Blackfoot CNC rigid enough for routing .1 6061-T6 and drilling .125 aluminum stock?

[j.steensen]

Hey all, is the blackfoot CNC rigid enough to router .1 6061-T6 sheet, and to drill .125 6061-T6 stock?

[michaelthomas]

Not really.

They are not very rigid, and the chain drive is bs. I made a belt drive version with reduction drive, which was better......but still not suited to aluminum work.

You CAN cut aluminum.....but it will be very slow, and not very accurate at all.

Avoid chain or belt drive for anything requiring higher rigidity......like metals.

[ger21]

From what I read, most of the build your CNC machines can't cut wood much faster than 100 ipm due to rigidity issues. I wouldn't think they'd be much good at aluminum.

[JerryBurks]

I am not familiar with the Blackfoot but I am using a Nextwave Shark Pro+ and (built from PE sheet with long unsupported rails) I can not imagine another machine to have much worse rigidity (I measured only 400 pounds per inch).

Anyway, lately I have been using this setup to machine 6061, 2024 and 2011 aluminum alloys for some parts of my new homebuilt CNC. With special 3-flute coated aluminum end mills (from MSC, look for the "Metalworking Deals" for better price), rather high revs (15-20k) at 10IPM (for 1/8" dia) and 15ipm (for 1/4" dia) taking only light passes of 0.015" I got good surface quality. Running the same tool path twice gave accuracy as good as the backlash of the screws (about 3/1000"). You MUST run climb mode path or the tool will be pulled beyond the intended line due to the machine flex. I tried alcohol for cooling/lubrication but that made the chips clump together. Running dry and letting the chips fly worked best and the parts got only moderately warm. It works well if you are not in a hurry. The large plate in the pic took about an hour or so to machine. The circular tool traces are visible because my spindle is not properly trammed.

I was not successful with drilling, the bits wandered and even when pecking got clogged. But I got nice holes down to 3/16", routing the hole outline with an 1/8" endmill (slow plunge). A smaller bit than the hole allows the chips to escape.