FWW Article: "you can't be serious" abount clamping.

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"Robatoy" wrote:

:)
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Alright, NOW THAT'S FUNNY.
All I have to worry about is nosehair in my moustache.
Robert
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Just wait till some of that "nosehair" starts growing on the outside of the appendage!
Nature will eventually humble you, one way or the other ...
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Years ago, I wrote that too much clamp pressure might cause glue starvation. Then a host of people came up with a "no way in hell" response.
I am willing to bet that if you use FWW's (or, rather, their author's) criteria, you'll have a good shot at reaching that stage, if you don't otherwise.
I've been woodworking for something over 50 years--54 years ago, I was working after school at the Katonah Altar Factory--and I have never once heard anyone recommend pressures like those.
Still, I have to admit, I'm seeing some delamination in cutting boards I made 20 years ago. I think most of that, and probably all, is due to the boards getting a too wet swipe with a rag too often, without being dried. Not good for Titebond, which is what I used back then.
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Charlie Self wrote:

...
If you really applied that kind of force on dense hardwood, I tend to agree without anything more scienfic other than, like you, a long time doing this.
It isn't available how the author did the testing reported in the paper to achieve the reported pressures, but he claims it isn't a problem from his work.
But, if it was done by counting more clamps as added pressure, that really doesn't produce a direct increase in total pointwise clamping pressure as the force is distributed in a ray from the clamping point and the maximum total pressure is the vector sum of the applied forces. Consequently, only actually increasing the ability of the clamp itself to apply more force will actually make the total pressure increase linearly at the clamping point--the other clamps added along the length of the joint only add their reduced overlapping partial contribution. Consequently, except under the laboratory conditions of having a massive press with which to do the testing, the pressures applied in the shop aren't anything approaching what the simple summation of all clamps' total force would imply. Which, by the way, is the assumption made in the article in the "formula" for determining the total number of clamps required. (And, btw for anybody else who has the article or looks at it, there's a mistake in units in it as printed -- the force/clamp is given units of lb/in instead of just lb.)
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[snipped for brevity]

I agree with everything said. I consider myself a beginning woodworker and look to FWW and other sources for expert and trustworthy advice.
The "trustworthy" part is very important. What happens when something is published that I know enough about to know is wrong, is that it then casts suspicion on everything else that is published that I don't know anything about.
Even as a beginner I'm seeing the "dumbing down" and repetition of content. Handcut dovetails have pretty much been covered before haven't they?
And another time that is really pissing me off is this trend of having "additional content" on a website. (At extra cost, of course.) I'm in the country with no available broadband, so subscribing to get video feeds is out of the question. That's why I want a paper copy, but somehow I don't think FWW or FHB is listening to me.
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Wes Stewart wrote:

