Foundry.

[grim_d]

Thought id share a few pics of my just completed foundry and propane burner.

Made entirely from scrap with the exception obviously of the refractory and crucible. I know its a bit naughty to use gas bottles but since the company that owned it no longer exists and it had sat outside for years with no valve they are unlikely to have wanted it back.

Made for an a8 size crucible, no cares given for looks, only function, almost everything was eyeballed, I might need them calibrated....

My 180A mig was struggling a bit with the thicker stuff but with some preheat and big chamfers its plenty strong if not very handsome.

Refractory was cast yesterday so going to let it cure for a while before starting to heat cycle it.

If I was doing another I would make then lid less deep. FYI there is some rebar welded inside the lid to stop the refractory falling out, and I still need to make a cap of some sort but for now a fire brick will do.

Hinge was made from a peice of round stock with a hole drilled through the middle and then split into 3 then welded onto some flat bar, works great.

If ive made any huge errors please let me know, open to suggestions on improvements.

 

[Screwdriver]

I don't think you want the end of the inlet pipe inside the foundry, it will melt. Even if it doesn't melt, the whole length will get red hot.

 

[grim_d]

I don't think you want the end of the inlet pipe inside the foundry, it will melt. Even if it doesn't melt, the whole length will get red hot.

Noted, ive just been copying designs ive seen online. I should add this is only to melt aluminium, possibly some brass etc, never steel so the temperature should never be high enough to melt the steel pipe. If it gets too hot ill certainly cut it out and move it back.

 

[Keith 66]

Looks good to me. Im seriously thinking of building one as i am in need of a pile of fittings & parts for a vintage powerboat restoration, the cost of having virtually everything custom cast in bronze is staggeringly high.

 

[Touchdown]

Yep, another thumbs up here. Have you got the dimensions of the torch/burner that you'd be willing to share? I want to smelt some copper pipe to make a heat sink and do some rudimentary lost wax or sand casting work

 

[grim_d]

It's basically a version of the burner in this video which kindly provides some dimensions.

Some key changes of mine are that the diameters of everything is slightly bigger because that's what I had. I also doubled the length of mine as it provides more time for the gas and air to mix, it really helped stabilise the flame.

I didn't mess around making threads for a fitting, I just turned a barb on the end of the gas inlet.

I am using a 0.8mm mig tip as per the video. I think I'm going to put some more air slots in as I think I can get a little more air in without it blowing out

It's important to have the nozzle taper correct and as smooth as you can make it.

I am running it between 1 and 3 bar depending on how hot I want it.

 

[Kram]

I need one of these, Ive got 20kg of good quality scrap alu from engine casings to melt down. What refractory did you use? my attempt with perlite failed, it works great as outer insulation but not in the hot bit.

 

[captain-destructo]

have a look at this one

 

[Seadog]

You can buy his book - http://www.ebay.co.uk/itm/The-Artfu...e=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649

 

[grim_d]

I need one of these, Ive got 20kg of good quality scrap alu from engine casings to melt down. What refractory did you use? my attempt with perlite failed, it works great as outer insulation but not in the hot bit.

This.

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/302095877660

I needed 2 bags, got about 5kg left.

 

[Kram]

Was looking at this, similar price with delivery, bit too expensive
http://www.castreekilns.co.uk/dense-castable-1700c-25kg-bag-869-p.asp

 

[grim_d]

There are some homebrew recipes that might work out cheaper. I wasn't delighted to pay £60 for it but at least I know it would be right.

I did get a lot of bits free, or have scrap for this project but I'm still about £170 into it by the time I got a crucible and a propane bottle etc. It's not a cheap thing to do!

 

[grim_d]

Did my first proper melts tonight. I'm attempting to cast a blank for my 127t gear, approx 9.5" x 1".

The foundry had no problem at all melting about 1.5 litres of aluminium.

The first one was a bit unsuccessful as I was too impatient with it and broke a chunk from the edge of the blank, crumbled off like it was made of sand...lesson learned!

I've left the second one in there to cool overnight so there's no repeats of that!

Running a dreadnaught file over the edge of the first one there seems to be some minor inclusions, hopefully not too bad, find out when I machine the second one. I don't think the grade of aluminium I used is particularly suited to casting.

 

[julianf]

Are you using flux and degassing?

 

[grim_d]

Are you using flux and degassing?

No, I've done a bit of reading about it and decided to just go for it and see how it goes. Some say it's not too critical in smaller melts. Any tips?

If it doesn't work out I can get some degassing tabs and give them a go. I can always remelt it! The only place online that I've find that sells them wants £20 delivery which is a bit steep!

The biggest thing was to confirm it had the guts the melt the quantity I needed

 

[julianf]

I've not started yet, so I'm only regurgitating, but lo sodium salt (supermarket) is supposed to be a good flux, and soda crystals (again supermarket) for degassing.

Degassing needs them plunged though. Think tea strainer or egg sepparator on the end of a pole.

 

[grim_d]

I'll find somewhere to get some degassing tablets from.

Yeah I've read about using salt too. Nothing to lose there!

 

[grim_d]

Here's the results. There are some minor inclusions, not too bad I don't think, certainly wouldn't affect what I want it for though I'm keen to improve on this significantly.



Unfortunately it shrank a bit more than I'd anticipated so after machining the crust off it was a little small.

So it was smashed up and will be remelted. I noticed that the breaks were very grainy, I think I may have overheated the melt a bit, which won't have helped the casting either. Will have another go and try and control the temperature a bit better.

 

[Kram]

How did remelt go?
I saw castree have degassing listed but OOS other than large quantities.

Im going to order parts soon, but need to get a gas bottle.

 

[grim_d]

How did remelt go?
I saw castree have degassing listed but OOS other than large quantities.

Im going to order parts soon, but need to get a gas bottle.

That's flux is it not? I'm using potassium nitride, works excellent, available on eBay in small quantities.

I've tried degassing with sodium bicarbonate but it didn't seem to have too great an effect, I did get a lot of bubbling however. I would be interested in sharing the costs to get some ecogas tablets if anyone Is interested.

I melted some cast parts, gearbox casings etc and got better results understandibly, the grain was much tighter but I believe it's better to leave fresh castings a while before machining so the aluminium can age.

I was running it way too hot, I've reduced the pressure by over half (3.0 down to 1.2) and still can melt a full A10 crucible of material, I think it holds it around the 800-900c range

The big boys use titanium boron aluminium to refine their grain, I've got some boron nitride to try adding to see if it makes a difference.