Waste board - lessons learned

I decided to replace my waste board. The old one had seen better days and when I flattened it I had quite a step on one side.

First thing I cut a 22.5 X 19 - 1/2" baltic birch plywood. - Lesson #1 - it doesn’t have to be 19" deep as the router can’t go back all that far.

I laid out a 2" grid. -Again the back rows could have been left out. I decided to not have the Shapeoko do the work as it would limit the max size I could clamp down. If all the holes are cut in a 16 X 16 square then you can’t clamp down a 16 X 16 board.

I drilled 1/8" holes on all locations of the grid thinking it would be easier see where to center the forstner bit.

I used a forstner bit in the drill press to cut the hole for the plate of the t-nut. I set a depth stop so it would be just below being flush. Lesson #2 - it should be drilled deeper so the t-nut position isn’t as critical. Didn’t want any being proud of the bottom as I felt that would make the waste board uneven.

Drilled clearance holes for the t-nuts and started to put them in. Had trouble getting them all the way in due to not enough hole depth. Had a bright idea, use a 1’4-20 bolt, washers, and an impact driver to pull them into the board. Lesson #3 - the driver is so powerful that it would muck up the threads in the t-nuts and or just pull them apart.

So I would up drilling the bore a little deeper and then between a hammer and a punch got all 110 t-nuts inset into the waste board. Lesson #4 - next time use screw in threaded inserts.

Got this all done and put a dial indicator in the collet and found the new waste board to be about 0.040 difference from the lowest to the highest point. Guess I’ll flatten it next. I was hoping to get it closer than that, but…

BTW - while checking the offset all of a sudden it started acting really weird. When I would initialize, it would go home and then the right hand X steeper would keep trying to step. The final solution was to resend the default to the controller and then all worked as expected.


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I learnt the same lesson about the back rows of the waste board recently…

It actually makes the machine less versatile to have the wasteboard extending all the way to the back because when you surface/resurface it you end up with a lip of material at the back that is higher than your levelled work surface. That means you can’t run a longer workpiece back there for clamping etc or else it wont be level.

That’s why I’ve been advocating for a spoilboard the size of the working area (plus endmill diameter along X, radius along Y), w/ a corner radius which matches the endmill.

Similarly, designed this into the wasteboard setup I’m using now:

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