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Category Archives: tools

A mirror aid to drilling free-hand

Although I was sure that I’d read somewhere that there was a way of using a mirror to help judge when a drill bit was truly vertically, I struggled to find an account of how it was actually done. Eventually, after a lot of googling, I came across this letter and illustration published in Popular Mechanics nearly 80 years ago.

To find out if it worked, I bought a cheap handbag mirror.

First I cut off the hinge and trimmed back the plastic mount along one edge.

Placed next to the drill bit, the mirror showed when the drill was vertical…

… and when it wasn’t.

It’s a simple idea but I was impressed by how well it worked. A problem though, is that the mirror only tells you whether the drill is vertical in one axis. You have to move the mirror around the drill to check whether it’s vertical in the other axis and while you’re doing this, it’s easy to lose the vertical on the first axis.

One solution might be to have an L-shaped mirror or, perhaps better still, a mirror with a hole in its centre. Then, all you’d have to do to check that the drill was truly vertical in both axes would be to move your head.

So I ground a small hole in the centre of the other mirror and tried it out.

This is the view when the drill is vertical.

And when it’s miles off.

Of course, you don’t need a mirror to see when the drill is as far out as that. The benefit is that it makes it easy to spot small deviations from vertical.

Does it work in practice? As a test, I drilled ten 2mm diameter holes at 10mm intervals along a line in a piece of MDF and stuck cocktail sticks into them.

Not perfect – but not bad either. Certainly better than I was able to do in a repeat of the experiment when I used a small try square instead of the mirror as a guide, as you can see below.

Obviously, the best way to drill a truly vertical hole is to use a drill press. But there are occasions when this is impossible because the work piece is too large or too awkwardly shaped. It’s then that this trick with mirrors might come in handy.

Purfling and inlay marker

This tool, designed and made by Brian Hart, is a purfling marker. As violin makers will know, when moved around the edge of a violin plate, it marks closely spaced parallel lines a few millimetres inside the perimeter to guide the subsequent cutting and chiselling-out of the narrow channel into which the purfling is laid.

If necessary, the distance between the lines can be altered by placing shims between the marking blades and there’s a screw mechanism to change the offset of the blades and allow precise adjustment of the distance of the purfling channel from the edge of the plate. A feature of the design is that the handle and centre of gravity are below the marking blades. I find that this makes it easier to use than the usual design of purfling marker, which has the handle on top.

Here’s the corner of a cello where the purfling was marked out using this tool.

But of course it only works where there’s an edge. It’s no use if you want to imitate the Brescian makers and create an elaborate pattern of the sort seen on the violin below.

(I’m grateful to Andrew Sutherland, a violin maker and restorer in Lincoln, for providing this photograph and information about the violin. It was made in Dresden, Germany around 1870. Andrew reckons that the ornamentation was done by a purfling specialist in the workshop where the instrument was made after it had been completed and varnished. There are more photographs here.)

 
 
 

A possible solution occurred to me when I read Jeff Peachey’s description of how he sharpened the tips of a pair of jeweller’s forceps to make a tool to cut thin strips of tissue for book restoration. I wondered if the same idea could be adapted to make a freehand purfling marker.

Here I’ve re-shaped the tips of a pair of stainless steel forceps using a slip stone to create bevels on the inner faces, and drilled and tapped a hole for a small machine screw.

With the addition of a fold of brass shim stock between the blades, the width of the gap between the tips of the forceps can be adjusted precisely.

It works fairly well and can be used either freehand or to scribe around a template. I found it best to make one pass with the marker and then use a knife to deepen the cuts rather than trying to use the forceps to cut deeply. Here are some first experiments.

A little decoration goes a long way and not everyone believes that violins are improved by a double line of purfling and stylised floral motifs. On the whole, I think this ornamentation works better on cellos and viols than it does on smaller instruments. Still, there are times when a flourish is desirable – the fingerboards and tail pieces of baroque violins, for example – so my new purfling marker will probably be used occasionally.

