Jointing or Biscuits

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I don't see how they could at all. I am surprised they didn't put the Krieg system in there and call it a "metal rod biscuit" or some other baloney.
> Here is the supposed results of a relatively recent (07) "Wood" magazine

SNIP
I think it is important to realize that in some cases these magazines buy these tests, contract these tests, and in other situations probably just buy the copy outright. Mssr. Self would know the protocols on that.
But what gets me, is the way they test the machines. Once again, we are looking for the end all, do all type machine. Where is that machine? With a tip of the hat to the shop bound fellas that do this, I don't really care how well it works in the quiet confines of my shop with all the proper room, clamping equipment, and time I need to get the machine squared away.
I'd bet dollars to doughnuts that if you tried out those tools again in the hands of someone that drives up the the job to trim an house and build a couple of laundry cabs or a built in clothes hamper, he will take the Domino first, and the biscuit machine second.
As for strength of joints... great for those who want to exert several hundred pounds of pressure on wood working efforts. How many magazine/ casual/professionals have seen enough failures of any of those systems to be of concern.
I think too for the lowly biscuit, it is important to remember that they only test with one biscuit in the joint. Two biscuits give a tremendous gain in a joint, and unless it is 3/4" material, everyone I know uses two now.
I am not a big proponent of biscuits, but until I can justify the cost of the Domino (quit taking those damn roof repairs, Robert....) the biscuit joiner will stay with me. I will try to remember that I have NEVER had a joint that was joined with biscuits fail.
Who knows - since my joints don't come apart... there may NEVER be a Domino in the future for me. I actually be more interested in the Rotex Super MF 1000 Platinum Stealth Wood Transformer and Satellite Tracking tool. They sell it as a "sander" (yeah - right!) down at WoodCraft.
One day...
Robert
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wrote in message

No I have not tested them however, the smallest Domino is 5mm thick, 18mm wide, and 30 mm long. There are 4 larger sizes up to 10mm thick, 23 mm wide, and 50 mm long. All are made of solid Beech wood. Additionally and unlike the single thin thickness biscuits the Domino machine can be set so that the slot is a perfect fit, thick and width wise. This is great for indexing alignment as the machine has multiple ways to index the location of the mortice. The following mortises can be set to be cut a bit wider than the Domino, to ease assembly.
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Don't know how you can keep from getting out there and in Dr. Frankenstein's lab and come up with some kind of home built test. With the Domino testing so well against everything we know to use these days in quick joining, I would have to know how it stacks up in my little end of the world in my hands.
I would be thinking, "OK, looks good in the books, looks good on paper. BUT, how does it really stack up in the Leon Field Trials of Death?"
That's the kind of stuff I actually enjoy doing.
Robert
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LOL, For me the Domono had the advantage of using tennons with up to 4-5 times the mass of a biscuit and cuts the mortises in a lot smaller spot with no extra slot required as each biscuit slot does. Try using a FF biscuit on the end of a 1" wide piece of wood. ;~)

Actually I did sorta do a small experiment when I first got the Domino. I glued 2 pieces of 3/4" MDF to gether with 2 small 5mm Domino's. The pieces were orientated lake a rail and stile glued side edge to end edge The mortises were side by side a couple of inches apart, not stacked. The surface alignment was perfect and the joint was strong enough that the joint did not fail when trying to seperate the pieces by hand. I suspect with no tennons the 2 pieces would have seperated pretty easily if only glued edge to edge. Biscuits no doubt would have added strength too. IMHO biscuits are still goint to be hard to beat when joining 45 degree mitered corners when you want to have the extra reinforcement near the outer corner.

