I hopped on for a short solo ride through the parking lot, but soon the other workers hopped on and we were doing laps.  Everyone was delighted to see it pass by and we gathered up a few friends and neighbors to get some more weight on the thing.  We brought it back into the shop, repaired a few final broken spokes and loaded the Feast onto the trailer for a quick pick-up the next morning.

The day of the Pasadena Doo Dah Parade started early.  Aaron and I woke up at 6:00am to start getting ready.  We grabbed some breakfast and picked up the Feast from Syyn Labs.  We drove it up to Pasadena on surface streets and picked up our fancy table settings from the house on the way.  We parked a couple blocks away and started unloading the Feast.  Just the two of us were able to unload from the trailer, but it would’ve been easier with one or two others.

At this point some of the others started arriving.  We loaded up everything we needed on the Feast and started pedaling towards the parade starting point.  We were definitely getting a lot of attention.  We pulled in and started prepping the Feast for the parade.  We put out the tablecloth, put our food on the serving dishes, and mixed up a couple jugs of delicious mimosas.  Now all we had to do was pose for photos and wait.

When the parade began we were thrilled.  Almost immediately though, two of our chain tensioners failed and we were down to only 3 pedalers!  They were struggling to go up the slight grade of Colorado Blvd.  Spirits were high anyway.  The crowd loved us.  The entire time we were pelted by tortillas and marshmallows.  It was a mess.  Eating while pedaling hard was more difficult than I imagined.  The butterflies in my stomach kept the hunger down though.

We rounded the two corners of the parade and started coasting back towards the end of the parade.  The parade volunteers were inviting us to continue for a second lap, but since only three of us could pedal, it was exhausting.  We decided to pull off the parade and begin the post-parade celebrations.

The main organizer of the parade had approached us right when we first arrived.  He was thrilled to see us show up!  He was expecting us, but had no real idea of what it was going to look like.  He hopped on and pedaled a bit, with a huge smile across his face.  He left and returned with a banner.  The “Czar’s Trophy.”  It’s apparently the only award they give to participants of the Doo Dah parade.  We were thrilled and humbled to receive it.  We weren’t intending to compete for anything, just to have a great time and test out our kinetic sculpture in a real environment.  We couldn’t have been more pleased!  Thanks Doo Dah!

At the end of this short clip you can see the Feast in action:

On a final note, I just wanted to thank everyone who helped out A Moveable Feast. From all of the Kickstarter supporters to everyone who showed up for just an afternoon of metal grinding at the lab. From the bottom of my heart, thanks so much for supporting me and this crazy project. I feel extremely privileged to have such awesome help in bringing my dreams to reality. Thank you, thank you, thank you!

One of the elements that we needed to solve was the important drivetrain.  At first we tried hooking the cables straight to the sprockets on the driveshaft.  We attempted a “figure 8″ to get all of the gears turning the correct direction.  But, this solution has a lot of problems.  There is almost no way to tension the chain, except through the use of half links.  And once it is tensioned there’s really nothing to keep the chains aligned.  Even a slight bending of the frame would knock the chains off of their sprockets.  We had to come up with a better solution.

Meanwhile Oren made some great progress on the steering mechanism.  We had a linear bearing that was sliding back and forth across a ground rod as our “rack and pinion”.  The problem with this was that it allowed for rotation of the linear bearing, which would cause toe-in or toe-out on our steering.  We needed to restrain just one more degree of freedom for this to work.

Oren cut some metal attachment points.  The goal was to push and pull on the point that is aligned with the Ackermanm Steering geometry.  To do this we had to go around our aluminum hub.  We had to make some clearance cuts to allow for the dent in our Prius wheel.  (All four of our free wheels have nasty dents on where the tire’s bead was supposed to seal.)

On another workday, Paul and I decided to focus on a particular feature of whimsy.  It certainly wasn’t needed to get the Feast moving, but it was still very important, artistically.  We grabbed our last long tube of 1 1/2″ chromoly tube and started running it back and forth through the tube roller.  I’ve never rolled something with such a dramatic curve to it.  We found it necessary to take turns steadying the tube and “steering the boat” as it gets exhausting.

I welded a ball on the end of the tube with a hook so we could hang the chandelier.  You can see the fun curve of the holder as Oren hangs the 10 light crystal chandelier over the table.  We ran the wires through the tube so they would be neatly out of the way.  The details really make it fun.

