Thread: Full blind mitered dovetail case
8th Jun 2018, 01:29 PM #1
Full blind mitered dovetail case
So I've been looking around for my next project. I was looking at this video making a Japanese cabinet and watching the full blind mitred dovetail case details. At the 3:36 mark there is a pan across the dovetailed pieces before assemble, both lots of pins are shown and one lot of sockets. At 3:41 it looks to me like the last set of sockets has maybe been cut with one vertical wall. I'm not sure if it is just a sequencing issue with the video because at 3:25 it shows the freehand cutting of the sloping walls on the sockets.
What I'm wondering is if maybe one set of sockets is cut differently to aid assembly. I can't imagine how this would help but maybe it does. Is my 3D visualization failing me?
Has anybody tried a full hidden dovetailed case and found maybe the need for extra slop during assembly? Am I missing something in the video?Franklin
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22nd May 2019, 04:45 PM #2
I finally gave up trying to think the entire design through and just started working with some recycled Tasmanian Myrtle, deciding what I could manage to cut out of it that would fit the spot I have in mind for a small chest.
The Tas myrtle was the last panel I had left over from an old wardrobe that I had used the rest of for my Georgian inspired printer cabinet.
Having cleaned the horrid old tinted finish off, I now have the basic pieces ready to start joining the cabinet. In the spirit of the Honorable Oriental Gentleman in the aforementioned video, I have started hand ploughing some stopped grooves for locating the various pieces. This is proving harder than anticipated. Accurately cutting the sides of the trenches is challenging, I don't have any fancy cutting guages that can reach far into the case pieces like the master uses in the video, and I'm resisting buying an Azebiki saw, as is used in some similar videos, as I reckon I would have that jumping out of the kerf line as well. (I'm also resisting pulling out the router and a parallel guide )
Trying to use my best attempt at a western hand method I have cut the groove sides with handsaws and used a router plane to chop out the waste. Both techniques have caused me pain so far. Firstly I seem incapable of running the saw against a straight edge without something slipping and the saw jumping out of the kerf and marring the adjacent surface. The other problem is that running up and down the groove with the #71 is 'polishing' if not marring the adjacent surfaces as well.
Oh well, this is mainly a learning exercise so no real visible damage done so far.
To be continued....Franklin
22nd May 2019, 09:11 PM #3GOLD MEMBER
- Join Date
- May 2011
Yeah, you've got to love routers, downcut spiral bits and straight edges!
Those bench hold-downs look pretty serious.Forum members PM me for a discount on all my products - https://www.ebay.com.au/str/aldavsstore
23rd May 2019, 10:32 AM #4
Fuxzzie, there are probably a dozen ways to cut a trench. I'm usually cutting them across the grain, but I can see some potential problems going along it, including the router blade wanting to rip splinters off the sides if one is the least bit un-careful. I'd certainly be knifing those sides as deeply as I could (I do have a panel-gauge that would reach in far enough, fortunately).
Not sure how it would go on long-grain sides, but I use this 'trenching' saw I made, to cut the sides of sliding dovetail trenches or rebates: New S_D.jpg
It has no set, which is ok 'cos it only has to cut about 6-8mm deep, so it cuts a clean edge and I can start it against a wooden guide without damaging the edge of the guide. The wooden stock encasing the blade is the depth-stop. The blade has slots for the retaining screws so it can be adjusted for depth or to suit different guides. I keep a 'standard' guide on hand which has a vertical edge for straight sides and the other side is angled at my most common angle for a sliding dovetail, which also matches the plane I made for the tail part: Test 2.jpg
Before I made the potato-powered gear, I cut my SDs & trenches with the screamin' demon as aldav suggested. Not all that much quicker if you include setup times, but an awful lot quicker to wreck a valuable bit of wood when a bit or a guide slips....
23rd May 2019, 01:03 PM #5
Thanks Ian. All the trenches in this project will be across grain, so no problem with being caught in th egrain so to speak. I think my problem is more to do with impatience and trying to saw the trench sides too quickly.
The Japanese Azebiki saw looks like it does the job nicely and keeps the knuckles well out of the way. Some of the Japanese cabinet builds on youtube make it look ridiculously easy, but I'm thinking that cutting into Paulownia might be making it seem extra easy. In the linked to video the Master just scribes the shoulder lines and uses a wide chisel to chop the waste out across grain. I might try that on the next trench I cut.
