I’m ready for serious casting?

[C.Read]

How to you make your moulds? Do you have to make a wooden version to form the sand in the mould?

[Hans Richter]

Hallo E, dear Mr.Read, (do you have a first name too, make it more easy to address the PM’s and posts more personal)

Yes I made several flasks (wooden sand moulds) to use for my castings. There simple to made, only attention points are, -make them strong, -make their surfaces straight fitting to each other make the drag and coop easy attachable to each other.

Made my choice for Brussels clay (oil sand) after another wise recommendation (“play in the sand box first”) of a very unpretentious ‘improbable’ Curmudgeon .

You will find an assembly of the needed tools and equipment (on a humble dwarf scale ) below this post. If you need some specifications or measurements, don’t hassitate to ask by PM or post.

Cheers, Hans

PS. -regarding the moulds for your brass or bronze ingots don’t use the muffin forms that works fine for aluminium but in my case not for hotter materials, so make some solid self-discharging steel moulds too.

[ThomasPowers]

I use petrobond oil sand and have even used tunafish cans for flasks,  marked for alignment and held together with a hose clamp---works quite well for small castings. 

As for positives to use to make the mold I generally use wood, plastic or lexan or use an item I already have that I thought would do better cast in a nicer metal.  Using oil sand molds you can also carve them directly or tool the surface of the impression, (leather working stamps have been used to great success I know.) I use drillbits to make sprue and vent holes.

[C.Read]

Thank y'all!

My first name is Colton. Han I'm not trying to steal your thread and I'll delete this if you want me to. But here is my set up. I ran a batch today and I left a lot of aluminum in my dross, but I had much better quality ingots. I prefer to have no dross in my aluminum. In one picture you will see how much dross I had compared to my aluminum. That was a trash bag of soda cans. My steel crucible ( I know I need a clay, I'll buy one on payday Friday) has a weird spot now. I think it's where the burner was hitting it. So the next question is how do you get the stuck on dross out of the crucible? Is it worth running dross a second time if I see a big chunk of Aluminium? 

 

Then just a note, I’ve been using my welding gloves and pliers to take my crucible in and out. I learned that I can get a nice little burn blister through those gloves. So I ordered a more heat resistant gloves and some proper tongs.

[C.Read]

So I got the crucible cleaned out with a mini crow bar. Man that stunk horrible. Back in my last post I asked is it worth remelting dross if there is aluminum in it. Here are the pieces I’m talking about. I hit them with the bench grinder and it took a lot of the dross off. The pieces in the picture feels ( to a layman) like it mostly aluminum. It feels more like aluminum that the can I melted lol.

[Steve Sells]

your photos are missing

[C.Read]

Oops lol

[Frosty]

And that's another problem using aluminum cans for melts, the dyes in the printing is a contaminant and the anodizing that allows the inks to penetrate are millions of pinholes in the surface to collect more contaminants. 

What are you using for flux? You really need flux using trash aluminum like cans to help the slag and clean al separate so you can skim it. Even a pinch of 20 Mule Team borax will make a big difference. Better still, check one of the casting fora and ask an expert. I'm just another guy on the internet my opinion is worth what you pay. 

It looks like you're maybe over-heating it. Counter to intuition Al doesn't pour better hotter, in school we got the best results when it still looked lumpy when we poured, there were even  unmelted pieces still in the crucible sometimes.

If you want to get serious about casting use better Al, cans are extruded and the alloy is designed for that specifically. If you use things like old transmission cases you'll REALLY start having fun that alloy is intended to cast in THIN sections so it flows beautifully.

Frosty The Lucky.

[C.Read]

I'm not using any flux (head hangs low). I will have to find some places to get scrap aluminum. I just melted down about 2 months worth of soda cans, so I'm fresh out. But when I poured the aluminum it looked like the picture attached.

So I guess on payday I need to get a thermometer, crucible, skimmer (been using a make shift one with flat iron) and flux ( need to figure out the different types)

[Hans Richter]

Hallo Colton,

nice to have you here (especially in this treat) so don’t worry. Setup looks familiar to me. After every cast you will develop more and more and get more feeling for the material.

Indeed some tongs will be fine instead to ruin your gloves (Two holes on top of the steel crucible will be fine to attach hooks with handles to it, before you get the tongs).

Some constructive & safety feedback on your set up and technic.

-Put some dry wood a fire resistant blanket or brick layer under your furnace and ingot mould because of the enclosed (dangerous) moister in the concrete floor (cause spattering of liquid metal if contact)

-re-adjust your burner and let swirl/circle the burner flare around the crucible instead to ‘aim’ right on the body

-Your insulation interior of the furnace is made of mineral fibre, do you rigidize it to avoid emission of burned loos fibres (ones hotter than 1400F, they can cause cancer when respired)?

