New Beginnings

I have moved back to Burnley! Soon I should be able to start making progress on building my first instrument. Currently my tools and materials are piled up in crates and boxes in my bedroom and garage, and my milling machine is broken down into several pieces, so my first task is to convert this damp 6×8 feet garden shed into a cosy little workshop:

shed_before

At some point I hope to save up enough money to replace it with something a bit bigger and more substantial that is designed from the ground up to be dry, insulated and secure. For now, my plan is to install a tiny coal stove (which can later be transferred to the new workshop), repaint the outside walls, add more ventilation, and store as little as possible in there when I’m not actively using it.

The first thing I intend to make in the new shop is a workbench. Nothing massive or fancy, just a solid pine worktop (made from a spare kitchen table I found in my parents’ loft) at a convenient height, secured to the floor/wall, with some old cast iron vices and a planing stop. After years of working on flimsy trestle tables and Black and Decker Workmates, it will be great to have a sturdy fixed bench that doesn’t skitter across the floor when I try to plane something. In a stroke of good luck, just as I was starting to think about workbench design, I happened to stumble across a copy of The Workbench Book by Scott Landis for a couple of pounds in a local charity shop. It’s a hefty book filled with inspiring ideas. My first self-built workbench probably won’t be my last, but seeing what other woodworkers are working on has helped me to identify more clearly what features I think I will find most useful for the type of work I do and avoid some things I might have regretted later (e.g. I don’t want any dog holes in the top: too easy to drop small parts down them).

Making concertinas from scratch requires a lot of tools. Metalworking, woodworking, leatherwork, and some very specialised things like a tuning rig. In addition, there are opportunities to speed up production if you invest in special tooling and machines. In order to try to avoid falling into the trap of Tool Acquisition Syndrome (gotta collect them all!), I’ve started categorising tools like this before I decide whether I need to buy one or not:

  1. Tool that is the bare-minimum cheapest way to perform an essential operation. For example, it’s perfectly possible to cut out fretwork ends using a cheap and cheerful bent steel fretsaw you can pick up for a quid or two at most car boot sales. I have a few of these in various sizes. They are a bit slow and tiring to use for long periods, but they are perfectly capable of producing excellent results.
  2. Tool that speeds up an essential operation. For example, a scroll saw is a machine that does essentially the same job as a fretsaw but can cut perhaps four times as fast with less physical effort. The difference is actually probably less significant with more complex designs because you spend so much of your time stopping and moving the blade to a new piercing. I have both a treadle and an electric scroll saw. I should probably get rid of one of them to save space, but I need to do some proper side-by-side tests before deciding which of them I prefer to use.
  3. Tool that is a higher quality version of something I already have. For example, my scroll saws are both hobby-grade machines: either will do the job for now, but certain features are inaccurate, fiddly and annoying to use, or not built to last. If in the future I find myself with the budget to upgrade, it would be nice to step up to a higher quality saw like a Hegner, or maybe even a vintage industrial machine.
  4. Tool that would be nice to have, but isn’t essential to concertina-making at all. I’m struggling a bit to continue with the fretwork analogy here. Let’s say an electric bandsaw: one could perhaps argue that it could be used to rough out the blank more quickly than with a handsaw, but it isn’t of any use for cutting the fretwork itself because you can’t get the blade inside a closed piercing (and they can’t cut very fine details and tight curves).
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Milled Boxes

It has become a tradition for me to make several Christmas presents each year using whatever tools/skills I have picked up most recently. This year my latest tool acquisition is the CNC milling machine, so I decided to do a project that would show off some of what it can do, as well as giving me some useful experience in programming it. A friend suggested trinket boxes. After considering various possible construction methods, I settled on milling them from blocks of limewood with thin plywood bases and lids.

I needed to make presents for three people. The nature of one-off CNC manufacture is such that most of your time is spent at the CAD/CAM stage, because you have to plan every detail in advance and figure out how to tell the machine what to do (being careful to avoid anything that is physically impossible, for example asking it to cut a 3mm wide slot when your smallest cutter is 3.175mm in diameter). It would have been easy to design one box and produce three exact copies, but where would be the fun in that? I instead decided to do three different designs. I learned new things from each one and I feel the third design is the best, so it wasn’t a wasted effort.