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snipped-for-privacy@aol.com wrote:

The original poster is edge-gluing two boards to make a panel. The 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
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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 <glue only> 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 <<any>> 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<<.
Robert
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snipped-for-privacy@aol.com wrote:

Oh, I've got nothing against biscuits. My roll around drill press cabinet is made of MDF and biscuits...no screws.
My point was simply that in the context of a panel glue-up, if you've already got a joint that is "stronger than the wood itself", then the biscuits can't buy you any useful additional strength. If the panel is stressed hard enough that something breaks, it won't break at the glue line. Biscuits won't change that.
Chris
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"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.
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On Thu, 07 Aug 2008 10:18:18 -0600, Chris Friesen

let me ask you a question, Chris.
In all the tests that I have seen, although it is true that the glue line does not break, the break is always near the glue line. It does not appear to be the case that the break is in another part of the panel that is away from the glue line.
What's up with that?
Regards, Tom.
Thos. J. Watson - Cabinetmaker http://home.comcast.net/~tjwatson1 / tjwatson1ATcomcastDOTnet
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Tom Watson wrote: ...

Every test I've seen the two pieces are the same width so the joint is in the middle. When the board is loaded and supported on the edges, the point of highest stress is then in the middle; hence unless there is a weak point farther towards one edge or another, the most likely place for the failure is near the point of highest stress, the middle.
Since as noted, the glue joint actually is generally as strong as or stronger than the material, typically it is slightly to one side or the other of the joint where the break occurs.
Simply physics of the test geometry is the basic explanation... :)
The more interesting test that is illuminating is the one of the bridle joint joint loaded perpendicularly to the grain on one piece -- even there it is typically either the wood that breaks or a combination rather than a glue-line failure for well machined joints.
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Tomorrow I'm going to glue up a panel like I would use for a raised panel door.
I'll let it set up for a day or so and then apply force to the center of the entire panel, which will not be the same as applying a force to a single glue line.
I'll be interested to see what happens.
Regards, Tom.
Thos. J. Watson - Cabinetmaker http://home.comcast.net/~tjwatson1 / tjwatson1ATcomcastDOTnet
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A little ancient history from our own resources.
Please note the concepts of grain direction and the relieved shoulders.
"This history on the development of the plate joiner system was originally posted to rec.woodworking on February 12, 1988 in response to a discussion comparing the strength of biscuits to dowels. The author is Sherman Whipple, who has graciously allowed the republication of his exposition on the development of the plate joiner system.
There is an elderly gentleman by the name of Herman Stiener who lives in Switzerland. He would probably get the greatest kick from reading all the threads about biscuits vs. dowels, tenons, etc. You see it was Herman Steiner who started this whole thread back in 1955, two years before there even was an Internet and after 43 years, it is still going on; he's the guy who invented the things.
He also adapted a right-angle grinder to invent the first gadget to index the slots, as well. He also made a neat clamping system, defect patcher, and quite a number of other woodworking devices and techniques. Mr. Steiner was by profession an engineer, and from what I have been told was quite good at it. Cabinetmaking for him, as for most of us, was just a hobby. He invented it in his home workshop.
The design of the joining plate and the secret of its strength are based upon very sound engineering. For example, wood's greatest strength is against the bias. We all know it is weakest with the grain, but most of us assume that it would be strongest across the grain: wrong. It is strongest with the grain angled 45 degrees and beech is one of the strongest in this orientation. One would also imagine that a rectangular plate would add greater strength than the football shape. In dealing with wood, however, if the base of the slot were square, as in a long spline with the grain, the wood would be weakened. The elliptical slots prevent splitting. Basically the design of the plate provides the maximum spreading of the load and a better glue surface. The addition of the compression and swelling properties and the tread pattern to open the wood fibers all came later.
It is my understanding that when Herman began to share his invention he was met with considerable disbelief from the local cabinetmakers. To prove it, he would have them make a couple of simple "T" joints. One with the technique they thought would be strongest and one with his "lamellae" which means thin plate. After the glue had set he would challenge them to break the joint. Every time, the plates won the challenge. Every cabinetmaker became a customer and he started a business to make plates called Steiner Lamello. Soon after he introduced the indexing base and then the first dedicated plate-joining machine.
The first Lamello machines did not begin to appear in the US until the mid-to- late 1960's, but it was not until about 1977 that they started to see wide acceptance. This was mostly in industrial applications. The rest of course, is history. We don't know who invented the wheel, or figured out how to cut the first dovetail, but we do know who made the joining plate, biscuit, lemon spline, or Lamello. It was a guy just like us by the name of Herman Steiner.
Sherman Whipple
Whipple, Sargent & Associates Strategic Services
37 Derby Street, Suite 7B Hingham, MA 02043
Phone: 781-740-4025 Fax: 781-749-9474
E-Mail: snipped-for-privacy@whipplesargent.com
For more information about biscuit joinery see: http://www.ameritech.net/users/hankm/wme.htm "
Regards, Tom.
Thos. J. Watson - Cabinetmaker http://home.comcast.net/~tjwatson1 / tjwatson1ATcomcastDOTnet
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SNIP of great stuff

