Lost and Foundry - Another string to my bow

Hey everybody, what are you building? I'm Roger in Technology and welcome to the Lost and Foundry! This week I've been practicing my boywer skills and working on bowstrings.

Pictured here are three crossbow strings. In Green on the left, a commercially available heavy duty dacon string. You can buy these from amazon or any good outdoor sports centre and this will draw over 150lbs and made from 33 strands.

In Yellow on the right is my "get it done" bowstring, made from cheap poly cord. It was really a tools and technique practice on the flemish twist loop and winding. You can see the binding is a little scruffy, but this is perfectly serviceable at a low draw weight. It's about 3/4" too long, for lack of experience in how much slack it needs, and there are only six thick strands. I used this to test a synthetic prod, and around 70lbs the prod buckled because the shape was uneven and I've reasonable confidence you could push this up to 100lbs without it breaking. I think it'd fray easily and isn't ideal but it was a good trial run.

In the middle made from white dacron is my first attempt at a "real" string. It's a hand-wound flemish twist, made from 26 stands of 30lb line. It's still a little scruffy and my technique could be improved a little, but it holds strong and should be more than strong enough for a 100lb bow. It feels really solid, took a few goes to get right, but represents most of the tools and talent to get the job done.

After a few failed attempts I watched a couple of videos of this being done, and they don't half make it look easy. With practice you can hold the line in your hands, but for the rest of us there is no shame in using an extra clamp or two so you can focus on the bit you are working.
In fact, I'm considering a jig containing a couple of clamps on an axle. The jig has a two-fold benefit here, firstly in just giving you more control, and secondly my real limiting factor was that my hands cramped up from gripping and twisting the string. I'm sure with practice and experience you'd be able to make your own string quickly as part of a one-day-build crossbow, but for me I had to wind in short bursts and stretch out. A jig prepared in advance should make this pretty easy.

The second tip is to add beeswax to your fibres to bind them together. This gives you more control of the string as you manipulate it. Neither of my two efforts pictured above were waxed, but you can feel the green professional bowstring is waxy and it's something I've been experimenting with since.

There is another method for making strings called a continuous loop, which appears to be made out of a single long loop, and then wound and bound. To make this, a simple jig with the correct spacing for the length should be enough. I'm going to guess it's less traditional than the flemish twist but seems to require less tools and talent.

I'll report in with pics of the next few strings and then move on to prods and the furniture.

Lost and Foundry - Crossbows

Hey everybody what are you building?
I'm Roger and welcome to the Lost and Foundry. Today I'll be learning how to not to make a crossbow. If you already know how not to make a crossbow, this probably won't be exciting reading but if you want to hear how it's done the let me take you on a journey.

Right off the bat, lets talk materials.
I've got three options for the prod - wood, metal, plastic. Let's break down those choices a little so you can see where I'm coming from.

Wood. This is going to look The Boss, but is the hardest material to work with. Wood is an uneven density, with uneven strength in compression and extension. This means I can't just "cut" a crossbow prod from wood and have it work. I'll have to start carving and then get it under minimum tension so I can see it deform and slowly work it into shape.

Metal. This is me. I'm not a wood guy. Steel is my bag right now. Spring Steel is incredibly uniform as a stock material, and I can only make it worse by working it. Thankfully, I can make a jig that applies even force to both sides and get a nice smooth curve, and send it off for heat treat and temper so that it comes out just right.
The downside with this is that I'm not really going to "make" anything here. I'll be buying flatbar spring steel, putting a primary curve and maybe recurve in it and sending it off for heat treat.

Plastics. These are lightweight, and fairly easy to shape, with high restitution, high availability, good uniformity, and very low materials cost. There are good reasons why this the material of choice for a lot of people starting out. You start with something that looks like a straight pipe, and fashion it into the business end of a crossbow so it's a fairly satisfying build.

