Okibi wrote:Perhaps you could have an insert so a guide hole could be drilled with a smaller bit first, then pop out the insert and use the full sized bit?
Yes, I have thought of drilling a pilot hole first. I'm not sure whether to use a bush or have another stepped drill. I have drills that make very accurate size holes without a pilot hole. Trouble might come from the fact that the first few millimeters are only being drilled in the sprocket until the crank is reached.
As I need a way to make sure the hole is the correct depth and the stepped drill the the best for this as you can only go as deep as the shoulder on it. Alternatively a bush and standard drills is common practice but I need to control the depth with a collar to make it foolproof.
Some more thinking and some R&D I think.
Andrew.
