Apprenticeship Session 15

The end of our grant is fast approaching and we’ve got a few projects left to finish up. So today is going to be another double session of basically finishing the projects we were working on last week.

Viking-age Bellows

With the beeswax/tar goop that we painted on the canvas last week now dry, it was time for final assembly.

We affixed a couple of crossbeams under the bellows. They serve two purposes: 1) to allow air to flow into the valves from underneath and 2) to set the angle of the bellows for best airflow effect.

The best angle for the two bellows is to have the airstreams cross about three inches in front of the snouts with the soapstone barrier about an inch in front of that. We lined up some steel rods down the centerline of each bellows to determine where the airstreams would cross and then marked the crossbeams before affixing them. There’s no special measurements of where they should go other than the back one shouldn’t obstruct the valve holes and the front one should stick out the sides so that it can be clamped or bolted or staked into place when using to keep them from moving about.

The last step today was to attach the handles and test the results.

There is one final step left to do on the hinges which is to affix the leather hinges to the sides of the side, but we want to use them for a while and break in the leather before making a slice and tacking them down. And we also need to drill the hole in the soapstone and maybe build a portable table to hold it all for using at events or just outside on nice days.

Shears

Now back to the shears…

Shears are one of those projects that seem like it should be easy, but in practice turn out to be more difficult than imagined. We had started with about 18-inches of 9/16-inch 10851085 1085 steel is a hardenable steel round steel stock. First we flattened out the spring area in the middle and drew out the ends to thin them out. And that’s where we left them last week.

So this week we needed to create the blades on each end and fold it and then finish it.

It’s been a while since we’ve done blades so it was a nice refresher. Drawing them out, grinding them, heat treating, and tempering are things we are familiar with but with shears the blades need to be at 90º angles to the flat spring area and facing the same direction as each other. I can neither confirm nor deny that there were mistakes made in that process. It’s really hard to get two blades that are exact mirrors of each other.

The last step was to fold them and line up the blades. Keeping them equal lengths so that the tips were even required wrapping the spring area around a big steel rod (vertical worked best) and either push/pulling the ends or hammering a bit on the spring area.

Then the big test of whether or not they would actually cut anything.

will they cut?

Well, they did pass the test, but we learned so many things that we’d like to do differently that we may have to try another pair soon. Things we’d do different are: 1) longer blades and not so much concern about the length of the reins, 2) have the blades be flat on two dimensions (spine and one side) that that they don’t rub and interfere with use, and 3) set shoulders to define the spring and blades areas, and 4) draw out only the reins area and not the blades area (we needed a bit more mass to work with).

before and after

Good thing we brought donuts to the smithy today because we spent over 6 hours in the forge getting these two project finished up.

Apprenticeship Session 14

We had two tasks for today’s session: 1) work on the bellows and 2) start forging a shears.

The Viking-age Bellows

We did get our homework done and got the copper snouts attached and the canvas tacked on. Both were fairly simple jobs and we were happy with how easily the canvas laid in place. Working around curves and hinges we were a bit worried that it would get fussy, but it was pretty straightforward and fun!

So the next step in the bellows process is to seal the canvas. It’s not really intended as much to make the bellows air-tight as it is to protect the canvas from the heat, sparks, and hard use.

For a sealer, we used a mixture of beeswax and tar (pitch) and heated it over a campfire. It’s highly flammable, not to mention messy. We melted the beeswax first then added the tar pitch until it became saturated – the mixture will only take so much. Once that was done, it was time to brush it on the canvas.

Painting the mix on the canvas was easy enough, if a bit sloppy. The color of the mix as it dried … well, none of our suggestions about what we would name it should be repeated here. 😀

After that we set them aside to dry and started working on our shears.