I don't know how or where you found that or if you took the time to type it from your archives, but thanks for posting that piece.
Neat stuff.
Robert
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On Thu, 7 Aug 2008 17:41:12 -0700 (PDT), " snipped-for-privacy@aol.com"

I did a search for "lemon splines" which was the old name for biscuits.
When I was a young fella a lemon splined joint in the corners of the door casing was taken as a mark of quality, and also an indication that the trim had been run up in a cabinet / millwork shop prior to its arrival onsite.
Regards, Tom.
Thos. J. Watson - Cabinetmaker http://home.comcast.net/~tjwatson1 / tjwatson1ATcomcastDOTnet
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Somewhere in this thread, are my personal results from just such a hypothesis that was put to experiment.
My personal results completely agree with the tests you have seen. I am no engineer so I have no great, informed answer. All I know is them's the facts, and that's good enough for me.
Robert
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On Thu, 7 Aug 2008 17:32:39 -0700 (PDT), " snipped-for-privacy@aol.com"

My suspicion is that the very act of gluing creates a weakness in the wood fibers close to the glue line.
It's like a woodworking application of the uncertainty principle.
Regards, Tom.
Thos. J. Watson - Cabinetmaker http://home.comcast.net/~tjwatson1 / tjwatson1ATcomcastDOTnet
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wrote:

Please do not respond to me with posts that explain the workings of the actual uncertainty principle.
It was an attempt at humorous analogy.
Regards, Tom.
Thos. J. Watson - Cabinetmaker http://home.comcast.net/~tjwatson1 / tjwatson1ATcomcastDOTnet
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Tom Watson wrote:

:)
Being a nuclear engineer/physicist by training, I'll refrain (w/ difficulty)... <vbg>
The actual is owing to the general test layout and the physics of plate bending as noted in an earlier thread. If the material were actually entirely uniform as we all know wood isn't, the bending stresses would be perfectly symmetric and a solid piece of the same dimensions would bend then break right down the middle.
There's a small effect at the edge owing to the discontinuity of the fibers across the joint but w/ reasonably straight-grained wood it's a secondary issue. The glue joint is, in fact, stronger than the breaking strength and which side the test sample breaks upon depends on which board has the weaker point flaw assuming even loading.
If you look at some of the web sides that have the "sagulator" calculators for beam loading, some of them also have stress/strain curves associated with them for various loading patterns. For simply-supported ends and point load in the middle, the bending moment diagram is linear from the endpoints to the middle, then decreases in the other direction to zero again at the other edge. Something like
Load | \|/ ------------- Beam/panel
\ / -- 0 (zero bending moment) \ / \ / \ / \ / \ / ------ M (max bending moment)
--
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I am mindful of your explication.
My point, and I would say, my premise, is that the act of gluing introduces some deterioration to the fibers along the line.
The test that I have planned should be interesting in either proving it out to a degree that it becomes a theory, or putting the idea to bed.
I would be disinclined to bring Heisenberg into this discussion beyond saying that every time that I would try to look at my experiment the parameters would change - and that would piss me off.
Regards, Tom.
Thos. J. Watson - Cabinetmaker http://home.comcast.net/~tjwatson1 / tjwatson1ATcomcastDOTnet
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Tom Watson wrote: ...

I don't follow that line of thought at all -- why would any _deterioration_ cause a failure away from the glue line? And what mechanism is supposedly at work doing this?
I think your proposed test (iiuc) will simply again demonstrate the point of maximum stress is in the middle of the panel and the variation in wood properties will make for a moderate difference in actual breaking point from one side to the other a la Heisenberg...
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