We were getting very close to some actual live tests of driving around the parking lot.  We needed a way to connect our steering mechanism in front of the vehicle to the lazy suzan we had planned for the steering in the back.  We guessed at the pulleys, zip-tied them in place and ran some string just to check.  They worked perfectly.  We only needed 6 pulleys to get the cables where we needed them to go.  We welded some studs into place to hold the pulleys and it tested out perfectly.  Not pictured is our solution for the rotating linear bearing.  I used another ball bearing that was running through a piece of unistrut as a guide.  It doesn’t overconstrain the steering, and only keeps the linear bearing from rotating.  That fix only cost about $20 in parts, so I’m calling that a success.

After talking with Scotty C down in San Diego, I finally admitted to myself that we needed to put in tensioners.  Scott pointed out that if the frame flexes then our tight chains will either stretch or snap.  We needed some spring action to allow for movement on every chain drive.  I also followed Carl Mueller’s advice on how to make the tensioners out of Delrin and to reverse the direction of the chain without a figure 8.  I bought a length of 2 3/4″ diameter Delrin rod and made some simple chain pulleys on the lathe.  Both of these sensible solutions were relatively easy to implement.  I was just lazy and was trying the really simple solution first.  “If you don’t have time to do it right the first time, you’ll find time to do it right the second time.”

In this view of the undercarriage of our kinetic sculpture you can see the beautiful tablecloth that Meagan and Holden put together.  The fringe around the edge wasn’t cheap, but it’s another one of those details that really makes it something special.

We were right up against the deadline of the Doo Dah Parade.  We were very excited to get it running and finally do a little showing off.  Not everything was perfect, but it as good enough for a very short street parade.

Welding up the Drive Axle

We finally got started on the driveshaft.  We welded it between two of our large tubes.  This design allows for us to be able to remove the bearings and the shaft entirely if we need to change things up. The sides of the shaft are open, so we’ll be able to easily couple our 6 chains from the side.  I need to replace some of the bolts with shorter ones, but that’s no problem…

The start of the rear suspension. Ready to hold some weight!

We also made some great progress on the rear axles.  They’re split axles to allow for the differential to do its job and allow different speeds on the rear wheels while we go around turns.  If you don’t understand differentials, here’s a video to explain it all.

The rear axles are suspended on a trailer spring.  The frame is pulling down on the middle of the spring, and its leaves are in turn pulling down on the bearings that hold the axles of the wheels.  We’ll see how this design works in practice.  We still need to tie this rear axle to the axle of the differential.  This will lock the axle from moving forward and backwards.

Double shocks for extra bling.

The front suspension was finally tackled.  I had leftover parts from the golfcart, but I wasn’t exactly sure of their specs.  I figured that the golfcart weighed ~500 lbs and could carry a couple of chubby golfers with ease.  So let’s say the four springs were rated for ~1000lbs total.  We’ve got eight people, so we can estimate about 1,200 lbs in just human flesh.  Our contraption will probably make the difference up to a full 2,000 lbs.  So I put all four springs up front and hoped for the best.  I estimated how much pre-loading to put the springs under so that things sit flat while it’s loaded down with all of the weight.  If the pre-loading is wrong I’ll have to grind some flanges down, add some spacers to get them roughly flat.

It doesn't look this crooked in real life.

We started welding in the supports for our bicycle frames.  We used the driveshaft support as the anchor for all of the bicycles.  The result is a bunch of bicycles that we can finally put some weight on!  The front of the suspension also has a little platform that looks like it is mad to hold a cooler of beer.  Sometimes good design just happens.

We're a few welds and some bicycle chain away from a ride around the block.

With the front and rear suspensions finally welded into place, we were finally ready to remove the blocks from underneath the frame and let the Feast roll on its own wheels for the first time.  We put some weight on it and rolled it back and forth.  It’s quite easy to push.  We’re definitely going to fly on this thing.  Now we just have to make sure to not add too much weight so everything will still work.

The rear suspension is definitely more tippy than the front.  I still have some stiffening pieces of metal to add to the frame, so perhaps this will help.  If not, we might have to figure out something else to stiffen it up.

I already have more progress made on the Feast, but that will have to wait till another blog post.

Tube Rollers turn boring into awesome.

We cut out a large steel frame for the table top.  This will be a weight bearing aspect of the frame, so we used our beefy stuff.  We welded up a nice rectangle a few inches smaller than what our table will be and put it on top of our wooden jigs.  We just needed to attach tubes from the lower frame to hold it up.  But, rather than going with 4 straight tubes, we decided to utilize our cheapo tube roller from Harbor Freight to put some beautiful curves in the steel.  This gives us a few perks: it increases the room for our knees under the table, the curved lines hide flaws in our precision alignment, and it just looks fantastic!