So I'm "plumbing" for option three - thermoplastics. I'm using a synthetic thermoplastic pipe which is easy to shape and thankfully there is a plumbers suppliers just up the road. Need a tool? Make a tool! and the first tool for me is a flattening jig to form the overall shape.

Lesson 1 - Keep your recurves even. This prod failed because of a tiny kink at the start of the recurve that folded and buckled under about 15-20lbs of force.

Lesson 2 - Don't attempt to cold cut. The material isn't shock resistant and you can cause fractures. I was marking the shape near the nocks with a cold cut chisel, and decided I could tap it all the way through. Of course that doesn't reflect reality at all.

Lesson 3 - Don't overheat the centre. This second prod failed because the centre deformed a little out of my control when forming the primary curve. Since it's being formed by hand you want to work as cold as possible so that there is no sagging. The rule of thumb here, is that if it's too hot to hold your thumb against then its too hot.

Lesson 4 - Flatten the centre a little.
This third prod failed at about 70-80 lbs of force, which is it's full draw weight. It was actually cocked and ready when it buckled in the middle. I think if I'd flattened it a little that would have been OK. I can adjust a little to account for this.
Also, the Furniture wasn't super smooth and I'm worried it was applying pressure unevenly.
Need a tool? Make a tool! And this third prod had even, symmetrical recurves from a high tech recurve jig I put together.

That concludes the first session. I spent a while contemplating those and moved up to a 1" diameter material. Firstly I think that will give me more poundage and I think that will give me higher tolerances for error - not that I want to keep making mistakes! I've adjusted my flattening jig to just touch the centre on a 30" prod so its time to move on.

Lesson 5 - Become Familiar with your materials.
1" pipe needs more heat than 7/8" pipe. Its an obvious one but being only familiar with the feel of 7/8" stock I didn't apply enough heat to my first 1", and too much to my second, before finding the Goldilocks zone and the third one was just right.
If you've got an offcut, short end, scrap, or spare bit of material then it doesn't hurt to get a bit of free practice working it before you damage more valuable stock. In my case, my valuable stock costs about 50p and working with the real macoy is a cheap way to get hands-on relevant experience but there are times when this won't be the case.

Tune in next week for a Lost and Foundry post when I assemble the finished article, and for a photo tour of the new workshop.

Thing of the week - Bacon and Fire part two: First Knife

Hi everybody what is going on?
I'm Roger In Technology and welcome to Thing of the Week Part Two for 30th August 2015.  This week I'd like to talk about the first knife I made from scratch.

Ferrous materials are characterised by the way iron crystallizes as it cools, and you have to master iron from the earth, air from the bellows, the blazing fire and water to quench - truly the dawn of blacksmithing represents mankind's dominance of the four elements of the ancient world.

The first step for me is to grab some one inch rolled steel stock and draw a knife on it. This is where the magic starts.

This is the steel stock I've chosen, it's about an inch wide but very thick.

This girth will give it tremendous weight and I'll have to consider that when I profile and grind it.  I'm planning a Scandinavian style grind, with about two thirds of the blade tapering to a point. Because of the thickness of the blade I might choose a convex grind instead, I'll see how it goes.

You can never have too many clamps so I clamped a clamp to a clamp.  This was an everyman project with tools you might have in your toolbox already.  Just a regular hacksaw, a file, and some clamps holding everything to a picnic table out back. I'd love to have a heavy workbench and a bolted bench vice or a leg vice, but until I get that set up it's picnic clamps all the way.

The initial cuts are all made using a regular hack saw, with a bastard file used to round it off. Its a lot easier to saw through than to file, although I found the weight of the stock was really working against me.  Lesson learned, use thin stock and you will save a lot of elbow grease.

Next step, grind the bevel. This was all done with a bastard file, clamps and some curse words that really seemed to help get the job done. The bevel isn't as deep as I'd wanted but the angle is about what I was after so that just the shape it's going to be.

Once ground, I cleaned the millscale off and polished it up with some 240 and 600 grit sandpaper. I think I might have gone finer than that just to see how much shine I could put on it, and I wanted it pretty smooth before the heat treat.

