Here comes one of my dumb questions but I have to ask since I`ve learnt a lot from this thread. Rob - you sent a link for a 6mm spotting drill. Can I just clarify that you would have a set of these for each size hole? I`ve lost the plot a little as it seems that John is using them to cut the hole directly...say I wanted a 5mm hole and quite a depth, would I need a 5mm spotting drill to start the hole and then move onto my regular 5mm drill bit? Or say my hole was 5.5mm, would I use a 5mm spotting drill to "spot" the hole and then go in with my regular 5.5mm drill or whatever to finish it?
I suppose I`m asking are these just used to spot the hole and I only need a couple of sizes or are you using them to drill through?
Chris
Hi Chris
Not a dumb question at all ,,,,,,,,,,,,, I only have a few sizes , about the same rang as a set of centre drills ,the example i posted was the first on the Ebay search ,good price for a solid carbide drill , and as you said they are used for spotting for the drill , just the same as you would with a centre drill ,,, You can use them to drill all the way through the work as in the example John S posted , when the hole to be drilled is not as deep as the flute length .
This is just an example ,,,,,,,, I need to drill the holes in the bolt pads on my engine casting ,
10mm spot drill and large centre drill BSO3 i think

Centre drill in the chuck ,,,,,,,,,,it dose not reach the pad, chuck hits the casting

10mm spot drill ,, no problem ,as they are a bit longer ,,,,,,

Or you could spend more money and get long reach centre drills or just extend a standard one .

Regards Rob