More on sharpening fishtail chisels

A comment on the previous post asked about setting the honing angle.

Here’s one way of doing it. Set a sliding bevel to the angle you’re after. (I chose 30°.) Then, after fitting the chisel into the mould, adjust the position of the mould in the honing jig, by eye, so that the longitudinal axis of the chisel runs parallel with the blade of the sliding bevel.

 

 

I glued a strip of wood across the underside of the mould so that it can be located in the honing jig at the same angle every time. And that’s it.

 

 

Eventually, I suppose, repeated honing will shorten the chisel and increase the angle of the secondary bevel. That will mean that it’s time to regrind the primary bevel and repeat this process to restore the angle of the secondary bevel.

A point I forgot to mention in the earlier post is that it’s worth creating a stop in the moulding at its upper end to prevent any tendency for the chisel to slide up while it’s being honed. Here you can see a stop formed by the lip that mirrors the indentation between the socket and the handle of the chisel.

 

Fishtail chisels

A pair of chisels reground with left and right skewed edges is almost essential for cleaning out the sockets of lap dovetails. These chisels are useful for other tasks as well – tidying up the inside of the pegbox of a violin or cello, for example. I’ve got several pairs in different sizes and, although I don’t use them everyday, there are jobs where no other tool will do.

Actually, that isn’t quite true. A fishtail chisel makes a good substitute and, because it can work into both left and right pointing corners, you only need one tool rather than a pair. Last Summer, visiting Mark Bennett in his workshop in Yorkshire (see below) I saw him using one made by Lie-Nielsen. It was such an attractive looking tool that, even though I didn’t really need it, I couldn’t resist buying one to try.

After it arrived, I honed it, maintaining the 25° angle of the original grind. Perhaps it was my lack of skill – keeping such a small bevel flat on the stone wasn’t easy – but I never managed to get it properly sharp. What’s more, the edge that I did achieve didn’t stand up to use on hardwoods.

Of course, there’s an obvious solution to both these problems: create a secondary bevel at a slightly steeper angle. Indeed, Lie-Nielsen recommend exactly that in the leaflet that comes with the chisel.

However, I was reluctant to do this freehand because, although I was sure that it would work well enough the first few times, I knew that in the long run I’d be unable to maintain the same angle. This would mean that I’d end up with a rounded secondary bevel that would require more and more honing with each sharpening to get a decent edge. And, quite apart from the extra time this would take, it’s a bad idea to hone or grind a fishtail more than absolutely necessary. There isn’t much metal there in the first place and with each grinding the cutting edge gets progressive narrower. 

A honing jig would have solved the problem, except for the fact that I couldn’t make  the conical shape of the shaft of the tool  fit securely into any of the jigs in my workshop.

In the end, I got around this difficulty by casting a mould out of the sort of two-part wood filler that sets hard in about 30 minutes. I’ve written about this technique for holding awkwardly shaped object before (scroll down in the Tools and Jigs section of the website) so I won’t go into it in detail here. But briefly, you mix a generous quantity of the filler, spread it on a board (in this case a thin piece of wood of a size that would fit into an Eclipse honing jig), cover with a layer of cling film, and press the object you want to mould into it, holding it place with a weight or a clamp until the filler sets. Then, of course, you can take it out and get rid of the cling film.

I’m hoping that the photographs below will the idea clear:

And it worked – at least for one of the objectives. The edge on the chisel was keen enough to slice soft paper towel and to pare endgrain.

Whether it will achieve the second objective of minimising attrition of the blade with repeated sharpenings is another matter. Time will tell.

Jig for planing wedges

A couple of years ago, I wrote about a simple device that made it easy to plane a taper on small pieces of wood – something that’s hard to do accurately if you try to hold the wood in a vice. (The piece is still available in the Tools and Jigs section of the website.) After I’d posted it, Jeff Peachey, who specialises in the conservation of books, sent me a photograph of a rather similar jig that he had made, which had the advantage of an adjustable endstop. I’ve been meaning to incorporate this modification ever since, but have only now got around to it. Below is a photograph of the original jig with a glued endstop of 1.5mm plywood.

