Had a small welding job to do on the headstock of a Kuhn 5f master 120 plough- the pin welded just above the top link holes on the rear of the headstock which the turnover ram hinges on had cracked 2/3rds of the way through. To make it easier I stripped the headstock of the turnover ram and a few other bits before removing the circlip and cover for the mainshaft adjusting nut, then the lockwashers and the nut, that was when the job suddenly became a bit more complicated!
It started with the smaller front bearing coming off the hollow shaft with lots of damage to its inner flange and the 90mm step on the hollow mainshaft was in a poor state, it looks like the former owners may of had a similar issue and the damage was built up with weld, then ground back to fit another bearing? Probably because a new hollow mainshaft is around the £750 mark!
If you look at the first photo you can see the sort of damage which I covered up with a layer of weld. The next stage was to somehow come up with a way to accurately grind back the weld to the required 90mm.
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So after much thinking it was time to make a simple guide to hold a 4-1/2" grinder that could be slid across and along the straight part of the shaft so the disc would grind at a consistent depth all round just like the pro surface grinders!!
Using a section of channel with a slotted 10mm hole to mount the grinder by the spare handle mounting hole in the gearbox casing and angling the inner edges of the channels inner/underside so that slides around the shaft smoothly. Now time to see how it performs
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Using some 3-in-1 oil to help the "tool" slide easily, it soon started to make a decent job, I had buffed up the welds with a flap disc, using a simple stop-go gauge to get near the 90mm target size, then it was a matter of slowly working around the shaft in 4 stages. It took 6 discs using just the outer edge to complete, changing discs with only approx 1mm worn off the edge- all six went back up on the wall, perfect for further use
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