Sunday 30 August 2015

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!

Saturday 29 August 2015

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.

Thursday 21 May 2015

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.

Sunday 17 May 2015

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.

Tuesday 12 May 2015

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:



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.

Thursday 7 May 2015

Thing of the Week - Scones


Hey everybody what is going on?
I'm Roger in Technology and welcome to Thing of the Week for the Seventh of May 2015.

The discovery of fire brought mankind heat, protection and cooking but arguably it was the invention and refinement of the oven as a cooking space that revolutionised our relationship with fire.  Early ovens date back thirty thousand years and we've come a long way from the primitive pits used to cook mammoth. As far as I can tell, ever since then mankind has been striving to develop the ideal oven that cooks evenly to bake the perfect scone.

Ancient civilisations developed stone, brick, and clay ovens to radiate heat evenly, some employed smoke dome and chimney arrangements to use the heat of the smoke too. There are so many mechanisms and designs of oven over the centuries. From insulating clay ovens and metal agas that employed the huge heat capacity of their bodies, modern gas ovens allowed for precise fuel consumption to regulate temperature. But its the electric age that raised the bar by adding thermometer control. Thus the electric oven has taken its place as the final step in this long journey our civilisation has taken to reach peak scone.


The humble scone has existed in one form or another for centuries, and uses the most basic of cheap ingredients. Delicious sweet or savoury, they have become synonymous with cheese, cream teas or strawberries and bubbly. Whether you like butter, honey or fruit, the scone has a lot to offer as part of a balanced diet.

Top scones continue this tradition of self raising flour, butter, sugar and milk.  Often egg is employed to richen the mix, or an egg glaze is used for the same reason.  But do not trust a scone with egg, its a distraction tactic that just isn't needed on a good bake - the advice here is stick with the classic ingredients and use additions that theme and personalise your scone.

Fruit can be used, and often is. Sultanas are a classic for a reason, and they can be added to the mix or studded before baking. A little grated lemon zest offsets sultanas and lightens up the aroma and palate here.
Roast strawberries are a delicious addition too, although extra preparation is needed, and the addition of summer fruits give a fresh seasonal twist. Later in the year, orange and cinnamon can bring a delicious scone to life too.

Sifted flour should be mixed with sugar in a bowl. Typically only a tiny amount of sugar is used, even for sweet scones which can get their natural sweetness from fruit. Rub the butter in until you have breadcrumbs and slowly add the butter until you have the dough. Flatten it out and stamp some scones for baking at 220 degrees for fifteen minutes or until golden brown.
You can find details about proportions and recipes online, and should be able to find something that fits your tastes. I know less about baking than I do about history but even I can tell this recipe that has stood the test of time will be with us for centuries to come.

I enjoyed these scones warm with honey, which I can heartily recommend, as the subtle sweetness blends with the enticing aroma to produce a breathtaking masterpiece.  I hope you are inspired to get back to the simple roots of baking and experiment with the humble scone, as relevant in the 21st century as it was a thousand years ago.

Friday 1 May 2015

Knife of the week


Hi guys and welcome to Roger In Technology.

This week I've picked a bit of steel to talk about. The invention of steel represented a cornerstone in technology for mankind, allowing tools, machines and weapons to be built to a higher standard and precision than ever before.

From blister steel, through crucible steel to the wide ranges of air, water and oil hardening steels we have today the world has been taken on a one way technological journey. Steel revolutionised all aspects of technology, and new technologies were invented to refine steelmaking.



This is a Gurka Kukri style knife dating to the mid twentieth Century. It's a versatile tool and deadly weapon with a proud military history from one of the most famed and feared military units in the world. 

It's about 34cm and has quite a weight to it because of the broad belly and the width of the spine. In fact this small steel blade weighs easily as much as some steel swords, and is as heavy as a generation of bronze age swords.

Pictured here is the "before" from a restoration work I'm doing. The blade itself has clearly suffered a lot in its life. The blade is dull, and while somebody has attempted to sharpen it they just didn't have the right tools. I'm going to grind a new edge on it and then clean it up with about a 1200 grit and hone the blade.

Kukris are traditionally made from leaf spring steel, which was readily available from scrap vehicles so we can take our best guess on the properties of the steel but to be honest the exact metallurgy isn't too important for the restore work I'm doing.