To add a adjustable endstop, I inserted two short lengths of 6mm studding, drilling the pilot holes under size and then tapping the holes before screwing in the studding. Because the studs are inserted into endgrain, I was doubtful if they would hold so I glued them in too. And, to be doubly sure, I cross drilled the studs in situ and popped in a nail shank, the end of which is visible on the side of the jig.

Then I cut slots in a small piece of maple to make the endstop and fixed it in place over the studs with washers and nuts.

Here is the modified jig, ready for action.

A worthwhile improvement, I think. It will be possible to match the height of the endstop to the size of the end of the wedge and, should the endstop get damaged, it will be easy to true it up again.

In the meantime, Jeff Peachey has made a much bigger and better device, which is primarily intended for planing thin boards although it can cope with wedges too. There’s photograph of it on his website here.

A plane for guitar struts

Richard Nice, who among many other things makes guitars, recently showed me this attractive plane that he had designed for shaping soundboard braces and harmonic bars. He made it from an off-cut of beech and a discarded cutter from a plough plane and, so that there could be no doubt about its provenance, he signed it too.

The screw adjustment is simple but ingenious, depending only on a carefully sited screw tapped into the back of the plane and a slot cut into to the upper end of the iron.

The plane is comfortable to hold and works well. Its narrow cheeks enable it to take shavings from the lowest part of the brace and produce either a triangular or gothic arch section according to your preference.

Japanese style violin making planes

At the Easter Instrument Making Course at West Dean this year, I had the pleasure of meeting Wouter Hilhorst, who was making a viola. Apart from admiring the precision and delicacy of his work, I was also interested to see that he had made his own planes, 2 of which were in the Japanese style. He let me take a quick photograph – see below.

We’ve recently had an email correspondence and he’s sent me some better photographs, and some details of how he made them. He gets the blades from the German company, Dick, and recommends their Japanese blades writing:

They are laminated and can be honed to a very sharp edge. As you probably know, blades for larger Japanese planes taper in thickness and wedge themselves in the more or less resilient oak plane bodies, which works surprisingly well. The small blades from Dick aren’t tapered in thickness, but only slightly in width. When I made them I thought I would wedge them widthwise, but the little recesses which grip the blade on both sides are enough, just by friction (although I had to glue two little strips of paper in the recesses of the smaller plane). The blade needs some space widthwise to be adjusted laterally.

He makes the planes from European oak or boxwood and chisels them out of a solid block. This is a technique that I intend to re-visit. All the planes that I’ve made recently followed the Krenov method in which you start by sawing two slices off the block to make the sides of the plane, shape the bed and throat from the middle section, and then glue it back together. There are some photographs of this method of construction here and here.



Dovetail marker

Another useful aid to cutting dovetails is a dovetail marker. Several different designs are available to buy but I like this shop-made one best. Once again, it comes from Robert Wearing’s book, The Resourceful Woodworker (ISBN 0 7134 8006 8), and is fairly easily made from a sheet of brass 1 to 2 mm thick. Its advantage over the type that Lie-Nielsen and Veritas make is that you only have to set out the centre position of the pins on the edge of the board. The triangular ‘window’ of the marker then lets you see exactly where you’re marking out the joint. It works equally well whether you prefer to cut the pins or the tails first – an argument that I don’t intend to get into.

I suppose purists who like to use a steeper slope for dovetails in softwood would need two markers, one at a 1 in 6 slope and one at 1 in 8. I confess that I never bother about this, cutting all dovetails at 1 in 8, regardless of what sort of wood I’m working with.




