Charcoal Foundry - Few questions before I start

[guerd87]

Hi everyone,

Only new around here but Im going to be starting to build my simple Foundry soon to cast a few alloy parts for my CNC build. I am building a JGRO and want to cast the Leadscrew Bearing Mounts and Adjustment blocks out of alloy. (Ive wanted to learn to cast for a while but this is a good excuse to tell the better half)

Ive seen a few designs around which are cheap and some a bit more time is required. Some I have seen have used Clay pots set inside a drum with Refractory concrete. Is the clay pot needed? Wouldnt the heat cause the clay to crack?

Im just thinking of using a 60L drum, lining the floor, walls and lid with Refractory and using this as the charcoal 'burning' chamber. Does this sound right?

One more quick question. How much air is required for a charcoal foundry to melt alloy fairly quickly? I have an old Blower Fan from a car that I could use. Maybe just try it and see how it goes I have sourced the refractory locally and will buy it this week.

Anyway, hopefully getting the thing started on my next weekend off and will get some pics up of it.

Cheers
John

[Artie]

Hi John, you wont regret getting into the casting game... The pics below are of my beast which is over 20 year s old now. and probably due for renewal.... but it still works... and well....

Its a 60 litre drum as you mention but the only difference is I used and insulating wool between the refractory and the steel drum... its cool enough to touch while maintaining well over 900 deg C inside.

Mate I wouldnt use charcoal, up until late last year mine was charcoal but I converted it to gas using a burner design by a guy called Reil (google reil burner for plans). As to the air required I used an old Sadie shop canister vacuum cleaner using the blow hole rather than the suck hole... It worked really well.
 What you need is large volume not pressure.

But, gas is better... cleaner, quiter, more efficient and cheaper than charcoal, and quicker.....

Where in Aus are you? If you are nearby you are welcome to drop in and do a casting session so you can get a feel for the thing.








Here it is on chacoal showing the vac air supply.



Rob

[Rob.Wilson]

Hi John 

Good to here your going to get into casting    ,,,,,,,,,,,,, I would follow Rob T's advice ,,,gas is better 


Regards Rob W

[guerd87]

I was thinking about gas but wasnt quite sure on the right burner to chose from. I will have to try and find the 'Reil" plans and have a look at them. I know there are lots of little differences, but on average how many melts would you get out of a 9kg gas bottle with your burner? How much pressure do you run it at aswell? I dont want to chew through it thats all.

I live in Pakenham, VIC. Around 1 hour East of Melbourne, you?

Looks like you use your foundry in the shed with just the doors open, is it that clean you can do that?

I have an old shopvac here I could use aswell, Will look over it later on.

John

[Artie]

Hi John, the bottle will do 6 or 7 melts in aluminium (4 or 5 for brass) which equates to about 4 or 5 bucks per melt, much cheaper than charcoal (at least from my suppliers up here).

You will need a hi pressure regulator which can be had on fleabay (http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=400075441708&ssPageName=STRK:MEWAX:IT). I had no luck trying to source one from the normal stores.

The actual pressure you run depends upon what you are doing and how fast you want to do it, anywhere from 10 to 20 psi depending upon how well designed/made the burner is, which ultimately controls gas consumption, but as its pretty low in any case I wouldnt be too concerned.

Im in Griffith NSW 4.5 hours north of Melb and the offer is there but bear in mind that I work in Batemans Bay for 1.5 to 2 weeks of every month so Im not always available.

Ron Reils burner can be found here http://metalcast.boorman.us/reil_1.html

And as to why you should use gas..... Ron Reils own words " I have to include one reason to use gas that is probably the most compelling one, your health. One day after a full weekend of smithing work, using one of my open pan forges, I awoke with a very violent shaking of my muscles in my arms and throughout my body. I went to the doctor of course, and after a lot of testing and discussion they determined I was suffering from nerve poisoning due to breathing too much coal smoke. There are some bad things in coal smoke, especially various sulfur compounds, that can attack your central nervous system, as it had done to mine."

Uhm.. thats good enough for me......

CHeers mate and good luck... lots more info on supplies in your area if you need them... CHeers

Rob T

[Artie]

Looks like you use your foundry in the shed with just the doors open, is it that clean you can do that?

Laughing as I type this..... NOT ON CHARCOAL ITS NOT! But yes on gas, as long as you have a decent ventilation you can do it indoors, its very clean.  

[guerd87]

My arm is hurting..you've twisted it pretty hard ^_^

I guess gas will be the way then, I didnt think it would last anywhere near that long. Not much benefit over charcoal, same here with local prices.

About suppliers, Do you know anywhere I could get the correct sand? Seems to be the hardest thing to find.

I visit Shepparton fairly often and wouldnt mind making a day trip out to Griffith, I think im going to be heading up there in around a month. I could contact you before hand to see if your going to be doing a session in that time frame. Even if I have mine setup by then Id still like to meet someone in the game and learn some things from them. So yes, would appreciate it alot and thank you for the offer.

