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Spollen V-Bee Streamliner, Part 1
The Spollen brothers Chris and Tom recently completed a vacuum-molded foamshell streamliner based on the method described by fellow MARS member John Tetz, firstname.lastname@example.org, in his Vacuum Foamshell write-up. This write-up is divided into two parts because it contains 24 photos. Click on photos for larger version. Click here for Part 2.
By Chris Spollen, CJSpollen@aol.com
The story begins with a phone call from John Tetz, asking as he has done every couple of months over the years, “So, what’s going on with the Spollen brothers? You’ve both been very quiet.”
The club may not know this, but John has had a profound influence on our tinkering, literally pulling us along to a better quality of work - not to mention profoundly influencing our lifestyle as well, making us even more frugal, if that’s possible, and certainly less wasteful.
You also may not know that John lent us his mechanical drawing of his current LFWD (low front wheel drive) bike, along with three hand-written pages of how to do a mechanical drawing to scale. Drawings like these literally take him months.
Well, measuring my inseam and arm length and converting that information to a scale drawing is something that is not quite in my nature. So we did the next best thing: we simply copied as many of his measurements as we could and built our bike to his specifications. Needless to say, John was not very happy. He wanted us to build our own design from our own mechanical drawing.
Over the next year our current bike went through several changes, including all new rubber and wheels that did not come from a dumpster, as well as changing the front tire to a 20” from 16” to give us twin 20's. She really rolls along. Love those new bearings.
Then divine intervention happened within the club, as Andy Douglas found a set of molds in Florida which he thought John could use to work with the zote foam he had been experimenting and building with.
We had been running the V-1 low rider (see also V-1 update) for about three years up to this point. She has a zote foam shell made with the plug method that John had developed. Although a little lumpy, she provided faithful service both in winter and summer alike. The main problem with this form of fabrication is that uniform heat is difficult to apply using a hand-held hot air gun, plus our plug was far from a perfect form. It was all eyeballed. John had come out to our house and worked for about ten hours showing us how to heat bend and glue the foam for this design.
Recently we had some ideas of making a shape and pushing a form through the shape, in order to create a shell half. The form could be made by tracing the rider while sitting on the bike onto a large full-size cardboard sheet, and then making a half plug from those measurements. But these were more daydreams than fact, and as for building an oven big enough, we simply did not have a clue how to proceed in this area of fabrication.
To make a long story short, we knew that with the new bike we had something that was pretty fast and small. Through a series of photos mailed to John, he decided that our bike might fit into the mold size. All we had to do was cut 7” off the bike’s overall length, and re-braze as well as fabricate a new handlebar and lower the seat, a relatively small price to pay for such a tempting finished design.
I knew that John had always talked about blowing - or as he puts it, sucking - the foam into a shape, and with the molds he was actually able to achieve it. He figured out how to attach the foam to the forms, and with his homemade oven, a vacuum pump, and vacuum tubing, he created two beautifully formed smooth half shells.
John’s phone call was to see what we were up to regarding our fairing development for our little machine. As things would have it, he said that he was finished with the molds, and that if we could figure out a way to get them to our house, we could use them. Again, divine intervention: we rented a van and met him at his place.
Here the story gets a little more interesting, in that I asked him how did he ever get that oven up in that attic in the first place, to which he promptly replied that he didn’t: he had made the oven up there. “Well, how do you know that we will be able to get it down?” “I don’t,” he replied. Thank god that Tom is strong, for it was quite a task coaching this monster down an almost dead drop and navigating a somewhat questionable staircase, then through the house and into the van.
After setting both the oven and the molds in the van, it was back upstairs for a lesson in zote foam welding (see John Tetz's write-up). The material does not come in lengths long enough to cover the mold, so it has to be heat-welded together. John proceeded to sit down at the end of his attic workshop and bend over what can best be described by Tom as a "Jig-U-Later", a welder of some sort. All I know is that it was hard to keep a straight face as we helped John turn and guide the foam sheets through this strange machine. The smirks were quickly brought to an end as he asked me to try and pull apart the test pieces that he had just welded.
We agreed at this point, after we had patiently welded both foam sides, that when we got everything home and set up, he would come with his vacuum pump and help form the Zote foam into the molds.
I might also add here that both John and the Spollens do all their work in relatively small work areas. We operate out of a small one-car garage, and John creates out of his attic, yet the amount of machines and things that come out of these relatively small shops is amazing.
Tools of the trade.
Tom and I clamped and screwed all the wood sections around each half of the mold, making sure to apply plenty of silicone, because a nail-size hole would cause the vacuum to fail, and we would be unable to suck into the required forms. After completion of these first construction requirements, John pulled up outside our garage as promised.
The next task was to run extension cords through the house to allow the oven to be run on two sets of breakers, so that while forming the foam, a breaker would not blow and the foam collapse inside the mold. Once the vacuum lines were attached to the back side of the mold, we began a series of vacuum tests. This is where our troubles began. With each test, the foam would break away due to insufficient clamping force.
The plywood flanges surrounding the molds were simply not thick enough to support the thin screws we had used. Plus, we didn't have a proper power screwdriver, so the screws stripped out. By this time, my neighbor Ed was in the shop, and he ran over to his garage and cut a bunch more wood strips so we could apply more clamping force on the form. This did the trick.
As evening began, the glow of the oven underway was accompanied by the sound of John’s vacuum pump pulling the material into shape. Tom and I peered constantly through the end door to witness the magic of the foam being pulled up against the mold.
The heat and vacuum on, and the foam being sucked up into the mold.
Voila, we had done it! Side A was formed. Then, just like Henry Ford, side B was laid in place, and after a little tweaking for leaks, it was pulled into shape as well. Before John left at around 10:30, he penciled in on the inside of one shell the position lines for the internal braces and door. Great help for the homebuilder.
First half cooling.
Patient Tom again.
Click here for Part 2.