5 Boro Bike Tour Tandem Trike: Gettin’ It Together
Fingers crossed that Thursday was the last snowstorm of the season. I’d say 7 inches of snow is a good amount for a last hurrah. Warmer temperatures are forecast for the week ahead.
I didn’t waste any time taking advantage of the break in the weather. After clearing the residual snow from my workshop, that would be my back porch and the 3ft by 4ft concrete landing at the bottom step, I proceeded to get ready to weld the main parts of the frame together.
Being a tandem there’s a front section of the frame for the captain and the rear section for the stoker. Each section forms a kind of “L” shape with a back rest and boom for the crankset. I started with cleaning off the mill scale on the areas to be welded and then I jigged up the joints with angle iron and clamps for welding.
What’s nice about square tube is that it aligns so easily. A lot of time working with round tube is dealing with alignment issues. Here if you’ve got one face aligned you’re pretty much guaranteed the rest of it is going to fall into alignment. Getting a straight frame is easy, which is important if you want the trike to track straight and true.
From here it was just tack and weld. OK, in theory it was that simple. Tacking was easy. I did have some issues with my welding until I built up a rhythm. Even then it wasn’t all smooth going. If you tackle one of these projects with an arc welder you may deal with the some of the same issues.
One of the problems I had was getting an arc started and holding it. This is a function of a couple of things. First, my technique is rusty so I had a lot of false starts and sticking of the electrode to the work. Second, was getting the right settings on the welder. You need slightly more current to start the arc than to weld. If you set the welder to the minimum current you need then you might have trouble getting the arc started. If you set the current higher to compensate, you may find that there is too much heat and you might burn through the work. Finding the right balance is the key.
I found a pretty good balance but I still had moments where I couldn’t hold the arc through the entire pass. I also had times where I burned a hole through the work and was faced with repairing the damage. The thing to remember is that you can always grind away the bad weld or part of the weld and make another pass over the area. I had to this on a few joints. It was more work, but grinding my first pass flush with the tube showed me that even though the top looked terrible, I actually had good penetration all the way through the joint. It just goes to show that you can’t always tell a good weld by what’s happening on the surface. My second pass was more for reinforcement and aesthetics than completing the weld.
I should say here that I’m using a 110V 95 Amp DC stick welder. It is a transformer based welder, typically called a “hobby welder” or a “buzz box”. You won’t find many people who weld that think much of these things. This unit cost me about $65 in 2007. I think it was the cheapest 95 amp welder on the market at the time. All of this is to say that it is not a high end piece of equipment and while I’m not one to blame my tools for my workmanship, some of the issues I am having with my welding are due to the welder. Having said that it also proves that you can build this project with an inexpensive welder. On my next project I plan to buy an inexpensive inverter based welder from Harbor Freight that I have heard very good things about. We’ll see how it compares to what I’m using now.
I still have this project to finish. With some work and some patience, I got the captain and stoker sections welded. The next step is to get the two sections together.
The plans have an alignment procedure to put the front and back of the frame together in the proper orientation. With standard plans you’d have to cut your pieces to the proper angles first. If you messed up your angles, somewhere down the line in the build you’d get a big gap or something wouldn’t fit right. What’s different about the Atomic Zombie plans is that they proceed in sequence, building off of the previous step. I cut my tubes with good precision but even so, welding introduces some distortion. Since I haven’t made my final cut to join the frame halves yet, I can allow for that distortion during this alignment process and set everything right going forward. It’s a good method. Errors don’t compound since you’re fixing them along the way.
It pays to get this right. I spent a good 45 mins to an hour measuring, marking and setting up my saw to make the cut. Using my chop saw made welding the first two parts a breeze. My joints were tight because the cuts were clean and precise. I was going for the same with this cut. It was a little harder because it was the very end of the tube and a little awkward to set up.
The extra time paid off. It took less than 10 seconds to cut the the tube but fit couldn’t have been better. It was nice and square with no gaps. Now I could prep for welding.
I’d been proceeding up to this point without a clue as to how I would manage enough room to weld an 11 foot frame together. Well, I managed. It turns out the top deck of my porch and the surface of my workbench are pretty close to the same level when my bench is set up at the bottom of the stairs. It kinda works out to having an extended work surface and support. Once I got everything clamped up, I just welded as normal. That is to say some passes were clean and others required grinding and re-welding, but I got it done.
One tip I would pass on if you attempt this project; Do not bother trying to stick weld the joint with the really small angle. It’s nearly impossible to get a clean weld and if you can’t, cleaning off the flux is a nightmare if you want to try and continue the weld. The plans say that this joint can remain unwelded but I was concerned with moisture getting into the tube at this joint. I tried welding it and it was a mess. In hindsight, I’d probably leave it and then use some silicone sealer in the joint after painting. If I went with powdercoat it would probably get sealed up anyway.
So that’s the main frame all together. This beast is loooonng. We’re talking 1966 Cadillac Coupe de Ville Convertible long. Now let’s get some wheels on this thing.