I have an MF70 that I converted to CNC a few years back. It's a neat little machine, but to be honest it's not as much use as one would hope. Reasons below.

Starting with the good and working downwards: it's a well-enough built machine. To compare it to a Dremel is a little unfair -- the head is cast aluminium with good bearings and no play in the spindle -- but in terms of scale, it's much the same (although it has a metric spindle nose of Proxxon's own devising, so Dremel collets, chucks etc. won't fit.) The base and the saddle are chunky castings too, giving the whole thing some degree of rigidity. The column is an aluminium extrusion which isn't terribly rigid but good enough for the small forces needed to take small cuts in light materials. The 150w spindle motor is reasonably sized for the machine, but has a habit of letting the smoke out if it's allowed to stall.

The table is another flimsy extrusion which bends as you attempt to clamp anything to it, affecting the fit in the saddle (as you tighten a clamp bolt, the table edges pull inwards and take you from a snug fit to a wobbly one.)

On to operation: It will cut aluminium perfectly well, but makes a hell of a noise while doing so, and you can only get away with very light cuts (1mm width/depth of cut is reasonable, much more than that and it will seriously struggle.) If you try to make it bite off more than it can chew, you will either stall the motor, or get terrible chatter and a poor finish as the column/table flex around too much. The spindle will only hold tools up to 1/8"; if you were to jerry rig anything bigger in the motor probably wouldn't cope with it anyway, and machine rigidity would be even more of a problem. The actual working envelope of the machine is pretty small but that's just as well because it would take forever to machine anything larger than a couple of inches on each side.

Overall opinion: the machine is well made and (unlike many Chinese machines) doesn't need tweaking to make it work, but its working capacity is too small to be useful for very much. It will work aluminium (to prove this point, mine was used to make its own parts for the CNC retrofit), but you have to take it very very slowly, and be prepared to put up with a lot of high-pitched noise. Much better value for money would be something like the Sieg X1, which (despite forgoing warning about Chinese machines) is a much more capable little mill.

Just my opinion, of course.

Richard