Wednesday, 27 June 2012

Clay base is almost cured

It looks like the clay that I have lined the forge with is almost cured. Still a couple of days to go until the weekend, but if all goes well, I will give the forge a test firing on the weekend with some hay and softwood. Definitely don’t want t he fire to get too hot, just enough to help the last of the moisture to be driven from the clay.

I still have to make the cone at the top of the forge, attach the flue, out a hole in the roof of my lean-to and then put the chimney up.

Probably the hardest part of this operation is going to be making the cone for the top of the forge. At the moment I have a cut a chord cut from a circle in 18 gauge steel. I have to bend the chord evenly to make a cone. I reckon that a simple bending tool should do the job.

Basically, the design for the bending tool is a three long steel pipes with a threaded rod through one end. The middle pipe will be used as a lever to bend the sheet. I’ll put a hole in the end of my chord and bolt the pointy end to the underside of the middle pipe so that the sheet rotates relative to the anchor point. That should mean that I end up with an evenly bent bit of steel sheet when I’m done. As the pipes are quite long (two of them are 8m long and one is 5m) I should get quite good leverage to apply to the bend.

Anyway, that’s the plan and I’m not sure that it will work yet. I’ll post pictures of the bending tool on the blog when I’ve made it and of the results of my conjecture.

When the hood is made, I’ll be bolting the hood onto the forge body and riveting the flue onto the top of the hood, that bit should be straight forward.

Sunday, 10 June 2012

Sunday work on the Forge

I checked out the welds on the tuyere today in the daylight and I realised that the joint was not closing properly AND that the weld wasn’t good enough. So I cut the hinge off the pipe, moved some bits around and redid the weld.
The hinge is much more satisfactory now and the closure is much better. I’ve also reversed the hinge so that the flap opens to the opposite side to the air intake pipe.
I could still cut away some of the hinge piece so that it is prettier, but it isn’t interfering with the closure so it isn’t critical.
IMG078Closed … and
Next I needed to weld the tuyere on to the base of the forge. Actually, this was a bit of a pain. I had to weld some reinforcing steel onto the tuyere so that I had a better welding joint onto the thin steel of the barrel.
Then weld the tuyere inside the forge for added strength.
I’ve used some offcuts from the pipe to make a cupping joint inside the forge body. The top of the tuyere comes up about 2” into the base of the forge. This will be the depth of the clay lining of the base.
The clay is pounded into the base and then smoothed over. There is an overall depression in the centre of the forge so that the fire is in a bowl like structure.
I’ve added the lining to the forge in place so that I don’t have to fart around with moving the forge around afterwards. That’s 30kg of clay plus the weight of the tuyere (about 1.5kg) and the barrel. Easier to move it in bits first.
Now I just have to wait for the clay to cure and then I can fire the forge up to cook the clay.

Saturday, 9 June 2012

Work on the Tuyere

Well, today I made some more progress on the tuyere. I’ve made the hinged, counterweighted waste trap for the bottom and fitted it to the bottom of the tuyere.


I did this in pretty low light as I didn’t get around to do anything until late in the afternoon. I’ll have to have a look at the welds again tomorrow to make sure that they are OK and maybe redo some of the welding. It looked OK, hopefully I won’t have to do any rewelding.


To make the hinge, I took a piece of steel pipe, cut it lengthwise and then spread the pipe out and hammered it flat. Then I cut the flattened steel and drilled a hole in it for the pivot. I’ll be cutting the hinge piece to shape so that it doesn’t interfere with the opening of the waste door.

You can see from the picture above that the weld isn’t the neatest … I can clean this up with the angle grinder, but then again, it isn’t supposed to be a thing of beauty.

The waste door was cut from a piece of 18mm steel plate. Again, it isn’t perfect or pretty, but it does the job.


Above is a view of the hinge showing the pivot and the waste door. When I was drilling the hole, I managed to break a 13mm drill bit … damn rubbish  drill bits.

