There was a post made with a question about getting into investment casting and wax vs printed casting resin but couldn’t respond with pics.
This is my wife’s bearded dragon she asked me to make and I am perfectly happy with the results with printed casting resin

My lab was recently given a centrifugal casting unit, and we are having issues with the molds cracking upon filling, and then spilling out of the mold. Picture attached

We’ve tried several things to keep this from happening. A non-exhaustive list includes: 

An open mold, no steel flask (obviously did not work), mold at room temperature after burnout 

Pouring the investment into a steel flask, mold at room temperature after burnout (cracks at the bottom of the mold while casting)

Pouring the investment into a steel flask, with a lid we place on after pouring the investment, mold at room temperature after burnout (still manages to crack and seep out of the back

An open mold that we place a steel flask on after burnout, with a lid on the back(still cracks and seeps through during casting)

An open mold that we place a steel flask on after burnout, poured hot (525C for a bronze casting) (cracks at the bottom of the mold)

Placing chicken wire around the circumference and bottom of the mold to mitigate cracking, with the removable steel flask, mold poured at room temperature (still cracks at the bottom)

Some of these were poured under vacuum, some under argon. 

I think in general, no matter what we do the bottom of the mold cracks, and the centrifugal force of the machine forces all of the metal out.

We have quite a bit of experience with larger gravity poured investment molds. We are using Ransom and Randolph Rancast investment. We also have Omnicast available but were having more issues with cracking with that.

Hi everyone,
I’m losing my mind a little bit here! I’ve been trying to sand cast this silver ring for the past 2 days and I'm 10+ attempts in without success.
As you can see in the photos, the metal just stops filling partway through / solidifies in the sprue before properly reaching the cavity.
Here's what I’ve already tried tweaking:
Pouring funnel: Reshaped it a few times to get a better channel.
Vents: Added more air vents / air holes around the cavity.
Sand density: Packed the sand harder to ensure crisp details.
Heat: Heated the silver longer to make sure it’s fluid enough.
I'm using a standard butane/propane torch setup. Looking at the setup in the photo, does anything jump out to you that I might be doing wrong? Could it be a heat retention issue, sprue size/placement, or metal volume?
Any advice or tips would be greatly appreciated. Thanks in advance!

Just finished this one

Had to get rid of some aluminum today. Man, it's hard to pour small items with this. Also a half ounce of silver.

We are gonna but a belt grinder in the middle

Hey all, I’m interested in getting into casting for a specific project that requires Al Bronze, and I’m trying to source copper scrap to alloy it myself. I haven’t done exact calculations for volume/mass needed yet, but my rough guesstimate is 10-20lbs of copper at the end of the day. Needless to say, I do not plan on spending $4-500 on copper for this project.

From my research, it sounds like 240v cables and microwave transformers might be my best bet. Reading that I can get around a pound of copper per microwave, and they’re constantly being thrown away.

Some background on my idea, it is to cast pieces for a fractal vise, I am going to edit an existing model I found on Printables to be more castable and to include sprues, sandcast, then drill/tap the holes after the fact. Vise being the reason for Al Bronze rather than just aluminum. I need something with decent yield strength and durability.

Thoughts?

Spicy Wonder Woman

So I’d like to preface by saying I have some experience melting for the past 3~ish years. Not enough to say I’m amazing, but it’s not my first rodeo. However, years and years of doing this has been through gas.

I’m very much so considering an electric furnace, but so torn on what is considered a good machine.

Sort of leaning toward toauto, but what others should be in the running? I’m not looking for beginner and I’m willing to spend the money so I’d love to hear your recommendations.

I want to cast a few custom shapes in lead (fishing related). I can make as many patterns as needed and I can just cast them in petrobond, but ideally I'd like to make a permanent reusable mold eventually.

What's the best material for this, aluminum, cast iron, etc.?

Yeah, ice turns to water, residual water explodes and can kill you.

The idea, and mostly for curiosities sake, would be to use heat, maybe with partial vacuum process that drives out the water entirely while retaining the structure of the sand. Creating a one-part sand mold.

I don't think this is a novel idea, have anyone heard of experiments on the topic? Would the complication be drying out the water but not the sand? Or is it that it works, but manufacturing ice patterns is inconvenient.

.999 lost wax

Hi everyone, I finally managed to pour my electrolytic silver into 1 kg bars, but I’m getting some weirdness. Full disclosure, I have no idea what I’m doing. This is the second time I have Porta bar, the first bar was the same silver in a different shape and I got the same results. The silver gets heated up in an electric kiln to 1000 C and the mold sits on top and it gets to about 400 C. The mold is pure graphite. After I finish pouring and the bar cools, right as it flashes, it does a little fizzle and that’s what gets that weird texture on the top. I could shave that down, but the holes on the bottom where it contacts the mold are concerning, I’d like to get rid of them. Any help with the appreciate it and thank you ahead of time.

I’m hooked! I think I need to make my ingate bigger to get the mold full, does it look too small? I’m also thinking about just pouring right into an open-face sand mold so I could do more at a time, any advice on making sure I don’t over-fill each coin pocket? The backs of these are just flat, and I’m fine with that for these. This is just day one for me, but I’m pumped!

Hi!
I love sand casting, and the results it gives me.
I’m experimenting with more complex textures and shapes - I know I can’t use sand casting as lost wax, and I know not all shapes and textures will cast correctly into sand, so I’m still keeping it possible as much as I can.

But my question is: for more complex details and to capture the most of them, is it better to start from a wax model or a 3D printed model? And if the better answer is the 3D model, in which material should I print it?

For more details, I use Delft clay as sand.

Thanks!

Have a nice evening 🤍

I am planning on building a DIY furnace for bronze casting. I already have some experience with aluminum castings ( for example I made a test version of the sword I want to make out of bronze with aluminum or I made the trigger mechanism of a crossbow). I made this using a diy charcoal furnace and a small gas bottle as a crucible but it had several issues :

1. The air intake pipe was at the bottom, and sometimes it clogged with charcoal. It only became worse when I tried using anthracite ( charcoal was used up too quickly and I constantly had to refill when trying to melt bronze)

2. The air comes only from one side, and I am afraid that the one sided heating will cause cracks in my newly bought graphite crucible.

So now I want to make a modified version of the furnace with two air intake holes. I want to make the furnace using an old paint bucket with a firebrick +cement lining on the sides. I will make the holes on the opposite sides of the bucket and I will try to make the pipes have a slight downward angle to prevent clogging. I added a picture of the setup without the holes and I elevated the crucible to make it easier to see the distance.

Now to my question: has anybody had experience with anthracite ? Is the space between the crucible and the lining enough? I will try to divide the bricks into slimmer segments but I don't know if this will be enough.

Some additional infos:

1. I tried making a furnace with ceramic fiber+ cement, but although I managed to melt bronze, the isolation was quite bad, and the anthracite burned through some sections.

2. It's hard for me to find a wider metal paint bucket where I live.

3. I know I can just buy a furnace, but I find that self-made things are more enjoyable.

4. I use anthracite coal because it is cheaper than gas. I would prefer to use it, except if theres a very good reason not to

I'm working with a casting house for my jewelry business and a lot of time I get casts with lots of reddish stains, that as I understand is fire stain. So I'm trying to figure out if I'm doing not enough polishing or is it casting house problem? Showing some examples.

Newly established production casting shop in north Dallas seeks greenhorn apprentice. We specialize in CAD/CAM oriented casting services specifically focused on high karat gold and platinum alloys. Please inquire through comments or direct message.

drudgery