When do we start calling it a carriage?

Next we welded in some brackets for our riding lawnmower transmission and differential.  A few notes about this thing…  It was hooked up to internal combustion engine, meaning that it’s expecting an input in the range of 500-1000 RPM at least.  We surely can’t pedal that fast.  The gears inside of it step down the RPMs quite dramatically.  Low gear is 1:64 and high gear is 1:16.  To get a decent speed we had to step up the gear ratios of the rest of our drivetrain.  From pedal crank to cassette, from cassette to driveshaft, from output shaft to wheels, all are stepping up the speed.  I plugged all of the numbers into a spreadsheet and arrived at some decent numbers for us to use.  If each person is pedaling at 60 RPM the bike should be moving at ~2 mph in low gear and ~8 mph in high gear.  That seems about the right speed for a banquet table.

The differential built into the transmission (is it called a transaxle?) allows for the rear wheels to turn at different rates.  This will allow us to turn much more easily than if we had a solid axle.  We’ve also got a built in reverse, so we’ll be able to comfortably parallel park.

The tried and true leaf spring suspension.

Next we had to start installing the suspension so we could actually have this thing sit on it’s own 4 wheels.  I appropriated a trailer spring built to hold up a 2000lb trailer.  This is only one of the pair of springs, so it’ll hold the 1000 lbs we’ll put on top of it.  The ends of the leaf spring will pull down on the wheels, all of the weight will be transferred through the spring.  Hopefully this will result in a comfortable and smooth ride for the passengers and their delicate meals.  The wheels will be pivoting on the axles of the transaxle so the chain connecting them will never lose tension.

The lower supports welded in place.

We once again decided to utilize our tube roller to get some great looking curves.  We had to have clearance for our rear pilot’s pedals, of course.  We’ll finish it by attaching some more curved tubes that come down from higher up.  This will result in a strong geometry and almost a roll cage around our rear pilot.  He’ll have to do some climbing to get into the bike, but he should be the most limber and alert rider on the table anyway.

We’ve got a lot more work to do, but we’re definitely making progress.  We’ve got 5 weekends before the Pasadena Doo Dah Parade, so we need to hustle!

Watch the clips here:

Check out the rest here:

http://whatsnext.blogs.cnn.com/2012/03/08/an-electric-triumph/

Testing the alignment.

Now that we had the basic frame in place, it was time to figure out how our drivetrain was going to fit inside.  My model had the transmission behind the rear pilot, but with the hardware in front of us we figured out that we could just barely put the transmission in front of him.  This greatly simplifies the attachment points for the rear suspension and shortens the vehicle overall.  We had to make sure there was clearance for his legs, but a simple jig helped us determine everything we needed to know.

We also made some progress in welding up the sprockets for the drivetrain.  We bought a handful of sprockets from the Bicycle Kitchen so we could start welding the larger ones to our bicycle hubs and the smaller ones to the hubs that will fit on the main driveshaft.  So far so good.

Starting to come together in our heads.

The next big hurdle was to figure out how exactly our suspension was going to work.  Suspension is an important feature of 4 wheeled contraptions.  We have to figure out how to get the weight supporting the pilots over the suspension points so the springs can compress (as most are designed to do).  I think this means that our table top will become a part of the structure of the bicycle.  This will allow us a large moment and it will result in some strong triangles for support.  I just hope we can build something that’s not only strong but light and beautiful.

Part of our first haul!

On the next day a group of us loaded up on mimosas and headed down to the PCC Flea Market to begin scouting for the decorations that will top our lovely banquet table.  I had set aside money for the decorations of the sculpture, so I didn’t feel bad about spending it.  The goal of the project isn’t just to make an interesting engineering sculpture, but to also make a work of art.  We combed through hundreds of vendors looking for objects that might help us out.  Prices fluctuated wildly between them.  We picked up deals were we could.  If you would’ve told me that I’d be having fun shopping for silver tableware I would’ve thought you insane.  The mimosas helped.

We'll have to work on our pinky placement.

Among the items we scored was a very large set of Japanese fine china.  It came with everything from plates to teacups, a gravy boat, and a few serving dishes.  We’ll definitely get some use out of this set.  You might be asking: “Won’t the items jiggle off the bike while you ride?”  Stay tuned for future blog posts where I’ll discuss my solution for that problem.

We still need a nice table cloth, and a chandelier for overhead.  As always, I’ve got ideas, but not enough time to execute them at the moment.

It starts with a few tack welds.

