Thread: Oversize blacksmithing project

If I understand right, it looks like you have a form. You don't need to form the shape in one heat.
I'd heat one end at what ever length your forge will handle and start forming, then do the next section and so on until done.

Alternatively, if you want to do it all in one heat, dig a simple trench forge long enough to heat it all at once.

ron

I think originally you'd find these were formed in a roller specially designed or set up to handle the ribs or a press form.

Thanks for your response

Originally Posted by son_of_bluegras

Alternatively, if you want to do it all in one heat, dig a simple trench forge long enough to heat it all at once.

That's kind of what we had in mind, but no idea or experience about how to do it. Like, for example, what to use for fuel (coke?); presumably we would need a forced air feed in at the bottom; would we bury the work in it (the coke) or lay it on top; would we need to cover it (e.g. with fire bricks?);

We thought we would set up the former and lay the heated work over it (4 guys with tongs should be able to do that).

Any special considerations to avoid having the ribs collapse while bending? I guess we'd have to get it pretty hot.

See if you can get a copy of 'Early British Quick Firing Artillery' on Inter Library Loan. You want one of the appendicies which covers tyre bending and other field expedient blacksmithing - and how to make leather hydraulic washers from scratch etc. It also tells you how to lay out the loooong fire for heating the iron, tyre shrinking etc, most of which is useful when working with malleable iron.

The main part of the book is fascinating to sad cases like me, but the technical stuff at the back is incredibly useful, I think he got most of the info from the Royal Horse Artillery demonstration troop, who do the horse drawn gun demonstrations for the public in Hyde Park (UK) from time to time.

Originally Posted by onthebeachalone

Thanks for your response


That's kind of what we had in mind, but no idea or experience about how to do it. Like, for example, what to use for fuel (coke?); presumably we would need a forced air feed in at the bottom; would we bury the work in it (the coke) or lay it on top; would we need to cover it (e.g. with fire bricks?);

We thought we would set up the former and lay the heated work over it (4 guys with tongs should be able to do that).

Any special considerations to avoid having the ribs collapse while bending? I guess we'd have to get it pretty hot.

To make a trench forge, dig a hole long enough for heating the piece. Fuel could be any carbon based solid fuel - coal, coke, lump charcoal, wood, dry dung. You'll probable need additional air (although maybe not depending on the gauge of the metal, thicker metal bend easier with more heat, thinner will bend ok with less). That is simple as a pipe with some holes drilled in it and some air source (bellows, hand-crank blower, compressor). The fuel choice will determine how much air is needed (coke need most, charcoal can work with just fanning the fire with a palm frond). The air pipe doesn't need to be on the bottom (and for charcoal may prove easier to work with if it's part way down on its side).

As for burying, laying on top or covering with some insulative material that will depend again on the specific metal alloy and its thickness which determines how hot it needs to get. A simple wood fire may prove sufficient to do what you want.

I recommend getting a few pieces of similar sized material and trying a few test runs before having a go with the real piece.
I really haven't a good guess to prevent the ribs collapsing, it may not be an issue. Or it may take a form that keeps the rib shape.

ron

I am curious if you've got this done and if so how you did it?

ron