Saturday, April 30, 2011

Ginpole anyone?

Two of these little gems will be employed to raise the Lattice truss walls once they are assembled at their final location in South Wayne. Installing the lifting yokes to the top chord and rigging the pulleys on the ginpole was a good practice run that will be repeated and studied before the real thing latter this summer. The 3/8" to 1" scale model is just the right size for this.

A good critical analysis of the steps in the process will insure that the maximum safety practices are used and followed by all those involved with the raising.  Safety. Think, what is the worst that could happen?

 (Above) With a rope tied and "wrapped" around the bottom chord and secured at the bottom of the ginpole. This rope keeps the bottom of the truss from slipping outward during raising. The bottom of the ginpole will be placed in a hole to prevent sliding of it also.

 (Above) Two lifting yokes will be attached to the outside of the top chord of the truss. The yokes keep the ginpoles aligned and prevents it from sliding sideways along the top chord during lifting.

 (Above) The gilpoles must be long enough to leave room for the pulleys at the top of the ginpole when they have done their work bringing the truss to vertical. Finding out the ginpole is to short with a 2,500 pound truss 3/4 of the way up would not be appreciated.

(Above) Here is a close-up of how the pulleys are rigged. The pulley at the top of the ginpole, reverses the force on the rope. The "moving" pulley,  attached to the lifting yoke,  acts as a second class lever providing a 2:1 lifting force mechanical advantage. The pulling end of the rope is attached to the hand winch at the bottom of each jinpole. The winch provides more mechanical advantage and braking control as the truss is raised.

Puzzler - How many things could go wrong during the truss raising process using ginpoles? Will winches having a 2000 pound capacity each do the job?

Tech Vocab - 1st class lever - 2nd class lever - 3rd class lever - 6 Simple Machines - Fulcrum - Lever Arm - Mechanical Advantage (MA) - Ratio - Winch - Ginpole - Moving Pulley

Thursday, April 28, 2011

Bring out the EASY BUTTON...

More on the EASY BUTTON later in this post.

With all the roof changes in the works I had some time on my hands and thought that some practice with reassembling the lattice truss parts might be in order. Much to my surprise (relief) this went well and I look forward to sharing what I have learned about the reassembly process with the students.

BEFORE - The carefully numbered and stacked 6 layers that will make up one lattice truss of the 3/8 scale model.

 AFTER - The carefully reassembled 3/8 scale lattice truss model.

                                                     Bring out the EASY BUTTON
The EAST BUTTON and "That was EASY", was the tag line from the Staples office supply company promotion that ran a few years ago. I loved the EASY BUTTON and kept one handy in the shop at school for my students to use when they encountered problems with their projects. One push of that baby and all was well... EASY as they say.

I am a bit "old school". My saying would be, "nothing" is EASY.  Doing "nothing" will be EASY! I found out that getting from BEFORE to AFTER required careful thought, planning and deliberate action. I took a dozen pictures and wrote up the specific step by step details I took along the way. This takes up much time and space so I will defer to Milton Graton's straight to the point description of the process from his book, THE LAST OF THE COVERED BRIDGE BUILDERS, page 90.

                                                             Reassembly of Trusses -
     The bedding timbers are leveled and laid out and the same clamping process is followed.
     To insure perfect alignment, drift pins made of sharpened trunnels are used and driven into the holes which have been well lubricated with heavy cup grease.
     First, two members are lined up with short 4" pins. Next, the first layer of lattice is pinned in place with a drift pin 2" longer than the first, and the second layer of lattice is secured with a still longer pin. This takes place in groups located near end joints.
     When the next chord member, which makes the fifth layer, is laid out, a longer and a blunter pin is used which forces the first short pin out and replaces it through the five "layers".  As the final chord
members are laid out, the second short pin is replaced with a trunnel if alignment appears correct. From then on, trunnels are used in well greased holes to punch out and replace other drift pins.
     Before full length trunnels can be driven, a block supported by a jack must be placed near the driving area, to back up the timbers and prevent them from bouncing.

There you have it, as they say at Staples, "That was EASY". It is a wonder, to many high school students today, how Milton and his sons managed without an EASY Button from Staples!

Puzzler - How can two people raise each 2,800 pound truss assembly by hand?

Tech Vocab - Cribs - Jacks - Ginpole - Lifting Yoke - Pulleys - Hand Winch 

Sunday, April 24, 2011

My neighbor taught me to shingle...

As I plow through the process of learning about the difference between Cedar Shakes and Cedar Shingles I am pleasantly surprised by all the THINKING "field trips" I get to go on. Jump on the bus.