After hacking up the bicycle frames to distill them into just the parts that we’re going to use, it was time to start welding the basics of the frame together.  I purchased 120′ of 1 1/2″ x 1/16″ wall chromoly tubing.  Alloy 4130 for those keeping score at home.  I’ve also got some 3/4″ tube on the way, but it hasn’t arrived yet.  Chromoly is more expensive than 1020, but it’s got a high strength to weight ratio.  It’s used in high quality bicycles, so I’m not going out on a limb here.  It’s easy to weld to, and plenty strong.  The 1/16″ wall is thick enough that I won’t blow through it too much with my bad welding.  There are times to cut corners, but the frame of the vehicle is not one of them.

The first of 8

The first thing I put together was a square frame.  This thing will ultimately carry the weight of all 8 passengers.  It’ll be the lowest frame element on the sculpture and it will sit 6″ off of the ground.  I hope that will be high enough to clear speed bumps.  My Spitfireis lower than that, so I’m not too worried.  I mitered the steel tubing and first tacked everything together.  If I was going to change anything, I wanted it to be easy to grind it off.

Fishmouth notching made easy.

Then I welded the first bicycle triangle onto the frame.  We held everything in place with a wooden jig to make sure the pedals would clear the ground and our square frame.  I had the help of two other sets of eyes to make sure everything was aligned before we welded it into place.

The nice fit of notched tubing.

Now we had the process down, it was a simple matter to churn out the other 7 tubes and use the jig to align everything.  We used a tube notcher to cut the round parts out of the tube and cleaned up the edges with a grinder.  We had to grind a few of the tubes for clearance of the bicycle frame tubing, but it was an easy step of trial and error till everything was close enough.

You can almost see it coming together.

At the end of the day we were able to finish welding our 8 bicycle frames onto the sub frame.  It really helped us get a picture of how big everything was going to be.  Suddenly it’s easy to imagine the drivetrain, the wheels, the suspension, etc.  There will be a lot more steel welded in to keep the frame rigid with 8 people (~1200lbs!) riding around.  But, so far things are starting to come together.  For the first time I’m having to deal with storing this monstrosity and keeping it out of the way while I’m not working on it.

Getting a rough idea of the geometry

We had a vague idea of how things are supposed to go together.  But, eventually, we’ll have to actually do it.  I took some measurements of the parts I was planning to use and started to put them into Google’s Sketchup.  It has a little bit of a learning curve, but the tutorials were helpful enough.  Once I learned enough to get a few things sketched up the rest started to get easier.  Thanks to Tyler and Holden for helping as well.  It seems everything in this project is a group effort.  Now we need to start adding the drivetrain, frame, suspension, and steering to the drawing.  But it’s much easier to add that now that we have the main elements roughly in place.

Their motto: "Steal it back."

Aaron and I picked up a dozen bicycles from a police auction site called Property Room.  Luckily our local pick-up location in City of Industry auctions off bulk lots.  It’s all a grab bag, but at least it’s cheap.

Lots of helpful workers

Our Saturday work crew now had something productive to work on: dismantling bicycles and preparing them for their new life as part of A Moveable Feast. We proceeded to remove all of the parts we won’t use: brakes, lights, cables, handlebars, etc. We stripped everything down to the bare tubes.

Cutting off the extra weight.

We then cut off everything but the rear triangle. The bicycle engineer gods had already figured out the geometry of the pedal powered drivetrain, so there was no reason to reinvent the wheel

Cleaning out the grimy bearings.

While we had everything apart we might as well clean out the bearings in the pedals. We dismantled the bearings and soaked them in some handy solvent (in our case kerosene). I’m sure they’ll fill up with dust at Burning Man, but it feels good to start clean. We’ll repack them with the appropriate grease once we’re done with the welding.

Seven of our eight pedal points.

We churned through 7 bikes. We didn’t use the rest of the bikes from our supply for a variety of reasons. Two bikes were just too good to cut apart. One of them had an annoyingly constructed pedal geometry.  And a couple of bikes were for small kids. We have a couple more frames on the way, so we’ll be sure to get our full eight.

We flipped around the pedals on the bike at the great advice of Scotty C. By doing so we avoid a potential problem. The bike pedals and bearings won’t loosen as we go! The left pedal is threaded on with reverse threads, and the right pedal with normal threads. If we don’t flip around the pedals, we’ll be pedaling in the direction to make them loosen. We also need to flip around the side that the chain is on so that the ratchet in the drive hub is pointed in the right direction.

I’ve got a huge pile of drivetrain parts coming in the mail soon, and I hope to make our steel tube purchase after we finish up a little bit more design work. We’re definitely making some progress!