10

Having just completed my first woodworking project (a twin-size bed made of 1x poplar and plywood), there are of course many things I would change if I were to do it again. Perhaps one of the more surprising to me (as a beginner) is my desire to not use butt joints (with only glue, or with pocket-hole screws).

Butt joints look easy, especially for beginner woodworkers who may not have a big selection of tools - just cut the pieces to length and glue, screw, nail, whatever. Their main disadvantages - strength and appearance, IMO - may not be a concern if it is strong enough, and the final piece will be painted or edges covered up with trim. Especially compared to cutting dadoes or M&T, butt joints are simple to execute - in theory.

In practice, though, I found they are very difficult to align precisely and even a very shallow dado / groove or biscuits (though that's another tool) would have helped with alignment immensely. This was compounded by not having a good and flat surface to assemble everything on (an assembly table just moved high up on my project list). Having the glued-up pieces slide around while trying to tighten down clamps or nail in a brad with the pneumatic nailer was frustrating, and would have been a moot point with a different kind of joint.

Are there any other not-so-obvious drawbacks to butt joints, that may not be apparent to (beginner) woodworkers?

2 Answers 2

9

In practice, though, I found they are very difficult to align precisely and even a very shallow dado / groove or biscuits (though that's another tool) would have helped with alignment immensely.

Where a butt joint is an appropriate joint to choose the difficulty in alignment is their main downside. There are simple construction tips that can help overcome these problems, including creative use of clamps and registration surfaces (e.g. a stop block, or just the top of the workbench sometimes) to butt matching surfaces against1 but there's no denying it can be a tricky thing to do in practice.

Having the glued-up pieces slide around while trying to tighten down clamps or nail in a brad with the pneumatic nailer was frustrating, and would have been a moot point with a different kind of joint.

Yep, all wood glues are very lubricative and they can make a joint surprisingly slippery!

Anything in the same vein as a biscuit (including dowels, Dominos and splines) is one of the primary ways to fix alignment and stop things slipping around during glue-up because they lock in the positions of the two pieces of wood, sometimes relevant to the face sides only (biscuits) other times both up and down as well as side to side (dowels and Dominos).

But when making up large panels from a number of boards there's really no reason to resort to any of these because you can use a caul to force alignment as you are clamping up.

Note that splines, dowels, biscuits and Dominos don't add any needed strength in a joint like this and in fact may slightly weaken the joint as paradoxical as that seems.

Are there any other not-so-obvious drawbacks to butt joints, that may not be apparent to (beginner) woodworkers?

Other than being careful where one or both faces is end grain I don't think so. Anywhere that face grain is glued to face grain (whether longitudinal or radial) the joint created will be at least as strong as the wood around it.

This assumes the joint faces are properly prepared of course. They should be:

  • Flat (or occasionally with a deliberate curve, as in a sprung joint).
  • Smooth (the smoother the better, roughening the surface is almost never desirable).
  • This last one doesn't get mentioned often enough — freshly worked (older wood surfaces don't glue as well as those which have just been worked, ideally within an hour).

And on top of the above it's important that enough glue is used so that it can fully wet the joint face on both sides and that sufficient clamp pressure is applied2. You want to clamp hard, firmly enough to squeeze out all excess adhesive because a thin film is nearly always the strongest3

A little more on some aspects of this in What are the different grain directions, and how do they affect joint strength?


1 These surfaces should be waxed or otherwise protected (e.g. with tape, packing tape is excellent for this but just about anything will do) so that any glue that squeezes onto them won't bond them to the workpiece.

2 Many woodworkers, including some pros, under-clamp and the fact that there aren't more joint failures is a testament to the bonding strength of glues. But where joint strength is critical, and in butt joints the glue is the only thing holding the wood together so it's a critical example, you want to tick all the boxes and that includes very strong clamp pressures being applied to ensure a thin glue line. In butt joints we should be aiming for glue lines that are nearly invisible, certainly not easily seen at arm's length.

3 An exception would be when using epoxy, which doesn't require clamp pressure to ensure a good bond and which can make a very strong bond even in a thick film.

-1

The butt joint is the simplest joint to make since it merely involves cutting the material to the appropriate length and butting them together. It is also the weakest because unless some form of reinforcement is used, it relies upon glue or welding alone to hold it together. As the orientation of the material usually presents only one end to a long gluing or welding surface, the resulting joint is inherently weak.

3
  • In woodworking at least, "butt joint" also covers side-to-side joints (long grain joined to long grain) as used to make up wider panels, tabletops etc. These are not weak, if done even moderately well they exceed the strength of the wood around them (so that if the panel is broken apart the breaks completely ignore the glue lines). This may be different in metalworking which you also refer to — please do note that this is completely irrelevant here in Woodworking, and on a technical front there are no parallels to draw either.
    – Graphus
    Commented Oct 31, 2022 at 16:43
  • @Graphus - I've literally never heard anyone call side to side glue up a butt joint. Wikipedia also has absolutely no mention of that (en.wikipedia.org/wiki/Butt_joint). Butt joint is end-to-end at 90 degrees, and nothing else.
    – Davor
    Commented Mar 23, 2023 at 12:12
  • @Davor. Wikipedia is not a good source for info on woodworking (and many other specialist subjects with their own lingo). "Butt joint is end-to-end at 90 degrees, and nothing else." Nope, not so. Any mating of wood where two plain edges are butted up against each other, i.e. glue-only joints with no interlocking aspect, is technically under the broad umbrella term. You don't have to take my word for it, see "Good Wood Joints" by Jackson and Day. It continually makes reference to the sub-types of butt joint. Going back further, see Fairham's "Woodwork Joints" from 1921.
    – Graphus
    Commented Mar 23, 2023 at 19:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.