After the steel is knife shaped, Its time to heat treat the blade. First off, I'm going to pack my crucible with sugar and cap it off with clay and place the knife in it to case harden it.  Case hardening means you have to get the steel really hot and allow it to soak up additional carbon. I'm doing this because it's a low grade piece of steel stock I had that isn't really suitable for knives.
I'm going to cook the knife in sugar at about nine hundred degrees so case harden the blade a little before the quench. Since it's a soft steel, the case hardening will help it retain a really good edge. I was offered some Kasenite to harden in instead of sugar. Kasenite is a great source of carbon but it also contains Potassium Cyanide and I figured I'd stick with the non-toxic version this time.

After case hardening, the blade is back in the forge again for the heat treat. Here I'm using a graphite crucible to raise the knife to hot temperature and get it evenly cooked. I'm also cooking bacon, although the fire is a thousand degrees too hot for bacon which starts to vaporise at this sort of temperature.

OK, I said this knife was made from tools you might have lying around, and not everybody has a raging inferno to hand. But it was a very simple build and you can put one together in an afternoon with reasonable cheap materials. It's an insanely powerful fire despite its small size and can be difficult to control but if you are used to working with forge or foundry fires it isn't that bad.  For the astrophysics crowd, I've peaked at internal temperatures as hot as a Red Dwarf star and the steel bucket on the outside didn't melt. It's all about the heatproof lining.

Whole essays could be written on quenching steel, so I'll skip the details here and perhaps we'll go into those another time. The quench hardens the steel, and then the temper brings it to the exact hardness that you want. Because this is a mild steel I went with a water quench.

After the heat treat the blade is covered in scale and needs a really god grind, polish and buff so its back to the sandpaper and elbow grease for this one.

I'm hoping to get it cleaned up, tempered and get a handle on it soon. It might not be next week, just depending on how busy everything gets. But hopefully I'll have an update before long with a picture of the finished article.
This is pretty much "finished" though.  Its a knife shaped object, and its been hardened. Really it just needs handle scales pinning on.

Lessons Learned

You learn as much from your failures as you do from your successes, and while this wasn't a failure, it wasn't a complete success either and there is a lot I can do to refine the process.

Choosing such thick stock doubled the amount of work I had to do cutting and grinding and really cost me time. Its good practice on being patient but next time I'm going to choose something much thinner. It just depends on what you are trying to make.

Doing this by hand was a lot of work. Bottom line, its recreational hard graft - but still less effort and better tools that our species had for thousands of years. And I could pick them up cheaply from the local hardware store.

Next time, I'm going to want a proper height workbench and I've got to consider a belt sander too. Getting a workbench at the proper height for you is crucial else your back will ache the following day. I choose the hard way because I wasn't spending any money like this, but if I could pay sixty bucks to take away the pain right now I would consider it.  Money comes and goes but you've only got one back.

My handle pins look a little puny. I could easily have chosen 3/8 or 1/2 inch pins, and I might find something bigger when I come to do the handle. Overall I'm not that fussed - again it's about learning the process but one of the processes to learn is having an eye for what looks good, and what I like the look of.

Choosing to case harden made things more difficult. Its a way of hardening steel, which means you can start with a softer, lower grade stock. Our ancestors used to have to do it and it's not a great hardship. But I don't think I'm likely to try that again for a while. The local metal supplier didn't have any O1 steel which is what I'm after, but I found a few places I can buy one inch bar online so I'll order a few meters when I'm ready and make a few knives.

Fire! Running the fire is great fun. It gets hotter than I thought, and just for a short while I lost my nerve. Literally, it got so hot I started to get scared. So I'm going to fabricate a blast regulator to reduce the airflow.

It amazes me at every step how much mastery of the elements we have and how much power, knowledge and versatility we have within our grasp. I'm going to improve my workflow, maybe buy some more tools and have another go soon.  It's quite possible that the next few projects will be brass and bronze so it could be a while before I'm working with steel again but I want to have a few attempts until I've got something I'm happy with.