The CAM workflow was basically the same as with the maker’s mark stamp except the designs and machining operations were far more complicated. An additional step was deriving the profiles of the lids from the shapes of the rebates they sit in; this was complicated slightly by the fact that I needed to round off all the points because the internal corners of the rebates can’t be any sharper than the diameter of the router bit.

The milling operations themselves mostly went OK. I suffered one stepper motor stall while milling the first box, but I heard it happen and managed to hit the e-stop in the nick of time before it did any noticeable damage.

milling_box

routing_lids

I made one design mistake: one of the lids was cut to the wrong outline (you can see it in the next photo). I didn’t spot it at the simulation stage because it was approximately the right shape for the compartment, just slightly too big.

milled_boxes

When I cut the replacement lid I took the opportunity to make a little Christmas tree decoration at the same time:

snowman

The boxes looked pretty plain with ordinary birch plywood lids, so I bought a selection of patterned decoupage paper on eBay and pasted various combinations to the lids. I also pasted plain coloured paper to the bottoms.

pasted_decoupage

I turned the knobs by hand from beech. Because there was quite a bit of variation I made more than I needed and picked out sets that went well together.

turning_knobs

turned_knobs

Here are all three finished boxes after lacquering:

finished_boxes

The ‘S’ box is my favourite (made for my mum, Sandra):

s_box

I came up with the basis for the design while playing around with mathematical knots. It is based on the 8 18 knot.

Incidentally I now have an Instagram account and I’m using it to post pictures of things I’m working on.

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New Stamp

I’ve been spending quite a bit of time recently working on my CNC milling machine and learning how to program it.

The main improvement I’ve made is to replace the spindle drive motor. The one that came with the machine was a 1/4HP single phase motor that ran at a fixed speed that gave me, on the top pulley ratio, something like 4000RPM at the spindle.

new_cnc_motor

The new one is pretty much the same physical size and weight (maybe a little bit lighter) but it is a 1/3HP three phase motor that, paired with a used Mitsubishi Variable Frequency Drive (VFD) from eBay, can run at any speed from almost 0RPM up to higher than I’ve dared to take it (it’s comfortably fast enough to run the spindle at its rated maximum speed with the standard bearings: 10,000RPM). It’s a fully enclosed industrial induction motor, so it should be robust and have a long lifespan in the presence of dust and swarf. I’m surprised more people don’t go down this route to put a variable speed motor on their Taig mills; it seems almost ideal if you’re happy with the standard Taig spindle. Eventually I’ll probably put a similar setup on my lathe. The main drawback is that it’s fairly complicated to configure the VFD to get it to perform optimally.

The VFD replaces the contactor (the glorified on/off switch bolted to the old motor) and I won’t be mounting the VFD on the side of the new motor, so that has reduced the weight on my Z axis a bit more.

The drive shaft key had been removed from the old motor to avoid having to cut a keyway in the pulley (not me: it was like that when I bought it). Although I’ve never had a problem with it, that felt like a bit of a bodge so I used a square needle file to cut a keyway in the pulley for the new motor:

motor_keyway_1

motor_keyway_2

motor_keyway_3

The VFD can take an analogue voltage input to set the speed, and the machine controller I’m using can output a PWM signal when the G-Code commands it to switch the spindle on, so at some point I’ll build an interface board to connect the two together. For the time being I’m just manually controlling the motor using the VFD’s front panel. I wrote a little Python script to figure out what pulley ratio and motor frequency to use to get a particular spindle speed.

If there’s anything in the new motor setup I’m not totally happy with, it’s the Gates miniature V belt drive. When it’s working well it’s adequate for the task, but the belts are stupidly expensive and seem to be quite easily damaged. After having a couple go bad recently, I have taken to slackening the motor mounting bolts and releasing the belt tension every time I change pulley ratios and when I’ve finished using the machine for the day.

