Repairing the push plough

I should have been out doing this from the start of today, but it wasn’t to be. When I was cutting furrows yesterday afternoon I noticed that the plough was coming adrift from the gooseneck that holds it to the main frame. When I packed up for the day, I took the plough down to the workshop, applied a little WD40 to the nut on the back of the breast, waited a few minutes, then turned the nut about a quarter turn, and snap! The square-shouldered screw sheared off and the plough fell off the gooseneck. Oops.

To make matters worse, the screw was a specially made one with both a squared shank that passed through a square hole in the breast of the plough and a concave head that fitted flush with the face of the breast. I couldn’t just pull a suitably sized screw from my collection of assorted odds and ends—I was going to have to make a new one and that had to wait until this morning.

When I returned home from nursery this morning, I dug through my collection of screws and bolts to find a square-shouldered, truss head screw that would fit the holes in the plough and the gooseneck. Fortunately, I had two overlength ones that were the right diameter, so one was worked to something approximating the original.

With the appropriate power tools, it would be possible to refashion the screw in half an hour or so. But I don’t have a bench grinder or a Dremel, so I collected my metalworking files and headed outside to enjoy the sun as I worked. Some people would be stressed and irritable at losing a morning’s planting, and risk making a mess of the job. Not me. The sun was shining, I had something to tinker with and it was a nice break from the backbreaking work of cultivating and planting the field. First, I filed the underside of the screw head to curve it to fit the contours of the breast. When it fitted neatly, I fastened it in place with a nut and began filing the top of the screw head down. It took a long time to work it down, mainly using flat and half-round files.

One thing that I quickly realised was that it would be a mistake to try to cut the exact curvature into the screw head. Instead, if I filed the head down enough, tightening the nut would pull the metal to the correct shape—but I’d have to be careful not to take too much metal off. After a couple of hours work, I had a reasonable shape to the screw head and was able to fasten the plough to the gooseneck. As I suspected, tightening the nut pulled the screw head into the hole and the contours weren’t bad. However, the edges were still raised slightly, so I braced the plough on a piece of wood and lightly peened the edges of the screw head with an engineer’s hammer until they were flush with the breast.

Not bad. The refashioned screw head was slightly larger than the original, but fitted well and was flush with the surface of the breast. This is important to avoid soil getting stuck in and around the screw head, where it builds into larger and larger clumps that eventually stop the plough (and me) in its tracks. The final task was the cut the screw to length using a junior hacksaw, which has a very fine blade that fitted into the thread. Once the excess length was cut away, I carefully re-cut and cleaned the thread with a small triangular file until the nut went on without sticking or catching.

An advantage of the new screw is that it’s metric and takes a hex nut, instead of the old screw’s square nut. That means I can use a ring spanner for adjusting or removing the plough in the future. I also put a smear of copper grease on the screw to make it easier to remove in future. After that, it was back to work. 

Thanks to the Wee ‘Un for helping with the photography.