OllyO

Alcosa forge dimensions

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I've just inherited the remains of an Alcosa forge. It is in two pieces at the moment and a lot of the metal will need replacing. I was hoping that someone on here might have a similar foge and could give me an idea of the original height from bottom of the rear legs to the top of the hood.

It has a 30 1/2 x 24 1/2 inch bed. I have the original blower but not tue iron. The slack tub looks as though it was mounted to the bed at the left hand side if you were looking at it face on.

Alcosa Pattern no. MF 34 F

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I'm altering this question slightly now. Could people give me the measurements between the top of their hearth and the bottom of their hood on their forges please? The top of my hearth is 30 1/2" so if I have a rough recommended measurement between that and the hood the rest shall fall into place.

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Hello again all,

Well I've finally got some time to start work on the forge but there is one thing that I am unsure about. I want to copy the design of the original Alcosa product as closely as possible so that I know it is an efficient forge and not a non functioning half breed born of my whim. I've measure the hearth depth of the original as 6" but I easily have room to make that 7 3/4". I'm making the hearth from 3mm hot rolled steel and intend to line the bottom with fire cement to help insulate the steel. This would likely bring the internal dimensions back to approx the original 6" depth. Can anyone see a problem with this before I proceed?

I collected the steel I needed to make the Tuyere this afternoon as well so all I now need is some heavy gauge steel for the back plate (correct term?)

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After I cut down the tree that had grown through it and dragged it out of the hedge;

P1090623.jpg

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What do people reckon to the angle of the tue iron in relation to the hearth? The pipe I have is already cut at an angle that ould have it at 53 degree to the water bosch. The photo below shows this. Does it want to be closer to be just off parrallel at around 47-50 degree or is this suitable?

P1090905.jpg

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Just finsihing my forge but not totally sure how far the tuyere needs to protrude into the hearth. The hearth is 30" long.

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This is a bit of a rough one but about a third of the way in, maybe a little less even but is defo say no more. I'm no master forge builder but from all the forges I've worked on they've been at a third or less.
Out of interest is this your first time using a side blast? Let alone building one :P
Hope it goes well you should get some pics up soon!

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How about setting up the forge so you can change the depth of the tuyere. It may be helpful to run the forge for a day at one length then try a different measure the next. After a few weeks if you decide where is best for your forge then you could bolt it on more permanently.

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Not a bad idea that, but with the tyuere being a long cone shape it may not be the easiest thing to do, be interesting to see it done though :)

Edit: because I can't spell

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Not sure where to post this reply really as my other thread is a bit dead so apologies for splitting up my progress. (we put it back together so people can follow the thread rather than search all over for both parts). I have made the tuyere out of a 4" OD steel waterpipe with a smaller 7/8" ID steel pipe welded inside. My neighbour (an engineer) had a buscuit of off cut 20mm thick plate that I had him bore a hole in and welded this to the end forming the tuyere. Becasue it is not tapered as per the cast items I can adjust it. Below is a picture of the forge so far. The tuyere/ water bosch unit is bolted to the back of the forge at the moment but I'll make up some sets of spacers in due course to experiment with how far I want it to protrude into the hearth.

Justj2; Yes, it'll be my first go with a forge of any kind and it is also my first attempt at making one albeit a pattern of an old Alcosa I found in a hedge. I have the original blower but haven't checked to see if it works yet. From memory it has F20 cast on the casing.

I was lucky in that a friend donated the steel tube and the blower came for the free. The angle was found in a hedge as well. This means the total cost so far comes to around £50. Not bad going I reckon.

After I make the hinges and flaps for the side of the hearth it'll be all but complete! Time to start looking for coke. I'm thinking of using 'Breeze', what's the word on this stuff?

P1090911.jpg

P1090912.jpg

P1090913.jpg

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Old threads never die, they just sleep and wait for the next post to return to life.

Once you get a fire going, if you have smoke issues add sheet metal to close down the sides and front, maybe as much as 1/3 ot 1/2 of the distance from the hood to the forge. Be sure to leave a door or window open to resupply the room with the air you send up the chimney.

As to the distance of the twyere into the forge, keep in mind that the end of the air supply will be the edge of the fire.

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Hi olly,
Suggest mounting your tank independantly on an angle iron shelf at the rear, this will allow you to slide the tue to adjust the depth of penetration into the hearth. It will also allow an air gap between rear wall of forge and bosh which is advisable,

Your cut outs seem overly large and should be in front of or level with the front of the tue, (this is where the adjustment will help) They are also possibly a little too low as they will allow coke to spill out when you try to bank up the fire with the flaps down, the fuel should not be allowed to fall below the top of your tue when forging, and the material when being passed through the fire should not be next to or below the tue's opening.

As you are using a plain tube for the outer casing for the tue, use a couple of small wedges to tilt the tue down at the front slightly as this will eliminate any potential air locks in the system.

Otherwise looking good. Are you coming to Finch Foundry do on Saturday?

by Breeze, I assume you are talking Monkton Singles, that should work well in there.

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Yeah I thought that John as soon as I had cut them out but what's done is done I guess. I was thinking of welding a bit of plate to the back of the cut outs (inside the hearth) to increase its depth. The other idea would be to make a grate that would hold the coal/ coke in when the cut outs are in use.