The new motor did show up a problem with the CNC controller. It seems that VFDs put out electrical interference. Lots of it. I had previously found with the old motor that I would sometimes get a spurious E-stop input when I switched it on or off. With the VFD I could get them at any time the motor was running, and also the steppers sounded ‘lumpy’ and kept randomly stalling. I found that if the spindle motor was running while an axis was doing a rapid move and I picked up the VFD and moved it close to the CNC controller box, the stepper would inevitably stall. Conversely if I moved the VFD and controller as far away from each other as the cables would allow and placed a metal bucket over the VFD, the problem went away. The permanent cure turned out to be that I needed to connect the 0V rail of the Arduino in the controller to the chassis earth star point. Since then it’s been behaving itself.

I’ve fixed quite a few bugs in Handwheel and implemented a few new features, and it’s running pretty well for me now. I’ve been doing the development on an old dual-core Macbook Pro and my workshop machine is a quad-core Raspberry Pi 2, and it performs great on both of those. Handwheel is divided into several threads, structured in such a way that as long as your computer has at least two processor cores (ideally four), the overhead of updating the GUI shouldn’t slow down a file send. I decided to check that it worked OK on a standard (not overclocked) single-core Raspberry Pi 1: nope, the experience was dreadful because the rapid GUI updates were chewing up all the CPU and slowing the whole system to a crawl. Several hours of optimising later, the experience on the Pi 1 is now acceptable and faster machines like the Pi 2 are even snappier. I think it will run pretty well on the new super-cheap Pi Zero too, which has the same processor as the Pi 1 but is clocked something like 40% faster. I’m hoping to finally put out an initial public release over the Christmas break.

I also got side-tracked into working on a problem that was causing data corruption between the computer and the Arduino at 250000 baud: I tracked it down to the firmware on the Atmega 16U2 processor they use as a USB to Serial bridge, and came up with a fix.

I’ve started learning how to take a design and make it into a set of instructions to control the machine. This is called Computer Aided Machining, or CAM for short, not to be confused with Computer Aided Design (CAD), which is basically a way to do engineering drawings on a computer. There are a huge number of CAM programs available, with a wide range of capability and maturity at prices from free up to thousands of pounds per year. After quite a bit of research I settled on a program called CamBam, which seems to be the most capable option I could afford. Awkwardly, because it’s a Windows program and I’m a Mac user I ended up also buying a second hand Windows XP license and installing it on a virtual machine. A little bit clunky, but it seems to be working OK.

There’s a pretty steep learning curve to CAM, particularly as I haven’t got a great deal of experience or any formal training on manual milling machines. For example when milling manually I would guess at a spindle speed and depth of cut, then adjust the feed rate by gut feel based on the sound of the tool (and perhaps how much smoke/steam was coming off the cutting lubricant!). With CNC you calculate the parameters in advance, configure them in your CAM program, double and triple check everything, and hope you didn’t put a decimal point in the wrong place and accidentally command the machine to stab the end mill into the work at 500 miles per hour. Actually, I’ve found with my initial experiments with routing wood using carbide bits, the limiting factor in how fast I can cut is my machine’s top speed (1400 mm/min, 55″/min), which is set by how fast the Arduino running grbl can emit step pulses (30KHz). As a result I’ve been turning down the spindle speed to something like 5000-7000 RPM in order to get a decent chip load and avoid making a lot of dust and heat. It isn’t really a problem for what I’m doing with the machine, but I must admit the part of me that wants to optimise everything has been considering overclocking the CPU in the Arduino to increase the maximum pulse rate!

The first thing I milled under CNC control was to flatten the top of a plywood spoilboard I made that bolts to the bed of the machine and allows me to easily screw down work and to cut through it without damaging anything important (when it gets too chewed up I can re-surface it, and when it gets too thin I can glue a new piece of plywood on to build the height back up).