Tomorrow I will be welding the tuyere into the base of the forge, cutting the forge opening, rolling the forge opening and then lining the base of the forge with the clay/fire clay mix. When that’s done, I need to leave the clay to cure for a week and then I can fire the forge up … woohoo … it’s getting closer.

Wednesday, 6 June 2012

Plan for this weekend … work on the Forge

After last weekends abysmal effort, I’m scaling back my plans for what I intend to do with the forge on the weekend.

My overall plans have not changed, just the speed that I expect that I’ll be able to do it.

I’m getting another 3 bags of cheap clay this week, along with another 25kg bag of fire-clay. So my main goals for this weekend are to cut a hole in the front of the body of the forge and roll the edge. This will be the front access to the forge where I will be working, so the hole needs to be at least big enough for me to feed the fuel and work pieces into the forge. Next, I will be trying to finish the tuyere and weld it to the base of the forge body.


I need to weld the hinge on to the bottom of the tuyere and make the counter-weighted flap. The flap and hinge will be made from a flattened out piece of tube steel while the counter weighting lever and pivot will be made from some old reinforcing steel rod that I got from the tip-shop last weekend.

When the lever is raised, the flap opens and the spent fuel waste is dropped out onto the concrete floor ready to be swept up.

When these two jobs are done, I will be lining the base of the forge body with the clay to make a thermally protective bowl in the bottom of the forge.

The bowl shape in the base will direct the fuel down toward the tuyere and provide a point where the forge will be the hottest.


As the fuel burns, the idea is that the ash will fall down the tuyere and be let out using the counter-weighted flap on the bottom of the tuyere. This is going to be interesting because the ash will also be being blown by the air pump blowing up into the forge, so I am guessing that it will only be the heavier bits of waste that go down the throat of the tuyere rather than the fine ash. The fine ash should be blown out of the forge through the flue.

Anyway, that’s still plenty to do.

Saturday, 2 June 2012

Todays work on the Forge

Well … I didn’t get as much done on the forge as I wanted, but I got some done!

Instead of setting the tuyere into the side of the forge as I had planned, I did a bit more research and realised that this would have been a mistake. Instead, I have made a tuyere that enters the forge body from underneath. This means that I can get the air directly under the fuel and it also means that I can put down a bed of refractory on the base of the forge to protect the thin metal and keep the heat in the forge where it belongs.

The design of the tuyere is basically a three way pipe.


The ash end is shut by way of a counter weighted hatch. When the ash hatch is closed, the air is pushed up into the forge.

I’ve welded the pipes together and this is looking good so far.




I’ve also made a frame for the forge body to sit in while it sits on a stack of cement blocks keeping the forge body up at about 60cm off the ground.


Here is the Forge body sitting comfortably in the stand.


Next I’ll finish the tuyere and fit it into the body of the forge and then it will be time to lag the base of the forge with my clay/sand/fireclay mix. Next weekend … it’s off to collect firewood today, Tasmanian winter is here.

Friday, 1 June 2012

Working on the Forge this weekend

Well, the plan for this weekend is to complete the shell for the forge. I’ve made the body of the forge (mostly) and I’ve cut the steel for the cowl. So now I need to bend the cowl into a cone and fit it to the body of the forge.

On top of the cowling, I need to connect a flue to take the exhaust smoke, etc. out of the lean-to where the forge will be.

The next trick will be to fit the tuyere to the side of the body. This will be a fairly simple affair. Make a 45o angle housing with a curved face to weld onto the side of the forge body and with a hole cut into to oblique face.  Cut a steel tube with one end at a curve that is the same as the curve of the barrel. Weld a steel tube into the housing, welding the tube at the circular hole in the oblique face and also to the inside of the forge body. This is so that air that is blown into the forge blows around the body rather than straight into the centre of the fuel. I’m, more or less, mirroring how the air moves in my smelting furnace. I may need to change this, but that’s the plan for now.

I also need to weld up a stand for the forge so that I can have the forge body at the right height for me.

I have pretty much all of the materials that I need to weld the forge to completion and I reckon that this will take about a days effort over the course of the weekend (depending on who has other jobs for me).

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