-Use Flux (powder) to peg down dross and impurities and prevent oxidizing of the alloys in the melting metals (specially brass and bronze)  In my case pure/clean Borax from the local pharmacy store

-Use base material from the Al 1000-4000 alloy series (pure or silica AL) but also a set of old aluminium-magnesium car rims (6000 AL-series) are a nice material source.

 

Save the money for the pyrometer for later. I have some nice indicators to see when melting temp is reached or it's to hot

-If slowly stirred there is no resistance or massive part in the crucible

-If the clean liquid surface in the crucible slightly start to spin around

-To hot,  if green, yellow smoke appears from the furnace chimney just before you want to cast

 

Cheers, Hans

[C.Read]

Put some dry wood a fire resistant blanket or brick layer under your furnace and ingot mould- I guess that is what the extra wool was for with the foundry. I've been pouring into my ingot over sand. I can get due bricks if that's better.

-re-adjust your burner and let swirl/circle the burner flare around the crucible instead to ‘aim’ right on the body- will do!

 -Your insulation interior of the furnace is made of mineral fibre, do you rigidize- No, because pmc's website set it was ready to fire. If that's not true I will rigidize it. No one wants cancer.

 

I weighed all my ingots and a bag and a half of soda cans gave me 1 lb 11 oz. 

As for finding scrap aluminum, I might go talk to my buddy who owns a car mechanic shop.

My tongs should be here tomorrow, and my gloves will get here today. Another valuable lesson I lessened this batch was how to control my fire. I have been going full blast with air open. But this time I limited the air and built the temps up slower. Hopefully that will help prevent shattering another crucible. I've read about putting flux in the crucible when hardening it, is that good to do? After you harden it, will I have to slowly raise the heat every time still? Or will it be good to go?

[Frosty]

Nothing to hang your head about I think we've all melted cans. I just spent a few years in shop classes in school. A butter knife makes a fine skimmer just hold it across the end of the crucible when you pour so clean Al flows under it leaving the slag behind. It works just like separating fat from drippings.

We didn't use thermometers in school it was all by eye, when it's almost all melted it's ready. Easy peasy. You have to have decent Al though, cans suck. Places that might have castable scrap: Transmission shops, off roaders tend to break things under their rigs, Aluminum rims slipped my mind thank you Hans so include tire shops, especially those that cater to off roaders and racers. A box of doughnuts is good PR when you talk to possible material sources. 

Add the borax when it begins melting so it can consolidate the slag as it forms and shield the melt from oxy. Borax will melt and form a surface layer that prevents oxy contact. 

Tongs and pouring holders are way out of my realm. In shop class there was a tong that slipped straight down over the crucible which was lifted out and set on a fire brick into the pouring tool ring. The tong that lifted the crucible out of the melter had bits like a basket or fingers on your hand and had to be close to the crucible to fit in the space between it and the furnace wall. The pouring gizmo was a piece of pipe with a T handle on one end and a ring on the other so one person could lift, maneuver and pour safely. Heck, I don't even know the names of the tools.

Frosty The Lucky.

[ThomasPowers]

If you will be casting items that will need to be top notch, look into degassing the melt as well.  Alloyavenue.com should help.

[C.Read]

So I've been researching the different crucibles. From what I've read it seems pure graphite is less likely to get thermal shock. What are yalls thoughts on that? I just don't want to keep going  through crucibles, and maybe there is a little reluctance with clay graphite because of the last one.

[C.Read]

My buddy hooked me up with 4 swing arms, and some other pieces of aluminum.

[Hans Richter]

Hi Colton, nice stuff this swing arms and this ‘looks like a pump house’. Chop them in to pieces fitting in your crucible and start real melting.

Before you add new cold material to the crucible place it over the chimney of your furnace to make sure there is no moister in it anymore.

Start with lost foam or a simple sand form. Add some flux to take care of the dross. Skim the dross an replace the furnace back to the furnace to let the liquid ‘spin’ and pore.

Regarding the crucible, you only ones have to pre-heat the graphite crucible (slowly heat up and cool down) after that the possible inner material tension of the crucible is gone and you can use is as usual (but never ever place a ‘stone’ cold crucible in an already glowing furnace (temperature chock)

Till soon, regs, Hans   

[BIGGUNDOCTOR]

Colton, first thing I would do is clean those parts to get as much crud and road grime off of them as possible.

