Recently I reviewed the Stepcraft-2 420 desktop CNC machine and covered the basic assembly and setup of this kit built CNC system. When it comes to the actual operation of the system you have to start using programs to create and convert CAD drawing files of the parts you want to machine and produce the G-code file that the machine needs to function. Here’s what I do to make parts with the Stepcraft CNC system. (See the full review in the upcoming September issue of MAN).
The system kit comes with a CD containing the UCCNC drive control software you have to install on your computer.This takes no effort at all however you do have to also input the licensing code, provided by Stepcraft when you purchase your kit.
Your system has to be full assembled and running for the program to operate properly. If you simply launch the program without the machine connected It will run off line but will not be able to determine the limits of your machine. But more about that later.
Once you launch the UCCNC driver program you will see the basic dashboard for the machine. It is the nerve center for everything the machine does. But you first have to create the G-code and to do this you need a separate program to create the tool patch information to create your part.
(Above) This is the dashboard for the UCCNC driver program. The upper left corner is the tool path preview window.
The first thing to do is create a vector based drawing of the part you want to create. There are all kinds of CAD softwares that can be used, from Solidworks and Autocad, to free software like Sketchup. 2D and 3D projects can be created also in commercial programs like CorelDraw, Adobe Illustrator, as well as free software like Inkscape. I used Ashlar’s Graphite 2D CAD program to make my drawing and then I exported the file as a .DXF format.
This the my test piece which is a flap hinge for my Nick Ziroli Skyraider project. I imported the part from the cut file I created for the parts of the model. After this, I then exported it as the required .DXF formated file. Before for you export your file, be sure you have all the dimensions correct, and assign a thin cut line. My default setting is .002 in.
Now you can import your drawing file into a program like VCarvePro. Stepcraft is a reseller of compatible programs including Vectric, Cut 2D, Cut 3D, Photo VCarve and V-CarvePro (shown below), which is the program I use to output the G-code.
The first step is to start a new file and then enter the size of your work piece plus some added area for clamps or other devices needed to secure your work piece to the CNC. Once the space is defined, you import your vector file and center it within your job work space. The next step is to input the material thickness and the X-Y datum position.
Basically this is the start point where you want to position your spindle and milling bit before running the job cycle. You can place the datum point in the center of the job or at any of the corners show to the left. The larger dashboard shown above shows a 6×6 inch work space with the X-Y datum positioned in the center.
Once this is done, you import your drawing, modify it, add or delete unwanted items and center it on the work space. As shown (far left), the drawing is cleaned up and the ID markings has been removed. The drawing above shows the added holding tabs positions, and the vector lines have been selected and appear as purple dashed lines. This is what the drawing looks like when you take the next step and assign the tools and and produce the tool paths. The two windows below show the menus.
There are several choices for assigning tools paths but the most common is the 2D profile tool path. This makes the tool machine the outside shape of the part and the inside areas of any openings within the part. The menu shown above is for the 2mm end mill bit I chose for the job. You can also easily add more tools to the tool menu as you buy them and you can assign speeds and feeds to the list as you experiment and find the ideal settings.
Once all the tool paths and the type and size of the tool bit is selected, you can then run a 3D preview that shows the actual paths the tool will follow. The preview is shown below.
What’s even cooler is that you can run an animation that shows the tool running the path and cutting out the part. The preview below shows the part part way through the job. The path shows all the travel vectors including the up-down Z-axis.
Shown to the left is the animated view. This one shows no holding tabs and it is a single pass tool path. You can select multiple passes for your job if you like and this is good for hard materials like G-10 fiberglass material and other plastics.
Once the part is checked for proper operation, you save the file and the G-code selection window opens so you can choose the code that your machine runs on. Stepcraft give you this information. You can now save the G-code file and power up the CNC system.
Each time you want to run a job, you connect the CNC to your computer, power it up and launch the driver program. You then place your work piece and a spoiler board under it and clamp them into position. Load the G-code file and zero the X, Y and Z axis gantries with the “Zero All” function. You then manually move the spindle to the required position, (using the arrow direction controls), over your work piece. Install a milling bit in the spindle, and lower the Z-axis until the bit just touches the top of your work piece. Now manually assign the new job zero points for all axis and when you see the yellow dot in the tool path preview screen. Switch on the spindle motor and you’re ready to go.
Here is a sample of the part I cut from 1/8 inch G10 fiberglass. The cutout part still in the main piece of material is being held in place with the tabs I assigned to the part and it was cut with three passes. The other part on top of the material sheet was cut with one pass. As you can see it is very smooth and required only a little clean up around the edges with some sand paper. The part was cutout using a 2mm diameter (double flute) end mill bit, with a speed of 21,000 rpm and a feed of about 60mm/second. No chattering or chipping occurred.
Overall, I found the Stepcraft-2 420 desktop CNC system very easy to assemble and set up. The required programs are either included with the kit or are available from Stepcraft. If you are comfortable with assembling and operating precision equipment, and can understand the basics of computer programs, you’ll find the 2/420 CNC 3-axis milling system a wonderful addition to your modeling workshop.
Stay tuned, I will be posting more information on the operation of the CNC system and show some other parts machined using the Stepcraft-2 420 desktop system.
For more information on Stepcraft desktop CNC systems, CLICK HERE.