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Dovetail Chisel?

A

Andy Kev.

Nordic Pine
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Bear with me on this as it is speculation.

If you want to do a sliding dovetail housing, it is typically done by cutting the housing/dado then using an angled block with a chisel to get the dovetail wall angle in. A couple of people seem to have made a plane to cut the female bit of the dovetail (Derek Cohen springs to mind).

Has anybody ever made a chisel to cut the female bit: one that would go into the end of the housing and be pushed along it thus creating the angled wall after a number of passes? I imagine something looking a bit like a mortice chisel, broad at the bottom and narrower at the top. The bottom would obviously ride along the bottom of the housing.

It occurs to me that if something hasn't been developed, there is probably a good reason for it. Do you think that would work? Or is it a non-starter for reasons that I don't know of?
 
I know what you mean....... but I try to keep it as simple as possible.

On the occasions when I cut sliding DTs by hand, I excavate the 'female' section in the conventional manner with chisels and angled blocks. Both sections are done with careful paring. I have tried using a long, very thin paring chisel length-ways along the sides, but I found it difficult to control, but that's not to say that i won't work for others.

By preference I try to smooth the mating surfaces as much as practically possible so that the fit-up goes with hang-ups.

To do this I do use a plane.... but nothing more elaborate than a side rebate - in my case the first rebate to hand for this is a Stanley No: 79.
It has a side fence that will sit on a thin, suitably angled piece of scrap to align it with the sides and then a few judicious strokes, trying the fit as I go. I try to get the fit right with the least number of attempts so that the joint does not get bruised and a sloppy fit.

When it is almost there, I revert to a few strokes with a half round file to remove any high whiskers on the full lengths of both the mating surfaces.

As with anything connected to working wood, what works well for me and my style of work is a not for everyone, so there will be other methods, I'm sure!
 
That's a good question. I didn't know of anything like you describe. I would just use a broad chisel, stepping along, cutting down into the corners at the bottom of the groove.

But thinking that the Japanese go about things differently and use sliding dovetails more, I found this in Toshio Odate's book, about the Kote-nomi or trowel chisel.

IMG_20220928_091450140.jpg
 
Argus: the Stanley 79 technique sounds like a cunning idea.

Andy: I googled kote-nome and found these for sale:

https://www.fine-tools.com/kotenomi.html

The straight ones look nearest to the idea I have. They might even be perfect for the job.

I'm afraid that I have zero experience of metal work but if I did, I think I'd like to have a go at modifying a mortice chisel, with a detachable tapered (both laterally and vertically to provide a way of holding the chisel to the bottom of the dado at the start of the pass) toe piece, so that it could be used for stopped sliding dovetails as well.
 
I've now remembered that Rutlands used to sell some rather odd looking chisels that might be another answer. Here's a pic from the last paper catalogue I have, dated 2012. I can't see them on their website but you might find them on Ali Express or similar.

IMG_20220928_094141178.jpg
 
I happen to have a kotenomi from Kiyotada. It's about 9mm wide and was modified by the tool store in Tokyo that sells them, such that the curved heel also has a cutting edge, so you can also cut / clean up on the pull stroke.

They are inexpensive in Japan unless you go for the super duper artisan stuff. I expect Dieter Schmitt sells equivalent tools.

However, I would urge a little caution. These angled chisels work really well on relatively soft woods such as Japanese cedar or the European equivalents. However, in a true hardwood such as oak, they are much harder to control - at least in my inexpert hands.
 
AndyT":1yx4gj71 said:
But thinking that the Japanese go about things differently and use sliding dovetails more, I found this in Toshio Odate's book, about the Kote-nomi or trowel chisel.

Click to expand...

I have a couple of those 'Kote-nomi' chisels........ but they are called 'dog-leg' chisels around here, used for grounding a carved background.

One's an Ashley Iles No: 52, the other's a Henry Taylor No: 82. They have been in my carver's box for many years. I got them for a particularly inaccessible bit of carving at the time and haven't used them since.

