[jsheerin]

I need a cnc milling machine. While I'd like to pick up a used machining center, the moving and the space in my garage are both problems for me. So I decided to try to build my own. I'm going for something that's massively built but in a small space. I decided on a gantry setup to carry the y and z axes. The x axis will be a moving table. Of course this depends on me coming up with a frame I'm happy with in this configuration. A sketch of this is shown below. I'm shooting for a machining envelope of around 36" x, 20" y, and 14.5" z.

I found a Setco RM5-5 milling spindle on ebay. This is a 385 pound worm gear milling spindle with a NMTB 50 spindle nose. The top speed is limited to 480 rpm, so this is definitely a low speed head. It can handle a 29.7HP input (and put out 27.3HP) at that speed. A pic of me unloading it out of my truck is below. It came on a truck to my work. They have a lower height loading dock that I backed my truck up to and we slid it in using a pallet jack. At home I backed into the garage, slid the engine crane under my truck and picked up the pallet slightly using chains around the milling head. I drove out from under it and then set the head down on the dolly. I might add a high speed spindle on a second z axis to complement this or use a spindle speeder in the Setco. I found a higher speed spindle on ebay (about 6k rpm) that looks okay, but it uses BT35 tool holders which seem rare. I'd rather get something that uses 40 or 50 size holders.

Movement will be via Fanuc AC servo motors run with Granite Device drives and THK HSR25 bearings and rails. Initial calculations show the life expectancy of the bearings should be >10 years when run continuously for 8 hours a day 5 days a week which is way less than I'd actually use it. Ballscrews are on the way for some of the axes and I'm still looking for parts for the Y and second Z.

At the moment I'm working on the design of the frame. I'm getting too much deflection from the z axis structure and am trying a few different ways to reduce it.