Kenny, my truck driving neighbor, "taught" me how to shingle on his house when I was a teenager. 
With only this one 15 minute lesson I went on for years shingling. He must have been a very good teacher! Over the years I handled many bundles of asphalt 3-tab shingles. One day, looking at a stack of bundles and noticed that the full back surface, of each and every bundle, had something printed on it. They were instructions!!! For a moment I thought... I thought, what a waste of ink, for such a simple process that I had "learned" as a teenager from my truck driving neighbor Kenny! I thought, who needs written instructions, to put on shingles? I thought, who reads the instructions on the back of a shingle bundle???

Then I wondered if anyone, had ever read them? No. Then I would be the first!!!

It, was, amazing. I was awe struck. Did you know, there were different ways to stagger the courses? Did you know, you could "buy" starter shingles and ridge cap? Kenny never told me any of this. I couldn't believe I read the whole thing! All the "new" stuff I learned. As a teacher I was enlightened. I would share how reading the back of a shingle bundle opened up a whole "new learning" experience to me with my students the next day in class. I tried to get my Building Trades students to read and study it like I did. Lets just say, they were not as impressed. One student said he had helped his Uncle shingle and "knew" how to do it. With that, they ripped open the bundle and shingled away. Happy, but lost, and did not know it.

I knew little or nothing about Cedar Shingles and had read only a paragraph in the textbook about putting them on. They are not popular in the Wisconsin area. So I started with a Google search on Cedar Shakes. Like a Horn-of Plenty, the information flowed out. After several hours of reading I was full and felt I knew enough to be dangerous!  I began looking for suppliers, comparing costs and shipping. Next looking into the manufacturers. Here is where it gets fun. A company called BuildDirect has a web site and Blog. I ordered a free sample to look at, one Hand Split - Cedar Shake #1 Heavy 3/4".

Got the free sample just fine. They missed the mark a bit by sending me a Sawn Cedar Shingle #1 Medium 3/8". Other than that just fine. When I called Ryan, from BuildDirect, he apologized and told me they had some new hires and they were having some product knowledge problems. I feel much better knowing this.

While waiting for the new sample I continued thinking.  I explored the BuildDirect Blog and came across a great post  Google -  8 Secrets To Success - if you want to see a great 3 minute You Tube presentation by Richard St. John, at a TED meeting.  My favorite is #8 Persist - persist through failure and CRAP! which stands for Criticism, Rejection, Assholes and Pressure!

Also for a hair raising sight seeing how Cedar Shingles are made today Google - Sawing Cedar Shingles on You Tube - nice flick. Makes you want to wear your safety glasses!

Puzzler - How will the parts of the Lattice Truss be re-assembled at the site in South Wayne?

Tech Vocab - Spaced Sheathing - Cribbing - Drift

Wednesday, April 20, 2011

I want the double wide Sub-Zero refrigerator...

Did anyone see the movie, Sleepless In Seattle?

When the South Wayne group told me they wanted to change the roofing for their bridge from Steel to Cedar Shakes a scene from that movie flashed through my mind.  Remember in the movie, when the home owner came in and told builders, Rob Reiner and Tom Hanks, that she had changed her mind and wanted the double wide Sub-Zero refrigerator in her kitchen!! Reiner takes his tape measure across the opening, looks at Hanks and says, "You know what this means! We'll have to move the wall." Hanks, the architect, jumps in with, "It's a bearing wall so we'll have to change the living room." Looking at each other they both say, "That means the front of the house has to be pushed out, changing the roof... "

For sure, changing the roof material from Steel to Cedar Shakes will require some considerable changes. I'll call it the "Sub-Zero Effect".

Example of a Hand Split Cedar Shake roof

The answer to the last Puzzler - What changes will be involved to change roofing from Steel to Cedar Shakes? In a nut shell...

1. Add four Intermediate Primary Roof Rafters to reduce the span between rafters to 4' O.C.
2. 2x4 Purlins will be changed to 8' and mounted over Intermediate rafters & between Primary Rafters.
3. 1/2" CDX plywood sheathing will be added to the roof.
4. Tar paper for underlayment and interlayment will be added.
5. Stainless steel 6d box nails will be needed to attach the cedar shakes.
6. Change the 'cut list' for materials from the sawmill.
7. Find suppliers for Cedar Shakes and Stainless Steel 6d nails.
8. Heavy - #1 Grade 18" long 3/4" hand split/resawn Cedar Shakes will be used.
9. Starter and Ridge Cap Cedar Shakes will be added.
10. Change materials cost spread sheet.
11. Learn about Cedar Shakes and how to install them.