Dovetail vice

I’ve been making a few small wooden boxes to give as Christmas presents. They don’t really have much practical function, except as a place to keep pencils or stamps or other odds and ends, but they’re fun to make and people seem to like them. Part of the pleasure of constructing them comes from the small scale of the project. It’s a day’s work rather than a month for a guitar or a violin. And they allow you use up scraps of wood that were too nice to burn but that are too small to make much else out of. They also provide an opportunity to show off a bit, which brings me to the reason for writing this post.

Even people who know nothing about woodwork and cabinetry have heard about dovetails and recognise them as an emblem of craftsmanship in wood. So that’s the method of construction you should use if you want your skill to be noticed.

If you’re going to cut dovetails, it’s much easier if you’ve got a proper vice. Because of the position of the screw and slide bars in most bench vices, it’s only possible to grip the edge of the board that you’re dovetailing. A dovetailing vice, on the other hand, grips the whole work piece, preventing it vibrating and aiding accurate sawing. They are especially valuable for wide boards but they’re good for smaller pieces too. The idea came from Robert Wearing’s book, The Resourceful Woodworker, (ISBN 0 7134 8006 8). He uses threaded metal bars to provide the clamping force but I cannibalised the wooden handscrews from an old clamp that I picked up in a second hand tool shop. The vice is simply cramped to the top of the bench when needed.

I left the screws much longer than necessary for any dovetailing so that the vice would open wide enough to accommodate the body of a guitar when working on the tail stripe.

And, should you be wondering how the boxes turned out, here are a few photographs:


Minimal router table for Dremmel

Last week I made a bridge for the guitar that I’m building at the moment. Here’s a photograph taken while it was being French polished. It’s in Rio rosewood and the tie block is inlaid with a strip of spalted beech to echo the rosette that I wrote about a little while ago.

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To cut the channel for the saddle and for the recess behind the tie block, I used this very simple router table. The idea came from an article in Fine Woodworking (No 182, February 2006) where Doug Stowe described how he made something rather similar for a full size router. There’s a brief description of his table here where there’s also a link to a full explanation and downloadable free plans.

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In my table, the Dremmel is mounted overhead on a cantilever. The table itself is a board of mdf. The adjustable fence is simply a straight strip of wood that pivots at one end and that is clamped at the other – an arrangement that allows a remarkable degree of precision. Depth of cut is controlled by the position of the router bit in the collet. The Dremmel isn’t powerful enough to cut slots to their full depth in one pass so, to avoid the fiddly business of repeatedly having to change the position of the router bit in its collet, I place a shim of 1.5mm thick plywood under the workpiece for each subsequent pass.

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The only bit about making the table that’s not straightforward is how to mount the Dremmel firmly and vertically in the cantilever in a way that allows removal. I solved the problem by buying a 3/4 inch diameter 12tpi tap, which matches the thread on the nose of the Dremel when the collar above the collet is removed. Then it was only a matter of drilling an undersized hole and tapping it out.

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The table is quick and easy to set up and it doesn’t take up much room in the cupboard when it’s not being used. It isn’t big enough to deal with anything very large, of course, but for making guitar bridges it works fine.

Toothed blade for planing difficult wood

A while ago, I wrote about using a Millers Falls scraper plane to cope with some highly figured cocobolo that I was using for the back of a guitar. It’s an excellent tool for finalising the thickness and it leaves a clean finish even on the most awkward wood. The disadvantage however, is that it takes only the thinnest of shavings so if you’re starting with wood that’s way too thick, you’re in for a lot of time and effort to get to the right final dimensions.

Of course, the usual way to get around the problem is to run the wood through a drum sander. But I haven’t got one, partly because there isn’t room for it in my small workshop and partly because I’m allergic to sandpaper. I don’t mean it literally – I don’t come out in a rash if I touch the stuff – but I do think that there are nicer and quieter ways of shaping wood than grinding it into dust.

Another solution is to use a plane with a toothed blade. This won’t eliminate tear out completely but, should it happen, it’s limited and shallow and can easily be dealt with by a scraper later. Toothed blades work because the individual teeth are too small to grab enough fibres running in the wrong direction to rip out a large lump.