I seem to remember Derek using an Azebiki to cut sliding dovetails in one of his builds, probably on Jarrah. I'll see if I can find that thread and see if he had any trouble with the harder woods.
23rd May 2019, 02:13 PM #6
OK, I obviously didn't look properly, I thought your pic was showing a trench along the grain. Yep, as I said there must be at least a dozen ways to go about making a trench. I'm with your Japanese master in knocking out as much waste as possible with a long chisel, & only use the router to level the bottoms to depth, wherever I can.
I think I saw the Derek thread you mean - he chops a 'vee' along his cut line to make sure the saw gets a good start. I had to look up what an azebiki looks like, not being familiar with Japanese saws. No reason it shouldn't do the job. I considered making something similar when I was conceiving my 'trenching saw', but opted instead for the configuration I posted above. I've been pushing saws for too long & found it hard to change. It's all about personal preference & perseverance. I find that by the time I finish something using a new technique, I've almost got it down pat, and by the time I next need to do it, often years later, I have to start from scratch. That's the fate of the amateur.....
24th May 2019, 05:20 PM #7
Got time to knock out a few more trenches today. I knew I had a reason for buying a 2" Cobalt chisel when Master's was closing down. Finally I have a good use for it! Scribed a deep enough line to start the chisel in an worked my way down the trench. Much easier than trying to saw shoulders!Franklin
30th May 2019, 04:12 PM #8
A slight diversion as I knocked up a new dovetailing vise that can hold the wide panels required for the carcase joinery. I had made a smaller one some time ago for drawer making (old jaws in the background) but the new one will hold panels up to 620mm wide. As usual made from scraps I had lying around, this one uses 5 different timbers. The new jaws are thinner than my original which was made from a piece of recycled ironbark joist. I decided to add an outfeed block to the rear jaw this time which I think might be a useful addition.
10th Jul 2019, 06:05 PM #9
OK so this build is still limping along. So much other crud has been getting in the way lately.
Today was pin cutting day. I had previously rebated the lip for the mitre and marked out the pins. After cutting the oblique kerfs to the line, I swapped to my kerf follower to complete them by chopping square down to the line. Next I started chiseling out the waste...
pinCuts.jpg pinKerf.jpg pinWaste.jpgFranklin
11th Jul 2019, 05:55 AM #10GOLD MEMBER
- Join Date
- Jun 2014
- Seattle, Washington, USA
I've done a few full blind dovetail joints. The first time I cut the joint, it was on the feet to a cabinet, so it had to be cut behind a moulding. I made several practice attempts, and eventually got it to an acceptable state, but neither of the two feet were perfect. The part which eludes me is getting the mitre angle to meet at a perfect 90deg. With the feet, it wasn't a big deal for them to be 92 deg or whatever slightly obtuse angle it was, because they didn't have to form a box with other joints, they just got screwed into the bottom of a case.
The true challenge is making a form with four of them. That's the true master work. If any of them don't meet at exactly 90 degrees, you're boned. I tried to make a small box with blind DTs last year. I ended up making it twice and scrapping both attempts. The first time I was able to get the mitres to meet, but it required so much trimming that the inside was complete and utter slop, and I wasn't willing to release it into the wild like that.
The second attempt I got the dovetails to fit well, but the mitres didn't meet correctly, and the box ended up very slightly rhomboidal. It's hard to see, but it's there. When I put a lid on which had a small bead around the inner frame, it really highlighted the skew, and I had to trash that one too. In the end I just cut through dovetails and called it good. So technically, I've never actually been able to pull this joint off on an actual case and feel comfortable calling it "project quality".
I also find it difficult to get the mitres to meet when you view the corner from above (or what will be from the front for yours, I believe). I somehow manage to always leave a gap and I don't really know why. I've gotten to where I always saw the mitre off a bit fat and pare it down to meet the other side.
I know what you mean about that one socket being left square. I've seen this as well, and I can't figure out why it's important. All of the tutorials I've read/watched show this, so I do it for that reason alone, but none of them have really explained why it's necessary.
What you're doing is Olympic level joinery. If you pull it off well, it will be something truly world class. I consider a wide, blind dovetail joint to be about the pinnacle of hand tool work. Even more difficult than carving. Just my personal opinion of course.
