CNC Mill – Background

Robots and CAM fascinate me. My woodworking skills are OK, my metalworking skill are poor. Much of this is down to impatience, rushing to get something working before my attention drifts elsewhere.

Cheap CNC machines offer the possibility of faster development and better quality results. Having a robot make me something repeatedly, with much better build tolerances than I have the patience for has great appeal. What is there not to like?

Decision Factors

In June 2017 I took the plunge and ordered the materials to make an Openbuilds C-Beam Plate Maker CNC mill. Several factors drove this decision:

  1. Price
  2. Non ferrous metals
  3. Rigidity
  4. Modularity

Price

My target price ceiling was AUD 2000. This included the mechanism, spindle and  controller hardware.

Non ferrous metals

A goal for the mill has been the ability to machine aluminium. The reason for this is simple. Being able to machine aluminium stock, plate in particular, results in a machine that is capable of replicating or improving itself. I wanted a machine that could machine plate aluminium 3-8mm thick.

Rigidity

In discussions with more experienced makers, i.e. those that had used a CNC mill before, machine rigidity was always a key issue. Some of the people I spoke with had Chinese 6040’s. All were happy with their ability to cut softer materials such as ply, MDF and plastic. None of them were able to mill aluminium satisfactorily.

Modularity

Building your own CNC machine means embarking on a journey. I want to be able to make ‘things’. I do not yet know all the details of what these ‘things’ may be. As I learn more about my desires and the laws of physics I know the machine will need to adapt. Being able to reuse and recycle components as the machine evolves is desirable.

Decision Narrative

I got my shortlist down to four options, a Chinese 6040, X-Carve, Shapeoko or Openbuilds.

EBay and AliExpress list thousands of 6040 machines, too many to choose from. There appears to be hundreds of manufacturers offering a myriad of options, things like threaded rod, acme screws, balls screws, stepper size, spindle type, bearing shape and controller hardware. I did a lot of research but must admit that I never got to the point where I understood what I was actually going to receive.

X-Carve seems to me to be an excellent woodworking machine. It is well designed and ‘slick’. It just seems a little light on in the rigidity stakes.

The Shapeoko appears to be more rigid than the X-Carve. Their website now boasts that some users are cutting steel. It’s been a while now but I think the reason I rejected the Shapeoko was the freight cost to Australia.

The decision to go with the Openbuilds machine came from 1) watching their assembly video on Youtube and 2) finding an Australian distributor for their components. I immediately GOT the way their system was meant to work and knew that if I needed to change things I could re-use most of the parts. That and I wasn’t going to be r%^&d with the freight charges.

Endnote

It is now January 2018. I have finally got the machine assembled and am making my first test cuts and real components. I am at the ‘commissioning’ point, very much a work in progress. Yesterday I was able to machine an aluminium bracket. Broke a bit on the first attempt and the second wasn’t deep enough to release from the sheet.

Early days yet but am really happy with the way this is working out.

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