The blade is showing no scaling or flaking that would be evidence of heat damage, so I'm going to assume the temper is good and we don't have to heat treat it.  Heat treating a blade like this was a daunting task that I wouldn't look forward to, and I was somewhat relieved to see no evidence of overheating on the steel.
In Nepal, there are guys that quench the cutting edge with boiling water and allow the spine to carry its heat and temper the blade. I've got no desire to water quench this mystery steel as there is a good chance I'd crack it and ruin the piece. Actually, I've got no desire to heat-treat this at all, as I'd have to remove the handle and then I'm making a lot of work for myself.

There are some spots where water has go to it, but they appear to be surface marks and will polish right out with some high grit paper. The blade is fullered, which I didn't expect from a Kukri blade where I wouldn't have thought weight reduction was a consideration, but I'll admit to not knowing anything about this type of blade so it might not be that unusual.

Other than that, the blade shape is a little uneven and there is evidence that part it has been ground down. I'll try and get a nice even shape although that will mean a little more materials reduction than would be needed to just sharpen an edge and this brings me back to the temper. If its had a differential temper then the edge will be harder than the spine and I don't want to cut into the steel too much but it looks like I've got no choice.  There is also no point second guessing the properties of a mystery steel. I'll learn a little more by working the metal but for the most part it is what it is.

The handle is maybe a little long for a Kukri, but apparently this isn't unusual for service issue blades, and it appears to be a partial tang which again is traditional.  I first thought it was an integral bolster that had taken some damage but its clearly a second block and this is where the craftsmanship lets the blade down and seriously questions the authenticity of the piece.

I don't like the workmanship on the bolster, I don't like much like the decorative/mosaic pins on the handle either. They look out of place and more what I'd expect from a replica sold to tourists than a functional tool. There is an ugly boss on the pommel too, that can't be seen in this picture, but it doesn't scream quality. The chakmak is missing but the karda is a tiny thing that looks like its been stamped out of a sheet. No attention to detail and no craftsmanship on this which again is probably a bad sign.
Finally in my appraisal of the knife my mind keeps coming back to the uneven blade. Either its been used to hit rocks and somebody has ground those nicks out, or the steel is so soft it picked them up from normal use - so it'll be no good for a knife.  Since I'm already pretty certain it's not an authentic blade, I'm worried the quality of the steel is poor too.

My next step is to grind a new edge on it and sharpen it up. I'll use it to process firewood and see how well it holds an edge. If it survives some pretty rough treatment then I'll clean it up and get a dab of oil on it and it can be used as a camping and woods knife, or out in the garden to clear the brush and weeds.
If the blade goes dull quickly then it'll have more value polished up and looking pretty than cutting anything so I'll get it semi sharp and then polish the hell out of it. I can either mount it on something or sell it on to somebody who cares more about aesthetics than practicality.

Tuesday 28 April 2015

The foundry is built


Project of the week is making a firebox suitable for a foundry that can be used to cast brass, bronze, or aluminium. .. and with a bit of elbow grease, the foundry has been built.

A refractory lining made of equal measures plaster of paris and sand has been used to line a 12 litre galvanised steel bucket.


The process is reasonably simple, although I'd recommend thinking twice and acting once in most cases as having to think and act at the same time can prove difficult.  I'd mostly planned the build and it went mostly to plan so I'm considering this a success.

Having not mixed plaster by hand before I will confess some initial concern that I'd make a lumpy mess that wouldn't be a smooth mix by the time it started to harden, but within 5-10 minutes it was smooth enough that I couldn't feel any lumps with my fingers and I decided it was time to pour.

The centre space for the fire was formed easily enough and with only a little fuss and bother, and the mix solidified up reasonably quickly once its fifteen to twenty minutes was up so all in all the timing was pretty good.

The finished product, or about as finished as it'll get tonight.  My reservation is that I should have made more lining material so that the firebox is deeper. I'd want it higher up the sides and deeper on the base.



The measurements looked good on paper, and I did a test run with water to work out how many measuring buckets of water fill the steel bucket. So I expected the volume of the lining to be spot on, but the drymix doesn't pack like water and the overall mix was about 30% smaller that I'd expected. The lesson learned, of course, is that I can afford to mix too much and tip some away but not having enough is a bit of a pain.

