I’ve made a set of panels in hard maple about 20″ wide to form a rectangular case. When assembled, the grain of all of the panels runs in the same direction. That is, there is no cross grain joinery.
At what will be the two top joints I’ve cut through dovetails.
But my question is about what I’m doing with the bottom panel. I’ve cut sliding dovetails to join that panel a short distance (4 1/2″) up from the end of the side panels.
Here’s my question: I’d like to glue them along their entire length of about 20″. Yellow glue, being water based, begins swelling the wood almost immediately making assembly of such a joint difficult to impossible.
But here’s what I’m thinking – I could use epoxy (West System) or Polyurethane (Gorilla) for the task. Neither of those is water base. I kind of lean to using the epoxy, but I’d probably get some of their slow set hardener just to be safe. Of course, I already have some Gorilla on hand.
What’s your opinion?
Replies
j,
you're talking about a sliding dovetail in a dovetail dado right?
the friction when assembling can make things go very badly and the setting glue makes things worse. i have solved this by cutting away the middle of the dovetail. one only needs it at the front and back of the dado. i guess you could leave some in the center also.
eef
Yup. That's the kind. Dovetail on end of panel sliding into a dovetail shaped dado.
One might question why I chose that joint for this location. This cabinet has the Shaker style look to it. The sides reach the floor, so the bottom panel (which this is) has to meet the sides somehow. So regular through dovetails like at a corner are out. Yeah, I could have done some through mortises, but they don't look right for this piece. And a regular 'ol dado just doesn't have any pizazz.
since I've used sliding dovetails on a smaller projects, it seemed like a good choice. Until I got a little anxious about the glue. I remember what it was like putting glue (yellow PVA) all along a 6 inch length. That was a little difficult.
That's why the question concerning non waterbased adhesives. I'm thinking Gorilla or epoxy won't swell the wood, and at least with Gorilla, maybe even let the thing slip in easier.
I'm going to sound like a broken record -- the topic's come up before -- but polyurethane works fine ; it acts as a lubricant to help the dovetail slide along. Epoxy with a long open time should work too, though I've never used it. The only problem I have is with the brand -- Gorilla. They've reduced the open time of their product to something like 5 or 10 minutes, which might not be enough for a complicated glue-up. I use Titebond poly, which as far as I know still has 20 minutes open.
Jim
Wow! Only 5 minutes. Thanks for the tip. I'll switch.
If a sliding dove tail is well done, you don't need to glue the entire joint, jut a little dab on one of the ends will keep the joint from sliding, that's all you need.C.
I like sliding DTs too, but to avoid the 'lockup' problem I shave about an 1/8" or more 3" from each end. Straight bit, RT fence set roughly to let the bit protude 1/8-3/16. Eyeball the point of entry and exit. Leaves enough of the dovetail for support and visually looks normal. I can't remember offhand the last time I tried this on a 20" dovetail, or if I ever did, but it works for tops and bottoms of bookcases. Let us know how you workaround this and BTW, I use yellow glue with a little brush.
Tapered sliding dove tails are the answer, the joint locks only in the last few inches.
I make my pieces a little over size, I make a dry trial and trim.
It works like a charm !C.
I've read about those. It's too late for me now, but in the future?
I routed the dovetails I have with a Leigh jig. I'm not sure, but I don't think that thing can do that. That's o.k., I'm aware that when I try a tapered one I'll go about it differently.
Actually one option I was turning over in my head was to seat the panel most of the way in, then apply adhesive to only the last 3 or so inches at both ends. I'd apply it to the portion of panel waiting to go in, and to the last 3 inches of dovetail slot yet to receive the panel.
Is there a particular reason for wanting to glue the entire length of this joint?
If none then the accepted method is to apply glue on the last inch or two and at the other end just before you pushes it home...but ya gotta be snappy.
If you have the tool another option is to plane a slight taper so that it only gets tight as it heads home.If you did the joint with a router then use a chisel with a scraping action to ease the tailat one end.
I am not familiar with your glue options but the thought of Gorilla glue and fine cabinet work makes me nervous.
I am not familiar with your glue options but the thought of Gorilla glue and fine cabinet work makes me nervous.
Have used that glue on some archery bows. Not sure why some folks hate it? Yes you have to scrape off some pubbly stuff!
Mess, stains.....And I read somewhere that it is not permanent ie one day it just lets go....And it hardens in the bottle no matter what you do to remove air.....Philip Marcou
I'd agree with you generally about the qualities of polyurethane glue. I don't use it for anything but sliding dovetails. These should have a tight mechanical fit, and not need much gluing at all. The major problem is sliding them into place without causing damage from too much force. The purpose of the polyurethane applied sparingly all the way along is to ease their passage through lubrication. Permanently fixing them in place is a bonus. Glue failure is unlikely to occur all the way along the dovetail, but if it did it wouldn't cause much of a problem in most applications where the joint is horizontal. The problem with sd's is getting them in, not keeping them in place once they're there.
I used to watch Norm Abrams using the stuff, and he would have to scrape prodigious amounts of dried foam off the next day. If you use the stuff sparingly and lay off the water you don't have that problem. What vestiges of foam you do have in the corner scrape off easily.
Hardening in the bottle is a problem. If you store it upright you soon wind up with a solid bowling pin. Stored upside down, only the glue at the bottle's base is in contact with the moisture in the air -- the rest is usable for a few months.
Jim
Wow, unless you make a lot of sliding dovetails, you must have a lot of polyurethane go bad through age. The smallest bottle I've seen is still 2oz. That much would go a long way in a few SDs.
