Posted by: nwracing | June 6, 2015

Andromeda Tow Kart Part 4

My next part of the build was to finish tacking all the tubes together and make sure that everything was in line and fitted where it should. After my initial enthusiasm with the welder I had managed to distort the rear tube that the wishbone attached to. After a lot of heating with a blow torch I was able to tease this back in to position. This was a real pain and a proper gas welding torch would have made the process much quicker.  That said if I had done it right in the first place I would not have had this issue.

Rear Chassis Tube

tow kart chassis

The chassis tubes all in place.

As you can see from the picture the tow kart is really taking shape with all the tubes now tacked in place. My intention had been to weld everything using the TIG welding process which would give me some useful experience. However, I came up against an unexpected issue. No matter what I did the main tubing which has a 1.5mm wall thickness refused to weld. I was blowing holes and for all the world it looked like a pigeon had been depositing its droppings…  …not good!

However, no matter what I tired I could not get it to weld so I switched over to mig welding and this worked a little better but was still not great. After calling a few professional welders they thought I had contaminated the tube and recommended I clean everything with acetone. So I scrubbed everything and looked forward to having an easier time. Still no joy; it continued even with the mig welder. In desperation I took a couple of pieces of the tube to a welder I know and asked him if he could show me where I was going wrong. He had the same problem as me! On closer inspection of the tube the wall thickness altered around the circumference, and there appeared to be contaminants in the tube.

Lesson: Don’t buy cheap tubing. With the amount of time it took me to weld and clean and then re-weld those areas I was not happy with I would have been much better spending a little more and saving time and aggravation. Sometimes a bargain is not a bargain in the end!

The next job was to weld the shock mounts to the rear tube and test fit the rear wish bone. It  looked exactly as I had envisaged it would: result!

Tow Kart rear suspension

Rear Suspension fitted with shocks

Next time I build the front wish bones and then were are almost ready to put the engine in!!!


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