3 August 2021 at 6:35 pm #723489
Im looking at making an European Oak exterior door as the only rubbish you can buy seem to be stave core construction and quite frankly are excessively expensive and will not last.
I’m an engineer and have designed many laminated beams with all the inherent positives that this involves, mainly stability from bowing or twisting but they are usually used in a single humidity environment. That got me thinking about laminating three ~15mm thick planks to form the stiles and rails. The positives I see is that with a waterproof glue, the outside plank could accept a higher moisture content from the inner face and the middle plank being relatively stable and isolated from differential moisture ingress especially with an end grain treatment.
So my question: Has anyone had experience of this method and its long term stability?
Further musing on the fabrication, would be that I could laminate the door frame using the 15mm thick planks and create the joints as the three layers are glued. Obviously I would have to clamp the whole unit as one between two stable and flat boards, say phenolic coated 25mm thick ply all supported on my very stable and flat bench.
Your considered thoughts are welcomed.
BTW it wont be the first external, internal or furniture l door I have made – so no worries about my skill level5 August 2021 at 11:07 pm #723780
Based on garden gates made by this method, I’d say that if water somehow finds its way in between the laminates (usually at the joint lines) and temperatures then fall below freezing, a long lasting door might not be the outcome.
Another reflection, if allowed: if the glue (epoxy, I imagine) were to block moisture from penetrating into the middle board, could that, given the strength of glued butt joints, result in the outer board still taking the two inners ones with it as it warps?
London, UK; Boston, MA9 August 2021 at 5:04 pm #724234
Sven, interesting thoughts. To be honest Ive made many exterior gates but never even thought about laminating as all faces are in the same atmosphere.
On your second reflection. The grain on inner boards would be turned so that the natural tendency of warp would be to pull in the opposite direction, still worth thinking about. I suppose selection of timber would be of essence to prevent major twisting or cupping force.
Glue as long as its correctly applied and clamped any waterproof glue (titebond or similar) is stronger than the wood itself. I know this through experience, having repaired many broken guitar necks and having to repair new splits a few years later.
Any other musings are more than welcome.9 August 2021 at 9:16 pm #724270jeff FisherParticipant
Wooden boat builders do a fair bit of laminating wood with epoxy. Might find some information by searching in the boat building world.9 August 2021 at 9:52 pm #724277
Jeff, great idea. You cant get more differential in humidity that the inside to outside of a boat!10 August 2021 at 9:20 am #724312Larry GeibParticipant
I’ve built and repaired a fair number of boats. The two glues that have never failed are the old two part cascamite plastic resin glue and the more modern epoxies. I generally just get the West system products because I’m familiar with them and the seem to have very long shelf life. I still have epoxy from the early 90’ that is good if I decristalize ir by warming it to 145°f. The epoxy will also be gap filling, so your clamping pressures need not be high. In fact, just moderate pressure so you don’t squeeze epoxy out of a joint.
If you go with epoxy, consider epoxy encapsulation, which is just coating all surfaces with a thin coating. The wood will be more stable and boats last longer. Encapsulated wood can still be varnished or painted.
Gugeon Bros, the West systems folks, have o
Lots of literature.10 August 2021 at 5:36 pm #724352
Thanks Larry17 August 2021 at 8:10 pm #725223
It struck me that once again I might have fallen into the trap of thinking I have some form of command of the English language. Hence, here’s an illustration on how I made that garden gate that only lasted for a couple of years, before the expansion of freezing water broke it apart.
While trying to find the term for “gluing faces together”, I found the link below – among some other concepts…
In between all the posts there were a couple that possibly can be of relevance
London, UK; Boston, MA17 August 2021 at 8:35 pm #725228
Sven, your English is perfect and I was assuming that I would create blind mortices, less chance for water penetration.
I read the article you posted however I dont think some of the comments are correct. Being a Civil Engineer, I have designed numerous laminate beams, and a few that are arched. The timber is always laid with opposing grain, its adds strength and arched are under tension, as the curve is only achieved on final glue up. The glue does not fail, but the structure of the wood. Most issues with glued joints, are preparation (specifically joint gaps when using PVAs) and compression whist setting.
The other thought is that the edges will be within the jamb of the frame with weather seal to protect from driving rain.
Ill think some more, but I am leaning towards laminating.18 August 2021 at 9:38 pm #725408
London, UK; Boston, MA
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