With a bit of luck I should have my first lathe in a few weeks, a Super C3 Mini Lathe! I want a good set of 1 to 10mm jobber drills to use with it and I've been told it's worth looking at Dormer as they can drill so accurately you don't need reamers and they'll also last a lifetime.I've been looking at the huge range they have to offer and need some advice.The carbide drills look brilliant, but way too expensive! Dream on... Same for ADX drills sadly.So looking at the ready made Dormer sets of general purpose jobbers, the choices simplify to:A set with steps of 0.5mm or 0.1mmA100, or A002 HSS, or A777 HSCo types. These have various cutting head geometries I don't know how to compare.Whilst a 0.1mm stepped set sounds nice, I'm thinking that in practice I'll just be drilling whole number metric diameter holes or tapping size holes, so perhaps I should get just a 1,2,3,4,5,6,7,8,9,10mm set of a more expensive type and buy other individual drills as required. But maybe the A100 or A002 drills are already good enough to last a lifetime?Advice appreciated!

In article , Scrim writesFirst point, I can guarantee you will need drill bits in 0.1 mm steps, for all sorts of reasons. The most obvious is that tapping sizes (whether for metric or imperial threads) mostly do not coincide with 0.5 mm steps. If you need to ream holes, you must first drill 0.1 - 0.3 mm undersize depending on size (and you probably will need to ream holes, for several reasons). Buying a set is so much cheaper, per size, that it would be a false economy to start buying individual sizes across the range (but see point 3).Second, don't buy carbide drill bits until you need them for drilling exceptionally difficult material; they are much less robust than HS ones.Third, do you really need to get a 6.0 - 10.0 mm set straight away? Only you can say what type of work you will be doing, but you may get by for now with a 1.0 - 6.0 mm set and a couple of larger bits as needed.Fourth, I doubt you need worry too much about exotic types or geometries. This set: suit your needs for...

Which set of Drills for my first Lathe?

Oct 10, 2010 22 Replies

Rate this thread:

Scrim 15 years ago

Thanks folks, that's all invaluable stuff. I'll get a reasonable set of drills to start me off and see how I get on. By the way, I've been doing lathe like work on bits of acrylic by sticking them to the front of a motor and 'machining' it by hand using a blade. I've also drilled centered holes and noticed how easy it is to get it right on centre even holding the drill from the side in a pair of pliers, so the centering effect is very real. It helps to start the hole with the tip of a sharp blade first though. Hopefully all that 'hands on' work will help me when my Super C3 turns up...

Scrim

Vote

Cliff Coggin 15 years ago

To my mind people using the frames of reference argument often forget that we are dealing with a dynamic problem not a static problem, and therefore it is necessary to include axes of motion in the argument.

Take that into account and it is easy to see that the situation in which the work is stationary and the drill moves, the axis of rotation is the same as the axis of movement so the hole will not centre itself in the work; whereas in the other situation where the work rotates and the drill is stationary the axis of motion is not necessarily the same as the axis of movement. The result in the latter case is that there is a tendency for the drill to correct its path and self centre.

I find it easiest to visualise by exagerating the angular difference between work and tool. In the former situation the hole will just be a parallel hole; while in the latter case the drill is trying to carve a conical hole and hence will be turned in to the centre.

Cliff Coggin.

Vote

Scrim 15 years ago

I though someone might find this useful. I decided a 19 Piece set of Dormer A002 drills in a plastic case for ~£35 inc. VAT from here, which seemed significantly cheaper than anywhere else I found: Dormer part number ZZ01A002SET

formatting link

Seemed like a good deal to me. The case is ok too.

Scrim

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required