Experiments with Glue and Wood

I wanted to glue up a workbench top 90” long, 30” wide, 4” thick using laminations of 1 1/4" southern yellow pine (SYP). To do it with clamps every six inches would require 14 clamps. I only had four clamps over 30" long, so I wanted to try another way. I got advice on the SawMill Creek forum and decided to try applying glue, screwing each board to the next one, then after the glue dried, removing the screws and gluing on another board.

I wasn’t sure if the screws would apply enough pressure, so I experimented.

Experiment 1:

Two pieces of SYP each 9" x 7”.
Screws centered on long axis 1.5” and 4.5” from one end.
#10 x 2-3/8" ProMax Round Washer Head Dry Lube Screws - from McFeely’s
Titebond glue spread with the objective of just getting a bit of squeeze out after clamping

As you can just see in the lower left corner, the screw force caused the two pieces to bend away from each other on one side. In the right picture, the 9 x 7 grid has been cut into 63 pieces for testing.

I laboriously started measuring the breaking force for each joint.

It's not a sophisticated system, but I was able to fill the bucket hanging at the end of that cord with junk until the joint broke, then weigh the bucket. I soon noticed that there was a lot of variation in measurements but there were just three kinds of breaks: 1) at the glue line, 2) partly at the glue line, and 3) all in the wood. I stopped weighing the bucket and started breaking the blocks and recording the kind of break.

Here are the results of experiment 1:

Clearly, the bent boards I mentioned above caused the upper board to bend away from the lower along the left edge and there was little or no clamping force there.

Conclusions from Experiment 1:

The screw force was sufficient to make a good glue joint.
The clamping force appeared to extend along the grain at least 4 1/2”
The clamping force appeared to extend across the grain 1 1/2".
Wood bends when you squeeze it.






Experiment 2:

Two pieces of SYP each 13" x 4”.
Screws centered on long axis 2.5” and 4.5” from one end.
#10 x 2-3/8" ProMax Round Washer Head Dry Lube Screws
Titebond glue spread with the objective of just getting a bit of squeeze out after clamping

Here’s a SketchUp version of the setup.














I cut one inch squares the long way and short way. Because my circular saw doesn’t cut deep enough, I finished the remaining short cuts with a handsaw. It wasn’t necessary to finish the long cuts.

You can see in the right side picture that the square on the right edge of the glue-up, furthest from the screws broke off cleanly with no adhesion.




Here are the results:

There is a definite anomaly here. It was caused by an oily knot which was on the bottom of the top board. I had hand-planed both boards, but I had not wiped them with naptha as is suggested for SYP.

Conclusions from Experiment 2:

The clamping force appeared to extend along the grain at least 8 1/2”
The clamping force appeared to extend across the grain 2 1/2".
Oily spots, usually related to knots, do not glue well.















Experiment 3:

Based on the data above, I had a theory. A screw puts a point load on the top surface of the wood where the head rests. Force spreads from that point in an oval which is substantially longer in the direction of the grain. For a 1 1/2" board, it covers about 4” side to side and about 12” along the grain. Because it’s an oval, it doesn’t cover the corners of that rectangle.

Based on that theory, I thought I could glue up my 4” wide board with screws every 5” staggered from side to side and an extra at each end. It would look like this, but it would be 90" long.



Two pieces of SYP each 26x4.”
Screws centered on long axis 2.5” and 4.5” from one end.
#10 x 2-3/8" ProMax Round Washer Head Dry Lube Screws
Titebond glue spread with the objective of just getting a bit of squeeze out after clamping

This is what it looked like after I had broken each 1" square and put all the samples back in place. All had broken in the wood, meaning that the glued joint was stronger than the wood itself.


Because the screws were removed after the glue dried and before the next board was glued on, there is no metal in the top. And, it worked. It's been about six months and my top has not shown any cracks nor has it warped at all since the first month.

Conclusion: A $7.50 box of screws can substitute for $500 worth of clamps. But it will take a whole lot more time and effort.

Podcasts

I like to listen to podcasts. Music doesn't interest me - I'm tone deaf. Podcasts are like talk radio except I can choose my area of interest and choose hosts who aren't idiots. That's not generally an option on broadcast radio. I listen while I do housework, yardwork, work in the shop or drive. It's great just about anytime when I'm alone, don't need to concentrate too hard on my work and in the mood to learn.

I don't always listen though, often I give my full attention to my work or I prefer natural sounds.

This has changed the way I consume news. I still get most of my news in written form from the Internet, but I don't pick up as much from radio (and I don't watch TV at all). That gives me a less frenetic response to current events. I know enough about the world that I don't need fresh details every hour. I need more quality analysis and less distraction.

