TaleSpinner

My Journey into Lost-Wax Metal Casting

133 posts in this topic

Lol, running power lines is the part I would have had an expert do... :)

Good luck, have fun, and try not to burn your face off!

Kang

 

edit - just reread the thread more carefully, now that my excitement has abated a little, and I'm curious - is the rubber vulcanizer for making molds of your greens to be cast offsite? I can't see a role for it in your lost wax setup, as the rubber isn't porous enough to fill with vacuum assist, and your description of it seems like it won't make molds big enough to fill with gravity alone...

Edited by Kang
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I just got my electrical permit.  I'll start roughing in the power circuits and building the ventilation system after Thanksgiving. I do not need either though to start playing around with making the rubber molds and wax copies.  I might play with that soon, depending on how soon I get my current sculpting project done.  Maybe as soon as this weekend.  

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Have tools, will travel. If you need advice or help running the circuits, let me know. Not a licensed electrician but i do controls for water plants for a living. Did all the wiring in my own shop. 

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My high temp melting kiln just arrived today and my pewter melt pot came yesterday.  

 

The kiln is a lot smaller than I expected.  The crucibles will only likely hold enough metal for 2 to 3 rings at most, but that's OK.  It is a relatively inexpensive setup and it is probably a good thing for me to begin my experimentation on a small scale. 2000 deg molten metal is really dangerous, and I'd rather cut my teeth on an 1/8 of a cup of it than on a cup.

 

Here is what it looks like (that picture is larger than life size, at least on my PC; it is actually about 4" in diameter, hence the reason I thought it was bigger):

 

 

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517vZ4TpNRL._SL1280_.jpg

 

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Here is a video of the inventor using it.

 

 

I also got a larger melt pot for low temperature metals like pewter.  This is what I will use to make miniature casts.

 

 

61PQ7vuR45L._SL1500_.jpg

 

 

 

The excitement continues.

 

Andy

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Very cool!

 

The only problem with this kit over a torch is that I won't be able to make my own white gold because nickel melts at 2651 F.  

 

Not sure offhand what the temperature needed is, but nickel dissolves at a much lower temperature than it melts.

 

Think of alloys like salt water: Salt has a very high melting point, but it will dissolve into water at room temperature. Most alloys work the same way.

 

Some quick googling suggests the alloy melt point is around 2000 F, so you might well be able to make your own white gold.

Edited by fectin
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Very cool!

 

The only problem with this kit over a torch is that I won't be able to make my own white gold because nickel melts at 2651 F.  

 

Not sure offhand what the temperature needed is, but nickel dissolves at a much lower temperature than it melts.

 

Think of alloys like salt water: Salt has a very high melting point, but it will dissolve into water at room temperature. Most alloys work the same way.

 

Some quick googling suggests the alloy melt point is around 2000 F, so you might well be able to make your own white gold.

 

I was just reading about that the other day.  It sounds too good to be true (and a bit weird), but totally plausible.  Thanks.

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Hi Andy!  I've been following your setup here, and everything looks awesome (and envy inspiring)!!!  From everything I'm seeing, you are certainly starting down a great path between furnace choice and ventilation setup, so keep up the great work!  Just be advised that vacuums and combustibles really, really, really do not mix.  If there is any way to use more of a fan-in-a-tube air evacuation setup to move air out of a window or something along those lines, that would be my first choice.

 

I'm actually a metallurgical engineer in real life, and so I've done some tin spin-casting in vulcanized silicone molds as part of a college project (I cast my own minis!), and I also work at a steel mill for a living (where our liquid metal is usually nearly 3,000 F).  From a safety standpoint, my biggest pieces of advice are:

 

1)  ALWAYS wear cotton or some fire-resistant material while casting.  Synthetic clothing melts into a burn (essentially leaving you with melted plastic clinging to your charred flesh) and often lights on fire far too easily.  Cotton simply burns away cleanly.  You will probably be surprised by a stray little droplet of molten metal which skitters away on you every now and again, so it's best not to give it an easy target.

 

2)  Get a full-fledged face shield.  Safety glasses are nice, but you will probably find yourself looking over what you are pouring in order to accurately hit the mold inlet, and that puts you in prime splash-back range.  Plus, you can get one with some dark tinting to it so that you can still see what you are doing with the oftentimes painfully-bright molten metal.

 

3)  Make sure you have a nice secondary containment vessel around your mold to catch any spills!

 

 

And, lastly, in regards to alloys, they do indeed often melt at lower temperatures than their constituent elements due to some thermodynamic principles that are beyond the scope of this post.  But, if you take good-ol' leaded solder, for example:

 

post-7158-0-72668000-1479821626_thumb.jpg

 

You can see that, at a ratio of about two-thirds tin (Sn) to one-third lead (Pb) the alloy melts at a little under 200 C, which is well lower than the melting points of either tin or lead (the right and left edges of the graph, respectively).  So, when you hear people griping about how leadless solder (which is essentially pure tin) doesn't work as well as leaded solder (which is the alloy we just discussed), that's actually grounded in the fact that tin doesn't melt until 232 C, which is more than 40 C higher than the old solder blend!