The second thing I made is a wooden stamp of my maker’s mark. I started out by designing it in Inkscape. It began as a Futura ‘A’, then I tweaked the proportions a bit and added the arms and the outer border:

makers_mark_inkscape

Next I exported it to DXF and imported it into CamBam. This screenshot shows the finished design including all the generated toolpaths. Figuring out how to do this is what took the bulk of the time spent on the project. Now I have a better idea what I’m doing I could do a second one fairly quickly:

cambam_screenshot

While developing the CamBam design, it was extremely useful to be able to be able to simulate what would happen if I was to machine the part. For this I used an open source program called CAMotics (formerly OpenSCAM). It’s still a little rough around the edges but I found it super useful. As soon as I actually make some money from CNC I’ll be sending a donation their way.

makers_mark_stamp_simulation

Before making the real part, I did a test run using some scrap pine. Good job I did, because it turned out I’d set the stepper motor acceleration parameters a bit too high and part way through the Y axis started losing steps:

failed_test_run

After dropping the acceleration by 20% I completed a second, successful, test run, then made the real part from end-grain limewood:

finished_makers_mark_stamp

I’m pretty pleased with the end result. The wood soaked up the ink like a sponge; in hindsight it might have been a good idea to seal it with a coat of shellac or something before using it.

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Octagonal English Earrings

I made a new design of silver concertina earrings; an octagonal 12-button English layout, slightly larger than the previous two at 25mm across flats. The reason I reduced the number of buttons and also increased the overall size a little was so that I could fit in a more complex fretwork design than on my earlier hexagonal English design:

octagonal_english_earrings
(Don’t try to make sense of the layout from the picture; I accidentally posed them the wrong way round.)

The pair in the picture was a birthday present for my mother. If anyone wants to commission a pair, I’ll do them for £75 + postage. Drop me an email via the contact address to reserve some time in my schedule, the sooner the better because I’m very busy with other projects.

As you might have spotted from the video in my previous post, this is the first design where I drilled the pilot and button holes using CNC. I still cut all the piercings by hand with a very fine jeweller’s saw because the details are extremely small with lots of sharp corners. Obviously all the soldering, polishing, and making the ear-wires are done by hand too.

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CNC Mill Progress

A little over ten years ago I bought a manual Taig milling machine with the intention of converting it to CNC. For reasons too boring to go into here, the conversion got postponed indefinitely. It remained in its manual configuration and saw little use (probably a couple of hours a year, mostly as a glorified drill press with XY table).

About a year ago I finally started collecting parts to do the conversion: Chinese stepper motors, switch mode power supply, driver boards and an Arduino Uno clone via eBay, and motor mounting kits from Lester Caine at Model Engineer’s Digital Workshop.

I was happy with most of the components, except for the Chinese driver boards which turned out to be a hopeless waste of money (basically, a design flaw means they only ever run at 30% power level, and poor quality components mean they would probably quickly burn out if you hacked them to work at full power). If money was no object I would have bought Gecko drivers, but they are very pricey here in the UK so I searched for an alternative and found these THB6064AH kits. I went for the ‘special’ model because it’s easier to mount to a heatsink. It took me a couple of hours to assemble three of them, and I’m very pleased with the design and performance of them.

drivers1

I mounted them on a couple of large P3 Xeon heatsinks salvaged from old servers. I’ve left space for a fourth driver board in case I ever decide to add a rotary axis for gearcutting or something. They barely get lukewarm.

drivers2

The stepper motor controller is a cheap Arduino Uno clone running grbl, which interprets simple g-code and generates step and direction pulses for up to three simultaneous axes. I needed a way to connect it up to the drivers and various switches so I knocked something up using a (poorly designed) prototyping shield and a bit of stripboard:

arduinoshield

This is currently working fine for interfacing to the drivers, but I think I need to add opto-isolation to the inputs because I’m currently getting an occasional spurious e-stop when I switch my spindle on or off. Luckily it hasn’t happened at any other time and the program execution is always paused when I start/stop the motor, so it hasn’t caused an issue yet. It’s more likely to cause a problem once I get around to fitting limit switches. At some point I’ll probably switch to using an Arduino Nano soldered to a custom PCB with full isolation.

