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Last week I also decided to swap the forks from my tired old S4. First, I had to make arrangements to hang the bikes, so the forks and front wheel could be removed. This involved cutting some stout steel to make what look like car rear leaf spring hangers to bolt through the rafters of the garage. I had some 8mm thick by 40mm steel flat left over from a railed fence I made for the house, and, with the trusty angle grinder within 20 minutes I had the requisite 8 pieces 170mm long. I then had to make 16 holes x 8mm. This took hours and hours. On the pillar drill I drilled pilot holes first at 4mm then took them out to 8mm. I had lots of time to ponder what I was doing wrong and what I do not know. The drills were sharpened regularly, they were coming out blunt but not hot or showing any sign of scorching. I use 20k mile fully synthetic sump drainings for lubricating when drilling and machining, was the lubricant too good for cutting? Was the speed too high or too low? An 8mm drill at the outer cutting edge is travelling 25mm per revolution. If you are drilling into a 4mm pilot hole the distance per revolution is effectively half that at least until the drill has effectively countersunk itself. How do you calculate the optimum speed for cutting with a drill, the point of the drill hardly moves at all. The swarf coming off was chipped not that satisfying spiral - why was that? Is there an optimum ratio between pilot size hole and final diameter hole and what is it? I am 65 years old and I do not know any of these things – you get the picture it was bloody boring work.
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