 

Incidentally, these types of graphs are called phase diagrams, so you can look them up for many common, two-component alloys fairly easily on Google!

 

Have fun with all that awesome liquid metal!!!

Edited by Kuro Cleanbrush
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+1 For proper PPE!  I wear a full face shield, leather welding apron and long heavy welding gloves, long natural fiber sleeves and pants, and leather shoes or boots, ideally with steel toes (ignore the kitchen oven mitts I'm using to grasp the Eye of Sauron and everyday fall clothing in my avatar pic :)).  I consider that the bare minimum, and I have no illusions about my thin apron or my gloves actually stopping more than just tiny drops of molten bronze.   Seems about on par with other hobbyist aluminum casters I have interacted with though.  I would like to invest in some better gloves though.  Or at least get some small aluminized heat shields to strap over the ones I have.  If you really want to get geared up on the cheap, I have read how other backyard casters have gone to their local firehall with a 6-pack or a box of donuts and asked real nicely if they have any expired turnout gear that is headed for the landfill that they would part with (make sure your setup complies with local regs first though!). 

 

Make wearing your PPE a non-optional part of your regular casting process, and I recommend you also do a dry run on the whole process before actually starting your furnace.  Maybe not every time, but at least whenever it has been a while since you cast something.  Figure out a way to lay out your work area to eliminate tripping hazards and having to run across the shop for tools that are needed in one area but located in another.  If everything is within arm's reach of where it is needed, you won't make the mistake of needing to think about what you should do next when you should really be focusing 100% on what you are actually doing right now - that is how you make dumb mistakes that might cost you some skin, or worse. 

 

This means setting up everything exactly the same way every time, other than when you think of ways to improve or streamline your process.  For example, I have 2 extra pairs of the long cuffed heavy leather welding gloves I work with.  Sometimes one will get so hot I have to toss it off to avoid burned fingers.  When that happens, my first backup pair is right there next to the furnace, sitting on top of my second backup pair, in separate piles - a pile of lefty gloves on the left, and a pile of rightie gloves on the right, so when I need a new glove it is literally a no-brainer because I do that little bit of thinking and setup before I light my burner. 

 

Make sure you aren't laying hot tools against fuel lines etc. too.  Be aware that your open furnace lid/door is radiating intense heat at whatever it is facing, and make sure that "whatever" is not any flammables, such as your fuel line(s) or your self.  With my furnace that is easy - I built the lid to be able to swing to either side, but I always swing it left, away from where the burner with its propane and oil lines are located.  The only thing it is facing when open is the ground.  So, which direction your melting furnace's oven door opens is one factor you can use to help determine the best place to locate some of your other gear.  Also, consider any tool that may touch molten metal that is cool enough to touch barehanded as being wet - your alloy will do likewise!

 

This computer won't let me copy/paste to or from this site for some reason or I would paste a link, but there is a YT video called "how not to pour aluminum metal" or the like that shows why it is really important to preheat any tools that may come into contact with molten metal.  Notice how they lie to the prof afterwards and say they both wore face shields when one only had goggles on...  I'm sure that watching it will also bring up some recommended videos showing other dramatic foundry accidents as well.  You will be dealing with smaller amounts of metal than those guys or even I am used to doing, but make no mistake, there are non-obvious dangers to beware of.  Those guys' ingot mold in the video probably looked completely dry to them, but residual moisture is sneaky like that.  Ingot molds get rusty quick, which is good - it helps your ingots from sticking to the mold.  But rust also gives residual moisture some really good nooks & crannies to hide in.  Preheat everything...

 

I hate to admit this, but it's worth it if it keeps anyone from needing a skin graft.  I experienced a POP! like the guys in the video when I was casting my aluminum bronze axe, and forgot to preheat my dross skimmer.  It happened the very INSTANT the skimmer came in contact with the melt.   I would blame it on the fact that I had not followed my own advice and done the dry run first despite it having been a few weeks since I melted anything - my extra gloves were nowhere to be found when I needed one, so I had to grab a cold skimmer barehanded - if it were not for the fact that I have done the same exact thing on multiple occasions with a cold skimmer in cast aluminum, with plenty of gloves available... and there was no more than a bit of sizzling.  I got lucky, is all that proves.  Not that that was a safe practice.  There is no excuse for that kind of carelessness no matter what factors went into me forgetting to preheat that time - I had seen those guys in the video and still did that, how dumb was that?  That POP of molten bronze was the attitude adjustment I needed and I won't be taking that sort of risk ever again! 

