for the next handful. Don't bother cutting them up, it makes no difference to the melting time, and just means you've got millions of strips of bag to try gather up & add...
  • Once all the bags are in and shrivelly, poke them a few times to get the wax into the mass, then close the fryer lid & leave for 5 mins.
  • After 5 mins, the bags will soften. Using a stick (or screwdriver if you don't care about the non-stick finish), pierce the mass of bags and drag to the side. Push the stick all the way through the mass, effectively cutting it. Repeat, then start picking the blobs of plastic up & allow gravity to stretch/tear them back into the melt. Repeat until bored, or it's getting difficult to pick any plastic up. Wait 5 mins.
  • Start stirring. Keep going until the mixture is smooth. Squash any lumps of plastic agains the side of the pan to try to break them up
  • After 30-45 mins (total) you should have a silky smooth mixture. Fish any remaining lumps out with your stick (sometimes it's worth leaving the pan for a minute or two, as most lumps will float to the surface), wiping them on a suitable surface - a piece of scrap wood, cardboard, kitchen roll, etc.
  • Pour into mould. I pour directly from the fryer, rather than using a ladle, mainly because I've not got a ladle here; also, I have a very low boredom threshold.

Finally; I got my best results using Tesco freezer bags (with tie handles - i.e. 100% plastic bags). I tried some Wilko bags, but they turned out to be more expensive for the same weight, and rubbish at dissolving. Whatever the white write-on stuff is on the Wilko bags, it doesn't dissolve:



Ignore the purple colour, I was experimenting with candle colours again.


Finally, I wondered about the yellow Argos bags the fryers came home in.... 'twas the work of but a moment to stir them into some wax:



The bags weren't LDPE, they dissolved differently; and the resulting mixture took a lot longer to set, and cool off, than the LDPE based stuff. It machines OK, but as you can see there's lots of air bubbles in it. It seems to be somewhat softer than the other wax I've made. Looks good, though, as a garish orangey-yellow colour :)

That's pretty well the end of this thread for now, I think; I will add to it if I ever find a source of raw plastic, or if I modify the setup I'm using at all.

 :proj:

I do plan to automate the stirring..... as that's the really boring bit...
Cheers!
Ade.
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Offline raynerd

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Re: Machinable wax
« Reply #40 on: February 23, 2010, 07:16:29 PM »
 :offtopic: Several years ago, when I was a "teenage skateboarder" we use to make this exact stuff, only we would also add bars of soap with the candles and plastic bags. It was quite clever actually, those nice hard yet waxy blocks that you are using to machine, we use to rub them on the curb/hand rails so we could grind out skateboards on them!  :wack: :wack:

Looks good stuff, supprised it machines so well, I would expect it to chip looking at it!

Chris

Offline AdeV

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Re: Machinable wax
« Reply #41 on: February 25, 2010, 04:44:15 PM »
Chris - that's an interesting use! I guess the soap makes all the difference there, this stuff is quite hard & I doubt it'd lubricate handrails to any extent...

Fine features will chip, if you're not careful, but it actually machines really nicely. You get a good curly chip off the lathe, and small discrete chips off the milling machine.


A quick "general" update.... it turns out this stuff is a bit of a bugger to get melted again. It must be a really good thermal insulator, as both the saucepan AND deep fat fryers were really struggling to get solid back into 100% liquid. A pan in the toaster oven fared better, presumably because the heat was going in on all surfaces, rather than just the bottom.

Pouring wise: My nichrome wire heater worked:



There just wasn't enough of it. The wax solidified around the wooden framework, and anywhere more than about 1/2cm away from a wire. So, unfortunately, I had to abandon that idea (as well as the 1/2 inch or so of poured wax - what a mess). For now, I've just poured fresh melt over the top of solid; hopefully the layers will bond themselves together sufficiently well that I won't have endless voids or any overly-stressed bits. Time will tell.

In future, I will use the "melt it all in the oven in a metal oil can or two" method; which is currently hampered by the lack of an oven, and the lack of empty metal oil cans (loads of plastic ones  ::)). If anyone in the Wirral/Cheshire region has an older car - which uses that Halfords "classic motor" oil, that comes in metal tins which I will cheerfully take empties of (heck, fill 'em with your old engine oil, and I'll take 'em like that - if it's a useful favour).
Cheers!
Ade.
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Offline SAM in LA

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Re: Machinable wax
« Reply #42 on: February 26, 2010, 10:16:13 AM »
AdeV,

I admire your tenacity.  :clap:

I have been following your project with interest.