This American Life
I’ve been listening to This American Life on public radio since it started back in 1995. It is a mix of fiction and non-fiction always told as a story. “I laughed. I cried.“ I had a cliché moment. I don’t think there’s anything out there like it or better than it.

The Skeptics' Guide to the Universe
When this comes up on my mp3 player, I know I'm going to enjoy the next hour. Dr. Steven Novella and his "Rogues" discuss the latest science and the state of rational thinking. More than a little irreverent, but they take reality seriously. One of my favorite podcasts.

Bill Moyers Journal
A very smart, very experienced journalist who interviews experts in detail. I often learn that what I thought I knew about an issue was wrong and/or oversimplified. I understand the world better because I listen to this. Some topics don’t interest me as much, but the intelligence makes it worthwhile to listen to anyway.

The History of Rome
A straightforward telling of what happened and when in the the Roman Empire. Made interesting by describing competing interpretations of personalities and motivations and by placing events within the sweep of history. I often listen to each podcast twice because I am unfamiliar with the names and the time line. I visualize the podcaster, Mike Duncan, with a bit of a smirk on his face as he tells his stories.

The Classic Tales Podcast
Classic short stories read by B.J. Harrison. Many stories and authors I’ve wanted to read, but never got around to.

To the Best of our Knowledge
A calm-and-rational detailed look at a topic twice per week. I've been listening to it on public radio for years.

Skeptoid: Critical Analysis of Pop Phenomena
I enjoy hearing from Brian Dunning as he blows another bit of pseudoscience out of the water. Unfortunately, in trying to make his points, he sometimes uses logical fallacies himself. Especially creating a straw-man arguments implying that a few points represent an entire concept. Many skeptics don't want to be called debunkers. Skeptoid attacks bunk every week.

Media Matters with Bob McChesney
This comes out of my hometown public radio station - WILL AM. Bob McChesney has high-powered, knowledgeable guests on every week to talk the world with special emphasis on the media. Recent guests include Naomi Klien, Ralph Nader and Noam Chomsky. Similar to Bill Moyers Journal in that I learn that what passes for news and discussion is really just a mask covering the real issues.

Slate’s Political Gabfest
Three smart, knowledgeable and opinionated people talk about the week’s national politics. Very “inside the beltway.”

Blast the Right
A look at the talking points of the political right, addressed from the political left. Presented as arguments to use when you meet your favorite “right-winger” at the water cooler. Host Jack Clark has a confrontational style, but the facts are good and the style is exciting.

Radio Lab
A highly produced science program asking irreverent but relevant questions about science and our relationship to science.

Point of Inquiry
Calm and incisive interview show put on by the Center for Inquiry “focusing on CFI’s issues: religion, human values and the borderlands of science“.

Science Talk by Scientific American
Calm and incisive interview show put on by Scientific American. Science and technology are always interesting.

Selected Shorts
Short stories presented live at “Symphony Space” in NYC. Mostly modern fiction. Some stories can be challenging and sometimes I’m not in the mood for the story presented, but there are plenty of good ones to make it worth listening to.

Grammar Girl: quick and dirty tips for better writing
Grammar should be fun. Short interesting discussions about grammar and usage.

Stuff You Missed in History Class Podcast
I finally came up with the word to describe the hosts: glib. This show brings out the curmudgeon in me. None the less, I enjoy it and learn from it.

Live Blogging - Iran

I've been following Nico Pitney's "live blogging" of events in Iran for over a week. It has been an exciting and frightening experience. My admiration for Nico Pitney's work goes out to him. My admiration even more goes out to the Iranian people fighting for democracy. Their best and most effective efforts seem to be in non-violent struggle.

http://www.huffingtonpost.com/2009/06/13/iran-demonstrations-viole_n_215189.html

It's worth pointing out that "live blogging" does not rise to the level of journalism by itself, but it is a valuable way of communicating what "seems" to be happening with a wonderful sense of being in the moment.

Health Care Reform # 4

The President has a lot on his plate right now. I’d rather he take health care reform off the table and deal with it right in two years.

I’ve been reading about health care systems around the world and I’ve been reading about proposals being made to change health care in the USA. In my opinion, NONE of the proposals being advanced by those in power are worth fighting for. Here’s what I believe we need:

• Single payer or even a public option is not necessarily required. But for health care to work without it, insurance companies must become public utilities, simple administrators of a plan set by law. That appears to be the format in other countries which do not have single-payer plans.
  