Same here on the broadband unavailability and ticked off about added-cost web sites. Of course, the Taunton site was always so slow as to be essentially unusable anyway, so it's not like we really lost anything except the potential... :(
As last followup on the gluing clamping force article --
I looked for the corroborating science behind Dr. Rabiej's article on his web site -- http://roman.rabiej.com/cv /
The only published articles on glueline strength all have to do with laser-cut materials, not normal shop panel glueups. Under those conditions, I could _perhaps_ believe something differing from previous experience, but it's simply ridiculous to publish an article as was done that so much flies in the face of experience without at least a reference to the science behind the work claimed to support the conclusions.
These are typical research projects found above, none of which could I find actual articles online for...
Optimizing Glueline Strength of Laser-Cut Hardwoods. Funded by the United States Department of Agriculture.
Factors Affecting the Magnitude of Glueline Shear Strength Between Veneering and Particleboard Substrate. Funded by Karona, Inc. in Grand Rapids, MI.
Gluability of Wood on a Laser-Cut Kerf. Proceedings of the Second International Conference on Automated Lumber Processing Systems and Laser Machining of Wood. MSU. June 1994.
Factors Affecting the Load Bearing Capacity of MOD-EEZ Connectors. Forest Products Journal, 43(9):49-57, 1993.
Glueline Shear Strength of Laser-Cut Wood. Forest Products Journal 43(2):45-54, 1993.
The Effect of Clamping Pressure and Orthotropic Wood Structure on the Strength of Glued Bonds, Wood and Fiber Science Vol. 24, No. 3, July 1992.
One assumes that the last might have the basis for much in the article.
Well, the text of the article is protected content, but the abstract is available.
<http://swst.metapress.com/content/1050536165217317/?p 5006db06be4640acd2801679e46c4e&pi=3>
R. J. Rabiej, Associate Professor1, H. D. Behm, Professor and Chairman
Department of Engineering Technology College of Engineering and Applied Sciences, Western Michigan University, Kalamazoo, MI 49008 Abstract
Reference values for compression strength perpendicular to the grain were determined for radial and tangential sections of samples of sugar maple and ponderosa pine. Samples to be glued were matched according to specific gravity and orthotropic structure and bonded along the grain in tangential or radial sections. Magnitude of clamp pressure was controlled throughout a range of pressures commonly applied in industry, up to about 80% of the compression strength of the wood sample. Tests were conducted on the bonded samples to determine glueline shear strength and percent of wood failure at the bonded surfaces. Results were subjected to regression analysis to ascertain relationships. It was determined that clamping pressure had a different effect on both shear strength and percent of wood failure depending on species and orthotropic section. It is possible to maximize joint strength by applying proper clamping pressure. Results similar in direction but differing in magnitude were obtained with both PVAc and U-F adhesives. A generalized measure of clamping pressure was defined as the ratio of applied clamping pressure to the compression strength (CP/CS) of the wood section to be glued. Using this concept, the optimum clamping pressure for sugar maple was found to be 0.3 times compression strength using U-F glue and 0.5 times using PVAc glue. This approach to determining reliable clamping pressure data can lead to improved gluing practice and more precise testing procedures.
\endquote
So, using the data from FPL at <http://www2.fpl.fs.fed.us/TechSheets/HardwoodNA/htmlDocs/acersp1.html , the compression strength for dry sugar maple perpendicular to the grain direction is 1470 psi. Half of that would be 735 psi for his optimum by my reckoning. That's at least in the ballpark of his table values so guess the paper probably does form the basis for the article.
How applicable it is to "ordinary" woodworking and, most interestingly, how "peaked" is the maximum of his regression curve and what other factors were controlled (and not controlled) would be of interest and necessary to know something of in order to judge if there's anything in the article pertinent to typical work of the type done by FWW's readership.
I seriously doubt there's much work been done by the past masters that seems to have survived quite nicely that had anything even remotely approaching those kinds of clamping pressures. And, interestingly enough, later on in the same issue there's an article that extolls the use of the old wooden screw clamp (w/ whose flavor I'm quite consonant, btw).... :)
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"Results were subjected to regression analysis to ascertain relationships."
Well, shit... that explains it.
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Robatoy wrote:

:)
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dpb wrote:

<http://swst.metapress.com/content/1050536165217317/?p 5006db06be4640acd2801679e46c4e&pi=3>
You do know that there are several different satellite Internet services available that are available pretty much anywhere in North America except a cave, and are reasonably affordable? They aren't as inexpensive as DSL or cable where those are available, but they're getting pretty close and I believe they all offer residential flat rate plans vs. the old per KB type plans.
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Pete C. wrote:

...
...
Well, actually, the local ISP has put a wireless transmitter on the microwave tower north of the house that should be within range. The short coming to date is getting a line-of-sight location to it without cutting into the windbreak--here, having that is worth far more than broadband! :) The plan is when get the barn renovation done, to put the receiver in the cupola which is high enough to be above the cedars and a wireless router to the house. The holdup is far more pressing things on the schedule so it's more fun to complain about the shortcoming... :)
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wrote:

Unfortunately, there's only so much you can do. Take 10 magazines with 6 issues a year each, over a decade... it isn't like woodworking changes all that much, you're going to get a lot of repetition, especially since they've got to think about new readers who are picking up the magazine for the first time.
If you're looking for original content, don't pick up magazines.
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On Fri, 05 Oct 2007 07:15:07 -0700, RicodJour

Unfortunately, I believe it was there. FWW has recently (last year or two) had a large scale change of staff which has resulted in it morphing into a publication that I no longer take seriously.
It's unfortunate because thanks to my father-in-law, I have the complete collection. The older publications were treasures. The latest ones, not so much.
==========================================================================Chris
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I thought the article last month saying that yellow glue was stronger than epoxy or poly in gap filling was pretty stupid. Maybe it has changed to being a humor magazine.
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Maybe next month will feature Alfred E. Newman on the cover.
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Woodworking with Don Martin. That I would LOVE to have seen!
FoggyTown
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on 10/5/2007 6:07 PM FoggyTown said the following:

How about the Furniture Guys from TV, Ed Feldman and Joe L'Erario? I mistakenly typed 'furniture gays' in Google, but I don't think it was too far off. :-)
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Bill
In Hamptonburgh, NY
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wrote:

Any good sites with photos of wood? <G>
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B A R R Y wrote:

My guess, the latter (photos of wood), yes, the former ("good" sites), not so much.
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If you're going to be dumb, you better be tough

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Don Martin is one of my very favourite artists. That guy could express emotions in the silliest ways. His Mona Lisa is my favourite and I used it many times in a few Photoshop contests to wit:
http://i123.photobucket.com/albums/o290/Robatoy/weeeeee.jpg
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