This week is seems that I have been doing everything and anything except turning wood on the polelathe and I’m getting more than a bit paranoid about it. But for the last 3 years I’ve managed to spend a day at the Old Kiln Forge (Rural Life Museum, Tilford) talking plenty of bowl hooks. Last year I produced a couple of hooks that improved my bowl turning and I had a fairly clear idea of what I wanted to do this year so better to do it before the season starts in earnest and I also have to fit with my blacksmithing mentors.
The forge is really coming together. It’s the little things that make the difference and I can sense that this smithy is both loved and used!
My visit to the museum also included the opportunity to drop off this old Avery fuel pump (last used on Haslemere High Street for dispensing Paraffin I’m told – and that must have been a few years ago) to its new home. And on Sunday I’m teaching polelathe turning at the museum so it was a chance to check the setup and preparations as well. But that didn’t get in the way of the metal bashing too much and I got plenty done.
The aim of the session was to make an improved bowl hook for turning bowls on the pole lathe – the search for the ultimate bowl hook is probably just a manifestation of the inevitable gear freak in me. Here’s one of last years in use on the lathe. You can see how the shape of the hook allows working into the deep curve of the bowl and it’s evolved to suit working sideways into a bowl held between centres – but there are few things on this one that I don’t quite like, for example, the tip is too long for undercutting the central core easily.
I was going to put all the bowl hooks (if you’ll pardon the expression) into one post but it was taking a long time to write and I’ll lessen the pain on you by splitting it into more manageable chunks (maybe). A bit like the material I was using, which started life as a coil spring – a 1987 Range Rover coil spring to be exact and first needs to be split into chunks.
In this post I’ll look at the preparation of the material and issues with reusing old metal. It’s invariably the wrong shape to start with and you’re never quite sure what it is. But this can be simply overcome with a hammer (also known as Landrover Special Took No1).
There are several ways to shape the material. I cut a couple of rings off the coil using an angle grinder which makes it more manageable in the fire – you can see the rest of the coil to the left of the fire.
But essentially you just need to heat the metal to make it malleable and easier to bend. It’s not necessary to heat it right up to a bright yellow but its very easy to bend at that heat and here John shows me how to strighten the coil with a minimum of blows from the hammer.
But given a chance he’d prefer to straighten out the spring in one piece with no nasty angle grinders and here Robert gets on with unwinding the coil whilst I’m making up the first hook.
Instead of a hammer Robert does most of the work by using a cunning yoke shape that fits into the hardy hole on the anvil (The hardy hole is the square hole on the top of the anvil).
Using old springs is a natural place to start for making sharp tools that will keep their edge. Unlike normal mild steel which is relatively soft, Spring Steel has a high level of carbon and will become very hard (and possibly also very brittle) when worked and tempered in the right way.
The first and easiest way to test the steel you have is to try filing it. If it won’t file then its a harder steel than mild steel (does depend upon your file of course). Another way is to put it on a grinding wheel and compare with mildsteel. A harder steel will produce lots more sparks on the wheel.
By using Spring Steel you already know it must be high carbon but unfortunately you don’t know just how much carbon is in the spring steel you have, nor whether small amounts of other metals, magnesium and cobalt for example have been added to give the spring its characteristics. So buying in fresh stock metal to a known specification is a more consistent way to achieve results – tool steel 01 is the commonly used spec. Though its important to remember that consistency and specification are not the same as performance. It just means its always the same.
But 4 coil springs gives you a lot of metal to try out – it will probably make me enough bowl hooks for life! So I can afford to try out a few and when I find the right springs keep the rest of the set to make more tools. As it happens these range rover springs cracked in service, a hint that they will likely be plenty hard enough for me to use.
When you forge high carbon steel you will soon learn not to heat it too hot. This is probably around the limit -as soon as you achieve bright yellow going towards white hot the steel starts to burn and becomes a sparkler. You’ll know when you see it. This is another test for your steel – mild steel with little or no carbon will not burn in this way. Unfortunately when this happens you will ruin the steel, but you can always cut a bit off or use that end for the tang (handle end) of the tool.
The job is finished using a hide hammer which allows blows to straighten the rod along the flat(ish) top of the anvil without squashing the crossection of the rod. Again a minimum of blows to achieve the job not only saves your back, but also time and burns up less of the hide hammer – though the smell of the roasting leather mixed with the normal hot metal and coke smell of the forge is a bonus.
There is something undeniably satisfying about making your own tools – especially when you are reusing old metal and giving it a new lease of life. It can take a long time to prepare the material for use – but if like me you don’t bash metal too often it’s not a bad way of getting to grips with things again before getting to the business end of the tool, which I’ll look at in another post.