This change to cedar shakes adds significant labor, plus some cost and weight to the bridge project. I believe, however,  in the long run will be well worth while. Plus, the opportunity for some "serious new learning fun" has begun, the "Sub-Zero Effect" is welcomed.

Puzzler - Just what kinds of things might a person learn in this Cedar Shake change over process?

Tech Vocab - Froe

Saturday, April 16, 2011

Back on March 6th...

A little over a month ago (check the post of March 6th) I started a little experiment and posted the picture shown below.

Well the results are in! I can answer the puzzler that was posted with it. Maybe some of you figured out that these two boards crossed at right angles and pined together with 5/8" diameter pegs was to simulate the full sized joinery that will be used on the 32' South Wayne bridge. The boards were "green" at over 30% moisture content. The test was to confirm that when the wood dried and shrunk the area around the pegs would split in both pieces and severely reduce the strength of the lattice in bridge truss.

As a rule wood shrinks the most across the annual rings and little to none, grain wise, from end to end (arrow direction in picture above). In the picture,  you can see that the bottom piece grain would hold the pegs in place while the top piece would shrink causing the pegs to split the wood. The same results would happen to the bottom piece because the wood grain is at right angles to each other. Two drywall screws were placed in the "green" wood across the width grain in each piece and using a dial caliper a careful measurement made and recorded. This piece was then placed behind the wood stove for the next month to dry out the wood. What happened? Not much!

 I thought they would pop like a chess nut roasting in the fire. After a month of drying the moisture meter showed the boards now had less than 10% moisture content. 
  Re-measuring the screw distance it is clear that the wood did shrink by almost 1/8" and I did notice some cupping of the wood but no splitting at the pegs.

  I still agree with Milton Graton's  take on potential problem shrinking wood could have on the lattice structure strength and we will still have the bridge truss material Kiln dried down to 17%. I may try this again with full sized 2" x 10" material and 1.5" diameter trunnels to see what happens.

Puzzler - Just how much "fun" will it be to change the South Wayne bridge roof design to go with cedar shakes instead of a metal roof? This will be some "serious fun" new learning!

Tech Vocab - square - 12 by 12 bundle - 9 by 9 bundle - hand split - resawn - shake - shingle - premium - No. 1 - heavies - mediums - 18" - 24" - 3/4" butt -  1/2" butt - exposure - 6d box stainless nail - interlayment - underlayment

Tuesday, April 12, 2011

Another Good Day of Work

Alex and Bruce have been busy at school this past week and got a "pile" of work done. They took apart the .60 scale assembly test model of the bridge so that we could bring it back to Darlington. They also finished up the Buttons that will be used to attach the roof and floor to the bridge trusses. They also cut and drilled the 2x3 Oak material that will be used for clamps (pictured below) during the assembly of the trusses.

I loaded up the trailer and took the Roof Rafter assemblies Alex put together last week and hauled them to be finish coated and stored at the South Wayne Co-Op. Alex came back to Darlington for the afternoon and we went through the work that he and Bruce could work on this week, cutting Floor Joists and threaded rod for the clamps.

Did not take Alex long to get the hang of it and here you can see how he has drilled the holes for the Tie-rods and Rabeted  the bottoms of the Floor Joists where they will sit on the lower truss chords. Very important that the top edges are all level to keep the 1.5" x 6" Deck Boards even.  Alex and Bruce will finish up the rest of the Floor Joists in Ag Shop class at South Wayne this week.

Puzzler - Can you explain how and what each different size clamp (shown in the picture above) will be used for when the trusses are being assembled? Note: I have placed clamps that were used in building the 3/8 scale model truss earlier in the process for comparison.  

Tech Vocab - Rabet - Drill Guide - Milwaukee Hole Hawg - Shoulder

Friday, April 8, 2011

Why didn't I think of this before...

The picture above is just a little teaser. What could this have to do with bridge building? What got me thinking about this was a trip to the sawmill where the material for the South Wayne bridge will be cut. Scott had just made his "slab cutter". He had taken a section of skate track and mounded a spring stop at the end of a gap at the end. Now a helper could feed a slab down the track it would hit the stop and with his chain saw mounted on a pivot make a nice swing cut to produce a nice uniform length piece of stove wood. We even talked about automating it. I joked how I could see a slab feeding magazine. PLC, pneunatic cylinders and limit switches! I liked the idea and even asked around about locating a piece of skate track so I could build one myself. Lucky for me things got busy and I had time to "think".

Presto! My bed of nails. To cut my slab wood from the logs used for bridge materials.