How big should the cut outs have been? Only an inch or two?

Although only by a few degress the tue is pointing downslightly for exactly that reason but I have considered increasing the angle. A shelf seems like a good idead, I was concerned about the stress of the bolts and spacers with a bosch full of water.

I'm hoping to get down to Finch Foundry on Sat but not 100% sure yet. Im pretty flooded in at the moment. What time do things kick off?

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Hi Olly, about 9.30 at Finch

Cut out depends on position of tue and fire in hearth in relation to them, probably 6" to 8" wide by 4" deep, but having said that what you are going to be making will also have a bearing on wht size would be best for your situation.

With regards to the shelf, weld on the angle to the frame and weld some support struts to the hearth legs, or bolts M8+ size will also be more than adequate should you wish to use them rather than welding the frame together.

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Besides what John and Glenn said, of which I agree: I would suggest no more than 4 to 6 inches of tuyere , unless you plan to build really huge fires. What I don't see is the size flue you plan to use. Big fire needs bigger flue....

When I was burning coal, I had switched to a side blast system. I used much smaller pipe. As long as you keep water in it, (had to use antifreeze when I was not full time, and lived in Western New York,) it can be much smaller. I ran 1 1/2" over 1 1/4" pipe, and welded a 1/4" rod as filler. I also used a side draft chimney with it as I really hate hoods.

Now for the hearth area, I simply laid in loose brick to form something of a fire pot area. I let it fill with gaps with ash and had the option of changing the size of the fire. I could expand or constrict at my pleasure, or even put another layer in to make it deeper. I preferred this method oppose to simply relying on the coal and as to form a bed type pot/fire area. Once I settled into my preferred size (about 2 bricks worth of area) I rarely changed it.

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a web site we can not mention shows a schematic of a side-BLAST with the pipe pointed down, so I'm guessing it's common even though all the ones I've seen were perpendicular to the water tank even if they outer pipe was tapered. I don't see any reason that your pre-cut pipe wouldn't work as long as there is enough room between the pipe and the floor of the forge for you to form a good ash bed and coal.

You show solid craftsmanship in your pics, so I don't have any worry that you'll do less than smashingly!


error corrected, a side draft is an exhaust style, side-blast is a tuyre variation. Also links and referances removed, because Jock does not allow link to his web site.

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Thanks for all the replies/ info, much appreciated.

With regard to the flue I have not made the hole/ collar yet. What would people recommend? I thinnk the original forge from which I took the patterns had a 8" pipe. Lengths of this diameter would be easy enough to find but I've seen some forges with massive diameter flues.

The Tuyere, from the bosch is 12" at present. I thought it'd be better to make it too long than too short. So 6" protrusion would be best? I'll be mainly working smaller stock to begin with. I guess the usual starter projects of companion sets, curtain rails and the like.

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The tuyere sticking deep into the box means that you'll be moving the actual fire over to the side of the box where you don't have any cut outs for access. The fire starts where the pipe stops and you will be working about 4" from the end of the pipe, in the neutral zone of the fire. And if these forge works anything like a bottom-blast, you'll want another few inches of burning coal on the far side, making for about 8" diameter of fire with your work piece smack in the middle.

As for the chimney, I've really been impressed with the performance I've seen in 10" and 12" pipes. Even without a hood, those suckers draw the smoke away like nothing I've ever seen. Of course, a lot depends on the finished height from the roof peak, too.

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With regards to the flue, this forge will be installed outside in an open sided shed. Where the flue goes up there are a few trees, I can cut the branches back if people reckon this will interfere with draw. 10" or 12"?

Forge nearly finished now. Made up some hinges and flaps for the cut outs. I will also make some slides to go in board of the hearth to reduce the size of the cut outs. I started grinding back some welds and got a coat of paint on some of it last night.

What do people reckon to the finish of the inside of the bosch. I've spent too long under cars swearing and getting peppered in weld splatter for me to rest easy pouring water into a bare steal bosch! I guess it'd need to be a heat proof paint but I can't imagine that stuff is very corrosion resistant?

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Ya know, I've always wondered about lining the inside of the water tank to prevent rust-out, but getting the innards coated completely seemed something of a chore. Thought to use hot roofing tar that I could kind of roll around to get all the nooks and crannies. Car under-body spray might work, too.

I wouldn't think the heat would be an issue. With the water tank full, you'll have a lot of mass to absorb any heat transfered up the metal and I just don't see it getting up in temperature any time soon.

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I really like to fit a tuyere plate at the back of my hearth purely for aestheic reasons.  I know  I can insulate this area in manyt different ways not needing a plate but I'd prefer the look of a plate.  Daft I know.  I was thinking of cutting the desired shape of the plae out of 3mm and then adding a 20mm trim of the sides at 90 degrees to the plate.  I would then put this face down (trim facing up) and cast some 1200 degree fire cement in it.  This could be slid of the tuyere and would fit against the back of the hearth insulating the area with a 20mm thick fire brick and 3mm steel plate.  Would this be sufficent or would the steel warp?  Opinions?

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