Do you have a picture of your whole setup including the gas tank? Would give me a good idea of the complete size.

Thanks for all your help, looking forward to it even more now

Cheers
John

[Artie]

Sand.... wow.... you could debate that one all day.

I have a mate in Bathurst (Hi Tel) who uses coarse brickies sand which is available everywhere and he gets very good results from it. I use very fine screened river sand from my local gardening soil man and that works well also. Fresh supplies pic here, last for ages... cost about 6 or 7 bucks.


Purists will tell you you 'need' silica sand... well, Im no purist..... get what you can, in my opinion as fine as you can and as clean as you can.

The real problem you are going to have is finding Bentonite clay (assuming you arent going the Petro way).

I had heard in past that its used in stock feed, and I must say I dismissed that rumour...... and chased a supply for ages... Tel from Bathurst had found me a supplier and was waiting for a reason to travel to the town that sells the stuff, then he found it at his local CRT (Combined Rural Traders) as a stock feed suppliment.... guess I shouldnt have dismissed THAT particular rumour...

Try that avenue, cost about $50 bucks for a 20kg bag which will last me a lifetime. Prior to that I was grinding up kitty litter. By hand. Slowly. Painfully.

[guerd87]

I will need to do a bit more research on the subject of sand then. What percentage of Bentonite clay do you add to the sand?

I have seen a few methods just browsing around. One of them is to mull the sand with oil, the other is to just dampen it down with water until it holds it shape, which seems alot easier.

Clay similar to this? http://cgi.ebay.com.au/Bentonite-clay-superfine-imported-highest-quality-500g-/250650360110?cmd=ViewItem&pt=LH_DefaultDomain_15&hash=item3a5becf92e

Depends on how much you need for 20kg of sand, I will experiment with it when the time comes.

[Artie]

The ratio depends a bit on the sand... typically around 10 to 15% but experiment is the only way. I used to use the oil/sand but mulling by hand was a problem and it can be messy when working it.

Unless you are doing rudimentary shapes in an open mold, then just watered sand wont work. On youtube there heaps of vids about using it. Have a look and you will see why.

Some guys swear by the green sand and others by the petro. Its up to the individual. Ive used both and prefer the green sand (with the clay).

If you need about 10kg of sand to do a pour, a clay mix of 15% means 1.5kg of clay, thats $60 of that stuff (x 3 plus freight), the 20kg for $50 sounds a better bet. Thats why I chased this stuff up so hard.

Im off work today...woke up with  back in spasm... thats why I can deal with this now.... in case you were wondering why I wasnt out earning.... 

[guerd87]

Today was my first working day of the week, But ive been pretty sick over the weekend and not feeling quite right either. Been checking back here after falling asleep in front of Austar all morning on and off :\

yea...buying in small packets is not wise.

We have a local monthly farmers market that sells alot of feed and supplies that I could check out, Do you have the Product name by any chance?

[Artie]

You're gonna love this....... just took a couple pics of the bag for ya... the stuff is almost next door to you! Even got you a phone number.... man this sites great!




For the refractory  and the insulwool I use these guys...

Darley Refractories
144 Keys Rd, Moorabbin 03 9553 5800 www.darleyrefractories.com.au

[guerd87]

 

I love this site

Thanks for that, Im heading over to Geelong next week to get some PC parts, Ill stop off and get a bag on my way.

Darley Refractories is who I was going to use for my refractory supplier, I found their website the other week.

http://www.darleyfirebrick.com.au/castables.html

Which set did you use? Litecrete around the outer of the drum for insulation and then some Densecrete for main refractory?

[Artie]

They have a product called Ceramic Fibre (wool sheet) to insulate and Denscrete 145. The new one will have Denscrete 150 or 155. That will give me an increased margin should I ever decide to do cast iron.... (unlikely though).

[guerd87]

Awsome, thanks for all your help.  Now I have more knowledge I can start building this thing!

Ive got some prices from Darley and going that I just want to do Alloy they recommended these items

Ceramic Fibre rated to 1200c - $132 per roll (they dont sell small rolls, only a large roll 7m long) How thick of a lining did you put in your foundry? Did you use much of a roll? Its alot of money to spend out first off thats all :\
Denscrete 145 castable - $49.50 for a 25kg bag

I just contacted Volcla about the clay. They dont have resellers anywhere, they are the only distributors. They can either ship it out to me for around $40 or I can pick it up directly. $1 per kg with no minimum order.

[Artie]

Lining was 1 layer.. dont forget this was over 20 years ago.... you could buy small lots then...will they cut you 2 metres?

[guerd87]

I asked about that, they'll sell me small sizes...But I still have to pay for the whole roll

He basically said that because they dont make it and have to buy it in large rolls they cant split it up. Apparently there is not much use for small pieces around the place, with most people needing more then 1 roll at a time.

Im not really willing to spend that much on a roll, I will talk to them about using some of their litecrete insulating castable instead. If all else fails, Ill just stick with straight densecrete, been done many times before.