Computer-Controlled Machining

Assignment- Make Something Big

This week assignment we are task to make something big. It is back to drawing block and i have to reckon my brain again to think what to build for this week assignment. A few idea pop up like a shoe rack , chair and a stool. As i am not a mechanical trained so i decided to make some easy which i can easily manage during the cutting using the router machine. For this assignment i be again using Autodesk Inventor to design my stool. In addition, i have also go through some tutorial to learn how to use master cam software before i am ready to use the router machine.

MasterCam 2D Machining Tutoral

Images of Design parts


My first trial was failure as shown in the picture. It is my first time converting the files to .NC on MasterCam

The seond trial was success as shown in the picture after a check on the coding and the bit end point.

With the sucession of the second cutting i am more determined to finished up my CAD work and ready to convert the files on MasterCAM.

Images of Actual parts



You can find my CAD files here:
Leg 1, Leg 1
Leg 2, Leg 2
Seat, Seat
and Stool Assembly

Rules of using the Mastercam


I like Rodney was not familiar with MasterCAM (this is my first router job) and I have to seek Roy Ang for his help to get through the software.
Here are the steps to follow in the MasterCAM production.
Import the STEP file, the wireframe of the objects will appear on the screen. Use the FRONT, TOP, SIDE, ISO icons on the top menu to help layout the objects. There are key some important keys function i must take note :
  • Rotate objects - use the center mouse button
  • Moving an object left or right - use the Alt + Mbutton
  • Alt-S - is to toggle solid / wireframe object

    • Placing an object in the mastercam :
  • The object on a slight ISO angle, and use Xform > Move Origin to place the origin on the TOP, LEFT-HAND corner of the object. It would be best to place the origin on the object.
    • To generate the tabs (small sections to hold the cut while milling)
  • first create a layer of x00. so that the origin of the object will not be affected even there is an error during the setup
  • Rotate the object to show the bottem section (where the tabs are to be created).
  • Second select Create > Curve and using the menu select the areas which the curve is to be generated on the bottom layer. if you have selected top layer it will begin the cut from the top and all the splinters will all come upwards
  • Use the Level to switch OFF all layers except the bottom layer.
    • How to Change the Attributes to a square
  • Use Create > Point > Dynamic to add tabs on the bottom layer. You can use the ADD button to keep adding while changing edges. Click Apply to keep the tabs.
    • How to change the tool
  • Use Toolpath pop-up to change the Tool to use
    • . Bits sand Spindle speed and feed rate for wood cutting
  • A 6mm Straight Bit with a Spindle speed of 1000 and feed-rate of 1000. Note that the SKC2030 does not change the speed at all and routes at a rate of 3000rpm.

    • Here are some of images taken by courtesy of Rodney when he is going through the setting up process

    Here are some of images showing i at work

    Conclusion
    Firstly, I have learn something new again this week like converting .NC to mastercam. Secondly,the draw on the XY plane and extrude downwards in Inventor is very important. It improved the efficiency and it can so minimize the flipping of parts. Thirdly, the poor finish shown below could be improved with the use of downcut sprial cutters that push the splinters downwards, recommend especially when milling wood. Safety is important all CNC macine always wear a goggle when you doing cutting.