I mounted the power supply, drivers and Arduino inside a steel box that started out as a dead fan heater (sorry for the punny name):

grblcage

I’ve never liked the sound of the standard Taig stepper motor couplers so I decided to go with the MEDW Oldham coupler kit instead. When I took off the handles to install them, I soon realised it was going to take a bit more work than I was expecting. First I had to carefully shorten the stepper motor shafts so the couplers fit as close as possible to the motor:

steppermotor1

steppermotor2

steppermotor3

Then I had to make something to fill the space left between the nut and dial when you remove the ball handles (which you have to do because they won’t fit inside the coupler tubes). Theoretically I could have just sawn and filed the arms off the handles, but that seemed like a bodge too far for me, so I turned up some spacers from 1″ aluminium bar instead:

turningspacer

Installation and adjustment of the couplers was slightly fiddly, but I’m very happy with the results: no backlash and more than strong enough to handle the motor torque.

yaxisstepper

The most time-consuming piece of the project by far has been that I got side-tracked into writing my own user interface software called Handwheel. Turns out it’s a huge amount of work to implement a good CNC UI, but I’m pretty pleased with what I’ve ended up with. I’m going to release it as Open Source once I’ve cleaned up a few more rough edges and written some sort of user manual. More on that later.

To finish off this rather long and rambling post, here is a video of the machine in action. This was slightly nerve-wracking for me, as it was the first time I’ve programmed a CNC machine, the first time I’ve used the mill to cut metal since the CNC conversion, and the first time I’ve used Handwheel on a real part. Just to up the stakes a little, the workpiece was £12 worth of sterling silver! Fortunately everything worked perfectly.

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Star Punch

I made an eight-pointed star punch today for decorating an item of silver jewellery that I have been commissioned to make. Although it is not directly related to concertina-making, I thought it might make an interesting article for the blog anyway.

I made the punch from silver steel, which is a high-carbon tool steel with some chromium in it that comes as precisely-ground round bar stock in a range of standard diameters. It’s pre-annealed so it’s pretty easy to work with hand tools and machines before hardening. The bar I happened to have in stock was 3/8″ diameter.
starpunch1

I started by grinding a double-angled cone on the end:
starpunch2

Then I filed the facets of the punch using square and triangular jewellers’ files under magnification and plenty of light, resting the punch in a corner of my bench peg.
starpunch3

I must admit this took me two attempts. The first time I completely messed up the relief angles (it produced a circle of eight triangles with no centre), so I had to file it back to a blank cone and start again!
starpunch4

I lightly punched  a piece of softwood to check how it looked prior to hardening:
starpunch5

I didn’t want to have to try to grind firescale off the working end of the punch after hardening, so I coated it in a thick paste made from a stick of chalk mixed with a drop of water. The idea is that it prevents oxygen getting to the surface of the steel so it doesn’t corrode despite the extreme heat. My research on what substance to use for this purpose turned up a wide range of possibilities from specially-formulated industrial coatings through cockroach poison (boric acid) to something that sounded like a recipe for white bread. I had some chalk on hand and I saw it recommended in more than one place, so I thought it was worth a try.
starpunch6

starpunch7

It wasn’t worth firing up the forge for such a small job, so I simply placed the punch in a (metal) bucket of dry coke and hit it with a propane torch. The coke quickly heats up and reflects heat back at the work.
starpunch8

starpunch9

Here’s where I made my second mistake. In the heat of the moment (literally) I forgot that you are supposed to quench the tool by lowering it gently into the water tip-first so as to minimise stress and risk of cracking. Instead I thought “must cool it as quickly as possible,” grabbed it with the tongs, and randomly dunked it into the bucket side-on. This resulted in a crack along the length of the shank, luckily not reaching all the way to either end.
starpunch10

I tempered it by heating the shank in a spirit flame until the straw colour reached the sharp end. This differential tempering makes the end you hit with a hammer much softer and tougher than the end that cuts into the work, which is a desirable quality in a punch.
starpunch11

The finished punch. The anti-scale chalk paste did a reasonable job I think; all I did after hardening was to clean it off with a wire brush:
starpunch12

Here you can see the crack most of the way along the shank. The tool seems to be working OK regardless though:
starpunch13

Finally, the proof of the punch is in the marks it makes. I haven’t tried it on silver yet, this is a piece of scrap aluminium. I rather like the slight unevenness of the points, and it’s nice how you can vary the size of the star by the strength of the hammer blow:
starpunch14

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Glue Pot

I’m a fan of hot hide glue for musical instrument work. There’s no need to rehash the pros and cons of HHG versus liquid hide glue and modern synthetic glues like PVA; suffice it to say that it has been used successfully for millennia and I think there are very good reasons to continue using it for certain things including high-quality instruments.

