Side blast forge - questions

[bogmonster]

I am making a simple bottom blast forge at the moment. Should get it done if I can find some time over the next couple of days. The firepot is a refactory lines bottom of a gas cylinder - wish I had simply fabricated one now but live and learn. Ideally though I wish I had just gone for a side blast forge so planning that now. I was thinking of using a stainless commercial kitchen table I have at hand as the frame and base. How will the stainless stand up? Maybe I will stand a sheet of mild steel plate on it as well or some fire bricks. For the tuyere I am planning some pipe with 3/4 inch internal, 1/2 inch plate washer and 3 inch external pipe (maybe a bit wide but I hava e some at hand). Does this sound about right? For the sides I will use whatever I can find but may need to bold some mild steel to the stainless table - only just started to weld and not sure mild steel to stainless steel welding is a good place to start.

 

For the water tank maybe a gas cylinder with the top chopped off? Yes, I know that can be dangerous and I need to be very careful....

 

For the tuyere height I am thinking about 5 inches to the centre, is that about right?

 

I will be using coke as fuel.

 

BW, Chris.

 

 

 

 

 

 

[Glenn]

You can turn the bottom blast into a side blast by putting a pipe horizontally into the forge.

Ash will cover the bottom opening, or throw a piece of metal over it.

[ThomasPowers]

Glen he's going the opposite way; as he'll be using coke I was going to let the UK crowd answer this one as I'm primarily a propane, coal and charcoal guy...

[rockstar.esq]

I have found sheet metal doesn't hold up under heat.  I tried using rebar as a support but the heat softens it over time.  What's worked amazingly well is thinwall conduit.  The hollow cross section holds its shape better under heat and it's much stronger than the rebar.  Be careful since it's galvanized inside and out.

[John B]

 I was thinking of using a stainless commercial kitchen table I have at hand as the frame and base. How will the stainless stand up? Maybe I will stand a sheet of mild steel plate on it as well or some fire bricks.

 

 

Stainless should be fine as the base for the forge,

 

 

 

 For the tuyere I am planning some pipe with 3/4 inch internal, 1/2 inch plate washer and 3 inch external pipe (maybe a bit wide but I hava e some at hand). Does this sound about right? For the sides I will use whatever I can find but may need to bold some mild steel to the stainless table - only just started to weld and not sure mild steel to stainless steel welding is a good place to start.

 

Weld some bolts to the sides of the mild steel sides, drill through the stainless as appropriate and bolt on the sides, leave cut out areas if you wish, although not always necessary.

 

 

For the water tank maybe a gas cylinder with the top chopped off? Yes, I know that can be dangerous and I need to be very careful....

 

So long as your welding is watertight and you take all necessary precautions that should work, the only doubt I have is the thickness of the material in the cylinder, they are really not that heavy a gauge steel

 

 

For the tuyere height I am thinking about 5 inches to the centre, is that about right?

 

4" to 5" should be fine

 

 

I will be using coke as fuel.

 

BW, Chris.

 

Have fun

[bogmonster]

Thanks for all the replies. I have finished off the simple bottom blast forge and that works surprisingly well. It is not very attractive and is a little fiddly due to its small dimensions but it certainly gets hot. I didn't let the refractory dry out properly as I was too impatient and had some more time off work and wanted to get going. Fortunately it didn't crack too badly and I should be able to patch it up. The whole contraption worked so well my neighbour is going to make another one on the same design next week. I will post some pictures of the ugly duckling when I get a chance. It was a good project to try and learn to weld on. I have already used it to make some fire tools and a Wellington boot stand made of 16mm round (very heavy wellies :)).

 

For the blower I used a 12v bilge fan. Neighbour had one unused from another project. The one I used was a SeaFlow 3 inch 130cfm blower and this was perfect for the small bottom blast forge. They are about 22 British pounds. I used it with a switch mode power supply from Maplin (from one of my previous projects). The power supply has variable voltage and in use running the fan on 9v worked well with the option to crank it up a bit more if needed. Not sure how well this fan would work on a side blast, maybe the small diameter tuyere would create too much back pressure?

 

Looking forward to building the side blast forge now but will play with my current toys for a bit longer. Need to get some basic skills under my belt......

 

A couple of other dumb questions. Dues the tue iron need to be tapered? I am guessing the reason is to ensure no trapped air but this sounds like a fair amount of hastle? Also. what height for the sides? I read somewhere they should be about 3 inches above the tuyere. I am thinking higher at the back.

 

Sorry for all the stupid questions. XXXXX  newbies....

 

Thanks, Chris.

[John B]

 

For the blower I used a 12v bilge fan. Neighbour had one unused from another project. The one I used was a SeaFlow 3 inch 130cfm blower and this was perfect for the small bottom blast forge. They are about 22 British pounds. I used it with a switch mode power supply from Maplin (from one of my previous projects). The power supply has variable voltage and in use running the fan on 9v worked well with the option to crank it up a bit more if needed. Not sure how well this fan would work on a side blast, maybe the small diameter tuyere would create too much back pressure?

 

Should work OK and worth trying first before going larger, its volume of air rather than pressure you are looking for

 

A couple of other dumb questions. Dues the tue iron need to be tapered? I am guessing the reason is to ensure no trapped air but this sounds like a fair amount of hastle?

 

Also. what height for the sides? I read somewhere they should be about 3 inches above the tuyere. I am thinking higher at the back.

 

 

The tue iron does not need to be tapered , just ensure it is either perfectly level or preferably slightly pointed down at the front to allow no air to betrapped inside when in use, any air pocket will likely allow the tue to overheat and burn through at that spot.

 

With regard to the sides, its a personal/practical  choice, the higher the sides the more fuel the hearth contains. as a minimum, the sides are level with the top of your working fire,

 

Better to make the sides higher to the rear so you can bank up a fuel reserve to rake down onto the fire when needed.

 

If you put in your location, there may well be people nearby who can assist you.

[bogmonster]

Thanks for your help again John. I will have a dig about and try and add my location but until I find the right setting it's the Mendips in Somerset. Of course if I drag my heals with it I can look at the ones in Exeter in Feb and pick your brains in person :)

[John B]

Of course if I drag my heals with it I can look at the ones in Exeter in Feb and pick your brains in person :)

 

Pick my brain? That shouldn't take long.