I see guys constantly skimming dross, and I'm thinking if you just leave it on until just before you pour it would help reduce more forming by acting as a barrier. Am I correct in thinking this?

Hans, if you ever get a chance to use an induction furnace , do it.  I helped run one at a small foundry I worked at as the tool maker. We poured at 1,450F and 3,200F(chrome cobalt alloy), and watching the molten metal being suspended and spinning in a magnetic field was pretty cool.

[Frosty]

That's much better, clean the grease and dirt off before breaking it up for the crucible. I don't know about the radiator though, I'd keep it separate from the other Al. We know the castings are casting alloy Al. The radiator on the other hand may be extruded tubing rather than a casting alloy so it might not work so well. Keep it and give it a try of course I just wouldn't mix it with the known good stuff. 

I have nothing to add to Hans' advice, it's solid.

Frosty The Lucky.

[JustAnotherViking]

Soild advice? I thought they were aiming for liquid 

[C.Read]

Thanks for all the advice! :). I got paid today so I'm going to order a crucible, casting sand and flux. Are any brands better than the next? Should I go with petrobond sand?

[Frosty]

23 hours ago, JustAnotherViking said:

Soild advice? I thought they were aiming for liquid 

A joker Viking? 

Frosty The Lucky.

22 hours ago, C.Read said:

Thanks for all the advice! :). I got paid today so I'm going to order a crucible, casting sand and flux. Are any brands better than the next? Should I go with petrobond sand?

Not in my field but I'll be reading along just in case by ship takes a new turn it might help me avoid an iceburg.

Frosty The Lucky.

[Hans Richter]

Dear gents, and ladies of course,

Still busy to build version 3.0 of my new furnace. Some data

-two pressured air forced 1 ¼ in Inconel burners (if necessary? already made a two propane hoses ‘splitter’ with all the appendages)

-capacity of a A12> crucible which contains +40lbs of bronze

-made from bottom up 2 ½ in soft bricks 26 covered by 1 in hard bricks layer to let a tripod rest on

-wall from 2 in Superwool layer and covered for all flame face with 1 in hard bricks below and on top with 1 in of  26 soft bricks

-stich the brick panels together with lantan / NiCr wire -so every part will be replaceable in case of damage

-the lid is insolated with 1 layer of 1 in Superwool blanket and 1 ½ in layer (exhaust) of soft bricks all hold together by a AISI 316 wire mesh

Use a new garden weed burner drum and lid as body (prefer a round one to let the flame 'swirl around the crucible). After final assembly I will coat all the wool with ridgidizer  and after that the whole stuff with Satanite.

If successful, a new propane 25lbs fuel tank stay’s ready to undergo the same treatment as a new forge.

If you have some feedback & improvements, please let me know.

Cheers, Hans   

[Hans Richter]

Finally, the furnace is ready. Glad to follow Frosty’s advice to use two layers of 1in Superwool. The outside is still quite hot after melting session. Use only one burner to melt down 16lbs bronze in a small (A5) crucible. Works fine, with enough space to grab the crucible. Will reinforce the SS-mash on the lid with kantal-wire to avoid collapsing the soft fire bricks in to the furnace.

Next step, build a slightly bigger gas forge 25lbs propane cylinder as addition to the 18lbs gas forge with cast refractory I already have.

Cheers, Hans  

[Frosty]

Frosty The Lucky.

[C.Read]

Looking good Hans.

I like my little foundry but I'm also looking to the future of getting a larger forge. I am wanting to make ash trays for a couple of my buddies cigar shops and I'm not sure if I can melt enough aluminum at one time to make them. 

 

I took a hiatus to try making some things and here are my results. My first try at casting was brass knuckles. They were not good but atleast it wasn't a total disaster. 

My second try was the ashtray is modeled after the red one ( I forgot to take pictures before I cut it up), I got the top 1/3 shaped perfectly but then I ran out of aluminum. So this is why I think I'm going to need a bigger foundry, or custom make a crucible like the one I use for brass (the steel one in the pictures I use for brass now). The clay graphite I got does not hold enough metal (you read that right, I used the new crucible and I cured it and it didn't break)

So I thought things were going better so I tried using Styrofoam to redo the brass knuckles, this time it was a disaster. The metal somehow went through the sand and created a mess. That is what the picture of a mangled mess was.

I seem to be able to pour ingots pretty good. So I have a buddy who has a cnc milling machine and is going to make me a negative of the ashtray for me and I can just melt and pour into steel like my steel muffin pan.

So I'll shut up now and let y'all put your Windom on me.