Machining Aluminium with the Genmitsu 3018

Machining aluminium with the Genmitsu 3018 has been a challenge ever since I bought this cheap desktop CNC. The challenge has been I have had to update so many aspects. The spindle is now belt driven, the Z-axis rails are now size correctly and backlash springs are stiffer. Quite a few updates, but even so it still wasn’t machining aluminium very well. Then I thought I would try some proper carbide cutters.

three different 2mm diameter cutters
Left to right: Milling Cutter Store, Rennie Tools, generic “3018 CNC” cutter.

Comparing the 3 different cutters visually is interesting. The generic CNC cutter that you can buy in packs of 5 or 10 for these small CNC machines are really burrs. Effectively a series of sharp points arranged around the cylinder of the cutter. The twist is poorly defined.

The Rennie Tools cutter is a proper 2 flute carbide slot drill. This is really designed for steel and works very well.

The Milling Cutter Store 3 flute carbide slot drill design for aluminium is very sharp and has very crisp edges.

Also, both the Milling Cutter Store and Rennie Tools cutter have a much shorter cutting length. Plus they taper from 4mm diameter down to the cutter over a shallow cone. These design elements all go towards increasing the stiffness. Thus it moves less when cutting and hence will result in a better finish.

aluminium machined on Genmitsu 3018

Machining aluminium with the Genmitsu 3018 test design was a square (30mm side) and a circle (27mm OD).

The total cut depth was 1mm with 0.1mm cuts per pass and a feed rate of 60mm/minute. This was done with the 2mm diameter aluminium cutter from Milling Cutters Store.

This is not perfect, but a huge improvement over the basic machine and generic “CNC” cutters.

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