Until next time, keep your projects projecting and maintain momentum - and Clamp everything down!

Thing of the week - Bacon and Fire

Hey everybody what is going on?
This is Roger in Technology and welcome to thing of the week for the 27th of August 2015.

This week - Foundry tools!

The bucket foundry I built here is exactly what the doctor ordered, its a galvanised steel bucket and a refractory mix of about four parts plaster, four sand and three water. There are details on the construction on a previous post.

While I had to buy a steel bucket, those things are cheap enough and I knew it wouldn't break the bank. Likewise for the plaster of paris and sand and making a thrifty blast forge capable of any amount of metalwork is easier - and cheaper - than you can imagine. Here is the little fellow in action.

There are a few more materials here, a one inch steel tube and a value hair drier for an air blast. These were bought pretty cheaply. The pictured timber supports are actually my cope and drag frames for the casting flask, so I'm not counting those in the cost. The air blast does need a dedicated support, although a few blocks or timber is going to be more than sufficient for a long time yet. It also needs a regulator, because the direct blast from the blower provides too much heat.

As well as buying the materials to make the forge, next on the shopping list was a graphite crucible looking something like this.

The crucible is a precision tool, and it was important enough for me to spend the money rather than fabricating a steel cup. The thing is rated a lot hotter than steel too, by at least a thousand degrees, which is a pretty good safety margin.  Melting Aluminium and brass isn't going to take more than a thousand degrees, and neither is hardening steel so I'm very happy to have a crucible that can withstand a lot more than I'm every going to need.

The lid is the same refractory concrete as the foundry walls, with galvanised steel hooks set into it. The two hooks were bought new from the hardware store - its a needless expense when they could be beat out of steel but the wide square bases will help it hold in the concrete and I didn't want to spend any time on such a trivial item.

Once the mix was poured in, it flowed around the hook bases and the plastic cup formed a circular hole and I just had to let the thing dry before popping it out the hold. The technique was about right but I want the next lid to be thicker.

With the lid off, the crucible can be seen here glowing a bright orange at its hottest point. You can see the ash line around the edge of the lid. While its clearly more the large enough to cover the foundry I might consider an inch or so larger diameter.

It's worth mentioning that the fire at this point is running too hot - which is why I had the lid off. Actually it's running at a tad over two thousand degrees by my best guess. If that steel stays in there too long it'll start dripping. As well as being too hot for steel, that temperature is far too hot to cook bacon. As far as I can tell, bacon vaporises at two thousands degrees (3600 Farenheit) and while I tried eating what was left of it after it had been extinguished it wasn't a pleasant experience.

Cooking bacon is reasonably easy in a fire up to two or three hundred degrees, where it will sizzle well and taste delicious, but I think that anything above about a thousand degrees centigrade (1800 F) is going to do more harm than good and the direct heat of a forge fire is unlikely to yield good results.
Using nine-hundred to a thousand degrees as a maximum cooking heat is probably a good rule of thumb. If its hot enough to liquidise copper then its too hot to cook with.  Our domestic oven will reach 230 ish degrees which is just shy of the temperatures needed to temper the steel of its construction.
A discussion on cooking over the forge will have to wait for another time, while I consider some sort of heat shielding that can withstand the inferno.

Todays heat used up the last of the summer BBQ charcoal, so was the last free burn and I'll have to buy some real coal next time. The crucible was packed with sugar and sealed with my knife while it burned for a couple of hours to case harden the steel before a water quench. It was a lot of work to go through, and a better grade of steel would have skipped straight to the quench and temper.

Until next time, keep your projects moving. Finding time for recreational hard graft can be difficult but maintaining momentum is important.

Thing of the week - Jamaica Blue Mountain Coffee.

Hey everybody, what is going on?
I'm Roger In Technology and this week I'd like to give an honourable mention to Wallenford Estate coffee.

