Now that I know what size of wood I want to use, I can make some decisions on how I want to cut the frames and how thick.
To the right is a screen shot of the plate cutout. I measured about 1 3/4″ from each edge and set a line. That leaves a nearly 2″ piece in the middle. Once those lines are set I can start disassembling the frame. To the right of the screen shot is the disassembled frame ready to be imported into the CAM software. I then select these pieces, export them as a DXF and next we’re going to bring this to CamBam.
There are two aspects to the parts we’re exporting. A ‘profile’ and a ‘pocket’. The profile is the outside of the part, this is the cut that will separate the part from the stock material. This is a single line cut and the width of the cut will be the exact thickness of the bit you’ve got on your mill. A pocket is an area where you want material removed that is larger than your bit. Let’s pretend you were cutting a circular piece of wood to hold a camera memory card. The pocket would remove a rectangle in the middle of the wood block only a few mm thick and then a profile would cut around the whole piece and separate it from your stock.
Not that you can’t use a pocket to go through the entire piece or a profile that is only a few mm into your material.
This is a screenshot of the parts exported in the CAM software, CamBam. I’ve only defined the left piece for cutting so far. Looking at this screenshot vs. the Sketchup screenshot with the parts disassembled you can see what’s going on here.
I have two pockets set, these are the two triangles inside the box that give the wet plate a place to rest inside of the holder. I selected each triangle and set a pocket. Then I moved to the outside lines of the part. This gets a profile cut, you may notice the boxes along the profile path. These are holding tabs, areas of the part that are not milled. Their purpose is to keep the part attached even when the mill is complete. If the part decides to come loose before the mill is done you run a high risk of the piece moving into the path of the mill and ruining the job or worse – being launched across the room by the spinning blade. We’re talking 35,000 RPM’s here.
As it is, this would be a waste of wood if I milled the pieces like this. Once I have all of my CAM definitions set I’ll move the pieces to cause as little waste as possible without putting them so close that they weaken the material between the parts where the tabs are holding onto.
When we’re ready to send this to the mill I’ll talk a bit more about the parameters necessary to set a cutting path like speed, depth and direction.