My hobby CNC mill has been really useful to become acquainted with CNC milling. It does a good job of laser cutting and engraving, and it can mill soft materials such as wood and plastic.  It will also engrave soft metals.  At a pinch it can mill soft metals such as aluminium, but this is slow and inaccurate due to the low powered spindle motor and excessive slop in the axial feeds (mainly due to the slide nuts).  It also has a very limited Z feed restricting cutting height to just 25 mm.

I have a whole bunch of production machining to do and my wee hobby mill just isn’t up to this task.  I’ve considered outsourcing but quotes for the parts are relatively expensive (US$12 each + tooling + freight and import taxes) and quality may be an issue.  I figure I can purchase a capable machine and manufacture the parts for about the same cost as outsourcing, and I’ll get to control the quality.  I’ll also end up with a 4 axis CNC mill capable of milling steel.

The first stage in the process is to specify an appropriate machine.  It needs to be:

• capable of machining steel.  This usually means robust and heavy, with a high-powered spindle motor and axial drives.
   
• accurate.  It needs to have precision ball screw drives to avoid excessive slop and maintain precision and repeatability at less than 0.05 mm.
   
• relatively small.   It needs to be relatively small to fit into my already over-crowded workshop.   I can’t accommodate a machine the size of a car or taller than 1.6 m above the bed.
   
• relatively low powered.  The available power is single phase, 240 Volts at no more than 20 Amps (10 Amps is preferable).
   
• relatively low cost.  I’m on a budget of about US$10,000 for this project.
• four axes.  Some of my prospective milling jobs ideally require a 4^th rotational axis.  This significantly increases the machine capability.
   
• maximum machining volume within budget.  The Z axis is most important.  The cutting tool uses up to half of the specified maximum Z feed.
   
• easy to use.  I don’t want to spend  months learning the machine interface, and I also want to use my available software for generating numerical control files.
   

There are a number of very capable machines available from reputable suppliers such as Tormach and this was where I started looking to refine my specifications.  Reviews suggest that these are excellent machines but they are also relatively expensive and some models are not available powered from 230 V 50 Hz single phase.

With my specifications refined I then went looking for an appropriate CNC mill sourced from China or Taiwan.  Some folk may have concerns about equipment made in this part of the world, but my experiences has been very positive.  My existing lathe and mill were a direct import from China and have done some serious work over almost twenty years with little more than routine maintenance.

The mill I finally settled on is an XK7113D from WMT CNC Industrial Company Limited (WMT) complete with a number of upgrades and accessories.  This is a tidy small machine similar with a tool workspace similar to the Tormach PCNC 440, but with a much larger 2.2 kW water cooled spindle motor at up to 12,000 RPM.   Unlike the Tormach machine it is rated as capable of batch production in steel.   The upgrades included a fourth rotary axis and precision ball screws.

WMT were very helpful in assisting me with selecting and specifying a machine, arranging shipping, and keeping me informed of progress.

In order to reduce cost, preserve my limited workshop space, and retain my existing software I had the machine downgrade programmed for MACH3, and removed the cabinet, stand and control computer from the order.  I have a number of spare high performance computers that can be dedicated to the mill, I can made a stand, and if necessary a cabinet.

The anticipated landed cost of the new machine was ~US$4,500 including factory to door shipping and import taxes.  With the order placed and deposit paid it was time to wait.  The machine took seven weeks to build to my specification and a further six weeks for shipping, factory to door.

This page has recently become way to big for ease of updating and navigation so I have split the content onto the following sub-pages.  Click on the image or associated text to navigate to the desired page.  Or use the site map or navigation bar at the top left and right on this page.  Each sub-page ends with a link to the following page

Click here to link to the Report Card