Bigger, better, faster milling machine
After years of pushing my little X2 Mini-Mill to the limits, and trying to cut aluminium on my large router table, it became clear that I need a bigger machine, that can handle metal with decent precision. And of course it has to be CNC, and it should be a capable beast. Fast, precise, versatile.
Selecting the machine
After lots of searching on the web, and talking to a friend at the local makerspace, the Optimum MB4 came to my attention. And of course the recommendations of Stephan Gotteswinter add a lot of weight. After some good experiences with my Optimum lathe, I went to Stadelmann (swiss Optimum dealership) to have a look, and to compare it to the other OptiMills (BF30, etc.). Of course I packed my bag with dial indicators for rigidity testing.
Here it is in the shop:
Compared to the BF30, which is roughly the same size, the MB4 definitely is the heftier, sturdier machine in any way. The deflection from spindle to bed (all ways locked down) with as much muscle I could muster was 0.02-0.03 mm, about half of the BF30, in this admittedly unscientific test. Just looking at the size of the Z-column explains this nicely though, it’s much fatter. The MB4 has a 6-speed gearbox, and a 2-speed selector for the 1.5kW motor, for a speed range from 80 RPM to 3200 RPM. While I like the vario drive on my lathe, and the BF30 offers Vario, I think having the super-lowspeed option is nice for tapping, and the gearbox will offer far more torque. The maximum speed of 3200RPM is a bit low for aluminium and small tools, but more on that later.
I also liked the 25mm lead screws, as this would allow me to put in some hefty 25mm ballscrews. The big advantage of the BF30 is that there is an official CNC conversion kit available. However, it is quite expensive, particularly when also buying the optional ballscrews (and a CNC mill without ballscrews is hardly worth doing). So I decided to go with the bigger machine, and do the conversion myself. The MB4 is also the less expensive machine, another plus.
Delivery and setup
The machine was delivered fairly quickly after ordering. Time to take it apart! 🙂
The parts looked pretty good. Following GTWR’s advice, a quick deburr and thorough cleaning is always a good idea. Next: taking measurements, creating a CAD model, and designing the parts for the conversion. While that is happening, I also welded a solid base for it. I didn’t like the base offered with the mill – not much storage space, and you can’t get a pallet jack underneath. So I built my own:
(continued in part 2)