Thoughts and observations about the DMS spoilboard …
Looks like good work by all
I originally tried several variations of iron-on edge banding … both melamine and real wood. No matter how hard I tried to heat and press the pre-glued strips down, they would start turning loose from the edges and then chip off badly when the table was surfaced. I even tried pre-gluing the edges and then applying edge banding. I know commercial shops do this successfully. Two things they may have in the their favor that are absent at DMS: 1. many if not all have commercial quality edge banding equipment that gets hotter more evenly and some even have pressure rollers to boot. 2. Many (most?) commercial shops have more vacuum force and can use regular MDF for their spoilboard.
Item 1 is self explanatory. Item 2 results because the vacuum blower size for the DMS 5x10 table is only adequate, and has little extra capacity to overwhelm leakage. The Ultralight MDF is softer & more porous to reduce resistance to the air flow. Unfortunately, those same traits make it harder to get glue to stick and stay stuck.
After numerous trial and error episodes, I discovered the adhesive on HVAC foil tape was the best thing I could find. In addition it has the added benefit of being wide enough to lap under the sheet about 1". That area under the sheet represents about 138 square inches per zone that is blocked from leakage. In addition, it provides a better surface for the double stick tape to grab on the bottom of the spoilboard sections. Mitch mentions it being difficult to machine, but I did not experience that. That said Mitch has seen a lot of shop installations and has experience I do not. My recommendation is to keep testing with a eye toward the best leakage prevention you can get.
The backer rod is an interesting thing to try. If it works out, you might consider milling a channel for it closer to the zone edges. Any uncovered spoilboard bottom that is outside the “contained” area is a leakage point. Just as the 1" band mentioned above adds up to be significant area, there is probably another 1-2 sqft between the backer rod sealing point and the edge of the spoilboard.
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