The firebox looks large enough to get a good charcoal burn and well big enough to work on small projects like tools or knives.

The mix stays butter soft for a long time, and I was in too much of a hurry to get the holesaw out and get the blast hole cut. Next time - if there is a next time - I'll be happy to wait a half hour or so before cutting. The steel is pretty thin and offers little resistance, and while you want to cut the mix quickly I didn't have to put myself in a rush to do it.

More news as it breaks, but with the bank holiday approaching I should be able to fire this up and see how it performs.

Wednesday 22 April 2015

Proper Preparation and Planning


Preparation and Planning
While I'm not getting much project time in at the moment, I'm not wasting the time I have in proper preparation and planning.

The first working fire is about to be built - I've got sand arriving tomorrow that I'll need for the refractory mix and I need to buy a hole cutter to make the blast so I should be able to go out this weekend and if the weather holds I'll put it all together.

My first working fire is a foundry that I'll repurpose for some hot metalwork. It'll be fine until I can build something bigger, and will let me make cast brass components that I may well need soon. To this end I also caved in and ordered a graphite crucible online, I think I'm going to make a steel one when I can but having "That crucible problem solved" for now is going to mean I can get stuck in.

I'm going to use a cheap air blower from an outdoor ship and see how hot the fire gets. Long term I've got plans for a peltier effect module to power the fan from the fire. But the first step is putting a blower on there and getting a feel for how much air it needs to get a good burn.

Patio Paving
After making a few sketches and standing in the space, I'm pretty much sold on a patio space 15" wide and 18" deep, with two benches and a circular firepit around 3" in diameter.  This second firepit will be mostly for heat and show, but I want to be able to cook on it so a good first project for the working fire will be making a rotary spit.

Practical Project
The rotary spit will start as a simple A-Frame and crank handle, but if I want to spend two hours cooking a chicken I'm going to need to automate that rotation and the blog comes full circle to Roger in Technology.

Presenting Peltier 
The three engines I'm considering are all quite different in their construction and maintenance, and each with its pros and cons. The first is to use it as an excuse to make a peltier generator, which is a remarkably good project to start now, especially if I want to use it to power a fan later on.
The simple construction is a metal squarebar with a peltier device and heatsink on. The squarebar can be staked into the firepit at an angle, with the heatsink off to the side. And then I'll run an electric motor on a belt drive to turn the spit.

The peltier solution is nice, but it'll be difficult to get much current without a reasonably large array of peltier effect generators and a large heatsink. I don't know how much current I need to generate the torque to rotate a chicken. In fact, I don't even know how much torque you need to rotate a chicken so I could test this with some 9V or 4.5V DC motors and see if they are likely to be up to the task.

Piston Power
While the peltier might not work, the age of steam has me covered. I know I can build a steam engine with a boiler I can place in a cooking fire that will have much than enough power available - so specifically I can build a very small steam engine that will do the job.

It's a little fiddly to have a steam boiler in the fire with brass pipes leading to a steam regulator and crankshaft setup. My concern is that I have two unique units connected by brass pipes, and the pipes will bend and break.

The next option here is an external combustion Stirling engine. Relying on the expansion and compression of the working fluid, the stirling could probably be a single unit. Like the others it would sit on the edge of the firepit. Its probably harder to construct than the steam, but doesn't need as much pressure in the boiler and feels like a safer bet.  I find the stirling a more interesting design, and it should be very easy to maintain and run - needing little tending compared to the steam that might need me to look after the boiler.

Practical problems
Whatever the build, I need something that is easy to store. Its not going to live in the elements all year round, so I want something I can easily carry from the firepit and stow away to cool once the cooking is done.

Thanks for reading everybody, I know this wasn't really an action report and I don't have any pictures.  I'll get some pictures of the gear and the space before the build starts.

This blog was brought to you by the letter "P".

Wednesday 15 April 2015

Firepit, Foundry and Forge.


Progress report on the technological terror I am creating.  This year, I'm in hardware mode instead of software.

Hardware this year doesn't mean valve amps and videocards, instead I'm going back a few thousand years and starting with the basics.  Aside from land clearance in the garden, the first construction is about to start - although land clearance and gardening is more challenge than you'd think.