Good luck. I look forward to the finished product!
11th Jul 2019, 07:48 AM #11
What can I say other than "It seemed like a good idea at the time."
I haven't a clear idea on how I am going to approach the mitre bevel yet. Some of the Japanese videos make it look so easy with just a big jig and a sharp chisel. I have a feeling they probably also have a specialized plane that does these sorts of 45 degree mitres as well. I pondered the square dovetail for a while and think it must be along one edge only to allow for some slop when fitting to get the last of the sides to clamp up true. My limited experience in doing mitred corners on frame and panel work have got 3 out of 4 corners meeting well, but the last one has always provided endless degrees of frustration coming together and squaring up!
When finished this cabinet will slide into a cavity in my old study desk that was originally made large enough to fit a couple of PC AT cases. This cabinet was never intended to be a show object, its more of a learning exercise and if the joints don't quite work out they will be mostly hidden from view.
Some of the Japanese chests also round over the jointed cabinet edges after assembly, and they still show nice clean joints with no gaps. That probably means it must be much more important to get the mitres to fit rather than over worrying the dovetails. For the moment I'm going with standard dovetails all round and I'll consider opening up one set of sockets if the case dosen't go together square.
11th Jul 2019, 09:21 AM #12
Luke, as I said earlier, I've only attempted full-blinds a couple of times, my first attempt was for something where I made full-blinds at the front & half-blind at the back, which made life a lot easier. My second attempt was this 'journal box' for my daughter, with full-blinds all the way round. Box2.jpg Box1.jpg
As I remember it, one part that challenged me was transcribing the tails to their mating piece (I think it ended up better to do pins first & transcribe those because it gave me more room to get a scribe in, but it was so long ago my memory is even hazier than usual). Absolute accuracy in layout, and utmost care in working to the lines was essential for a good fit - I took much more than my usual time over this job! My corners all closed up, but because I took the precaution of making it as a single, closed unit & cutting the lid off later, I can't say if it's a perfect rectangle. It could be ever so slightly rhomboid, but not enough to be apparent to the eye, fortunately. I don't think I had the nerve to put a square on it.
The pics aren't great, the box was made well before the digital camera age so these are from an old photo, so you can't get a really good look at he joinery. I can see a tiny gap along where the half tail in the top right of the lid didn't quite bottom out, but all in all, it came out rather well, considering my not-so-vast experience in doing full-blind D/Ts.
My advice is to choose a wood like G. robusta that cuts & chisels very crisply, keep the object fairly small (but not so small you can't see what you're doing), and work exceedingly carefully. And most importantly of all, if you're successful, never attempt them again.......
11th Jul 2019, 09:55 AM #13
I'm an amateur, it's shedware here... for the fun of it. At only one or two projects a year it will take me a long time to get to production standard.
BTW Nice box Ian! I like Silky in small doses.Franklin
11th Jul 2019, 06:11 PM #14
Actually, you have a very sensible attitude. Some of us get too serious about striving for the perfection which always eludes us. As amateurs, we don't spend endless days doing the same thing over & over 'til we can do it in our sleep. The challenge of each new job is the fun for me, & I agree, fun is really what it's all about...
13th Jul 2019, 05:28 PM #15GOLD MEMBER
- Join Date
- Jun 2014
- Seattle, Washington, USA
Sorry, I definitely didn't mean to be discouraging! It may be the pinnacle of difficulty, but it's also the pinnacle of style, so worth every bit of effort.
Regarding how to remove the material at the mitre, I believe that a sharp chisel is the go for the bulk of the material,and then a shoulder plane can be useful for the last swipe or two.
I've also tried making the angle of the mitre one or two degrees sharper than 45 in an effort to make the tips meet early so that they can be sanded to a nice corner. Yeah... don't do that. It might make the long mitre fit, but it ruins the fit of the dovetails and opens up the short mitre at either end of the joint. Luckily that was a practice joint.
According to any reasonable, theoretical approach it should just be a matter of being super, super careful, marking accurately, and sawing straight, so I'm obviously not doing one of those correctly. Either way, it's certainly fun and challenging, and I agree, that's the name of the game.
Looking forward to seeing what comes out of it!
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