To use HHG, you first dissolve it in water to make a gel, then heat it to about 60C (140F) to melt it. Too cold and the open time is reduced; too hot and it ‘cooks’, compromising the strength of the glue joint. Traditionally cast iron or brass double-boilers were used on a stove, an alcohol burner, or a charcoal brazier. Around the turn of the previous century somebody invented an electric glue pot, which used a thermostat and a heating element to maintain the correct temperature with much less fuss and risk of overheating the glue.

I know of two manufacturers still making electric glue pots. Hold Heet in the USA makes fairly large pots that are probably best suited for antique and reproduction furniture work. Herdim in Germany make smaller pots that seem to be targeted mainly at luthiers. From my research it seems that the Hold Heet pots are expensive in the US and very expensive in Europe, while the Herdim pots are expensive in Europe and very expensive in the US. Second hand electric glue pots of either brand never seem to come up on eBay in the UK, and it wouldn’t have made financial sense to import a used Hold Heet from the US and buy a 240V-110V transformer to power it. I strongly considered buying a new Herdim, and if money was no object that’s probably what I would have done.

If you search Google for alternatives to commercial electric glue pots, people have made them from various kinds of electric coffee pots, baby bottle warmers, old cast iron glue pots on electric hotplates, etc.

My new one is made from a mini deep fat fryer (0.5 litre oil capacity). I wasn’t happy with its built-in mechanical thermostat (it had about 15C of hysteresis and would probably have needed frequent adjustment), so I have instead hooked it up to a cheap Chinese PID temperature controller (a Rex C100 clone) with solid state relay output. This works remarkably well, regulating the temperature of the water bath to within a degree of the set temperature by pulsing a little bit of power into the heating element about once a second. I found I needed to set the water bath temperature several degrees higher than the desired glue temperature.

gluepot

I knocked together a simple wooden box to hold the controller and the SSR, and a Perspex cover to hold the inner pot in position and prevent the water in the outer bath evaporating away. The light blue gaskets are made from two-part mouldable silicone rubber. The inner pot is a 0.25 litre Stewart Sealfresh screw-top food container. I have several of them and I cut a brush-sized hole in one of the lids to reduce the rate at which water evaporates from the glue in the pot.

I also made several glue brushes in various sizes by whittling the handles from green wood and binding hog bristles to them with string. The smallest brush I made by boiling the end of the stick in water for five minutes, then smashing the fibres apart with a hammer:

mashed_brush

mashed_brush_2

 

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Lie Nielsen 101 Plane

It was my birthday recently, plus I had just been paid for one of my first commissions since I started Holden Concertinas, so I decided to treat myself to something a bit special. A new, high-quality hand tool that will be useful throughout my career as a concertina maker. After a lot of thought I settled on the Lie Nielsen 101 block plane.

It is very loosely based on the Stanley 101, which was apparently originally intended as a child’s toy but proved popular with modelmakers and was widely copied by other manufacturers. It features several improvements that elevate it to the level of a professional tool: a heavy, accurately machined, cast bronze body, fine screw adjustment for depth of cut, and a thick blade made from A2 steel. I normally prefer to save money by buying vintage tools and refurbishing them, but I think this is one case where the modern version really is a lot better (though if I’d had the option, I’d probably have chosen an O1 blade rather than A2 because it takes a slightly finer edge and is easier to sharpen).
lie_nielsen_101_planeLie Nielsen advertise it as a violin maker’s plane, though I don’t think there is anything about it that makes it especially well-suited for the tasks involved in violin-making. It’s really just a very small, well made block plane. I can see it being useful for many kinds of small-scale woodworking: model boats, doll’s houses, jewellery boxes, musical instruments, etc.

