(Winterguard) The Cauldron

The Cauldron

This project caused me more angst than any other because I could not deliver what the director really wanted. 

Concept Pics

After the fall Two Towers show the Winterguard show writer (different person from the Band Director) sent these pictures. He wanted an "angular" style cauldron like above reminiscent of the angular look of the towers. And he wanted a child to perform INSIDE the cauldron. He wanted it tipped toward the spectators like it was spilling over with a height of 6 feet at the rear and 4 feet at the front so the audience could clearly see the performer. 
Then the band director informed us that this year we would be going to compete in the Winterguard World Championships in Dayton, OH and he needed the props to fit in the charter bus in 2 baggage compartments that were 38" tall X 48" wide and 7 feet deep. The prop would also need to fit through a single door opening.

In looking at this the structure would be easy to build...as 3 pieces but I could not see how to break in into pieces small enough to fit through a single door and fit into the baggage compartment and set up in less than a minute. I just could not visualize how to do this with this design. At the time I was not using Sketch Up 3D modeling software so my hand drawings told me it was not possible. Everything I drew looked like a basket or a box...not a cauldron.  At this point I felt I could not build this design. Driving the band truck to Dayton would add several hundred dollars to the trip cost in gas plus the fact that this truck is hard to drive 2 hours much less 7 hours! No cruise control... So it was back to the drawing board!

So I started looking at pics of traditional style cauldrons and breaking it down to it's simplest form. And I saw it! I instantly recognized how I could make this work. A simple hoop to make the lip and bend pipe to create the form the cauldron shape. I could place the cauldron formed pipe around the hoop and section it. It would make pieces small enough for the kids to carry and each section would fit through a single door opening and fit into the charter bus. All requirements would be met!  I will need to fashion some sort of legs to support each section but I would design that on the fly.

I needed to figure out how large it needed to be so I grabbed the guard girl and her flag and had her perform in the drive way and I dropped markers on the ground even with end the flag. It turned out to be 14 feet! The director thought 10 feet would be large enough but there is no way anyone could perform it that small of a space unless the just hold the flag straight up in the air the entire time. The flag itself if 5 feet long. The show plan has a performer inside the cauldron the entire show. and at 14 feet it will be tight for them but doable. I also had to plan for an entrance and exit on either side of the cauldron since performers would be trading off . So the plan was for a 6 -8 foot opening on either side as an entrance and exit. This would be easy with this design. I would just leave out a couple of sections on each side.

Here we go bending 2" EMT. Just so you know this pipe is HARD to bend!  So enlist some strong guys to help!  OK to bend this to the right radius I simply drew a 7' radius arc on the floor of my garage with sidewalk chalk and bent the pipe until it matched the arc. Here is a tip to make sure the rest of the pipes match the first. Pull a measuring tape and note the length between inside ends of the bent pipe. Then bend the rest of the pipes to that dimension. EMT will NOT bend to the same dimension even if you count the turns on the screw on the bending roller. So do as described by measuring. It took 5 pieces to make a 14 foot circle.

After bending the pipe I trimmed the ends (where the pipe does not bend), laid it out on the floor and welded it together. The put it up on ladders and measured the spacing for the vertical cauldron shapes. I needed to bend 11 for the prop.

Had to move outside to bend these shapes. I first bent the tight 90 then flipped the pipe over and just rolled the pipe slowly until it looked right. The made the rest the same by using the measuring technique. 

The next step was to attach the cauldron shapes to the rim. I supported the rim 7' off the floor with the 2X4 braces you see in the picture and made sure it was level.Then drilled the 2" rim to accept the 1 1/4" pipe by marking the rim at about the 4 o'clock position at the the spacings I had set earlier. I hung the pipe from the holes and shimmed the bottom of the shapes to hold them in position.

A couple of hours of welding and they were all in place. To get the tipped look I dropped the front of the prop 2 feet to get the 6 foot to 4 foot relationship the director wanted. I measured down 6 feet at the center of the rear and marked the pipe, Then placed a 2X6 on the floor and made a mark on the board where it met the 6' mark on the pipe. and cut the 2X6 at the mark. I now had a gauge to mark the rest of the legs. I marked each pipe all the way around so after cutting the end of the pipe would sit flat on the floor. I found that my grinder with a metal cutting abrasive blade worked best. A Sawzall was hard to control. On reflection instead of using a gauge I should have used my laser level. My garage floor is not perfectly flat and it showed when I set the props on a perfectly flat gym floor. It created a sag at the rear that was a high spot on my garage floor. Live and Learn!!! 

Here it is cut and sitting on the floor. Now to fashion some sort of legs to hold each section up so they will stand on their own.

It seemed pretty obvious to make the stands look like flames... There was no pattern. I just shaped the 3/4" pipe until it looked OK and welded it.

I used the tubing notcher to make the joint tight to make welding easier.

Here are the front flames welded in place. They are pretty small.

Here is the center rear flame. It was the only symmetrical flame. Since there are 7 pieces at the rear I wanted to be able to quickly identify the center section on just by looking. I did not get a picture but after all of the flame stands were welded in place I cut the sections apart with a sawzall. Then I welded a steel cap on the ends of the 2" pipe at the openings of the cauldron to eliminate edges. To join the sections together I need a quick method of coupling. So off to the Depot and I found that a 2" PVC coupling was nearly a perfect fit inside the 2" pipe. It just took a little grinding on the belt sander to make them fit perfect. I riveted them in on one side of the joint and it slipped on the other side so assembly on the floor was really quick! I painted the steel with the 99 cent a can flat black spray paint from HD and the prop were complete. BTW our Winterguard circuit requires ALL props have duct tape on any part of a prop that touches the floor except if it has wheels. Check to see if you circuit requires this too. I wrapped these with 3 layers of black duct tape.

Here is the completed prop. As far as weight the largest section weighs 12 pounds. It was easy to set up and the only repairs I had to make during the season was touching up the paint.

Here it is...a 14 foot diameter, 6 foot tall cauldron in a single compartment of the charter bus with room for the flag bags for the trip to Dayton!  Mission accomplished!

On Reflection
If I had been using Sketchup I may have figured out a way to work with the original design concept. Sketchup makes it so easy to visualize the completed prop. I will never design again without it!