Large Bed Mill
Charter Oak 12Z mill
This is my Charter Oak (International Hobby) 12Z mill. It is destined for full CNC conversion.
I have the 2505 ball screws configured with double ball nuts for all 3 axis. This is probably dramatic overkill. I plan to use steppers to move the axis. Y axis will be 1:1 belt drive so the motor can be tucked under the table. The x axis will probably be direct drive. The z will be belt drive and at some reduction. I am planning to size the motors once the new screws are installed and the gibs are tightened by measuring the ounce/inch force required.
Download my 12z spline wrench dxf file. Lasercut from 1/4″ mild steel. Tested on 12z and Bolton ZX-45 mills.
On this build I decided to add a motion control card for more industrial like reliability and faster motor movement. I went with the Warp9tech Ethernet Smooth Stepper purchased from Automation Technology Inc. Anecdotal evidence suggests this is the most popular option in this market. I have a refurbished Pentium PC running 32 bit windows that I purchased some time ago from local electronics recycler CompRenew. It has a fresh install and no software added other than Mach3.
On to the ball nut mounts. I made 3 mounts all the same for X,Y and Z from 2 1/2″ sq 6065 aluminum.