Brian, did it fail to stick to the MDF? If yes, was it before or after you milled the surface? Lastly, regular MDF or Ultralight?
Certainly YMMV. My experience has been no need to mill the bottom IF it is Ultralight. Also, when I put my spoil board down on the second CNC I recently acquired, I put foil tape on the edges and folded it under so the double stick was grabbing the foil surface rather than the MDF. So far it has held perfectly. Now to hope saying that isn’t a jinx!
That was me (with help). I needed to get a full width sheet cut and that zone has been marked inop for a long time. Knowing that a full spoilboard replacement is imminent, We went ahead and attached it as well as can be done with that tape, then surfaced the top side of the entire bed. That material is LDF. No foil tape was anywhere we could find it.
We’re going to work with @IanLee to procure a full 5x10 sheet of LDF and implement a plan for the entire top of the table.
On a happy note: based on observations during table milling, the spindle appears to be trammed perfectly.
What I’ve been doing for individual zones appears to be working well. Cleaning off goo from double sided tape is the time consuming part that we will not have to do again.
Could we use aluminum, brass or nylon bolts, would make it less time consuming to change out a panel, the heads could be recessed below the surface. If you break a bit by hitting a recessed bolt you probably damaged the spoil board anyway so deserve to replace the bit along with the spoil board and fasteners
Those have been a good choice for my much smaller CNC machine. They stretch just a bit but I’ve not found that to be troublesome.
I like that idea. It would be great for us to get to that point.
In the meantime, this has been working well. It’s cheap. It’s easy to remove. It seems to seal. A firmer variety has done a good job of overcoming any unevenness in the bed. And, it goes on quickly.
I second nylon or aluminum bolts into the phenolic to hold down the spoilboards but it does take some strategy to drill the spoilboards in the right place to mount.