Coffee is a relatively modern tradition, dating back up to a thousand years by some stories but only becoming a global phenomenon in the last five hundred years. Over the centuries the coffee industry spread to Europe and the Americas and has grown stronger, spreading globally.

The technology behind coffee remains largely unchanged although products, practices and tolerances have improved to keep up the demand for quantity and quality. From the simplest stove-top pot to the largest, steaming, frothing, barista machines the sale and consumption of coffee has become an ubiquitous part of modern technological development, driving artists, philosophers, and programmers well through the night with its delicious aroma, taste, and chemical stimulation.

While apparently it's medically possible for a human being to go without coffee for long periods of time, it's not an experiment I could contemplate running. In the twenty-first century we drink well over two billion cups of coffee a day.  I'm doing my part, are you?

The Wallenford Estate review this week is based of off two cups of Wallenford long black, both purchased and consumed at a coffee shop local to me.

The long black was served as a 12oz cup, which is a good size for a double shot coffee. I used to enjoy it a little stronger but this is a good way to get the flavour. I take my coffee straight black, and while I never add sugar or syrup on the first cupping I will often pick something that goes well if it's a drink I will return to time and again.

The initial hit of the Wallenford was a little more acidic than I'd expected, not quite citrusy but certainly accompanied by some high notes. Drinking was smooth and easy and the body of flavour comes from its mid-tones, I found it very drinkable and the cup disappeared surprisingly quickly.

The overall palette is very mid-balanced, medium bodied coffee with few high notes and no great earthy flavours to drown out its almost buttery flavour.  If found it missing the sweet fruity, cherry, flavours I was hoping for and that part of the spectrum was surprisingly absent but its uncomplicated mid flavours were pleasant.

I will say there was a slight coffee-shop finish.  Filters in coffee shops often leave too much grit in the drink which does contribute toward a darker, more bitter finish to the cup than is otherwise fair. But even considering that the finish was fast and clean, and any lingering taste wasn't unpleasant.

My other critique would be the paler-than-expected crema typical of an over extraction. I'm not going to put too much into the colour of the crema, but darker is better and I find over extractions a little sharp and combined with the bitter body I think the preparation let the coffee down. Both of these are preparation artefacts that wouldn't be present if you made it at home and not inherent to the bean. Despite these points it was a very fast drinking cup and any bitterness was brief and mild.

I enjoyed shortbread with my second cup, which I thought would bring out the buttery sweetness and create a simple combo but I found the flavours clashed too much and didn't play to each other. Not to say it wasn't enjoyable, just that it was far from the perfect combo I'd expected. The Wallenford is missing a nutty body, so think hazelnut balocco or hazel syrup if thats your style. I did leave thinking that a dark chocolate brazil would go well, but didn't have the chance to try the combination. To the coffee shops credit the cup was the correct radius for a stroopwaffle, and although I didn't indulge I'm sure every long black works well with the dutch delight.

I didn't manage to make my own Wallenford yet, and I think that the fine paper filter of an Aeropress would significantly improve its finish, and bolster its strength without sacrificing its smooth body. I'm going to guess that it's best enjoyed at an americano strength where it's uncomplicated butter feel will linger and be enjoyed.

Overall the Wallenford Blue Jamaica was a good cupping, and I enjoyed the drink despite the number of flaws I've presented here. I've tried to be fair and balanced, and while I have a personal preference for some of the light, cherry and fruity coffees of Africa the Wallenford was a good drink in its own right.  I wasn't blown away but I did enjoy it.

Thats all for this week. If you've got a favorite coffee let me know and I'll try it as soon as I can. If you have any tips or suggestions for a future Thing of the Week then I'd love to hear from you.

Thing of the week - Casting Tools.

Hey everybody what is going on?
I'm Roger in Technology and this is a quick project update on the Foundry.

Since I want to cast some bronze, I've got to make some tools on a budget. The bucket foundry cost next to nothing, is lightweight, completely portable, clean-burning and far exceeds a thousand degrees. So far my efforts have been met with nothing but success I'm staring down the barrel of two significant purchases.