 

Luckily nobody caught any airborne molten bronze in my case.  A real heart-thumping eye-opener.  Don't wait until you experience one like that to wise up.  This is one of those 'do what I said, not what I did' things.  You can see me doing another no-no in my face-shield-free anthill casting pour video shot a couple years ago, dumb dumb dumb, never again, do not imitate.  All I had to do was walk across the yard and grab my face shield - that aluminum was way overheated anyhow!  I have no explanation or excuse for why I did not pause long enough to grab proper face protection, especially pouring into who knows what undeground.  You only get so many lucky breaks in life.  Metal casting is very rewarding but the risks are no joke.

 

Oh, another perhaps not so obvious no-no aside from ignoring invisible residual moisture is pouring molten metal over a cement/concrete floor.  Portland cement holds chemically bound water.  If that water flashes to steam while trapped beneath molten metal, the cement will spall and pop due to steam explosions.  This can cause flying molten metal!   Pour over a couple inches of sand floor if possible, even damp sand should be OK, since it should still be porous enough if not soaked to vent any stem downwards through more sand more easily than flinging metal upwards.  This may mean you have to build a little sandbox around your pouring area.  Perhaps spills are not that likely with the small pours you will do, but why chance it. - sand is literally cheap as dirt!

 

Good luck and stay safe.  Don't let these horror stories slow you down.  Rather, use this info to move forward in relative safety...  Looking forward to seeing what you come up with!

 

Kang

Edited by Kang
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Thanks Kuro an Kang.  Great advice I will follow.  I already built a sand pit for my little melt furnace. :B):

 

Tomorrow, I start putting in the electrical outlets and heat proof cabinet top.

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Well, I got a great deal.  We have a Building Material Outlet near us, which sells off the extra materials that builders have.  I got an 8 foot long composite quartz counter top for $100 (typical retail is about $700).  It is an ugly maroon color, but is a very good heat proof surface.  You should have seen the faces of the guys at the store when my son and I managed to get it into my Rav4.  :lol:   It weighs about 300 lbs.  It was quite a chore for Myles and I to wrestle it into the basement.  I added extensions to my existing bench to support it and it is perfect!  Pictures will come later once the electrical rough in is done.

 

Speaking of which, I also installed most of the conduit and boxes for the electrical.  I had a few hours of panic when I started obsessing over whether or not my home could actually handle the extra circuits (OCD went into overtime yesterday).  So I ran around the house like a madman collecting wattages from all of the appliances and such, then did all the derating calculations to find that our house is well under what our 150 A box can handle (it is currently sitting at 60 A, derated).  Even with the 5 new circuits, it'll still be only at about 115 A.  So tonight we press on with the electrical work, full steam ahead.

 

I promise I'll post more pictures when I get the electrical rough in completed.

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Sounds like a great deal!

 

Funny, I thought I posted this the other day.  Guess not... or maybe it was on the other forum.

 

If it turns out the (polymer resin?) binders that hold the engineered quartz composite together don't like the heat (no idea, perhaps you have already looked into this), you could always get a couple of firebricks to set hot things down on.  You can probably find them at Lowe's for couple bucks and change each. They have dense 2000F rated firebricks at my small town corner hardware store for making repairs to wood stoves (I usually beeline to that section; they have a variety of products useful for DiY high-temp applications), but I read recently on the AA forum that Lowe's in the US stocks 3KF-rated bricks - even better. 

 

Kang

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Sounds like a great deal!

 

Funny, I thought I posted this the other day.  Guess not... or maybe it was on the other forum.

 

If it turns out the (polymer resin?) binders that hold the engineered quartz composite together don't like the heat (no idea, perhaps you have already looked into this), you could always get a couple of firebricks to set hot things down on.  You can probably find them at Lowe's for couple bucks and change each. They have dense 2000F rated firebricks at my small town corner hardware store for making repairs to wood stoves (I usually beeline to that section; they have a variety of products useful for DiY high-temp applications), but I read recently on the AA forum that Lowe's in the US stocks 3KF-rated bricks - even better. 

 

Kang

 

Yeah, I don't think I'd trust the counter top to actually set the kiln top or crucible on directly. It'll take heat, but I don't think I'd trust it over 1000 degrees. It is more there as a general, not going to burst into flames surface (unlike the wood I used to have on that bench).  I'll stop at Lowe's.  Thanks for the tip; I wasn't sure where to get firebricks.

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If you have a local pottery or ceramics specialty store, you could look for kiln furniture. 

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A local pottery supply place is a great suggestion and they are probably in greater need of your dollar than the big blue box.  Maybe cost a little more than for dense firebrick singles though...  But they will have a greater variety of high-temp products and probably sculpting tools/supplies that may be useful to you, and will probably know where to order more if you need something they don't normally carry.  That is how I got all the insulation in my waste-oil fired melting furnace.

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Weirdly, all the local pottery supply places do not have this.  They have kilns, but no fire bricks listed.  

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