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biscuit joiners for edge glue ups?12/23
Just wondering how many people use biscuits for doing edge glue ups?
For strength,they are not necessary,but they can be helpful for alignment if you need flush joints on long pieces.Personally,I prefer Domino's for alignment,but biscuits will do the same thing.
I use biscuits for a LOT of things but not for edge glue-ups. IMHO they're unnecessary and can be problematic if not done correctly. Even if done correctly they add little except for help aligning…..which unless your doing an extremely large top, you probably don't really need;>)
Long grain to long grain is the strongest glue joint you can accomplish. When edge gluing boards you have 100% edge grain to edge grain and there is nothing you can do that will make the joint stronger. In almost all situations of this type of joint the wood will split before the joint fails.
It seems to be commonly taught in school shops that dowels and/or biscuits are necessary in these glue ups. That is completely wrong.
Since inserting dowels in the edge of a board mean that 95% of the dowel surface intersects with end grain there is virtually no strength added to the joint. It is not the same as in door construction where dowels give sheer strength to the joint.
Wafers of course will make for a long grain to long grain joint. However with the edges of the boards giving significant strength to the joint any added strength given by a wafer is insignificant. Plus wafers are well know for shrinking over time and drawing the wood surface above them down, thus potentially creating a wafer shaped depression on the surface.
If you are using dowels or wafers for alignment purposes that is fine.....but gluing them in place won't add strength to the joint and, as in the case of the wafers, can be counter productive.
Well I know when you are doing casing and use biscuits they align and add strength. Just use plenty of glue on the biscuit.
Edge grain I almost never use them.
Best use for me is when I am doing miters with plywood. Makes for great alignment, I never use glue in them for this purpose, better to get it done quick and have a good glue squeeze out.