Making a CNC Milling Machine -Ballscrew mounts

Converting a Grizzly G0704 milling machine to CNC – Part 2

Making a CNC Milling machine requires a lot of metal working. Most people will use a manual milling machine to do the metal work. I was lucky to have access to a CNC machining center so that is how I made my ballscrew mounts. A Ballscrew (sometimes spelled Ball Screw) is a type of linear actuator that translates rotary motion into linear motion. It uses ball bearing in a helical groove to transfer the motion with very little friction. The ballscrew mount attaches the ballscrew nut to the milling machine.

Ballscrews use ball bearings in a helical groove to convert rotary motion to linear motion.

 There are a variety of sources to order ballscrews online. Roton Products Inc. http://roton.com  is one source I have used in the past. Roton provides good service and reasonable prices. Another good source is Automation Technologies Inc, http://www.automationtechnologiesinc.com. This company also offers many other parts to build CNC machines.

Before we get started, I just wanted to say that replacing the leadscrews with ballscrews is a completely optional upgrade. The supplied leadscrews are very good for manual machining and will also work well as a CNC mill. However, ballscrews are more accurate and are designed to have less backlash than a leadscrew is capable of maintaining. Adding the three ballscrews to the machine costs about $200 dollars. I got mine from a seller on ebay: Linearmotionbearings2008 Ebay Store. There are also several other sources for ballscrews including Roton and NSK and Nook Industries. The nice thing about getting the ballscrew from the ebay seller was that he offers a machining service and will machine the ends of the ballscrews to your specifications. Since he has done this machining many times he already knew the sizes needed, which made the purchase even easier. The ballscrew mounts replace the leadscrew mounts on the Grizzly G0704 milling machine. They are designed to slip over the edge of the Ballscrew nut and bolt onto the flange with 1/4-20 screws.

I started with a CAD drawing from the Hossmachine DVD as the basis for my Ballscrew mounts but I made some modifications which I hope will be improvements. I used Vectric Aspire to convert the DXF drawings

I used Vectric Aspire to create the gcode.

to gcode. Then on the Z axis ballscrew mount I added some curved surfaces to match the shape of the Ball nut. The previous version was easier to make but I felt the curves were cleaner and used less material.  On the X axis ballscrew I

added a slot to allow the Zerk fitting (for lubrication) to have easier access through the top of the cross slide. I did not make any changes to the Y axis mount but I may make a slightly different version when I see how thing fit.

X axis ballscrew mount has a slot for the Zerk fitting.

The picture on the left shows the X and Y mounts just after I machined them from 7/8″ aluminum stock. The parts still need to be tapped and deburred. Tabs were used to hold the parts in place in the stock while machining. I cut the parts free later with a metal cutting band saw but you could use a hack saw.

Good fit

 If you would like more information about making a CNC milling Machine, why not subscribe to our free newsletter?