Metal Ingots
The first is the metal stock. Copper and Tin ingots can be bought, and are going to cost around £30 per kilo including postage, I think tin is more than that. I'll shop around and get slightly cheaper but that's the ballpark. I'm going to need one tin ingot, and I guess that means ten copper ones but I'm reluctant to make eleven kilos of bronze. It feels like a lot for the small projects I've got in mind.
Buying copper in smaller (than 10kg) quantities is more expensive, and the cheapest option is about ten kilos of copper and one of tin - but that's around a £300 materials cost. I guess I could soak up the cost but its a huge outlay this early on.

Recycling aluminium drinks cans is a good idea. It'll continue the thrift-shop philosophy I've adopted so far and allow me to make a casting flask, practice to process, learn how to make casting sand and generally run the whole process start to finish before I start ruining home-made bronze.

Anvil
Astute observers will notice that I haven't talked much about anvils. Until I have a forgehouse built, there is nowhere to put an anvil but I'm not going to be able to work steel, or even work harden bronze, without one.  The anvil is a versatile tool that so much smithing relies on.

An affordable cast iron anvil just isn't worth owning, you can buy cast anvil on amazon for fifty quid but they look terrible and frankly thats a lot of money for something thats just going to be used as a doorstop.
I've found a wide faced farriers anvil for £450 that looks perfect. But this alone costs more than I want to spend and it'd be a shame to come this far only to divert all my budget into a block of steel - no matter how fancy.
To this end I've managed to get a sledge hammer, its light - only 7lb - but once set into a block it'll give me a hard enough surface to make a few small tools and to work harden bronze on. I could buy a 14lb hammer very cheaply, but the 7lb head is light enough that I may actually use it later on so there should be no waste.
I'm going to back this up with a granite block from the garden centre. Its not too costly and will be equal or better than what was available to my bronze age predecessor. It'll probably be fine for work hardening bronze on, and in combination with the sledge head I think I'll do fine.

Crucible Tongs and other casting tools.
I've bought screws and some timber to make a flask, a couple of clamps and some more sandpaper. The costs there are low but mounting up and I do want to keep an eye on the spend. My makeshift hammer-anvil will be sufficient to make some tongs, and with those I'll be able to make some crucible tongs, a ram, rap and all some other trinkets for casting.  The overall cost here is very little. I could use scrap steel, and I've got a couple of mild steel bars including my thermometer that I could turn into tongs.

Lastly, I've spent some time carving a couple of patterns to cast. This was done with some timber and a stanley knife, and then 60 grit paper.  I can see myself making a steel whittling knife as a very early project once I start working steel because this was a lot of fun.
The most interesting of these is a pattern for a bronze dagger. Its in the style of a bronze age Wilberton, just a smaller blade - probably about ten inch. This was cut from cheap timber and is about the shape I wanted but I don't think I've left enough excess for shrinkage and finishing so the end product might be a bit small.
When I scale up, I'll probably try a full size Wilberton, or a Ewart Park style sword which I can cast and finish in bronze.

I've started carving a wooden ram and rap, and I'll be collecting aluminium this week.  I also need to carve some ingot casts for excess material but after that I'm ready to run through the whole process with my wilberton style dagger in aluminium.

That's a roundup of the project status, and my thoughts on tools and materials. I'm also arranging to borrow a video camera so should be able to start videoing the process from here on in.

If you have any questions on metal work, wood carving, or smithing then leave a comment. I'm not staying a hundred percent authentic to traditional methods, but everything I'm doing is with simple tools available to the everyman.

Thing of the week - Foundry part 2

Hey everybody, what is going on?

I'm Roger in Technology and welcome to Thing of the Week for the twelfth of May 2015

Mankinds mastery of fire was once a turning point of civilisation. Controlling and maintaining fire led us from the stone age to the bronze age which gave us access to all manner of new tools, toys and technology. Thousands of years later, we are able to casually and recreationally create a foundry from household materials, standing on the shoulders of giants that have forged a path before us.

