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.

ball screws


12z wrench

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.

2015-12-06 10.38.40

New stand with storage and integrated control cabinet.