Cutting a housing like the one in the picture would, for me, be a combination of chisel-hacking and then grounding with a hand-router-plane. Being a bit old-fashioned, I usually give the base a swipe with a sharp float.
 
Andy Kev.":2hqzpcja said:
It occurs to me that if something hasn't been developed, there is probably a good reason for it. Do you think that would work? Or is it a non-starter for reasons that I don't know of?
Click to expand...
The problem you run into is that the dovetail housing gets narrower, not wider, towards the mouth. If such a tool is sized to cut the bottom of the housing (i.e. the widest part) correctly, then it's impossible to work towards that line, because cutting any higher up will make the wall at that point too wide. If you were to address that problem (or accommodate more than one width of housing) by having the chisel profiled for only half the housing, you'd need a matched pair to cut a single stopped joint.

One approach to solving that would be the route taken by power routers - plough a straight-sided groove the width of the intended mouth of the housing, then come along with such a chisel, referencing the bottom of the ploughed groove, to cut out the side parts in a single pass. That's potentially a lot of material to be chiselling off in one go, though, and you still have the problem that the length of housing you could cut would be limited to the length of your chisel.

I'm sure somebody somewhere has tried it, but given the relative simplicity of angled saw cuts, a plain chisel and a router plane I suspect the results will have fallen into the "more trouble than it's worth" category.
 
spb":c7ryw8bx said:
Andy Kev.":c7ryw8bx said:
It occurs to me that if something hasn't been developed, there is probably a good reason for it. Do you think that would work? Or is it a non-starter for reasons that I don't know of?
Click to expand...
The problem you run into is that the dovetail housing gets narrower, not wider, towards the mouth. If such a tool is sized to cut the bottom of the housing (i.e. the widest part) correctly, then it's impossible to work towards that line, because cutting any higher up will make the wall at that point too wide. If you were to address that problem (or accommodate more than one width of housing) by having the chisel profiled for only half the housing, you'd need a matched pair to cut a single stopped joint.
Click to expand...

I always find it difficult to explain something geometrically but it looks like I have.

Suppose we have a 1/2" wide housing. The chisel I envisage would have to be narrower than the housing it is used on. It will be on one side (at least) wider at its bottom than at its top. The degree of narrowing is the angle of the dovetail. So the idea is that it runs along the housing. At first only the wide bottom of the chisel will touch one side of the housing but with each pass more of it would cut in until you've got the whole side at the dovetail angle. Obviously the last pass would be where the top of the angled side of the chisel just kisses the top of the housing.

I think that might be clearer than my last description.
 
I'm not sure what you are trying to achieve here Andy. Such a chisel could only be used at the final stages of cleaning up a dovetail housing, and there is no possible position in which you could use it and see what it was actually doing. You'd be doing woodwork by braille. It seems to me as though it would be completely unhelpful.

When I do dovetail housings, I make a little pattern piece of the profile I want, and just slide this along the housing until it gets stuck. You pare a little more off at that spot. I suspect any cross-grain approach, trying to work the housing from within the housing, is just over-complicating something which is actually rather simple. This is rather a forgiving joint. It doesn't matter if you remove too much from any of the faces anywhere except at the ends (in the same way that the shoulders of a m&t have been undercut for centuries, if not millenia).
 
Mike G":qg5izken said:
I'm not sure what you are trying to achieve here Andy. Such a chisel could only be used at the final stages of cleaning up a dovetail housing, and there is no possible position in which you could use it and see what it was actually doing. You'd be doing woodwork by braille. It seems to me as though it would be completely unhelpful.

When I do dovetail housings, I make a little pattern piece of the profile I want, and just slide this along the housing until it gets stuck. You pare a little more off at that spot. I suspect any cross-grain approach, trying to work the housing from within the housing, is just over-complicating something which is actually rather simple. This is rather a forgiving joint. It doesn't matter if you remove too much from any of the faces anywhere except at the ends (in the same way that the shoulders of a m&t have been undercut for centuries, if not millenia).
Click to expand...