This week we'll be talking about my new foundry, started in a previous article here:

Thing of the Week - Foundry Part 1

I took the time to test my foundry fire, using a piece of 3/8 inch roundbar as a thermometer and the results were as good as I could have hoped. And possibly better.

There are a few differences between this bucket foundry and the original build. I wasn't happy with the shallow depth of the first build so in the intervening week I poured a second layer to nearly fill the bucket with refractory concrete and get a good seven or eight inch depth to snugly fit my graphite crucible. For safety reasons this meant the foundry was out of action for a weekend while it cured, but it'll cleanly fit my 155mm crucible.

The mix was the same 50/50 sand and plaster of paris and poured in the top to fill out the height. The sand was less compact than the first batch so the colour is a fraction paler but it's the same colour once blackened with fire and colour coordination wasn't on the feature set. 

Air Blast

The bucket forge here is powered by a cheap hairdrier from the supermarket it's on a low setting, and a good six inches from the air intake to keep it cool. There is no ducting - the picture was taken live with the setup. With some ducting I could blast the air right into the fuel and get a much better burn so I think the airflow could be improved.

The reliance on electricity isn't a huge problem but one I'm going to move away from.  I'm estimating around 30-40 cubic feet per minute and fifty at the tops.  For under ten English pounds I can buy an eighty cfm brushless 12v dc fan and power it from a peltier thermoelectric generator using the heat of the fire to fan its own flames. I'm also considering steam power, which would be a nice metalwork project.

Sparky

Astute observers will notice there are a lot of sparks in the picture. I chose this picture simply because sparks look cool and I'm embarrassed to admit it - but they are just from some kindling I added. Most of the fuel was clean, which overall is a requirement for a hot burn. The fuel here was cheap lump-wood charcoal from a supermarket and it's quite good enough for a home foundry. It was a clean, hot, almost smokeless burn.

Off camera, two fourteen litre buckets of water stood by quench any cinders that ignited the dry recently cut grass and woodchips left from the afternoons whittling. Safety first people.

Temperatures reached

This 3/8 inch round-bar reached a good yellow colour and in the region of 1100 to 1200 degrees C, that's something like 2000 to 2100 degrees F and well hot enough for working with. From its softness I've no doubt it was that hot. 

My goal was to reach a steady nine-fifty degrees so that I could confidently melt bronze and frankly having exceeded that with a margin to spare this yellow steel signifies a reason to celebrate.

In fact I was amazed how quickly the fire beat the nine-fifty mark without the lid on or a proper air supply. It's already hot enough to melt bronze, and there are several improvements to be made.

Refractory lining

By the time this picture was taken, the exterior of the bucket was warming up but still cool enough to hold your hand against - maybe 50 Celsius rising to around 70 near the base compared to bringing steel round-bar up to a thousand degrees.  The base is slightly thinner than the walls because I wanted as much crucible height as I could get and it's the weakpoint in the design. 

The exterior wall eventually got hot - maybe even above a hundred - and and extended forging could be a problem.  As a foundry for small bronze, brass or aluminium projects then the bucket wouldn't get overly hot but it will really heat up if I run it as a forge for a few hours. A sturdy base of commercial firebricks - then it'll be fine. I don't think the bucket has any risk of failing.

Closing thoughts

You can do an awful lot with very little. Plaster of paris, sand, and a steel bucket cost next to nothing in this day and age.  I bought a value hairdryer from the supermarket and used some cheap lumpwood charcoal to get these results in my garden.

Armed with a modern understanding of metallurgy that outstrips my bronze age counterpart, I should be able to produce results worthy of a traditional redsmith. The first world information age has provided means and materials that would have astounded and amazed bronze age Europe.

I started this journey knowing very little about the technological landscape from three thousand years ago and I'm already impressed with what they achieved, and they did it without being able to drive to the retail park and buy sand or order buckets online.