started with . It can also be used for importing drawings from another CAD program you may have used , to then generate the G code .
Let ’ s now talk about the machine . As I said earlier , CNC can be used to control a number of different types of machines . I chose to build a router table of 1300mm long by 900mm wide with about 200mm of vertical spindle height . This is a straight forward 3 axis machine with the Y axis being the movement from front to back , the X axis being the movement from left to right and the Z axis being the vertical movement of the spindle motor ( router ). I chose a machine like this principally because the majority of the work I want to do is cutting out parts as a profile cutter , plus the occasional 3 dimensional job ( such as some molds I recently shaped to make gear doors for my new jet model ). With this size table I can cut materials of up to 1 metre long ( which is great for
cutting out spars etc .) and still get cutting accuracy better than 0.05mm for those tiny jobs . I ’ ll go into the construction details in the next edition of MFW .
Another free bit of software out there is a program called Mach 3 . Again , it is free with some limitations ( in this case , the number of lines of G code you can run ), but when you pay for it , these limitations become unlocked . Mach 3 is a program used on the machine to operate the axis of movement . Again , if you are sparked with interest , download it and try running some of the code you ’ ve generated with CAMBAM to see how it works . It has digital readouts to display the movements of each axis , to give you an idea of where they are tracking . At this trial stage it will be fine to run Mach 3 on any computer , but if you decide to persevere further you will need a dedicated computer to run the machine and use it for absolutely nothing else other than running the machine . Mach 3 is a program which works below the levels of the basic windows operating system and can be disrupted by other programs running on the same computer . For instance I spent weeks trying to find why my machine would hesitate whilst cutting circles and found it to be associated with the wireless card I had plugged into one of the PCI slots on the motherboard . Also with Mach 3 it is vitally important to reboot your computer after installing the program and before opening it for the first time , otherwise the main driver will become corrupted and give you headaches to fix it . This dedicated machine doesn ’ t need to be anything special . Mine is an old Pentium 4 with a fresh reload of windows XP which I had kicking around here and an old 13 ” flat screen monitor , all mounted in a cabinet to keep some of the dust out . Mach 3 can be downloaded at : http :// www . machsupport . com / downloads . php Download version Mach3 R3.043.066 . Excellent setup and configuration v i d e o t u t o r i a l s c a n b e f o u n d a t http :// www . machsupport . com / videos /
Stepper motors
I mentioned earlier about pulling stepper motors out of old printers and tinkering with them . Unfortunately these motors are nowhere near big enough to handle the loads of a machine this size . If you ’ ve never had anything to do with steppers , you can find an excellent You Tube , 2 part video of how they work at : http :// youtu . be / MHdz3c6KLrg Stepper motors do exactly as their name suggests by stepping around the axis of rotation in very precise steps . They need to be controlled by a dedicated driver unit to schedule the steps and the direction they step . By attaching the shaft to a drive source ( i . e . A ball screw or rack and pinion system ) we can now create the linear movement of the axis we want to move . The size of these motors are generally identified by their holding torque . I used 4 motors , ( one each on the X and Z axis and two on the Y axis ) rated at 425 oz / in and have found them to be matched perfectly for the size of the machine . As much as I prefer to support local industry , I was not able to find what I wanted in NZ , so ended up buying the motors , drivers , power supply and break out board
Top : Wing Spar assembly cut for Vigilante Sport Jet Middle : Gear door plates . Leaving the tabs in place make it ideal for gluing door hinges precisely in place . Above : Body parts for a tri copter cut from G10 fibreglass material
from China at a pretty reasonable price . Have a look at : http :// www . wantmotor . com / for what they have available as kit sets . Another great source I have used for parts and advice has been Peter Homann at Homann designs in Melbourne . He has a good deal of CNC gear available at very competitive prices . Have a look at his website at http :// www . homanndesigns . com /.