What is a side Blast forge like?

[Charles R. Stevens]

In the case of charcoal experimentation shows us that 6” is the practical maximum. For coal, you can go larger but 8” is about it as you can only forge about 6” in one heat. So ask yourself how big of a bowl do you need to support a 6-8” fireball?

Obviously a 4” block of steel needs a bit bigger fire

[Caballo bueno]

Are we talking about the width of the crater? What would be the width of the bottom of the crater at the top? From highest to lowest?

[Charles R. Stevens]

Depends on if we are talking about a side blast or bottom blast forge and the fuel type you are using. 

[Caballo bueno]

I am using side shot with mineral charcoal.

[Charles R. Stevens]

Ok, I think we have a translation error. 

mineral coal (one of a handful of types)

charcoal

coke (literally what I think of when I read “mineral charcoal” as it is either pyrolized coal or petroleum)

 

 

 

[Caballo bueno]

Okay sorry, then? How do they find out the width they will give to their blast forges?

[ThomasPowers]

In Spanish "carbón" is used for both charcoal and coal;  you differentiate by adding vegetal for charcoal and mineral for coal.

Much like they did it in Medieval times in England; when coal was charcoal and earth coal was coal.

[Charles R. Stevens]

Thank you TP. 

Good horse, I would try a bowl shape an inch deeper than the bottom of the tuyere opening and of a circumference equal to the depth. That is to say for a 5” deep tuyere, a 10” x5” half circle sloping to just an inch or two at the bottom.  Charcoal benefits from a trench because it doesn’t bank like coal due to fuel spread.  

 

[Caballo bueno]

I use coal, does the crater differ somewhat from that of charcoal?

[Charles R. Stevens]

Yes, you can bank burning coal against green coal but if you do the same with charcoal all the charcoal will soon be alight. With charcoal you have to build fire risistant banks to hold the fuel piled over the bowl. Add to the fact that charcoal really likes a tuyere that is 3/4”-1” ID and is about 1/2 as dense as coal. That requires a much gentaller air blast. 

if one is thinking about using both fuels, and are not forging stock over 1-1/2” a trench like I use is the most efficient set up this can either be done buy building a bowl out of plate like mine or buy building a box and filling it with loose fill. This size works great with a 3/4” schedule 40 pipe, as this is 7/8” ID: this fits right in the middle of the historic record. 
if one builds a box with loose fill one can use a larger tuyer and a 1/2” plate with a smaller hole drilled in it: this allows you to have a real big coal fire for forging anvils wile having a smaller fire for day to day use. 
Mae to the forge hearth, I like a 30x60” table, and for loose fill that would be a 30” square box 8-12” deep (depending on tuyere size) and a 30” square table next to it. In my case it’s steel but if building it permanently it can be wood covers with loose brick. Filling the box so as to leave a 12” square of lose fill (traditionally ash and clinker) around the tuyere. This allows you to modify the fire bowl for special projects
 

[Caballo bueno]

want to make the iron crater traditionally they have been made of earth but,  I prefer iron so I forget to have to fix it periodically. 

It has to be a forge that heats to the welding point of,
 about 10-15 cm long and a little wide too would not be bad.

[ThomasPowers]

Take a look at the forge in the video

Video link removed for advertising.

[Caballo bueno]

So, the width of the crater equals the depth? Could it be taken as the norm?

[Frosty]

Caballo: Please start paying attention to the font size hen you post a message. The one above is entirely too large and causes extra work for the site's moderators who have to correct it. It's also a problem for members who have dial up internet connections and have to pay for data. Huge fonts take up WAY more data space than common font sizes. 

The questions you're asking about side draft forges do NOT have an exact answer. What works well for someone else may not work well for you. You will need to adjust the size and shape of the trench until you find what YOU like.

It'd be nice if there was a simple exact answer but there just is not one. 

Frosty The Lucky.

[Charles R. Stevens]

For coal in a traditional forge, yes. How big a tuyere are you using? For my self using a 7/8 inch I’d tuyer 4” wide works very well. As mentioned it was a 12” square cut diagonally to form the sides. The slope makes cleaning easier and fuel settles naturally.  I find the trench to be more efferent of fuel. So with coal you will use extra fuel on the table (hearth) to bank the fire (build up the fire ball) this allows the coal to coke wile you work. In the case of charcoal you will find that using something that is heat resistant to hold up the fuel pipe is more efferent as it takes less fuel to heat the same work.

[Caballo bueno]

The tober that conducts the air to the fire tube is 6 cm thick and the tube that gives the fire 2.5 cm wide the crater has a depth of 8 cm and a circumference of 19 cm.

 

Thanks.

[Charles R. Stevens]

8cm is a bit shallow (a bit over 3”) for a 2.5 cm ID tuyere (1”) I would think 12-15cm would work better.  The simple expedient of adding 5cm of clay to the top of the hearth or in the case of mineral coal 5cm of fuel on the table will accomplish the same thing. 

[Caballo bueno]

Recapitulating the width of the crater is determined more or less by the depth of the crater and my tube that faces the fire of 25 mm completely including the wall is shallow and the nozzle through which the engine air circulates is too narrow

[natkova]

Why side blast need 3/4 opening of tuyere I noticed that in old bellows.they make tuyere in cone shape  why that.for.blast.forge it give you only  more preasure.

Why they funnel down tuyere for side blast forges?

[ThomasPowers]

It makes 1 bellows fit a lot of different sized tuyeres and easy to make a pretty airtight join.

[natkova]

4 hours ago, ThomasPowers said:

ws fit a lot of different sized tuyeres an

Thomas i heard that side blast forge need to have max 1‚inch i diameter tuyere dont know why

 

Why for side blast cant 2 " tuyere?

 

[ThomasPowers]

I would think it would depend on the size of the forge.  A sideblast for forging 4" stock would be different from one doing a max of 1" stock.

I'll check with the plans in "Mechanicks Exercises", 1703,  and see what they suggest.

[Caballo bueno]

OK thank you so much

[Caballo bueno]

How much would you make the side draft crater for a forge with a 30 mm air tube? I would like to know more or less a measure with the iron crater. Thanks

[Glenn]

The side draft pipe here is about 4 inches from the bottom of the pipe to the bottom of the forge.  The crater extends in front of and maybe just a little below the end of the pipe.  This is for bituminous coal.