I have had my micro mill for a couple of months now. In that time I have had chance to setup and test the machine. The first thing was to try some test cuts, find out about the right spindle and cutting speeds. I found some scrap metal and started cutting away with no real intentions of making anything. I wanted to know how good a finish I could get, how accurate I could cut, and how much I could cut in one go. The first thing I noticed is that the table slides seems a little wobbly. After some reading I found that this is down to the gib screw …
These are screws that tighten or loosen the dove tails on the bed. Just a small amount of torque should be enough, anymore and the table is hard to move. This sorted most of the movement, although there is still some left. I think I can solve it with a better screw and nut, but tbh its just a cheap machine so I am happy with how it is for now.
The next thing I found was that my cuts were creating steps. A easy error to make, This was down to a few things, 1 cutting too much, 2 not tightening the z axis when cutting, and finally 3 using a chuck to hold my cutter.
Although using the chuck to hold the cutter works, it causes a few problems. The cutter is more likely to creep up in the chuck creating said steps. The chuck is longer, which means the head of the machine must be higher, allowing for more flex and vibration. This means you cant cut as much as quickly, get a worse finish and have to put up with the nasty noise. By using a collet to hold the cutter, everything is in much tighter. The head is closer to the part, and you really notice a performance increase. I could cut 2 or 3 times faster! this makes up for the time changing cutters in a collet.
So once I had the machine working well and I knew what every bit did it was ready to make something! the scrap aluminium was pretty much a cuboid, so I cut it into a 40x40x40 cube, trying to see how accurate I could stay… managed within 0.125 mm which is better than we were expected to do in my apprenticeship cut some nice chamfers on the edges, and drilled some holes…. to make a new giant dice!
I have ordered all the bits for the cnc conversion, just waiting on the control board. The next post should describe my methods and success/failures on getting this machine cnc fitted!