I have found various links on creating supplementary wasteboard/spoilboard but they don’t really show how it is attached to the Shapeoko itself. Some assume an existing aluminum table, but I only have a piece of MDF.
I thought about maybe:
But would that then let me attach?
The video specifically mentions the aluminum table and I’m not sure the holes from the first link would be in the same spots.
I agree with the above advise but would add that you must countersink the screws low enough so you never hit them when flattening the spoil board. An alternative would be to drill completely through the stock spoil board and use 1/4-20 Nylon Flat Head screw and a washer and nut on the bottom. With the nylon screw it would not hurt your bit if you hit it. Ace Hardware has the nylon screws and maybe at Lowes and/or Home Depot.
(I added a fifth screw in the center to prevent any possible bending)
This works perfectly for my workholding preference, which is 99.9% tape & glue, .
As @WillAdams mentions HDPE is slippery, but that is irrelevant when using tape&glue.
Benefits I have found:
it surfaces like butter
no tearout at all when removing the tape (which was a problem on the long run with MDF, even with a protection coat)
it does not absorb humidity, therefore no impact from changes in the ambient humidity level depending on the season
no need to deal with messy & unhealthy MDF dust (I have developed a hatred for MDF over time)
Now to be honest, this only works very well for me because I am careful to always set my cut depths such that I barely scratch the surface during profile cuts, so the wasteboard sees very little damage and I can use it for 6 months before I needed to resurface it. If you need (or like) to overcut into the wasteboard and replace it regularly, then I would advise to stick with MDF, because a large piece of HDPE is somewhat pricy, AND you will get fuzzies on the edges of the overcuts, which eventually will prevent you from laying the stock flat onto the wasteboard.
I used 5/16" T-nuts installed into the base of the Stock-boards to attach. I recommend Epoxying these T-nuts when used in this configuration as they will have a tendency to want to “pull up” when installed from the top-side. If i had all the time in the world; I would have flipped the stock waste boards and installed my T-nuts from underneath the and drill through holes.
I’ve also used threaded Inserts in a similar fashion, but didn’t like how drilling and tapping the holes causes the MDF to deform and need sanding to flatten.
My biggest reason for wanting to usevsomething other then MDF is I’m in the south and during summer humidity is just terrible. Mdf changes so much with humility is why I’m thinking changing and was thinking of using threaded inserts.