Shears

Since a shears is basically two blades on one piece of stock we weren’t sure the best way to go about that. We had considered creating the blade on one end and then putting in the flat spring portion before making the blade on the other end – basically working from one end to the other. However, Doug recommended that we actually start in the middle and flatten the spring section first, then draw out the reins, and lastly add the blades to the end. Seemed like an odd way to go about it until we got into it and then it made perfect sense. It’s easy to make one blade, it’s hard to make two that match. His suggestion would give us the greatest chance of having that happen.

the finished dimensions we are shooting for

We managed to (mostly) get the spring section flattened out of the 3/8″ round stock and began drawing out the reins before calling it a day. By the end, we knew we’d been working with 10851085 1085 steel is a hardenable steel steel rather than 1020 all day. We’ll pick this up where we left off next week – and get the handles and mount on the bellows too!

Apprenticeship Session 2

So we started to build our Viking-age bellows tonight. Doug had the wood pieces all pre-cut and ready to assemble, which makes it sound quick and easy. However, three hours later we have one bellows only half assembled. There’s more to it than you’d think.

Making the Valve

Our previous session went over how the valves work and what they should look like. (Refresher: two pieces of leather – one square, one rectangular – placed over the air intake hole in the wood.) So today it was time to cut the leather and install it inside the bellows.

Making the Hinge

The next step is to make the hinge. This too is made of leather. We started by putting spacers in between the top and bottom pieces of the bellows so that they were flush with the wooden snout piece.

bellows wood pieces set in place
Bellows wood pieces set in place

After that it was time to cut the piece of leather that was going to serve as the hinge. We needed to determine the size we would need to cut. We wanted it to cover the wooden snout piece and then a couple of inches of the bellows surface (I’m sure that has a name, but I don’t know what it is). Plus it needs to fold over the sides too.

To be clear, the leather used for the hinge was a reasonably thick piece of leather since it’s going to get some hard work and different than the leather used for the valve as that should be more flexible.

After the leather was cut, we drilled a couple of hole through the top piece of the bellows as we planned on riveting the leather to that piece. The placement of those holes was about an inch or so from the front and sides.

We used an awl to punch holes through the leather hinge before heading to the anvil to rivet it in place.

Once the main rivets were in place it was a matter of adding tacks and small nails to secure the leather to the snout and the board and make the hinge as strong and tight as possible. We also added glue to make it secure.

At the end of our session we had gotten that far on just one of the bellows. Going to have to finish them up next time!

Apprenticeship Session 1

So we started our apprenticeship with Doug Swenson as part of the Folk and Traditional Arts Apprenticeship grant that we received. The work plan was originally developed about six months ago and we’ve learned a lot since then. And we are about to leave on a trip and be away from the forge for several weeks so we kind of are starting out of order with the Viking-age bellows.

We’ve used Viking-age bellows once or twice and they are surprisingly easy and fun to use. There’s actually not a lot of information about them because they haven’t survived through time very well and they aren’t mentioned to often in literature or historical accounts. There is a cool depiction of one on a runestone from Sweden.

ramsund runestone carving
The Ramsund Carving Sö 101 with Sigurd the Dragonslayer, note the bellows at lower left. Credit to Jonas Lau Markussen.

We spent a bit of time going over how bellows evolved and how they work. Some have a single chamber and others have a double chamber. Later ones got rather large and hung overhead, operated by a lever or a foot pedal. But they all essentially work the same way: air goes in one end and is directed out as smoothly and steadily as possible out the other end. And valves in the middle keep the air moving in one direction.

So we started talking about the valves for the bellows we are about to build. In this case we are going to use leather for our valves. It’s a traditional material and actually quite suited to this purpose. The air intake is actually just a round hole cut into one side of the bellows and the valve consists of a couple of pieces of leather that cover that hole. However, there’s a bit of elegant math to the size and placement of the leather pieces. There’s two pieces that are involved. The first is a square large enough to cover the hole plus a bit more. That piece is placed with corners to the front and back of the bellows and tacked down at the sides. The second piece of leather is twice the length of the first piece and covers it and is tacked down at the corners. It should be extremely taut as it will need to allow air to pass through it freely.

bellows design notes

After that we looked at the construction of the bellows that our master blacksmith instructor uses in his Viking-age demonstrations. Most of it is very suited to purpose and have stood up to use and time, but we might make a few minor adjustments when we build ours.