This is a case when ‘size’ does matter!
A popular joint in boxmaking and picture framing is the mitred butt joint, which involves endgrain to endgrain wood that has been cut on a mitre (photo 1). (Hover your mouse over the photos to see their numbers and captions.)
In an ideal world these joints would have splines or keys to give them added strength and rigidity. However judging by the number of boxes I have seen being made I know that in a lot of instances, for whatever reason, this is not the case.
Historically this is not a strong joint, one reason being that when glue is applied to the mating surfaces a large proportion of the adhesive is sucked up by the endgrain. This results in only a small amount of glue being present to actually joint the surfaces together.
A way of giving the joint the best chance of staying together without extra support is called ‘sizing the joint’.
1. First apply glue to the surface of the endgrain joint faces (photo 2).
2. Smear the glue over the entire surface (photo 3).
3. Next apply a small amount of water (photo 4). I use a squirt bottle to the wet the glue then rub it into the endgrain and then allow it to dry completely. This effectively seals the porous tube-like fibres of the wood and provides a more stable surface for the final glue up (photo 5).
4. Let the glue dry. Next apply glue and join as normal. You will find the joint will now hold much better that if a straight glue-up was performed.
The photo above shows the difference this little tip makes it makes. The piece of wood on the right has been sized using the method above before glue was applied. The piece on the left had the same amount of glue applied but the glue has been absorbed into the endgrain.
Steve Hay presents Woodworking Masterclass on 31 Digital TV, find out more at www.woodworkingmasterclass.com
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