Charging forward on "BigA Ox"
After being done with "Woody", I showed it to a friend, who is also now my business partner (Mr Johnathan Ho), who then came up with a "brillant" idea of building a BIG-A** CNC router... his personal belief in life as follows below. After a couple of weeks of "searching" and going through some sites, he suggested looking into OpenBuilds.com to build their BIG-A** CNC.
"Big can go small but small cannot go big"
- Johnathan Ho
I then rough-through a lot of their schematics, members' builds at OpenBuilds.com and decided on "Charging Ox build". Reason why I went with this particular build was
(3) The B.O.M. (Build-Of-Materials) and schematics was detailed and concise.
The only that I have to do was to figure out how to adapt the build to a 1500mm x 1500mm (actual cut size of approximately 4' x 4' that's 1220mm x 1220mm in metrics), the parts required, and the electronics required (i.e. extra A-axis travel) as the build requires 2 motor to drive the X-axis.
During the process of the getting the parts together, John came up with the idea that we could possibly become a affliated members and run an .SG banch of OpenBuilds.com. We liked the concept of Openbuilds.com and their motto of
"Dream it - Build it - Share it"
and thought it was "in-line" with our idea of a "company" that we would one to "own" one day. Over that few weeks, John did the necessary and BLAM... we are a .SG branch of OpenBuilds.com; OpenBuilds.sg
In came the parts and time to assemble
MORE PICS...
The Charging Ox build warrants a build page by itself and in the posting, I will not dwell into the details of the build but TONS of information can be found at the originator of this build by "Motions" at OpenBuilds.com. I will elborate our OpenBuilds.SG version in my build page "some day" when time permits.
Time to give it a name.... "BigA Ox" was the obvious name for it and dedicated to Mr Johnathan Ho... "A" for his "A-hole" moments =) Due credit has to be given to him on his help to put together "BigA Ox" but John (if you are reading this), I built it =)
After Ox was conceived, I started using it intensively to cut the housing for my homemade Arcade "housing" but over time, I realized a lot of manual work is required to sand down all the rough edges produced by the milling bits and it also took a LONG while to cut a "housing" for my homemade Arcade. "BigA Ox" was design to mill and in order to do fine and close-to-90 degrees cut for the joints, I have to mill with a 1.2mm bit. Thinner bit means I have to sacrifice on the speed and depth of cut so as not to break off the thin bits.
Other problems that I "discovered" while milling are
(1) "Rounded" finishes for right-angled joints
(2) "Rough" finishes which however, can be compensated by Fine and Pencil finishes in some software (i.e. MeshCam) but requires more time on cuts.
(2) Depending on the mill bits that you intent to use, the offset has to be adjusted accordingly on the software.
Just to elaborate on the point on "rounded" finishes, refer to the diagram below. As the mill is going top-down (on Z-travel) and because the mill bits are rounded, milling would definitely result with a rounded cut at the end. Depending on the size of the bits, the "rounded" ends will be more obvious with bigger bits. When the male and female parts are "join" (see the 3rd picture above), it is hard for them rest snuggly together due to the rounded cut.
Offset has to be factor into milling cuts. If you use a 3.0mm milling bit, taking the bit at it's center, 1.5mm (the radius) will cut into the border of the wood and the remaining 1.5mm will cut outside the wood leaving a gap of of 3.0mm in-between joints (male-female joints). The offset can be corrected at software level either at pre-cutting stage or post-cutting stage. I opt for the former using Meshcam or Lazycam which I automatically does the correction for me once I specify the size of the bits that I'm using.
A month after using the "BigA Ox", we chanced across some "home-boys" (IN SINGAPORE!!!!) that are the founder of the PortaBee GO. Honourable mentions and credit have to go to them for their willingness to share and "knowledge pool" to help us in our later built. It is really a privilege for us to "chanced" across them and learn how they have persevered throughout the years from their Portabee 3D Printer (version 1) to the Porta GO version (current version). It was through them that we were able to acquire a 60W Laser Cutter and off we go again with the newly acquired machine (more on the Laser in my later blog).
Though milling was an acceptable way to go in producing the housing, the cut time takes a lot longer than laser cut and it requires more effort to process the cut edges for final assembly (than laser) as the edges ends up rougher using milling bits on general ply. Moreover, after comparing the laser cut finishes with the milling cut, and through general consensus (mainly by friends), the “black” burn mark gives a “tone” to the finish product, which looks better than the milling cuts.