I use a No 4 Record bench plane fitted with a standard blade that I modified to look like this. Put the blade in the vice, cutting edge upward. Take a cold chisel and, against all your instincts, hammer a small gap into the cutting edge every 3 or 4 mm. Then sharpen the blade in the usual way.

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Another way of cutting the teeth is to use a thin grinding wheel in a Dremmel.

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Here are a couple of pictures of a guitar back in zebrano being thicknessed with the toothed blade. If you’ve ever used this wood, you’ll know that the interlocked grain structure makes it very hard to work. With a toothed blade and a wipe of wax on the bottom of the plane, the task becomes a pleasure.

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The marks left by the toothed blade are just visible running diagonally from bottom right to top left. And you can see the linguine-like shavings that are produced.

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Switching over to the scraper plane for final adjustment of the thickness and to remove the corrugations left by the toothed blade.

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Another way of constructing violin-making planes

Browsing through the surprisingly detailed statistics that WordPress provides for bloggers, I was intrigued to see that some of my most popular posts were about the workshop construction of small finger planes with curved soles for violin and cello making. If you’re interested and want to find them, go to the bottom of the page and type plane into the seach box. Or click here, here and here. There’s also a short entry about them on the tools and jigs page.

For a slightly different approach, it’s worth taking a look at Alan Dunwell’s website. You’ll need to go to the Luthier pages and select Making finger planes. He shows how to make several of these planes in a single batch, shaping different profiles for the soles on a belt sander. Dunwell recommends nothing fancier than a penny nail for the crossbar that holds the wedge and blade in position.

Spalted beech rosette continued

This is the second half of the story, started in my last post, about making a rosette from spalted beech.

The next step was to cut the channels around the edge of the rosette to receive the border strips. Again, I used my jig mounted Dremel for this.

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Here the channels have been cut and the decorative strips bent more or less to the right curvature on the bending iron ready for glueing in.

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And here is the finished rosette, planed flush with the soundboard and given a wipe of shellac. I shan’t cut the soundhole until I’ve planed the soundboard down to it final thickness.

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Spalted beech rosette

A few weeks ago, I bought a block of spalted beech from Mark Bennett and mentioned, in a previous post, that I hoped it would make some striking guitar rosettes. I’ve been trying out some ideas. Here’s the piece of wood that provided the starting point.

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Having decided which face looked most attractive, I set up the bandsaw for a fine cut and sawed two veneers at about 4mm thickness. Then I book-matched them to create a more or less symmetrical pattern, by gluing them onto thin (1/64 inch) plywood for stability. Actually, there’s a bit more to it than that. First, using weak hot hide glue, I stuck a sheet of paper to a 6 by 6 inch square of 6mm MDF. Then I stuck a similar sized square of 1/64 inch thick plywood over that, again using thin hide glue, and weighted it down until the glue was dry. This provided the base onto which the veneers were glued.

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Using a Dremel mounted in a jig (details of jig available here) I cut out the rosette making the depth of cut just through the layer of thin plywood. It was then possible to remove the rosette using a thin blade – an ordinary knife from the dinner table works well – sliding it between the plywood and MDF layers in the plane of cleavage provided by the paper. Any paper or glue remaining on the underside of the rosette can easily be cleaned off with a hot damp cloth, which of course was the reason for using hide glue in the first place.

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I missed the opportunity to photograph either the detached rosette or the routed channel in the soundboard but below you can see the rosette being glued into position on the soundboard, weighted down so that it dries flat.

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More about violin-making planes

Pictures are better than words when it comes to describing how to make something. So yesterday, I made a curved sole finger plane, keeping a camera within reach to record each step. I hope these photographs will be a useful supplement to the written instructions in my last post. Read across the rows to stay in sequence and click on any of the thumbnails for a larger view and (sometimes) more detailed comments.

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