I used it all afternoon and cut up my whole pile. I am amazed at how simple it is and how nice it works. The nails are 16" on center. The red lines are half way between the nail sets. A nice uniform 16" piece of stove wood every time! The cut pieces stay right on the nails and can be tossed into the wheel barrow and hauled away with out having to pick them up off the ground. This is a rare one.  Not often do I get an idea that works right out of the box and needs no refining! Must have been thought up by someone else years ago, for sure.

I have cut plenty of slabs from bridges #2 and #3. You should see the "contraption"!  A 24" buzz saw, 6 HP engine, belt tightener, etc set-up I built two years ago to make slab cutting "easier"?

Puzzler - Why didn't I think of this before?

Tech Vocab - Slab - Stove Wood - Skate Track - Buzz Saw - Belt Tightener

Monday, April 4, 2011

Looking at the past to see the future...

With the actual construction of bridge #4 for the Village of South Wayne now under way I though it might be a good idea to share with the readers some pictures of the past bridges.

Seeing the end product of all this detailed planning, model building, problem solving etc. will hopefully help keep the interest high as Bruce, Alex, other South Wayne community members and myself work together to build a "Bridge to the Future" for the Village of South Wayne, WI.

Come along with us, for the next few months, on the educational journey of a lifetime. We welcome your comments and feedback. Let us know what you "think" and "feel" about this project and 21st Century education by posting a comment or two.

Remember, "Crossing a bridge in your future will be a bit easier after you have built one or two."

Bridge #1 - A 44 foot long bridge (private owner in Darlington, WI). Side truss pieces are 6" x 6" pine timbers. Materials cost around $16,000 weight 28,000 pounds. Built during the 2003-2004 school year with three Darlington High School students. (Note: you can see my Dodge Ram truck parked in the middle.)

 Portal view of Bridge #1 with a 10 foot wide 2"x 8" Oak plank deck.
Side view of bridge #1 showing support system for stringers below deck.

Bridge #2 - A 24 foot bridge at 70% scale of bridge #1 design using 4.25" x 4.25" pine for side truss pieces (for the city of Darlington, WI ) . For pedestrian traffic only. Materials cost around $6000 weight 12,000 pounds. Built by 5 Darlington High School students in the 2004 - 2005 school year.

Bridge #3 - A 24 foot long bridge using 6"x 8" pine vertical posts and 5"x 5" cross bucks. All mortise and tennon joinery held together with wooden pegs (for the city of Darlington, WI ). For pedestrian traffic only. Materials cost around $4,000 weight 15,000 pounds. Built jointly by 2 Darlington Middle School students, 1 Darlington High School student and the first year UW Platteville Engineering students of UW - professor Ali Olclay in the school year 2006 - 2007.

Coming soon... Bridge #4 - A 32 foot long Town Lattice Truss using ...

Sunday, April 3, 2011

The chips are flying now...

Great weather and a good days worth of work. Alex showed up Saturday and we cut and assembled the six roof rafters for the South Wayne bridge. The extra help made "light" work of lugging the finished assemblies off the layout jig.

 Way to go Alex! In the upper left of the picture you can see the Primary Rafter pairs. Remember that these will be added after the rafter assembly is installed and anchored to the bridge trusses. The notch on the end of the Cross Brace goes over the top chord and the Secondary Rafter acts as a diagonal knee brace between the roof rafter and bridge truss.

Above Alex is chiseling out the notches in the Cross Braces that will fit over the top chords of the bridge trusses. Next using a 1- 1/8" diameter Forstner drill bit he starts making the mortise in the Cross Brace where the 1" x 6" Lateral Braces will be placed between the six Roof Rafter assemblies.

With all the pieces in place on the assembly jig each Roof Rafter can be drilled, screwed and bolted together. The Primary Rafters are numbered and marked as left and right, removed and stored. These parts will now be transported to South Wayne where Alex and Bruce will apply the finish and store them at the local Coop until they are needed in July.

As part of the total 21 Century learning process Alex and Bruce will be in for a little surprise when I get them to do a little paper "work". This will be a bit of an oxymoron to them but when we "work" on the spread sheets they will understand just how a three legged stool needs all three legs to "work". In this case the Community (paying for the materials), Business (supplying the materials) and School (Bruce and Alex are turning the materials into a bridge). Take away one of these three and nothing gets done, no materials, no work, no bridge, period! Thinking about all this is a good thing for high school shop students. Thinking is a good thing for everyone.

Puzzler - Without using a credit card how can you place an order with McMaster-Carr for 58 - 1/2" - 13 NC threaded rods 6 feet long? 

Tech Vocab -  1/2" - 13  NC  thread