You may need to coat your wood form/mold with some sort of release agent, perhaps motor oil.

Otherwise, when stripping the forms, some of the wood may stick to your block of wax.  :poke:

Keep up the good work, I'll be looking for your new postings.

SAM

Offline AdeV

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Re: Machinable wax
« Reply #43 on: February 26, 2010, 02:13:42 PM »
Sam - thanks for your kind words :) As it happens, I don't need to worry about releasing agent this time, for 2 reasons: First, I'm using a cut up kitchen cabinet, which has glossy surfaces. The wax has shrunk away from these without any issues, so I'm happy about that. And second, if it were to prove difficult to un-stick the wax, the mould can easily be disassembled, which will allow each side to be picked off in turn.

I would recommend, if anyone is planning on using wooden moulds, that you do use a veneered surface (such as a kitchen cabinet). I'm willing to bet that, when molten, the wax will soak into uncoated MDF or even plywood causing all kinds of nightmares when you come to extract it...

I'd think something like talcum powder would make a better releasing agent than oil or grease; but I'll admit I've not actually tried any kind of agent, except paper on the first two batches I made: Which, in hindsight, was a mistake - the wax came out of the pan OK, but the paper was firmly embedded in the wax! Anyway, the mould is nearly done now. I'm going to melt one last batch to pour down the sides, just to take up some of the shrinkage; I hope tomorrow to be able to start the first machining operations!  :headbang:
Cheers!
Ade.
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Offline No1_sonuk

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Re: Machinable wax
« Reply #44 on: February 26, 2010, 04:59:17 PM »
Candle source I saw today:  The local PoundStretcher store has 3" dia. x 9" white candles for £1.99.

Offline Weston Bye

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Re: Machinable wax
« Reply #45 on: February 27, 2010, 07:16:20 AM »
Forgive me for popping in after a long absence, (still here regularly, just lurking) but has anybody any photo examples of items made with machinable wax apart from the test cuts shown here?

How would the machinable wax behave for use with lost-wax casting?
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Offline John Stevenson

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Re: Machinable wax
« Reply #46 on: February 27, 2010, 08:50:53 AM »
Weston,
I believe the wax companies make a wax that is specified for lost wax casting.

http://www.trycut.co.uk/

These do one called jewel wax but I have never tried it.

When Aidie was here last week he brought a sample of the wax he had cast as shown on here, I also had a sample of what we had cast for the shows doing loco wheels and some of the blue stuff from Trycut  above.
In terms of hardness mine using the thumbnail test mine was the softest, followed by Aidies, then the Trycut

I put the difference in mine and Aidies down to the candles, Aidie used paraffin wax and we used surplus candles from Ikea which were a 2 part wax, inner and outer coatings so I don't know which one of the two was the better material.

I can get an example of a mouse chewed loco wheel later if you want, these are about 3" in diameter and machined with a simple D bit to get a draught angle on the spokes.
They are not for a loco, just a machining exercise to do at the shows.

John S.
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Offline AdeV

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Re: Machinable wax
« Reply #47 on: February 27, 2010, 12:10:25 PM »
Forgive me for popping in after a long absence, (still here regularly, just lurking) but has anybody any photo examples of items made with machinable wax apart from the test cuts shown here?

How would the machinable wax behave for use with lost-wax casting?


Soon, there'll be a BMW dry sump.....

This wax would be good for making the original model in, but I wouldn't try to use it as the wax that gets melted out - it's a bear to get properly molten, and is considerably more viscous than pure paraffin wax.
Cheers!
Ade.
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Offline Darren

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Re: Machinable wax
« Reply #48 on: February 27, 2010, 06:35:54 PM »
Just popping in to say, I am watching with great interest  :thumbup:

Keep up the good work as I'm learning lots in this thread  :ddb:
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Offline jatt

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Re: Machinable wax
« Reply #49 on: February 27, 2010, 06:59:28 PM »
U'all just reminded me of wax baths that physiothearapists use to treat folks with arthritis.

If u are doing lots of smaller castings a 4 Kg bath that plugs into mains power can be purchased new for around $200.  Seen heaps when I used to do the rounds of physio clinics in my past life.  Not sure what temp they run at.  They do take a while to melt parafin wax, but it is its kept at a nice constant temp and it can be left unattended.

Did a quick incanink search, didnt see any power ratings for the element....sorry.
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