Dakota Firepit
The first thought was to dig a dakota pit, and since I've uprooted some hedges I had a good starting hole to use that I've spent some time looking at.
The Dakota pit is a low-tech solution that I could build with stone age tools, and while I don't have any stone age tools I'm willing to improvise. It'll be enough to heat and beat some metal, and is a good cooking fire too.
I think I can get good airflow from a simple 12V DC brushless fan using an old chimney pot to duct air inwards, so I could upgrade the Dakota pit to get more heat and be a temporary forge fire. This blend of stone-age and modern technology pleases me.

However, the Dakota pit isn't a very visually appealing structure - its a hole in the ground full of fuel and ash at best - and at worse looks pretty naff. Ok, I'll be adding an electric chimney but it's still a hole in the ground. Rain will get to it too.
Its also fundamentally a floor pit which isn't a good height to work at. I'm not going to knock it - as a practical survival fire its amazing but for a domestic garden I can afford to go upmarket so I've been searching for practical alternatives.

Brake Drum Forge
The height of the Dakota pit is annoying, so I'm looking for a raised firebox at about waist high. Being portable is an advantage here because i'll be forging outside, but I'm going to want to store it in a shed to keep it safe from the elements.  Once I've built a forge house I can have a more permanent set-up, but I'm looking at getting started straight away so want something small.

A Brake Drum forge is easy to build, the parts are basically scrap metal and its reasonably portable. brake drums are galvanised, so can give off some fumes but I'll be outdoors and can probably deal with it. It's small, portable, and cheap and brake drums are the starting point for many blacksmiths.

Foundry
While the brake drum forge is probably the best starting project, there are some restrictions on its construction.  A Dakota pit can be dug with stone age tools that I could make myself, while a brake drum forge needs cutting, welding, and tooling.  Normally, practicing these skills is a great task but I want to avoid spending money on gear.  Also, the brake drum forge still makes your garden look like a scrap yard. There are also fumes from a brake drum and I'm not too into that.

The compromise is to make a storm-in-a-teacup, on this case a foundry-in-a-bucket.  I've got a twelve litre steel bucket - two and a half gallons - that I'm going to line with a refractory material and use as a blast furnace. With an air intake about halfway down I can use the same brushless 12V DC fan that'll get me between 30 and 50 cfm of airflow.  With 30 MJ/KG fuel I can get a thousand degrees in there and enough to liquidise brass.

Because the unit is contained in a bucket, it's super portable. It'll weigh in under 10 kilos (20lbs) and can be placed on a stand for working metal, or on the ground for stability if I'm heating a crucible.

Projects
I've got a few early projects in mind.  The foundry is one of the first milestones, and I should be able to 3D print patterns to make greensand molds from and cast shapes from brass. I'll have sand left over from making the refractory lining, and thats the principal ingredient in making casting sand.

Using it as a forge I should be able to make some fire tools, and a combination of cast parts and worked steel will make a rotisserie which will allow me to repurpose the whole thing as a cooking fire in time for BBQ season.  I guess I'll have to run the fire cooler for cooking - I'm not sure the melting point of chicken, but I'm pretty sure that a thousand degrees blast furnace will result in "well done".

The bucket foundry should be enough to work small steel and iron - tools, and some misc stuff. I'll be making nails with it for some woodwork projects. Kitchen hooks, bookends. Stuff.
It *might* be good for making chain, but there are complications and TBH I don't need any chain right now.
It'll be good for making knives, too, although I'll need a serious grinder for materials reduction and knives are a lot of work so its not a project to be taken lightly. There is a defunct lawnmower, so I'm thinking of taking the blade off and making a gardening machete from it. Reduce, Reuse, Recycle.

So overall, I'm hoping to get good use out of the bucket foundry. Pictures and videos are on their way.
Until then, Fly Casual.

Monday 6 April 2015

Can I axe you a question?


Today was an axe day, destroying the garden - uncovering & discovering a large Mahonia trifoliolata which put up a fight with its super spiky spikes of vengeance.

Only afterwards did I learn that its edible berries ripen in the spring, and can be used to produce wine or as a fruit drink. Damn, had I known I would have left it standing until harvested.  Possibly I was distracted by the amazing bright yellow wood, which I'll keep, season and hopefully make something out of. But dang, I could have had some tasty berries.