• Primary care must be the emphasis. Most health care is simple and people can take care of it themselves. Most of what remains can be handled by a family practitioner. Expensive specialist treatment should be the exception not the rule. Reimbursement rates should match usefulness. That means more time communicating with patients and fewer expensive tests and high-tech images.
  

• Evidence based standards for health care should be established and practice guidelines recommended. There is no reason why 10% of pregnant women get cesarean sections in one town, but 45% get them in another. This would also set standards for testing. That eliminates unnecessary testing and testing performed merely to prevent lawsuits. Similarly if a doctor follows established guidelines, they should be protected from lawsuits.

• I’m willing to make medical school free so that doctors don’t have to start out with huge debits. Of course, I think that should be true for all higher education, but I’ll start with those who serve our health.

• Mental health, dental health, optical care, substance abuse treatment, and prescriptions should all be included in the plan.

• Fraud should be investigated aggressively and punished harshly. Stealing from the public damages the public trust out of proportion to the dollars stolen.

I don’t want to sound like a revolutionary who wants things to get worse instead of a little bit better. But all the “serious” proposals being advanced support entrenched “traditional” interests which sap the current system and do not allow for real progress. I guess I am a revolutionary. I want CHANGE. Can we have it? YES WE CAN!

Health Care Reform # 3

I got an email from My.BarackObama.com asking me to "join up with local supporters, get the facts, make a plan for building support in your neighborhood, and start putting that plan into action." I attended that meeting this evening.

Of the 20 people there, almost all specifically advocated for a single payer health care plan. There was recognition that the perfect can be the enemy of the good, but there was also fear that the plans currently being discussed would effectively be a sell out. They would be so far less than perfect that they won't really solve the problem.

There was much to discuss, but it was hard to move forward without answering the first question. Is it worth working for anything less than a single payer plan?

Although we didn't resolve that, the next step seems to be some sort of a Health Care Day of Service on June 27th.

Change

I found this quote from President Obama in Thomas Friedman's 6/3/09 opinion piece in the NYT.

"We have a joke around the White House," the president said. "We’re just going to keep on telling the truth until it stops working."

Though I often disagree with the President, this is the kind of things that gives me hope.

Health Care Reform - # 2 Letters to my representatives

While each letter below says basically the same thing, I think of what I know about the person while I write and edit. They each come out a little different. Probably says more about my assumptions than anything else.

Senator Durbin,

A single-payer health care system is the solution. The math for real solutions only works for a single-payer plan. The people have made it clear in poll results that they want a single-payer. Any other solution just pushes the problem down the road.

Right now, opposition to the insurance industry may seem to be a politically expensive choice, but I believe that opposing a single-payer plan will cost more. We are capable of rising above deceptive advertising and scare tactics. In the modern media environment - deception will be uncovered and the facts will speak (not always, but enough to make a difference).

If you and the Democratic party take the lead, there will be a tidal wave of support as people stop having to worry about health care costs. In fact, if we get this done, I can’t imagine the Republican party coming back for 20 years.

There are millions of us out here ready to fight the good fight for a single payer plan. I hope I can be part of your legacy of solving the health care crisis.

Senator Burris,

I hope you are able to rise above the controversy surrounding your position and are able to work for the people of Illinois.

I want you to know that a single-payer health care system is the solution to the health care crisis. The math for real solutions only works for a single-payer plan. The people have made it clear in poll results that they want a single-payer. Any other solution just pushes the problem down the road.

The insurance companies do not own you or congress. We are capable of rising above deceptive advertising and scare tactics.

If you and the Democratic party take the lead, there will be a tidal wave of support as people stop having to worry about health care costs. In fact, if we get this done, I can’t imagine the Republican party coming back for 20 years.

There are millions of us out here ready to fight the good fight for a single payer plan. I hope I can be part of your legacy of solving the health care crisis.

Representative Johnson

I believe that a single-payer health care system is the solution our country needs now. The math for actually solving the problems only work for a single-payer plan. The people have made it clear in poll results that they want a single-payer. Other proposals just push the problem down the road.

A single-payer health care system is good for business, good for entrepreneurs, good for America. There will be strong opposition from insurance company lobbyists, but we are capable of rising above deceptive advertising and scare tactics. In the modern media environment - deception will be uncovered and the facts will speak (not always, but enough to make a difference).

If Americans put the troubles of this crisis behind them and the perception is that the Democrats made this happen and Republicans stood in the way, I don’t think it will be fun to be a Republican for a long time.

There are millions of us out here ready to fight the good fight for a single payer plan. I hope I can be part of your legacy of solving the health care crisis.

Each letter above submitted to the representative's website. I do put "cc blog" at the bottom of each to indicate that I consider them to be open letters.