I rarely use Poly glue -- only for sd's. I can't claim any credit for the idea. I got it several years ago from an article by a retired cabinetmaker who had been responsible for making all the prototypes for new furniture for the Stickley furniture factory. They had high standards, and insisted on sliding dovetails for all their case furniture. The guy (sorry, I've forgotten his name) pointed out that using any glue other than poly would cause sticking, waste time, and materials. I don't recall seeing many complaints about Stickley furniture falling apart because of failed glue joints, or suffering from an inferior finish because of messy glue. This is a tried technique that has been used by professional woodworkers who had deadlines to meet and standards to maintain. It seems to me a massive waste of time and energy to fool around with "traditional" glues that are in fact modern and don't do the job, or to give yourself the trouble of creating graduated dovetails when there's a simpler, faster technique that gives you tighter joints and doesn't raise your blood pressure through the roof.
I've used the technique a number of times without a failure. When I took early retirement I had to find a home, at home, for thousands of books in my office at work. I had to build more bookcases than I care to think about as quickly as I could, and found this technique a great help. I had tried yellow glue previously and found it a hassle. I still use sliding dovetails for 18th c. type casework, and the technique works well for pieces much deeper than the average bookcase.
Jim
That is a convincing case you make. What do you do about avoiding mess on work, self and clothes? And is there a convenient way to remove it from skin, other than using lacquer thinners?Philip Marcou
Thanks. I've never had an issue with mess on the workpiece. I cut a narrow tip on the bottle, and use it sparingly. It's pointless trying to clean up any overspill till next day when it's dry, and it scrapes off readily. It doesn't seem to set deep enough into the fibres to need much scraping, which I suppose doesn't say much for it as a glue. It's thin watery stuff with a long open time (Titebond is, not Gorilla), so you can wipe it off your hands with a paper towel, then use a handcleaner; mine's orange with pumice in it. As to clothes I'm a slob. I use coveralls in the (Canadian) winter, and shorts and t-shirt in the summer -- let the glue fall where it may.
Jim
And is there a convenient way to remove it from skin, other than using lacquer thinners? LOL..
My first thought was some left over sandpaper.
I did not post before but I would think/know for experience that any dry fitted tapered dovetail will work with any glue I have ever used.
Philip.. I do not work for them. I have used may different types of 'water proof', if there is such a thing. No glue fails that I know of. I do not use gorilla glue often but it has worked for me on more that one occasion. Now I like Titebond III.
If I want permenent I guess I'd use the expensive brown glue you mix with water. (I wonder, how can a powder, mixed with water, to make it. be waterproof?
Maybe a Question for God to answer?
"(I wonder, how can a powder, mixed with water, to make it. be waterproof?"--------Chemistry, chemistry.....
The only poly u glue I have used is Gorilla- and I haven't found a way to clean my hands of the stains, other than lacquer thinners. No hand cleaner gunk works- not even Swarfega, beloved of North Sea oil contractors....And it WILL get on the fingers, trust me.
If it is a tapered sliding dove then you can get away with normal wood glue, for sure. One of the main reasons for making it tapered...
We better talk as much as possible now, as the Forum Doomsayers predict imminent demise of Knots (;)(;)(;) reminds me of the Seventh Day Adventurers (modified name) who have re-scheduled Armageddon how many times now?
Philip, the UnpiousPhilip Marcou
Edited 12/12/2009 9:30 pm by philip
2012.. I HOPE I live that long to see the outcome!
reminds me of the Seventh Day Adventurers .. LOL
Catholic here. NO I DO NOT hate them but they are sure persistent! As I do with anybody. I listen but set in my ways. They go off after I listen for awhile and offer them a glass of Jack Daniels with ice...
Edited 12/12/2009 9:47 pm by WillGeorge
Is there a particular reason for my original thought to glue the whole length? No. What I've decided is last 2 or 3 inches at either end. Push the panel in until I'm at that point, apply the adhesive, push it home.
I've used Gorilla on projects before. Mostly for the longer open time, sometimes for it's reputed waterproofness.
With regard to that last point, about 10 years ago I built an outdoor planter/bench system (Norm's from NYW) and used Titebond 2 and Gorilla to make it. Split 50/50 between all joints that had to be glued. In some cases, some boards are even laminated to make them thick enough. At this time I can say through personal experience that even after all that time out in the weather, through 3 revarnishings, that all the glue joints regardless of which one, have held together with no indication whatsoever of impending failure.
I'd say that if someone is concerned about water resistance, just cut the surfaces smooth enough and the joints close enough and use yellow glue (Titebond 2) and it's going to work fine.
Open time and lubricity to aid assembly are different issues.
Just in case, have a big ol' block of wood and a sledgehammer handy at glue up. My sliding dovetails needed a bit of, um , 'persuasion' to go the last few inches.
I used Titebond III, glued the entire length.
Your instincts are correct!
J.
I am making a cabinet right now that has sliding dovetails to join the top/bottom to the sides. I tried to glue the entire joint and that was a huge mistake. As someone else has already pointed out, you only need (and only should) put glue in the dovetail housing at the closed end of the housing. A few inches of glue is sufficient. If the joint fits well, then it will stay together of its own accord and so doesn't need glue all the way across it. Also adding glue all the way across it actually makes getting the joint together almost impossible. The glue doesn't act as a lubricant, but it does swell the parts a bit. And that make for some seriously tough joint fitting (I recall needing two other guys, a block of wood, and a dead blow mallet. Oh, and quite a few four letter words.).
Good luck.Matt Kenney / assoc. editor / Fine Woodworking
Edited 12/11/2009 1:16 pm ET by MKenney
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