I would estimate 10m/s should be OK.

**LINK**

Speeds and feeds for production machines can be obtained from standard tables or textbooks, but these are for robust (big) machines, not the sort of machines hobbyists normally have. The tooling being used and the machine have a bearing on the "ideal speeds and feeds" if the machine is wimpy and can flex then chatter will dictate what is possible.

Speeds and feeds are normally quoted as linear or peripheral speeds in metres per second, (or feet per minute in older books!) so if the bar diameter is small you need to pick up the rpm a lot more than when machining a 1m diameter bar! Ideally if say you are facing a large diameter round section then at the largest diameter the rpm will be low but as the tool approaches the centre it can progressively increase to some maximum, keeping a constant peripheral speed. Not many hobby machines do this automatically, but specialised production lathes can do it!

But these guidelines are for maximum metal removal in an industrial environment where the machine can tolerate the stress and has an ample reserve of power. And regular tool replacement is the norm. In a hobby environment we don't have the pressure to churn out parts as fast as possible, so about 50% or less is normally the best we can attain. Aluminium can build up on the tool tip and weld itself giving a poor finish. Flooding the work and the tool with coolant will reduce the tendency for the ali to weld itself to the tool.

Hi Matthew,

LMS has a nice online cutting speed calculator here. It covers both turning, milling, drilling and reaming for various kinds of materials.

Thor