So I need some advice about joinery. I have a couple of questions for now and then I also wanted to ask for book recommendations. If it’s all in a book somewhere I don’t mind doing the homework, I just don’t know where to find this info.
I do landscaping so most of my joinery is for gates/fences that sort of thing. Usually redwood is involved. I’d like to integrate more woodworking into my landscapes so I’m learning a part of the trade. Many thanks for your help.
-s
My questions:
– how big do you make the tongue when you’re joining a rail to a post – 2×4 material in this case but there must be a general rule, no?
– can biscuits be used for outdoor joinery (say to tie a mitered gate frame together)
– if you *have* to screw into endgrain, are there ways of making it more solid – glue for example, are tapered drilled holes much better? Can dowels be used for outdoor work?
– how much stronger is a mortise and tenon compared to a half lap – are there rules for when to use different kinds of joints?
Replies
Storme,
<< how big do you make the tongue when you're joining a rail to a post - 2x4 material in this case but there must be a general rule, no?>>
This is basically a (loose) M&T joint, if I understand what you're talking about here; the "general rule" for M&Ts is that the tenon is approximately 1/3 the thickness of the piece into which it will be inserted (some will say 1/4 is better).
<<can biscuits be used for outdoor joinery (say to tie a mitered gate frame together)>>
I don't see why not, but I have no experience here. The type of glue used would probably be the most important consideration.
<<if you *have* to screw into endgrain, are there ways of making it more solid - glue for example, are tapered drilled holes much better? Can dowels be used for outdoor work?>>
Can't help you on the screw part of the question; dowels are used in outdoor work all the time, and, for many applications, work very well.
<<how much stronger is a mortise and tenon compared to a half lap - are there rules for when to use different kinds of joints?>>
That all depends on the direction of the force and what kinds of force you are trying to counter. For example, wracking/twisting forces would tear an unreinforced lap joint apart pretty quickly, whereas a dovetail joint would withstand them pretty well.
As far as "rules" for using joints, I suppose so, but, off the top of my head, I can't think of anywhere or of any books that have them explicitly stated. It's largely a matter of using a joint that will counteract the movement/forces to which the joint is subject.
As another example, a well-constructed M&T joint is pretty weak at counteracting force/movement 180º from the direction of insertion (i.e., in the direction of pulling the tenon out of the mortise)....but, if you peg or draw bore the M&T, it will do a reasonably good job of resisting force in that direction.
Hope that this is of some use to you.
James
Thanks for your response, very helpful! It just came up for me because I just built 2 gates. The basic design is 2x4's on edge with a plywood (T111 siding) field. The plywood is set in a 1/2" dado cut into the 2x4's and glued along the entire edge. the top runs all across the top piece (to keep water out of the endgrain) and the verticles have a tongue that sets in the dado. The deepest dado I could cut with the dado blade is 1 1/8" deep so the 2x6 top is more precarious than I wanted it to be. Thus my questions...Any thoughs on the long term longevity of the top bit? It's held on by poly glue along the edge and a 1 1/8" tongue on the edges. I'm considering ordering a pocket jig so I can set some long screws through the tongue up into the top piece.
If your going to screw into end grain, drill a hole for a dowel and insert dowel through board parallel to end grain so that when you screw into wood it will catch grain of dowel and hold tight. Hope that made sense.
Thanks for the tip, I just read about this and wondered how it works - does it force the dowel into the wood? Let me make sure I'm picturing this right: the dowel is put in longwise down through the center of your end grain - right?
If your grain is vertical, the grain of your dowel should be horizontal. There's no benefit to drilling a vertical hole in your stock and sliding in a dowel... then when you put a screw in, you'd still be in end grain!
Put another way, assuming the grain in your dowel runs lengthwise, and the grain in your piece runs up and down, the dowel has to run left and right.My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
that makes much more sense! I was thinking maybe it worked by simply being a bigger diameter attachment and/or by making the connection be a tight glue connection rather than a screw/wood connection.
You mentioned building gates and rail fences with redwood. I'm attaching some pictures of recent gate and rail done in reclaimed old growth redwood. I use a book - "Fences, Authentic Details for Design and Restoration" by Peter Joel Harrison. There are no mortise and tenon in these fences of the 18th Century. Also, I looked closely at the fences in Williamsburg and also noted that they were built without M&T.
Tim
nice work! So I can't quite tell from the gate pic what joint is being used - is that a half lap or something else?I just built another gate for my place today and thought I'd use it to experiment some, so it has straight mitered joints with a biscuit using polyurethane glue and then the field is made from old cedar stakes 6" O.C. which are cut *exactly* to fit inside the frame with glue and a screw dropped through the frame and into the end of the stake to hold each one in.It's doesn't sound real sturdy but it's quite stiff - the 7 cedar stakes, since they're in there tight, act like a framed wall. I'll be curious to see how it stands up to our 2 year old. I also dropped in 2 screws running across the miter each way and buried them deep enough that it's not esthetically too bad. I'm not at all sure it'll last, but this way I'll learn something.Thanks all, for the tips, it gives me something to think on. We have a couple of gates built by someone else that use M&T and half lap respectively, both with polyurethane glue and they stand up to a lot of abuse so far.