Nonetheless, everything at the back save some unidentified reeds and the shed had been cut down and they are next. We don't have a key to the padlock on the shed, but its exterior construction is a wood that will not survive my industrious axework and it won't last once I focus my attention on it.   If it wasn't for the fact that everything has been chopped down, I'd be shopping for a bigger axe right now.


The wood I've collected isn't enough to make the benches from but I'll make a logpile and it'll feed the firepit on a summer evening. There is a tree that I've got my eye on, that might have to come down and then I'd be really tempted to make a bench from it rather than firewood.

The base on the shed isn't all that - Its bordered by pavers and to be honest I don't expect to uncover much more. So now I've got an 18x25 foot space - once the shed is cleared and the ground is dug - to build the forgehouse and patio space. The Forgehouse looks like around 9x15 foot or therabouts, with space for stock, fuel, hot and cold workbenches and all the regulars and comes in under the planning permission radar as long as a few simple checkboxes are ticked. It has to be non-combustable, but I was planning that anyway, and it has to have a decent floor and not have a bed in it. Also, 2.5M eaves and a 4M pitch, but those are way bigger than I need so it should be a breeze.

The hot workbench will be commercial firebrick on a sand base, and hopefully suitable for casting brass and other soft metals. The cold workbench will just be a thick wooden worksurface with a decent vice.

Meanwhile the patio has space for probably three benches, or two benches and a gazebo, and a firepit around three or four foot in diameter. This will be an earth or sand base for wood and charcoal burning, and I guess cooking over. This needs a plan. For all I know at the moment, I have a square space around 18x18 foot and want to have at least a bench and a firepit.

So plans are coming together. The base and patio are going to cost around three grand if I get contractors in, probably more given there is little to no access to the rear of the garden.  I can do it myself for around 750-1000 looking at the materials cost, or around half that for cheap ass paving, and I'm torn between just waving a wand and having somebody do it while I'm at work or plugging away at it with flesh, blood, sweat and tears.

Materials for the forgehouse are expensive in this part of the world, and I've got to choose between stone and brick which may end up being a very very difficult decision. The firebox, anvil and forge tools I need are cheap enough and everything beyond the basics I can make once there is a fire going.

It's a huge plan. Its a grand design. Its a lot of work. I'm starting to feel that this year will be the groundwork and learning year and the construction might not be finished until after the winter.

Sunday 8 March 2015

Starting Hardware mode.


Hardware mode
Today saw the first in a revitalised project. As the winter washes away I find myself in hardware mode again, and itching to make - and break - all manner of things.

There is a space at the back of the garden that I can zone for outdoor projects, and I want to do some ironwork so naturally bought a woodsaw and hatchet.  Between those and some good garden shears I've been able to start the land clearance I'll need before the garden bursts into life with the upcoming spring growth.

It's a dependency satisfying side-quest, a matter of tracing the cause-and-effect back until I get from the ideal set-up to the status quo.  And the status quo is an overgrown area, a vegetable plot and a garden shed.

The Space
We're fortunate enough to have a bit of space at the back of the house, and the rear portion of it looks ideal for a toolshed. The entire width of the garden is about 25 feet, and in the back portion of that stands a garden shed, a vegetable plot and some unused land.  The rear of the property is a brick wall, one side is a 4" high fence with some bushes and the right side is 8" evergreen hedges and some trees.

That gives me an area about 25x18 feet, with a 6" brick wall along the long edge. I intend to replace the dilapidated old shed with a stone tool shed with a solid workbench, fire-pit and small anvil on a solid block.  I'm going to need a solid base on probably that entire area, which means digging it up.

So... naturally if I want to heat & beat the first step was to do some gardening. Raze the bushes so I can dig the earth to lay a concrete base to build a tool shed on. Then I'll be setup for metalworking. I'm thinking of keeping enough space for some seating - a couple of benches, but I might make those myself once I've got some toolworking space.  And to be honest if I'm making a bench, I'll probably make my own nails at the forge.

There are plenty of other hardware projects that'll go alongside this. The question of a smelting fire and crucible have come up.  We had a crucible at the forge I as at before but I was never brave enough to try it.  It was also an antique, and probably against conservation guidelines to use it anyway.  But smelting brass or aluminium isn't so much hassle, and you need to get to about a thousand degrees which is quite achievable in a small fire and I'm game.

So, that's hardware mode. It's a weekend project, and I'll try and get some "before" pictures taken so we can document the transformation.