If you read the article on the 3G chook tractor, you will know how happy I was with the design and you must be wondering why I would need a 4G if the 3G was so good. Well, one of the improvements of the 3G over the 2G was that all the wood bits got 3 coats of white paint to keep out the weather, and the rot. Unfortunately, even with all the extra work the service life was still only 5 years, which is not good enough! I had to do better.

The reasons for using wood in the first place were that it was cheap, available, comparatively light and most of all, I was confident working with it. Its major drawback was its lack of permanence, even after 3 coats of paint which proved to me that a new approach was required!

I happened to have a few 6.5 metre lengths of 25mm x 25mm x 3mm thick aluminium angle floating around from a previous project (OK,OK I bought the wrong size and never got around to taking it back….. happy?). While I was not hugely confident with it I came up with a design that would work, and I had my secret weapons – pop rivets!

Constructing the Frame Base

The first section which I made was the footprint of the chook tractor – a rectangle 1800mm x 1200mm. The idea was to cut out a 90° angled wedge of aluminium at each of what would become the corners, then fold each angle around to make the rectangle. I took one of the 6.5 metre lengths and made a pencil mark at 1800mm then 3000mm, 4800mm and then at the 6000mm mark. I got hold of a rectangular sawn timber offcut and used one of the corners as the 90° angle, holding it so that it was at 45° to the straight, then ran a pencil down the side of the timber to make a mark at the 1800mm point. I then used my hacksaw to cut out the 90° wedge of aluminium I had marked out. This allowed me to bend the aluminium into a 90° angle, two more cuts at the 3000mm and 4800mm meant I could bend the rest into the desired rectangle and then cut off the excess 500mm at the 6000mm point and then pop rivet the open ends together to form a solid rectangle.




To see the full article you can visit http://www.underthechokotree.com/

Or check out the article that has also been published under the ‘resources‘ page

Overall the new tractor is working well. It is considerably lighter than any of the previous models which makes it easier for Linda to help me to move it and it is considerably stronger. Also, the frame will not rot and collapse at some time in the future…….winner!