My one complaint with it is that the blade was dull out of the box. The back and bevel appeared to have been surface-ground and perhaps quickly swiped across a medium grit diamond stone. The surface finish was relatively rough and unpolished, and there was a slight burr at the edge. It would cut if you forced it through the wood but it wasn’t a nice experience. I know people have different standards with regards to tool sharpness and my standards are fairly high, but I wonder how many hand-tool beginners buy a high-end tool like this with the expectation that it is going to work really well straight away. They will have a disappointing first experience of the product because it is basically horrible to use until you have learned how to sharpen the blade. Particularly since the instruction leaflet claims, “The blade comes ready to use. Slight additional honing will increase performance.” Really. It’s a bit like a high-end car maker like Mercedes selling a new car with an empty petrol tank and claiming, “The vehicle comes ready to use. The addition of fuel will increase performance.”

There is an interesting parallel between Lie Nielsen’s business model and my own. Most of LN’s tools are basically copies of vintage tools invented by Stanley and others with slight improvements to the design, improved materials, and modern manufacturing methods. The tools aren’t cheap but they are well-made (apart from the dull blade thing) and highly desirable, and as a result their business seems to be very successful.

 

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Little Coffin Plane

Lately I’ve been adding to my collection of hand planes (I’m intending to mostly use traditional hand tools to produce the wooden parts of my concertinas). I picked up a cute little antique wooden coffin plane for a few quid in a junk shop this weekend. It’s a bevel-down smoother but it’s small and light enough to comfortably use in one hand. Here it is next to my Stanley no. 4 for comparison:

little_coffin_plane_1

I lapped the sole flat using fine sandpaper on a sheet of glass. In this photo from half-way through the process you can see how they tend to wear most in the area in front of the mouth because of the way the wood you are planing is constantly being lifted by the splitting action of the blade. If this area of the sole is too concave you get excessive tear-out in the workpiece.

little_coffin_plane_2

The back of the blade was very rough, probably hand forged by a local blacksmith from a piece of scrap tool steel. It seems nicely tempered though – it took a fine edge and didn’t show any damage after hitting a few hard knots with it.little_coffin_plane_3

It took me a couple of hours of tedious hand lapping on a coarse oilstone followed by running up through the grits to a fine polish to get the back to a decent condition. I ended up giving it a slight amount (a degree or two) of back-bevel to get rid of the deep pitting near the edge without removing metal from the entire length of the blade.little_coffin_plane_4

After sharpening and polishing the bevel and a coat of beeswax on the wood, it sizzled nicely through a piece of scrap pine, shooting nice curly shavings out of the mouth.little_coffin_plane_5If it has a flaw, it’s that it has a fairly thin blade and no cap iron, so the blade has a bit more flex than I’m used to, which means it doesn’t do very well on end grain and it has a tendency to dig in and stall when you hit a knot.

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More Earrings

I’ve been commissioned to make another couple of pairs of the hexagonal English earrings. Here are some photos from this afternoon’s work drilling and cutting.

I’m still drilling manually using the Taig mill. I used a 1.2mm bit for the button holes, a 0.9mm bit for most of the piercings, and a 0.7mm bit for the tiniest piercings. All re-sharpened PCB drilling solid carbide bits, and for a change I didn’t break any!

earring_making_1

Lots of silver swarf. Unfortunately it’s not very practical to collect it, though I do keep the scrap from the piercings. One day I may have enough to melt down and cast them into something useful!earring_making_2

The saw blade has to be unclamped and threaded into each piercing in turn. The teeth are too fine to easily see so you have to figure out which way to put it in the frame by running your finger along it. The wing nut is used to set the tension.earring_making_3

In this picture you can see my new bench peg clamped to the crossbar of a builder’s trestle stand. I like to work standing up with the saw table quite high so that I can get my eyes close to the template without needing to bend over, which would hurt my back after a while.earring_making_4

After a lot of frustration with paper templates that inevitably came unstuck or became illegible, I think I’ve finally found a template material that works reasonably well for very fine metal piercing: inkjet-printable matte white self-adhesive vinyl film. It’s not cheap but then you don’t need much of it for a pair of earrings, and if it enables me to produce a better end product with fewer headaches then it was well worth it!earring_making_5

Thanks to Juliet for the photos of me working. 🙂

 

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