Another play with the forge

After playing with the cart wheels, I had to wait for ages for the glue to cure, so I thought that I’d have a play with the forge.

I didn’t want to do anything dramatic, just get the forge up to a good heat and straighten some bent steel reinforcing rods that I have. The longer plan with the rods is to make them into forge tongs. To do that, they have to start out as straight stock.

I had loads of sawdust at hand, so I thought that I would also try out starting the forge using sawdust to see how that works. Apparently, this is a good way to start a forge fire. The particles of fuel simply disappear up the flu when they are ash and they take almost nothing to start.

Well, that’s partially true. When the sawdust burns, the charcoal particles form a crust over the fresh sawdust underneath and so only the top layer burns properly. When I turned the vacuum on to give it some air, that changed everything. The fire got started very well and was soon quite hot.

I put the reo into the fire and started heating it. After about 15 minutes the fire was hot enough and I got to about 650 degrees centigrade for a 5 minute bake. As I was only bringing the fire up to bend the steel, this was hot enough for me. Also I didn’t want to use up too much fuel.

I still have loads of reo left to straighten, so I’ll be doing some more of that.

More work on the Forge

So the plan for today was to fix the gap in the hood and to put the flue on the forge.

I started to cut a hole in the roof of the lean-to for the flue to go through, but all of the water on the roof from the dew came sluicing down on me … so I’ll leave that for later on (when the dew has finally evaporated off).

I cut the steel from the piece I cut out of the body to make some patches for the hood and fixed it on. It’s none too pretty … but then I don’t suppose that a forge is intended to be aesthetically pleasing … is it?

The hood will now direct smoke and ash upwards without getting in my face. Yay!

Like I said … it’s none too pretty. But I can always “hide” some of this mess with some pot-black, it will be less obvious if it is of a uniform colour. Also, the pot-black will help to reduce the amount of rusting that will affect the hood. Heat will make the rust flake off, but it’s better to have no rust in the first place.

You can see where the hole is going in the roof for the flue to go through.

Fitting the flue will be an exercise in expanding the bottom of the flue to go over the top of the hood, and then screwing it in place.

I got up on the roof of the lean-to and cut the hole through for the flue, then dropped the flue down and over the opening at the top of the hood. Fired it up and voila … chimney.

Still a lot of smoke coming out of the forge, but then I was burning straw. I need to cut the bottom of the flue into tabs, spread the tabs and screw them on to the top of the hood to make it nice and secure. That should also help with the smoke … a little bit. A good fire, when it is burning a better fuel will not smoke as much as this, so I am pretty happy with the outcome.

Now the flue has been attached to the hood and I’ve fired it up.

I’m burning a bit of straw and some old fruitwood cuttings. When the straw burned off and the wood was burning well, the flue drew most of the smoke as planned, so it was working.

With the air pumping into the forge from the old vacuum cleaner through the tuyere, I was getting a reasonably fierce burn in the middle of the forge. Of course, the fuel was used up pretty quickly as there wasn’t much of it, so it only burned for about 10 minutes. With some decent fuel in the forge, it should get quite a good heat going. I may need to put a grate over the top of the tuyere so that the burning coals don’t just drop through to the floor. I need to keep some coals banked to keep the heat going and so that I can get a good burn happening.

Anyway, that’s pretty much it. There may be some tinkering required as I increase the heat, but the forge is now ready to go into service.

Hood goes on

Today, I fitted the hood onto the top of the forge. Well, almost.

It would seem that I am at two with measurement. I didn’t take the overlap into account, so the hood has a gap of about 10 centimetres. Looks like I have some patchwork to do.

Fixing the hood on to the top of the forge body, I went around the hood with drill and screws: drill a hole, screw the hood; drill a hole, screw the hood. Slowly pulling the hood into shape around the forge body.

The scale of the gap wasn’t clear until I was about 3/4 of the way around the hood. By then, I needed the able assistance of my lovely wife and daughter to push the hood down to the body while I drilled and screwed.

I’m going to use the panel that I cut out of the front of the body to patch the hood.

I couldn’t resist firing the forge up to test the tuyere. It worked brilliantly. With the vacuum on blow and the tuyere open, the forge fired up nicely … with the tuyere closed, the thing got hellishly fierce. The flames from the forge started licking the roof of my lean-to, so the flue is going to be critical if I want to keep a lean-to and not just work in a pile of ash.

I also did some clay patching around the base of the forge body. The clay that I laid in the base had shrunk by about 2cm, so I pushed more clay into the gaps and increased the angle of the incline of the internal dish shape. I also made a bit of a clay shelf at the front of the forge for more heat reflection and protection for me.

As the forge gets used, the heat rising from it will anneal the steel hood, so I am expecting this to pop and creak a bit while I use it for a while. When that has stopped, I will replace the screws that hold it onto the body, with bolts with spring washers.

I may need to cut another aperture into the other side of the forge so that I can put longer stock into the forge and heat it in the middle. Well, that can wait for now, it won’t stop me from using the forge, nor will it really limit what I want to do … for now.

Well … I’ll get onto patching the hood tomorrow. It shouldn’t take me very long. Then I need to put the flue on and through the lean-to roof.

Not much time …

I didn’t get as much spare time this weekend as I would have liked to. Still, I got some of the shaping done of the hood of the forge.

