Its Engineering, But not as we know it! ...

Some months ago, I had the great idea to take the old go-cart, that my youngest Son had just about grown out of, and put an engine on it! I expect I have spent too much time watching the Discovery channel, and believed anything that a group of, seemingly poorly skilled, poorly organized, people could do on the various TV shows, I could do as well! (I certainly fit the desription of 'poorly skilled', and can also claim absolutely no experience in matters of welding and engineering!). I am now much more impressed at the what the people on the TV shows produce, and much more aware of the limitations of my own abilities! Still, we learn by our mistakes, and I have learnt a great deal already!!

The original idea was very simple, get the go-cart, get an engine, make a simple frame to mount the engine, connect the engine to the wheels, via the existing (pedal powered) chain - nothing to it! My wife decided this was not such a good idea ('Don't think I'm letting my young Son anywhere near that ...!') and tried to push me towards a more 'sensible' project (such as decorating the dining room!). But I was not to be deterred. I designed the petrol conversion and started to look for a suitable engine. It was at this point that my wife spotted a book about building a buggy. She immediatley thought it would be much more sensible for me to have this book and follow some instructions, rather than just go off and make something myself.

I read the book and began to wonder if the real objective was for me to see the complexity of the task and decide to do something else! But to her surprise I thought building the whole buggy from scratch was a great idea and immediately went about seeing what shiny new tools I would need to bring this project to reality!

First step was to build the frame. I ordered the steel tubing and began the task of cutting the various pieces for the frame. The buggy in the book was designed for teenagers and adults, so I needed to adjust the size to ensure that my youngest would be able to reach the pedals and the steering wheel. This seemed a simple thing to do at the time, but we'll see later that even the simplest things need to be thought through ...

As the frame is made of tubing, wherever one tube fits against another, the end has to be 'fishmouthed' (cut so that it fits round the other tube perfectly to enable the weld to have maximum strength). With my limited tools, this was a tedious job, but ultimately rewarding when the tubes fit together nicely. It took a week of evenings to cut and fishmouth the pieces, and most of the weekend to 'tack weld' ( tack welding is where you just weld a couple of spots for each join. The lets you check everything is in the right place, before you make the final weld which will be difficult to undo) the frame together.

I started the fishmouthing by making a tube of paper, the same diameter as the frame tubing, drawing the profile of the tube at one end, cutting this out with a pair of scissors, slipping this over the tube to be cut, marking the tube, and cutting it with a grinder and tidying it up with a file. This was quite a long process, and each stage is prone to error, leaving me with inconsistent results (my skill level didn't help here either!). I thought there may be a better way so I looked on the internet ...

The first thing I found was a program that let me input the size of the tube I wanted to fishmouth, the size of the tube it was to fit against, and the angle it would make against the other tube, it then printed a template I could use to mark the tube for cutting. This helped with the marking, but still left the cutting open to the vaguaries of my ability! Back to the web ...

I saw some advertisements for proper tools to fishmouth tubes, sadly these were too expensive! Then I read that you can use a holesaw to achieve perfect results, reliably, and at a reasonable cost. Basically, you get a holesaw (the type of thing you use to cut a hole for a spotlight) the same diameter as the tube, mark the tube as before, then align the edge of the holesaw with the marked line and cut the tube, easy!! This method made the job much faster and also significantly improved the results.

Top Tip #1 - Use a holesaw to get accurate, consistent results when FishMouthing steel tubes.

So after an initial flurry of activity, I had the frame tack welded together. Now I needed to get some wheels so I could work out where the axles need to be located so that the frame is level. For the front wheels I got two wheels that were originally intended to be uprated wheelbarrow wheels! they came complete with bearings and fairly rugged looking tyres. For the back wheels I really wanted some quad bike wheels with off-road tyres, but these were much too expensive new, and as rare as Unicorns Tears (took me a while to find a polite metaphor there!) secondhand.

After a month of searching I finally managed to buy two wheels that I saw advertized on eBay (what would we do without eBay?). These were fantastic, the right size, great chunky tyres and very reasonably priced. The courier tried their hardest to lose the wheels in transit, but the seller was very helpful and between us we managed to track them down, and I finally got my hands on the wheels two-weeks later!!

During the time I was sourcing the wheels, I decided to make progress with the seat. The seat is made from an old broken plastic stacking chair (the sort with metal legs and a rigid plastic moulded seat with a back cushion and seat cushion built-in). One of the legs had bent and the chair was ready for the skip. I managed to 'save' it and convert it into a 'racing bucket seat' for the buggy! This was done by removing the legs, cutting two pieces of sheet steel for the sides, and making a steel frame to attach the seat to the buggy with. The side pieces were pop-riveted in place, and the finished result really doesn't look too bad!

I also managed to buy a 50cc Scooter engine, so things are beginning to take shape ...

Next time, I'll move on to making the roll-bar ...

Best regards,

Nigel.