I just got my Shapeoko Pro XXL setup and was about to do my first test cut (the coaster tutorial they suggested). I had two questions before I start though.
When the router does the profile cut, wont that cut into the table slats underneath? I plan on using this a lot, so Im concerned the repeated passes into the table will mean I need to replace the table slats constantly. Are replacing those something I should be expecting to do? Or should I be putting a buffer piece (1/8" ply or something similar) under the piece I’m working with? Then I would tape my work piece to that buffer, and clamp the buffer I guess.
Also, when it finishes the profile cut, wont the freed piece of wood fly across the room? I have the clamps so I wasnt going to use double sided tape, but do I need to use tape if Im doing profile cuts?
If the thickness of your stock is measured accurately, and then zero’d correctly , then you can cut down to the wasteboard with only a very small amount of cut into the wasteboard.
This is one of the common cases where setting the zero to the bottom of stock is used. You then zero off the wasteboard, and you can be confident than any minor mis-measurements on the stock thickness won’t cause problems when you cut down to the wasteboard. Any mis-measurments only would affect how deep the first pass of the cut would be, and so long as you are reasonably close, it will cut fine regardless.
That said, if you are doing a project that works on the top face (for example, a V Carving), then in that case it absolutely makes sense to use top-of-stock as your zero, since an accurate location for the top face is crucial to getting a good V Carve.
You should expect that you will be replacing the wasteboard, but it doesn’t have to be often. For example, even if this project cuts into the board, the amount removed won’t really affect how flat your next project lays on the wasteboard. You can also occasionally use a surfacing bit to skim a thin layer off the wasteboard to smooth it off.
To secure the coaster, you can used double sided tape, or you can program your cuts to leave small ‘tabs’ connecting the coaster to the rest of the stock. I haven’t done that particular tutorial, so I don’t know what they suggest.