Storme, you asked about the details on the Gate.
Attached are two views of the gate design model. One is X-ray view so you can see the joints I used. In this case I went overboard with Mortise and Tenon.
I used Type IV Titebond glue on these joints.
Tim
wow, I'm impressed - what did you use to draw those? I've looked into SketchUp but I haven't had the time to sit down and learn it. Much obliged. I've used polyurethane glues per recommendations from others for outdoor applications and am not familiar with the different types of titebond - better in your opinion?-s
Storme, I have been using SketchUp for all my work (mostly furniture, but also small buildings/sheds).
I don't have an opinion on the comparison of the two glues. I've used both kinds, but like the new waterproof Titebond since it is like using the older versions of Titebond.
Tim
S,
James has given specific answers; but I can add a few general observations based on my construction of nearly a dozen wooden artifacts for the lady wife's garden.
Always use a durable wood. I'm not sure if "redwood" resists rot - is it a cedar of some kind? In Britain, which can be wet at times, non-durable timber will rot no matter how well-made the joint - normally mortise and tenon or bridle joints in my case. Water gets in the gaps and down the end grain as the joint expands and contracts. Then the fungus has its evil way.
I like iroko or oak, whichever I can get for nothing. :-) I imagine Wetern Red Cedar is good, if only someone would donate me some. Tanalised softwood is good, if the parts are tanalised all round and not subsequently cut to reveal untreated wood to the elements. Tanalisation forces the anti-rot chemicals well into the timber, especially the end grain. If you have to cut it, paint it with something to protect that bit.
It's best to use mechanically strong joints rather than joints that rely wholly on the glue. I've come to prefer bridle joints that are pinned with dowels - at least two but sometimes four in larger items. You can use stainless or brass screws if you prefer.
Paradoxically, bridle joints are better than mortise and tenon in outdoor stuff because, although the end grain is more open to the elements, you can also get at it for maintenance purposes - get it to soak up oil or paint. I've had a couple of M&T items go bad on me and the damage always began inside the joints, via that end grain.
In susceptible wood, the end grain of the tenon is where the water and rot first gets in, as the joint expands/contracts and opens up the gaps for capilliary action. Also, mortise and tenon have differential contraction of the two parts of the joint, so the glue line will inevitably break in time (as it will in a bridle joint as well, of course). Dowels used to pin the joint will minimise the consequent weakening and might even help to preserve part of the glue join by restricting the differential movement to just one area of the joint.
Biscuits might work if the joint is thoroughly glued with waterproof glue and the expansion/contraction of the wood due to seasonal changes is not too great. I wouldn't use them in Britain for outdoor stuff, though.
Screwing into end grain is generally not a strong bond but even less so in outdoor stuff, because of that expansion/contraction cycle. If looks aren't too important, I screw through the joint at an angle rather than stright down the end grain. This leaves a canted-over screw head visible although you can bury and plug over them if you're bothered. Of course, plugs too will tend to pop out when the moist/dry cycle has run a few times, unless you match the grain of the plug very carefully. Most of mine have certainly gone loose.
Lataxe
Hi Lataxe, I laughed when I read 'redwood' in quotes - sequoia sempervirons, one of the largest trees in the world, heart wood is soft and the heart wood is quite rot resistant, the wood of choice for decks and fences in my neck of the woods (N. California). Here's some pics, The second one has a car in it so you can get an idea of the scale.
http://www.terragalleria.com/parks/np-image.redw1441.html
http://www.pcimagenetwork.com/forest/forest15.htmlThanks for the tips, very useful. We don't have constant moisture, we have a wet season and a dry season so I'm guessing our climate is not quite so tough on wood, that said, RW is rot resistant enough that it's frequently buried which eventually leads to failure. Also, we've cut down all the really big, (better quality) trees so the quality of wood has really dropped in the last 20 years.Most of the gates I see use a simple miter joint, held together with screws, seems to work for the most part, but I don't know how well they hold up to abuse. I'd like my things to really last though so I'd like to figure this out.
Storme,
Homage to the Redwoods! I like a Big Beast.
In the NW of Britian,where I live, there are hundreds or possibly thousands of wooden gates in the dry stone walls that are traditional around here. I've been through a good number when out in the fells, walking about.
There's little doubt that some construction designs work better than other methods. Most of the older gates have pinned, through mortise and tenon joints rather than blind ones. They don't have any evidence of glue, presumably because the highly changeable weather here would loosen the joint in a year if it was glued.
The trick seems to be to avoid having end grain in the construction that can get wet but can't as easily dry out; and to allow the joints to move with seasonal changes whilst not allowing them to come apart.
Most of the older gates seem to be heading for their eventual demise via physical collapse rather than rot. It nevertheless seems also to take years and years for them to get beyond repair. They sag but rarely drop off. A wedge here and a brace there keeps them going seemingly forever.
They're mostly made of oak, although you often see part-rotted spars that have obviously had a bit of sapwood left on them.
But I suspect that you might not care for that degree of rusticity (ie loose, saggy, patched and part-rotted) in your own gate. :-)
Lataxe
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