G-Wizard?

[Jonathan]

I think G-Wizard is pretty good, but a bit of common sense always helps.

I broke 3x 3mm bits over the last week so thought it was time to get a bit more technical about it. However, I notice that what G-Wizard suggests is different from what I have read on this forum, mostly it uses higher spindle RPM. For example I know Jonathan likes to cut aluminium using a single flute 6mm bit at 8000RPM and 600mm/min. However G-Wizard suggests more like 13000RPM. Though actually I just noticed now, it suggests pretty much what Jonathan said for an HSS cutter instead of carbide.

Not sure where you read that - I use 600mm/min and 12600rpm (or thereabouts) for that cutter. If it's in one of my posts let me know as I should correct it.

I broke my 3mm cutters on acrylic. I understood that it is best to have quite a high feed rate and a low RPM or else the plastic can melt. However, G-Wizard suggests that for a 3mm cutter with 3mm cut depths, I should use 22000RPM (!) and 770mm/min. IS this what you would expect, or is it going to melt the plastic? I haven't tried it yet as I need to get more 3mm bits, lol!

For me it suggests the same rpm but 1300mm/min with single flute, however it also says the tool deflection will be too high if the cutter is longer than 18mm, hence the cutter is likely to break. Perhaps try a lower depth per pass and use the shortest tool you can. Bear in mind the tool deflection is proportional to the length of the tool raised to the power 4, so every little helps a lot.

I also notice that it never seems to use more than about 0.2KW of cutting power which seems a little odd, do most tasks really need so little? Additionally it seems to love TiALN coated cutters but I thought that only really made a difference for really hot milling applications, not cutting plastic for example.

Yes, but you still need your 2.2kW spindle to have enough power over the whole speed range.