Hi all. For my exterior door frame project.... I will be butting together two lengths of sapele/mahog. The individual pieces are about 22mm x 140mm and 1040cm long...and joining them on the long edges to make 260mm wide panels. Should I buy a jointing router bit or can I get away with using biscuits. Once they are joined i will be fielding them.
Thanks.
Arthur
You don't need either...just glue should be fine. You can certainly use biscuits for alignment, but they don't help at all as far as strength of the joint.
Chris
True enough.
NOT true at all. This seems to be a widely quoted myth parroted around here amongst the literati.
One minute of research will get EMPIRICAL research to show differently. You can get started here:
biscuits, not three. pieces were 2X4, about 15' long. Set 48 hours with Titebone #2. I was surprised how easily they (biscuits) broke, 1/2 in each piece of 2x4. Did not use a scale to measure force. Nothing failed but the biscuits. I asked the question about the difference between Lamello and PC here about a year ago. That was not answered, but got all kinds of reasons it failed. None applicable. After that, biscuits were for alignment, the added strength was secondary. I still would like to know if there is a diff between Lamello and PC biscuits.
Do you realise that there is a difference between gluing end grain to side grain and gluing side grain to side grain?
After many years of doing this for a living, yes. Check out the link, do some quick research.
Robert
wrote
Absolutely agree! ... to suggest that properly applied biscuit joinery adds no strength whatsoever to the joint under question defies reason, logic, personal practical experience, and more than one published testing.
There seems to be a proliferation of journalist woodworkers spouting these "truisms" that are more former than latter.
I'll say it again: You gotta love the "wired world" ... the more "facts" available from which to draw wrong conclusions, the more wrong conclusions there are available as "facts".
Agreed, biscuits add considerable strength to butt joints, and miter joints. Today Domino's work even better. ;~)
Richard,
I am not sure how your test disproved the data when your test was not the same (2 vs three busuits) and you did not do a comparison with a non-biscuit joint to compare amount of pressure required to break the joint.
Of course none of that would change the fact that you were surprised at how easy the joint broke, but just pointing out that it was not "the same" test and not neccesarily conclusive.
-Chef Juke "EVERYbody Eats when they come to MY house!"
Besides that with a 15-foot moment arm he could have broken _any_ rigid joint between 2 2x4s joined 90 degrees without much effort.
The biscuits broke, he said. If it had been a mortise and tenon the tenon would have broken. "Stronger than a butt joint" doesn't mean "infinitely strong".
Huh? The original poster is edge-gluing long grain to long grain to make a panel. The glue alone is at least as strong as the wood. How would biscuits possibly make the joint any stronger?
Chris
article you linked to says, "Modern adhesives can glue long or side grain areas of wood together making a joint stronger than the wood itself."
Chris
amongst the literati.
When I got my first biscuit jointer, I did a few experiments with it... just curious if the things were any good..
I built a couple of different size frames out of 1x4 scrap, using biscuits and Titebond for assembly.. I let then sit for a week or so and them started flexing and bending them until a few joints failed, and every joint that I managed to break had the wood breaking and the biscuit still glued in place on both boards.. I have no scientific basis for the holding power, but it impressed the shit outta me..
BTW: Robert, WTF is a literati?
mac
Please remove splinters before emailing
Leon, it's less expensive to have YOU do the joints, and pay labor and shipping, then buy a Domino.. Yeah, it's tool envy.. [ sigh ]
mac
Please remove splinters before emailing
More than one literato...
Regards, Tom.
Thos. J. Watson - Cabinetmaker
Please take a moment an reread. You will see that I agree with that.
The second comment was mine. I agreed with you until that point.
When I started in the trades back in the early 70's, we certainly did not have biscuits. Yet our work did not fall apart over time.
Yellow woodworking glue was just getting easy to find around here and we were considered heretics because we joined long pieces with once we got that stuff.
This was not an innovative experiment on my part. Based on the test results he had read, the structural engineer favored by the GC I worked for specified exact construction methods and materials for wood beams and other wood structural components.
Personally I didn't see any difference between the yellow carpenter's glue and the Elmer's Professional Super Strength, but that's another topic.
Regardless, I still don't believe in situation that biscuits add nothing to the strength of the joint. As J.Clarke said above, using a biscuit for joining doesn't make the joint infinitely stronger.
And again, if you read just that one article I linked and take a few moments to read even more, I think you will be surprised just how strong those little devils are >>when properly applied
"Chris Friesen" wrote
Other than your sudden introduction of the phrase "useful additional strength" (which proves you really didn't believe your original contention that none whatsoever is added. ;)), let's see some proof of your contention that ALL glue joints of this type will be "stronger than the wood itself" ... or have you simply not yet experienced joint failure?
It's safe to say that, in joinery, a lot of small strengths add up to contribute to total "joint strength.
To declare, unequivocably, that there are NO corcumstance/factors (including the obvious ones of wood type/species, moisture content, grain, defects, the glue, its type, quality, age, application, etc.) where any added strength from biscuits , no matter how slight, may prove to be a "useful" additive to the ultimate strength of the joint, simply cannot be supported as a statement of fact.
Fine ... then let's see some emprical evidence/test results that verify/prove these exceedingly broad, all encompassing statements.
;~), boy that Domino saved me lot's of time on my last job. I think I put in about 28 loose tennons on just the legs on the walnut desk. Throw in probably 54 for the top and shelves for aligning the pieces of wood and another 28 for the shelf skirts. Biscuits would have worked on the top and shelf panels but it would have been over 100 mortises done on the mortiser for the shelf and leg skirts. On this job alone the Domino probably saved me 1 full day of work and that is about 1/3 the cost of the Domino.
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