I started with a circle of steel and cut a chord out with the section length equal to the circumference of the forge body.

Next, I started shaping the cone from the chord. I was going to make a simple tool to bend the steel, but in the end, I didn’t have time to fart around with such a short lived tool. Instead, I used an old hardwood pallet and belted the steel along some radial lines that I marked on the steel.

This meant that I had a number of segments with sharpish lines.

Then I went around the partially bent piece and started rounding out the cone. There was a lot of stress in the steel at the point, so it took a lot of correcting the edge.

I drilled six holes in the steel (three holes per side) and used fencing wire to hold the edges together, twisting the wire to cinch the edges closer together.

The cone is still quite flat (more of an oval at the base rather than a circle), so I still need to bash it some more to get it even and … useful.

When I have the edges matching properly, I will weld the edges together.

To get the hood working properly as a cone, I will need to heat it and then do some more bashing. The heat will be used to relieve some of the pressure in the steel as it is only bent, rather than shaped with heat.

The point of the cone will be cut off and joined to the flue. The cone will also be used to make the cap for the flue.

When this is done, I will be drilling and bolting the hood onto the top of the forge body. The bent over top of the forge will be bent back to match the angle of the hood.

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 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.
Closed … and

Open!
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.

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.

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.

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.

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 45^o 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).

Progress on the Forge

Today I got out to the shed and made some progress on the forge. I had another 44 gallon steel barrel, so I cut the top of the barrel off (about 5” from the rim) and turned the lip over.

When I cut, I use a 1mm cut-off wheel on my angle grinder to make the cut and then I use a grinding wheel to remove burs and sharp bits. I like my fingers and I am fond of keeping my blood inside my body (mostly).

Rolling the edge is a really easy process. I just get a shifting spanner with a 1” deep mouth and lever the edge inwards. I then go over the bent edge with a dead-blow mallet to push the edge >90^o.

If I want to complete rolling the edge over (as I usually do). I put the barrel over on to its side on an old wooden pallet and flatten the rolled over steel with a heavy ball peen hammer, although it doesn’t need to be a very heavy hammer.

Okay, so next I needed to make a caul for the forge so that I can vent the smoke and exhaust from the forge out of the lean-to. I had an old sheet of 16 gage steel lying unused in my feed shed (from making armour bits and crossbow parts). This sheet was about 1220mm x 1300mm. I found the centre of two of the the factory edges and marked the centre of the sheet for 1220mm and drilled a hole in it. I set a nut and bolt into the hole and made a timber protractor from the bolt. Setting a scribing awl into the protractor, I scored a circle into the sheet.

Next I cut the circle out with my trusty jigsaw with a basic metal cutting blade. When I finished the cut, I then cleaned the edge up with the angle grinder (refer to be earlier comment about fingers and blood).

To make a cone, I needed to work out the arc of the circle that would be left. This was simply done by laying the steel circle down on the grass, marking the starting point, matching the joint on the barrel and then rolling the barrel around the edge of the circle until I got back to the joint. Mark it off. Mark a line from the start point to the centre of the circle and from the end point to the centre of the circle and back to the jigsaw. Clean the edge.

Well, that’s as far as I’ve made it today. I have to head off soon to play with goats and goat breeders.

Ciao

Forge

Some of the parts that I need to make the Mulling machine and the Furnace Mk II need to be forged, so I’m going to need to make myself a new forge. The old forge was just, frankly, rubbish. I used an old stainless steel sink and I drove the forge using the vacuum cleaner. Basically, I lost too much heat and the bed was too small.

Now I need to make something a little more appropriate and I have another 44 gallon drum sitting there doing nothing (but rusting) in my driveway.

The plan is to cut the top off the drum and make a hood and flue for the exhaust and drive the forge (initially) using the vacuum still. The vacuum works well enough for the furnace, so I think that it will work just fine for the forge.

The plan looks a little bit “Tin Man”, but the design is basic. I’ll cut a port in the front of the drum so that I can place the work-piece into the forge. The second “innovation” is that the forge will be placed in a lean-to attached to the side of my workshop. So I’ll be able to vent the exhaust out of the workshop entirely. I have a couple of pieces of steel that I’m using as anvils and I’ve got a mixture of flat and ball peen hammers that I can use for belting the metal. My first job will be to make some decent tongs. I have some but they are a little short (fireplace tongs). My work surface, apart from the anvils, is a 3’ x 1’ hardwood stump (eucalyptus spp.) that I’ve banded to control the splitting.

I am planning on making a volute fan for the forge that I will drive from the motor of an old bench grinder … but that is a job for later. I’ve drawn up the plans for the fan, I just need to get around to making it. I haven’t yet decided on weather or not to do this by forging, using sheet metal, or molding and casting the fan body … I will probably just take the easiest option and make it from sheet metal.

I think that, because of the priority of tasks, that I need to make the forge before I continue with the furnace or the mulling machine. Besides, my flowerpot furnace is still good for a couple of burns.

My lean-to is big enough for the forge, the furnace and the stump as well as giving me a surface for my molding flasks and tools. Although I think that, before too long, I may need to move into my other lean-to. Fortunately, I have options. I could also clean out the feed shed attached to the back of my workshop and do all of my forging and smelting in there with the added benefit of electricity!