I"ll go first ....


wtnhighlander

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Since this area has been open for more than an hour without a new post, I'll take a stab at it.

I am in the process of building a large, heavy trestle table. My joinery is cut, with a little fine tuning left to do. Mostly simple M&T, with a long grain panel glue up for the top.

My question is about adhesives to consider. Most of us seem to rely on a Titebond or very similar product, but I am concerned about long term (20+ years) glue joint failure. Is there a better choice than PVA glue? Also, should I consider mechanically reinforcing these M&T joints with drawbored dowels?

Let me say that this is a break-down design. The top is held with bolts through slotted holes in the upper rails (term?) of the trestles, threaded directly into the 2" thick top slab. The trestles are fixed together with a stretcher having tenons through each trestle and wedged. The whole thing can "pack flat" for moving. Its mainly the joints in the trestles themselves, and the top panel, that concern me.

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If the wood is dry, and a joint is glued, I see no need for drawboring.   I've never seen an old PVA glue joint that has failed because the glue aged out.  I've seen many failed, old joints that have failed from, I guess, over aggressive drawboring.   200 year old doors that I have taken apart, to replace parts, have not been drawbored, but still had good joints. 

If glue is not used, it's easy to fix almost anything that's mortised, tenoned, and pegged.  You just get the peg out without damaging anything else, and take it back apart.

If I'm building something for an old house, that I expect to last for hundreds of years, I don't use either glue, or drawboring, but make sure the wood is really dry, clamp tight, then bore, and peg.  I realize that's some different than a piece of furniture, but stuff I made like this in the mid '80's is still good, both inside, and outside of houses.

For your table, I'd glue where you need to, and think it will be fine.  The main thing I would worry about is the grain in the tenon outside of the wedge.

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Dowels or dominos in the top seams will give you better alignment during glue up and the thought of them as a backup in the seams. But long grain to long grain joints in hardwood are stronger than the wood itself. Abuse the slab massively and it will crack anywhere but at the joints. Jointing long edges accurately in heavy  boards is the hardest task. If you are at all worried about the fit of the joints in the trestles switch to epoxy for its gap filling properties. That kind of joinery has been around for hundreds of years , I guess if it would work with hide glue that PVA or epoxy shouldn't be a problem.

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I have been using titebond from the beginning. Then tb 2 and now tb 3. If the edges were not dressed true and straight it could be a problem. Otherwise my guess is there is no better choice than titebond 3. It seems to be flexible enough to move with the movement of the wood. Even with age. That is starting with dry wood...

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A little late for this, but I glued edge glued some oak boards for a project back in the late 70's with TB1. I just recently reused the panel for something else and the glue joint was still solid. I am pretty sure it will outlast me.

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