I’ve been cutting a new waste board (with issues) but, because the board is 32" wide and I’ve got a BitSetter installed, securing it to the baseboard off-centre slightly wasn’t going to work, so I made a small cutout to fit around the BitSetter and secured it using a strap, like this:
Has anyone done anything similar?
I’m surprised that this is giving you the hold-down power that you need to keep the board from rising. I could see the strap stopping lateral movement, but doesn’t it tend to want to lift a bit on the side opposite the crank?
When I did mine, I recessed a bunch of screws below the leveling depth and screwed it down to the base before leveling it. I left those screws in afterwards. That seemed to work.
It seems to be fine, as the strap is pulling it towards the front frame of the machine, and the stock doesn’t seem to move, so maybe I’ve just been lucky, but it’s not finished cut yet (there’s another thread on this!) so it hasn’t done the whole thing.
I’ve designed my spoilboard to have recessed mounting screws into threaded inserts in the baseboard, but I’ll cut these when the spoilboard is finished. In hindsight, it might have been better to do those first, then the rest of the holes - in fact, I’ll amend the design file now for future spoilboards.
I’m beginning to realise that, even taking time to carefully desiging, test, review, test, run, something can still go wrong somewhere during the cut!
As a general rule, attach first, then flatten — particularly since there may be some anomalies in the flatness of the base, the pressure created by the mounting, or the mounting mechanism itself - for which the flattening will compensate. You lose those if you flatten first, then reposition (even slightly) and mount…or squeeze the board with the pressure of the mounting screws
EDIT: Now thinking about this even more: The strap mechanism isn’t really putting any substantial downward pressure on the board…if you flatten it that way, when you screw it into the base later, it will definitely pull the board down more…and your flatness will no longer be accurate.
Sorry, I should have explained I’m going to flatten the board after the holes and tracks had been cut and the board mounted on to the baseboard, but thanks for reminding me 
OK…so what are you accomplishing during the passes with the strap?
I was cutting the slots and holes while it was strapped down, then fit the wasteboard and flatten it.
I acknowledge I probably should have cut the mounting holes and fitted it to the baseboard before the slots and the rest of the holes were cut, though.
No…actually, that makes sense…particularly if you’re using T nuts / track as your fastening system for the clamps. You need to cut out the underside. Makes sense.
When you are making a new spoil board there are some considerations to consider. I recently made a document to build a torsion box and posted it to t he forum. In the instructions I also included the considerations of flattening a spoil board.
To create your spoil board I would screw down your spoil board while machining the bottom of the board. Your clamping method may not hold your new spoil board down flat. If you use screws just make sure they are not where you will be machining.
Please check out the instructions I have in my pdf about spoil board leveling.
torsion_box.pdf (2.0 MB)
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