Starting Lost Wax Casting

[fltenwheeler]

Hi All

Here are some pictures of my first attempt at casting my own parts. These are waxes for stake pockets for a 1-1/2” scale flat car. There are 75 in the box. I hope to get at least 30 usable ones for my project.

Tim

 

[aonemarine]

I love lost wax casting! Any idea on what alloy your going to cast them in? And what do you have for casting equipment? Vaccum assisted?

 

[gus]

Hi Tim Hi Aonemarine,
Been thinking of going into this for a long time. Will be watching your post.
Done some gravity casting with aluminium into cast iron molds. Was tougher than I thought. So many factors to watch. Melt temperature and mold temperature.An most important personal safety.

 

[fltenwheeler]

Hi All

I was able to find a Jewelry casting setup for a good price. I purchased a 3kg electric melting furnace, programmable burnout oven and wax pot from one source. I will be picking up the vacuum casting machine this weekend.

The furnace is rated at 2799g of 14k gold. So if I am doing my math correctly it will do 1142g of Silicon Bronze, around 2-1/2lbs. Each stake pocket wax weighs 2 grams. That should be around 16.6 grams of bronze per stake pocket plus the sprue. I do not know how many stake pockets will fit in a flask.

Tim

 

[aonemarine]

glad to hear your going vaccum assist, those parts look very thin and I think youll need it. I need to come up with vaccum assist, last time I tried to do really thin stuff it didnt come out well at all, and I wound up having to steam cast which I really dont like doing.
Looking forward to seeing the finished product

 

[gus]

It is hard to believe,one African Tribe had been using lost wax to cast bronze head gear hundreds of years ago. Their equipment was at best very primitive. A hole in the ground to melt and alloy bronze using hand powered crude bellows and bee wax was their medium. Crucibles not shown. Where did this technology come from??? Was it indigenous???
Saw this Nat Geo documentary twenty years ago. Would be great if we could find this in YouTube.

 

[aonemarine]

Gus, look up the Dokhra metal casters on YouTube. I think its what your looking for.

 

[fltenwheeler]

glad to hear your going vaccum assist, those parts look very thin and I think youll need it. I need to come up with vaccum assist, last time I tried to do really thin stuff it didnt come out well at all, and I wound up having to steam cast which I really dont like doing.
Looking forward to seeing the finished product

The thin sections are around 0.032 thick. The part was drawn to exact full size and then scaled plus shrink. I then sent the stl file to Shapeways to be printed. My Son did all the 3D CAD work. He is very good at it.

Tim

 

[Buchanan]

The two most important things to watch when casting is that your metal ia hot enough and that your mold is near the melting point of the melal. Then thin walls are no problem. I cast a spider in bronze with legs 2"long and managed to get a few hairs on the legs as well.

Buchanan

 

[fltenwheeler]

One of the references I have, shows a temperature of 1010-1230 C (1850-2246 F) for Silicon Bronze and a flask temperature of 475-550 C (887-1022 F).

Tim

 

[gus]

One of the references I have, shows a temperature of 1010-1230 C (1850-2246 F) for Silicon Bronze and a flask temperature of 475-550 C (887-1022 F).

Tim

Hi Roman,

Please enlighten Gus..What is flask temperature? Is this mold temperature?
Watched some YouTube docs on investemnt casting of Stainless Steel
Propellers.The Zirconite Molds were white hot for pouring S.S.

I know nothing on investment casting.


Gus Teng

 

[robcas631]

Does brass have a lower melting temp. than Bronze?

 

[Buchanan]

Gus.

The flask is the container that holds the mold. this is heated as well as the metal but to a lower temp.

Brass melts at roughly the same temp as bronze (which alloys are we comparing?) but bronze flows so much better, in my experiance.

The principal, as I comprehend it, is that, the hotter your flask is, the longer the metal takes to freeze,the better detail you get and the thinner section you can cast.

Always follow the manafactures instructions and temps as some refactorys cannot go above a certain preheat temp with out losing bond strength.

Buchanan

 

[aonemarine]

Brass has a lower melting temperature than bronze.

 

[abby]

Plaster investments should be burned out at a maximum of 725°C , and the maximum metal temperature should not exceed 1200°C.
For metals with higher melting points a phosphate investment is used , or ceramic shell.
These are some brass castings I did recently

There are well over a hundred individual castings , some of the wall thickenesses are very thin so I poured this mould at 500°C with vacuum assistance.

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The wheels are for my G1 Merchant Navy Class engine

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If interested you can see more at http://www.unionsteammodels.co.uk​

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[aonemarine]

It's about time you chimed in abby.....lol

 

[fltenwheeler]

Hi Abby

What alloy are you using?

Tim

 

[rhitee93]

I'll be watching your progress as well. I toyed with this a few years ago to cast copies of some missing parts for a clock restoration project. I could get the wax positives, but had a hard time creating the mold. I am hoping to find where I went wrong as I follow along

 

[abby]

I use scrap , for the brass I prefer bar off-cuts - rod ends , plumbers fittings are also good.
I add a small % of silicon brass to the melt which gives a slightly harder casting.
I will use fittings soldered to bits of copper but avoid chrome plated scrap.
Anything that doesn't melt such as the odd steel bolt or spring gets scraped of with the crap.
I don't bother with turnings, I would have to fill a crucible several times to get a worthwhile quantity of metal.
For gun-metal ( red brass ) I use scrap steam valves if I can get them but sometimes mix my own 85/5/5/5 alloy.
I also collect old EPNS cutlery and horse furniture ie stirrups , mouth bits and bridle fittings as a cheap supply of nickel silver.
Farm and yard sales are good venues for sourcing raw materials and several local scrap dealers save suitable scrap for me.