How many times I wished there was some sort of magic machine that could make my boards longer. Sometimes I measured wrong, sometimes I cut off a board too short, and sometimes I just underestimated how much lumber I would need. All the times that just one board ... a bit longer would have finished the job.
Watch it on Youtube: https://youtu.be/yef7-vD60mo
Does that sound familiar? I get frequent emails from people looking for a way to make one board longer ... so here are some ideas ...
The first thing that often comes to mind is just a simple "butt joint" and for some projects, it would work. Unfortunately, it is not a very strong joint but it is one alternative. The way you can make it stronger is to apply yellow glue to each end ... let the glue sit for 15 minutes while it soaks into the wood and starts to harden, then apply another skim coat over top of the first layer of glue and clamp your boards together. This makes the joint MUCH stronger.
I have tried other glues on butt joints but I have not found any that really give a good solid bond that is as strong as the wood, so I have settled back on the old "standard" yellow glue, which holds as good as any I have found and is always in my workshop.
I have 2 of these End to Eng Board clamps, the best one I have uses 4 pieces of Oak, 10 inches long, but 1" wide and 1-1/4" high. I also used carriage bolts on that version because carriage bolts are threaded end to end which is important in a clamp-like this. What I don't like about carriage bolts in wood is that if you tighten them too much, they can strip the square holding part near the head that saves having to use 2 wrenches on it, but an easy fix for that, if it does strip, is to cut a slot in the rounded head of the carriage bolt that will end up making it like a slotted screw head, then you can tighten or remove it.
The next alternative which is a huge advancement uses the router table and a bit called the "reversible finger joint bit". The reason it is called this is that when you run both your pieces of wood through when you flip one those boards, you will find that you get an almost perfect fit
My favorite bit for this is the Freud Diablo bit, not a cheap bit but it can sure get you back on track with a good solid joint when glued and in some cases, is as strong as the wood it is being used with.
A close runner is the various other finger joint bits, some of which I have tried and yes, they do work ok, but not quite the same fit as the Freud, but still something worth considering.
Another common solution is to use a "scarf" joint. The scarf joint is basically any joint that is cut at an angle then re-joined. These were originally developed centuries ago by early building constructors to join wood together, but as woodworkers, we have adopted these same joints for use in woodworking.
The scarf joint is good for both adding wood to make a board longer, but it is also useful for replacing a certain part of aboard. Furniture repair specialists use this joint commonly to make furniture repairs and restorations.
There are of course a variety of other joint variations that can also be used, and any number of glues as well that, depending on the wood you are using may work nominally better, but for the most part, these are the basics for making boards longer ... at least until someone invents a magic board stretcher which we will all line up to purchase ...
Copyright Colin Knecht