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Thread: Charcoal Forge
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22nd June 2009, 12:53 AM #1
Charcoal Forge
I started this over in the hand tool section, and moved over here to metal working since this is probably a better place for this topic.
Last week, I was wandering around the local scrap metal dealers yard and spotted an old davy water pressure tank, that looked ideal to make that forge I have been planning for as long as I can remember..
You can make a forge from just a hole in the ground and an air blower, but I wanted a forge for making woodworking tools and heat treating hc steels. So I don't need anything too big and cumbersome... After trawling internet web sites looking for forge designs, I finally decided on a pretty traditional straight forward design with up-draft blower and refractory lining ( I can appreciate the simplicity of some of the side draft designs).. but with the bits and pieces I had this was easier...
Construction is pretty straight forward, you want a reasonable depth in the firebox so that the charcoal above the work zone acts as an insulator of sorts, and the bottom of the firebox can easily get hot enough to burn out steel, so I lined it with refractory stuff, (details further down). The basic shape of the pan comes from the cut-off top of the water tank and a bit of scrap 6" heavy wall steel pipe that forms the walls of the firebox, I only had 1/8 sheet to make the bottom of the firebox, but I figure since I am lining it it with refractory it should be ok.
After a few days cutting and welding, I have something that looks like I think I want it to look.
This is before the refractory lining.. I hope it shows the general layout.
There is an adjustable work stand on one side, and the air inlet on the other side
The blower is a $99 Aldi special, and air flow is adjusted with a gate valve, I melted some plumbing fittings test firing with this air setup, so I am pretty confident that I'll get the volume I need, even though the pipe diameters are a bit on the small side.
You can see the refractory in this picture, I used Pyrocrete 165 AR AFT, which is supposed to be good for 1650C It should provide insulation as well, so might burn less fuel and allow higher maximum temperatures.
Well that's it, hope it helps someone else...
I should add a disclaimer here, this is my first forge and I don't pretend to know anything about blacksmithing, this is the start of a learning experience. If anyone spots some silly mistake that I've made, don't hold back let me know!
Regards
Ray
The next project is a foundry for brass/bronze casting...
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22nd June 2009 12:53 AM # ADSGoogle Adsense Advertisement
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22nd June 2009, 07:54 AM #2
Looks fantastic Ray.
Some photos of the forge in operation please.
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22nd June 2009, 10:55 AM #3SENIOR MEMBER
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Gday Ray,
I have made a foundry out of an old hot water heater. It works great. I couldnt find any refractory cement to use as the liner in mine so I used an old stainless steel bin and portland cement. I have done 10 melts and its still going strong.
So far I have only tried aluminum in it, and I usually burn plain old hardwood. My crucible is an old fire extinguisher cut in half, however these are too thin to be called ideal but it has been used for all 10 melts I have done to date. Aluminum melts in 5 to 7 minutes with this arrangement.
I love old heaters. You can pick them up for free almost anywhere and there is a lot of good steel in them.
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22nd June 2009, 01:56 PM #4Senior Member
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You're in trouble now. Once you start hitting hot metal you won't want to stop. That is the same reason I started hitting hot metal. I've not had the time to forge that I'd like, but I find that for heat treating small tools (less than 6 inches) you need the hot center to be at least a 4 inch ball.
Anyway, if you haven't found it yet, here is an excellent on-line resource.
http://www.iforgeiron.com/
ron
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22nd June 2009, 07:23 PM #5Pink 10EE owner
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I bought two bags of refractory cement from this business over the phone... http://www.totalrefractorymanagement.com/
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22nd June 2009, 08:01 PM #6
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22nd June 2009, 08:42 PM #7
I had it fired up last week, before it was really finished, but now I am waiting for a bit to let the refractory cure. I will post some pictures in a few days.
The refractory I used is from these guys http://www.foseco.com.au/ I went down to Melbourne and picked up the refractory and some silicon carbide crucibles for the foundry which is a joint project between my son and myself.
Changing the topic to the Foundry/Furnace...
Still working on the design, but felt that burner design might be a good place to start...
We built a propane burner based on the reil design http://ronreil.abana.org/design1.shtml and was pretty impressed by it. This picture is without the flare on the end, without which the flame just blows itself out, but with the flare it burns nicely, the choke was a bit of rolled up cardboard.
Then we discovered the t-rex style burners, so we built a second based on the t-rex design a bit like this one http://www.hybridburners.com/
The main thing we were looking for was a longer tube, to suit the furnace size, the rolled flare will be replaced by a cast refractory flare in the final version.
The mixture adjustment is a bit too fiddly and the position of the gas jet tip is finicky, so I am starting to think that the expansion chamber in the t-rex design is essential to create the right venturi effect and get good mixing. So... version 3 coming up..
But I have to say, it's fun to vaporize coke cans with!
Regards
Ray
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22nd June 2009, 09:59 PM #8
Thanks for that ron, I hadn't seen that site before, that's a great resource. I can see how this could become addictive...
I won't know what size hot center I'll end up with until I fire it up with the new firebox, I guess I could always increase the area that air is applied to, and if needed increase the airflow if it ends up too small..
Regards
Ray
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23rd June 2009, 10:52 AM #9SENIOR MEMBER
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Thanks for the link RC. For a different project I finally got onto some refractory cement, it came from foseco in Fyshwick. If I ever make a version 2 Ill spend the extra fifty bucks and use refractory, but for now the portland works just fine.
The hardest part I have found is making proper green sand or buying petrobond. We have not been able to fine bentonite clay anywhere (for green sand). I found a bloke in melbourne who can sell petrobond, but its $25 a kilo or something. From what I have seen though, the results are worth the money. As petrobond doesnt contain any water (unlike green sand), the results are much much better as you dont get gas bubbles and dimples on the surface of your casting.
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23rd June 2009, 12:01 PM #10Pink 10EE owner
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23rd June 2009, 12:16 PM #11SENIOR MEMBER
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I have heard that its used in kitty litter, but you cant use that as a) its not pure and b) its granulated and would need to be pulverised first. All the "recipes" you find are american, and the stuff they allude to is a pure, fine powder. This is what you need to get quality results with green sand. Is this something that is used a lot in rural areas? Why would a livestock place stock it? Thanks for the tip though, ill give my local bloke at CRT a call.
Its the same with Petrobond. I found a recipe to make your own petrobond, but again there is a key ingredient called 'bentone' that is freely available in the states, and to date i havent been able to find it here.
Its very frustrating...it seems in the states you can walk down to any corner store and get all manner of useful things cheaply and easily....whereas here its very hard to get many things needed to do a lot of DIY casting/anodising/plating work.
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23rd June 2009, 12:17 PM #12SENIOR MEMBER
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P.S you can buy pure bentonite from health food places but its prohibitively expensive given the quantities you need to make green sand.
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23rd June 2009, 12:35 PM #13
You might try the suppliers mentioned in this thread
Cheers
Jeremy
If it were done when 'tis done, then 'twere well it were done quickly
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23rd June 2009, 12:58 PM #14SENIOR MEMBER
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Thanks for that link mate, very helpful....i'm back on the hunt!!!!
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23rd June 2009, 01:30 PM #15Senior Member
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I bought my bentonite clay from The Clay Shed. they also have fine washed silica sand. You may be able to find a pottery supplier close to you, otherwise I believe these guys ship. Unfortunately their website wasn't working when I just checked.
The Clay Shed
U 2 24 Hi Tech Dr, Kunda Park, QLD 4556
p: 07 54765977
BTW- if you are looking at casting, this site is worth a look
http://backyardmetalcasting.com/forums/
Regards,
James
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