Intro: Repairing Hair Line Crack/fracture on Lawn Mower Chasis
OK yes it is an ancient old Flymo lawn mower, but is it worth saving??? definitely as its perfect for the garden as other mowers are just far too heavy and cumbersome.
We have had this mower for around 30 years and after bouncing off every curb and wall around the garden down the years it inevitably suffered some wear and tear. However it developed two cracks very close together and fearing part of the chassis breaking right off and rendering the aerodynamics useless and hence the Flymo useless it was fix it or scrap it.
I couldn't let the old thing go so i opted to repair it. I had the obvious choice of using some epoxy resin to fix the crack however i didn't fancy it would last too long especially since it takes a real battering around the garden. So i opted for the sheet metal band aid.!!
Step 1: Stop the Fractures
When repairing the cracks in metals or thermoset plastics it is important to stop the fracture from developing any further. The simplest way of doing this is to drill a hole at the end of the fracture and thereby stopping any slip or dislocation from developing further.
I tried to drill the hole in such a way that the circumference of the hole was just about in contact with the end point of the fracture making sure that it would not develop further beyond the other side of the hole.
Step 2: Sheet Metal Band Aid
The next step was to cut a piece of sheet metal just about 1 inch wider than the distance between the two fractures giving me about half an inch on either side. I used 2mm sheet metal here as it was what i had at hand and it was easy to shape and pinch into the contours of the mower using a pair of vice grips.
Having shaped the sheet metal i then took it off and placed it under the two holes, it fitted perfectly to the underside as it had a similar contour. Holding it in place with the vice grips i marked where two hole would go.
I the drilled the two holes through both sides of the sheet metal.
Its important to mention that i used a 4mm drill bit for drilling the holes as i could then use a couple of 4mm bolts to hold everything in place. So as well as stopping the fractures the hole would also act as fastening locations.
With everything in place it was just a matter of using double washers [one on each side] and a spring washer just under the nyloc nut.
Job done and good to go for another few years.....