Glueing end grain - positive experiences

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White House Workshop

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I did a search but couldn't find too much on this topic - except it's not advised and isn't strong! That's what my woodworking books say, too, particularly one I have called 'The Joint Book' by Noll.

However, I have been glueing end grain to end grain a lot in order to get nice grain matches around corners, rectangular or otherwise. The only failure I had was end grain to cross grain, for obvious reasons. I've used several glues, depending on the size of joint/stock and the stresses the joint will need to take. I've glued small trinket boxes' corners with PVA and none of the joints have failed; even a large-ish box about 9" square and 10" deep has held for 10 years so far, and it gets a lot of mistreatment from the grandkids!

Recently I've been matching grain patterns across some quite obtuse angles, e.g. 160 degrees, and the stock is mostly half inch. For these I've been using slow setting epoxy (Araldite). It can be messy, especially with squeeze out, but careful use of a sharp chisel and cabinet scraper removes it quite well when it's in the inbetween setting stage - hard enough to hold the joint, but still soft enough to cut/scrape off the wood. I haven't had any problems with the glue soaking in and the wood has taken an even finish 24 hours later with no blotchiness. I did miss one tiny bit on the underside of a joint and by the time it was really set I had to file it off!

The big advantage of this simple joint is the ease of preparation. No fancy cutting, just careful set-up to get the right angle. If the saw blade polishes the cut (happens a lot on cherry, for example) I simply take a sharp point and scratch both surfaces to be jointed - that way I don't change the angle or dimensions. I invariably scratch the joint if I'm using PVA, but tried an epoxied test joint without scratching and it wouldn't break even by jumping on it - hurt my heel in fact!

The only end grain joints I've had fail on me have been really small cross-section framing, so I'm not really surprised in those cases. My own fault for not reinforcing them - and using the wrong glue?
 
I suppose the reason why end grain is not said to glue up well is by using an analogy with straws, if you take a stack of straws and glue them lengthwise then you are going to get much better results than if you try to glues a stack of straws end to end. AFAIAA the structure of timber is rather like a lot of straws anyway.

I am not too sure that it is best to score before using PVA, from what I have read the smoother one can get the surface then the better the glue will hold the timber together, this is because the surfaces are bound together molecularly by bonding the atoms in the timber, the glue fills up the irregular surfaces to be joined, a similar result of water between two sheets of glass holding them together.

When I glue end grain at 45 deg for frames etc I always give the cut ends a thin coat of pva first and let it dry before gluing properly, not sure if it's the right thing to do but it seems to make the joint stronger and helps the glue from being quickly absorbed.

(Another biker BTW Honda ST1100)
 
White house, end grain to end grain is definitely not a good idea as wood fibres are effectively like drinking straws, and if you think about it for a minute, glueing the ends of drinking straws bundled together will never be very strong
 
Tony":2nr44tkw said:
White house, end grain to end grain is definitely not a good idea as wood fibres are effectively like drinking straws, and if you think about it for a minute, glueing the ends of drinking straws bundled together will never be very strong

Agreed that end grain to end grain is not a good idea Tony but doing as Scrimper suggests is one way of nullifying the starw effect, I have used that method and whilst not recommended for anything constructional it does work.

Dom
 
Tony":34jrml9b said:
White house, end grain to end grain is definitely not a good idea as wood fibres are effectively like drinking straws, and if you think about it for a minute, glueing the ends of drinking straws bundled together will never be very strong
Agreed - to a point. I reasoned that if I could get the glue to work it's way into the straws it would provide a joint of the type used in metalworking by manufacturers of office chairs where they butt tubular or square section steel together and hold it with a shaped plastic insert. It seems to work for me as long as the joint is large enough to take a decent quantity of glue. As I said in my original post, the failures have been on small joints and I haven't had a failure on a large joint so far - touch wood!

Here are my latest boxes, both using end grain to end grain. https://www.ukworkshop.co.uk/forums/viewtopic.php?p=190598#190598
 
Chris - that is one complex joint!

I made a similar project some time ago and I used metal leg brackets - the type that have a cross-brace between the rails and a screw/bolt in the leg. My project as light and not intended to take any real weight, but if it had needed extra strength I would use two braces and two bolts. It's standing up to more use than was originally intended with no problems.
 
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