Machining the Part on the Phoenix CNC Router

Built your physical work piece (foam) oversize from what the virtual work piece is by about ¾” in all three directions. The reason for doing this is that it is impossible to cut foam using the band saw to exactly the required size, maintaining both dimensional and angular (90 degree) tolerances. If one was using wood or metal, you not do this but would make the physical work piece exactly the same size as the virtual one.

Fixture the foam to a hold down base. Use very little tape. A 1-1/2” long piece of tape, split down the middle to fasten the foam down.

Roughly locate the base in the router.

Start up the router and the attached computer, home the router, jot the head to where you can reach it and insert the appropriate tool.

Final position the block in the X and Y direction, setting the X and Y offsets on the router.

Turn on the vacuum hold down, locate the tool such that it touches the top of your foam piece and set the Z offset to +.125”. In effect, this will cause the system to flatten your work piece upon doing the Face mill operation (unless the work piece is not flat to with 1/8” from where you set the Z offset.

Run your Profile, Face and Rouging tool paths. Make sure you graph the tool paths before running them or you will get what you deserve!

After finish of the profile and start of the face milling operation:

After finish of the roughing operation:

Change the tool to a ball end mill (more than likely the ¼” tool) and touch this tool off on the “pedestile” that was left during the roughing operation. This is Z = 0.

Run your contour surface milling tool path(s).

When the machine is doing the corners, you may have to use the federate override dial on the front of the router to reduce chatter. Don’t let the router vibrate. It’s hard on the machine and the quick stops and starts that you are hearing are contributing to the servos eventually overheating.

After the contour milling (body and wheel wells) operation:

After this tool path, you can shut off power to the router. As long as you don’t turn off the computer, the router will still know where it is when power is restored. This will help the servos cool. Remember that when power is cut, the servo holding the router in the Z direction is released and the tool will drift down. Make sure your part is off the table before doing this.

Remove your part from the base and “backcut” the extra material from the sides that you are going to use to set the new X and Y coordinate system.

Tape the work piece on the part again, reposition in the machine and orient the block by traversing the machine in the Y direction. How accurate you are in positioning the block will determine how well the tool paths match up on both the bottom and top sides. Sloppy setup will affect your grade.

For the Z offset, touch off your roughing tool on the base and set this value to –X.XXX where X.XXX is the height of your virtual work piece. This should also be equal to the Z delta distance between the coordinate system that you used for top and bottom machining operations. Remember that we really don’t know the Z offset directly because our work piece is oversize in all three directions.

Clean the gunk off the end of the tools between tool paths. Keep the spindle speed lower that 15,000 rpm.

After rouging operation:

Part way through contour operation:

After contour body operation:

After all operations:

If the router overheats, you can shut off power to the router for about one half hour but make sure you do not power down the computer. If you do this in the middle of a tool path, you will have to rerun the entire path again because there is no good way to pick up in the middle of the file. The router will remember his location upon power up. Do not move the work piece!