Mike, you're speaking from experience of a widely used method which you know works and you mention the key point of it being quite forgiving, which is something that is easy to overlook.

On the other hand, I'm speculating and it would appear that whoever developed the Kote Nomi chisels had similar thoughts. What set me off on this was watching a video from Bridge City Tools:

https://www.youtube.com/watch?v=SBZXw59WTiA

The key bit is at 6 min 49 secs although I'm sure that most of us would find the whole clip fascinating. It represents a highly engineered alternative to the tried, trusted and simpler method which you describe and which we all know. Because it is a bit round-the-houses, I think that people would only adopt it for fun, or they'd just use a router instead. It is the last bit from 6:49 that led me to think about a chisel. BC does it with a specialised bottom for a specialised plane but the results do appear to be more or less guaranteed.

If I had any metalworking abilities at all (and believe me, I have none whatsoever), I'd have a go at adapting a mortice chisel - of which I have a clear picture in my mind - just to see if it would work. Would it be too fussy? How easy would it be to control in order to get accurate results etc? Would it simply fail when faced with cutting cross grain? I suspect that if it were to fail anywhere, it would be on the last point.
 
Hmmmmm.........that's a solution looking for a problem, I reckon.
 
:lol: That Bridge City method is a right faff. Would take under a minute with an electric router. He can't even claim to be a hand tool aficionado as he used an electric table saw.

I've seen in person Japanese craftsmen using the canted hand tool to make sliding dovetail cuts having taken out the slot first by hand with a rebate plane. However, this was in Hinoki which cuts easily and is aromatic. Our nearest equivalent would be red cedar.

This was actually jointing boards for a traditional Japanese wooden bath.
 
Mike G":3v8b655m said:
Hmmmmm.........that's a solution looking for a problem, I reckon.
Click to expand...
There's definitely a flavour of that about it. I can't imagine a professional adopting that system and I suspect that it's not much quicker than traditional hand tool methods. The plus points are that it does appear to guarantee precision and, to be honest, it looks like fun.

I imagine that you see the principle that caught my imagination: the notion of a tool which specifically deals with the side wall of the housing to make it accommodate the angle of the dovetail. As I mentioned above, Derek Cohen developed a plane to do that job. I thought of a chisel. BC came up with a plane fitted with a specialist iron and sole. I reckon that the ideal solution - I'm thinking of cross grain again - would be a single purpose plane with the relevant iron and sole.
 
That Bridge City tool is even more over engineered than its two failed predecessors. They were (I suggest) the Stanley 444 and the Howkins plane. Unsurprisingly, they both failed to sell in any quantity and have become expensive collectables, not practical tools. Just like the Bridge City design.

As Mike says, the "problem" of how to cut sliding dovetails has been solved by practical woodworkers around the world.

As an experiment, I once made a stepladder with hand planed sliding dovetails. I did it without needing any special jigs and without measuring anything to a thou. The point is that wood is not steel; it's just compressible enough to take up any irregularities.

For the female slots I used an old wooden dado plane. To open it out I gave each side the same number of strokes with a wooden side rebate plane.

For the male part I used a wooden rebate plane with an angled sole. I just planed until the angled cut met the corner.

I didn't take any photos at the time but can provide some later if wanted. It was a quick and easy job.
 
It seems that this issue has been addressed in a number of ways. In this clip a chap shows the use of a special dovetail saw (totally different to what is normally meant by the term):

https://www.youtube.com/watch?v=mrWVJhgH9t0

It looks like a nice, simple solution and effectively renders my chisel idea redundant.
 
I'd suggest that, as with so many jobs, the degree of specialisation in the tools needs to match with how often you use them. So yes, if you cut a lot of sliding dovetails or tapered sliding dovetails, special tools can help speed things up. But for the occasional one or two, ordinary saws and chisels are fine.

Those joints are much more widely used in Germany and Austria than they are over here. So if you want a special saw or a special plane, look at manufacturers such as ECE and sellers such as Dieter Schmidt.
 
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