Multicam spoilboard 2/1/20

I spent a significant time today working on the spoilboard for the multicam. @cghaly and @bbchops filed and cut down the burnt area flat.

I picked up some backer rod 3/8" from Westlake ACE hardware to seal the edges of the spoilboards

Luke and @Kevin helped seal the edges with aluminum tape. I dont recommend we use aluminum tape since heat press siding works and mills better.

I also re-trammed the spindle using the spindle tramming dial indicators in machine shop. I indicated them off the phenolic grid to under 0.003" but it would be better to tram it off the milled spoilboard. Brenton and I will probably work on making an easier more precise way to tram the spindle.


Back when I helped Bert with the inaugural installation and milling of the improved vacuum grid, he had me ironing melamine edging around several boards. Is that what you are referring to?

I think we have an iron in the sewing room that got gunned up beyond usability on fabric. I cleaned off the bulk of the gunk, but I don’t think anybody trusts it for their sewing projects anymore. Would y’all want to add it to the Multicam supply cabinet?

NOTE TO YOU BOZOS who are now thinking “Hey! I forgot there are irons at DMS. I’ll just go get an iron out of the sewing room for my messy-but-requiring-heat project, I pay my dues. It’s mine to use As I please.”

DON’T EVEN THINK ABOUT IT! @yashsedai is my friend, and he will hunt you down on the security tapes, and then I with come to you, very-sharp rotary cutters in hand, and say “MY NAME IS INIGO MONTOYA, THE SEWING SIG LEADER. YOU KILLED OUR IRON. PREPARE TO DIE.”


I completely approve this message! YOU ROCK!


Fabric scissors are great for cutting aluminum tape.


Something we had considered last month was also running a bead of silicone around the outside to try and prevent dust from getting on the double sided tape, since the boards tended to lift as they aged.

Also, might not be best to tram directly on the cut surface, as it won’t be flat locally (the out of tram cutter will leave that sawtooth pattern in it), might want to put something flat down on top of the spoilboard to provide a better reference for tramming. Just some parallels or something similar will probably do the trick.

There’s an iron in the multicam cabinet if I remember correctly

Again I say


You are right, usually I use 123 blocks and tram off that. The tramming is so imprecise on the multicam that it won’t really help until we make screw adjustment jigs. I tram it until you can’t feel a step in overlap with my fingernail.


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.


@themitch22, @cghaly, @bbchops, @jkraemer, @mdredmond , @michaelb, @Kevin, @shoottx


That MDF is a lot lighter I noticed. it’s not that the tape is hard to machine it just tore along the edge when flycut, it does stick better. We can consider using the router table and making slots for T-molding (like arcade cabinets use) that would seal pretty well.

I could mill the phenolic grid a little bigger but I don’t want to risk my cut not lining up perfectly. @bertberaht I’m sure you have the original cut file somewhere and know where you homed it so I can modify your original grid precisely.

I also didn’t mention I hotglued the backer rod into the grid so it wouldn’t roll and pull up when moving the boards. I do like this instead of doublesided tape because it makes it easy for us to replace spoilboard.

It would be nice if someone messes up a spoilboard and they fix it, we train people how to mill the spoilboard flat again, it sucks having all the spoilboards unlevel when someone wants to mill a 4x8 sheet.

What about going up to say an inch thick. More weight, dimensional stability, can be resurfaced several times and less replacing overall

If you can find it. Not many places carry Ultralite MDF and I don’t know of a local supplier who has more than 18mm, but that doesn’t mean there isn’t one out there.

The last batch of spoilboard had its edges sealed with watered-down glue. Is that an effective alternative to tape or edge-banding?

But it seems sort of moot as long as we don’t have paper to block off the table…

In theory on regular MDF, yes. In practice on ultralight, it depends. Either way you need to seal the section of the bottom of the spoilboard that is not captured by either the double-sided tape or now the backer rod that’s being used. That exposed bottom section is actually more area than the edge. Both are really important given how marginal the vacuum blower capacity is.

The 30 inch wide plastic coated freezer paper came from Uline.

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Mitch, I didn’t initially pick up on the fact that you are not using any tape for the spoilboards. Being loose and easy to replace is a benefit of no tape … but somebody better start watching the inlet filter for the blower like a hawk. Loose zone boards means moving zone boards which means easier movement of dust under the boards and off it goes to the blower filter.

It was amazing how much dust got there even with the tape and with the boards still freshly secured with tape. The filter can be blown out and reused repeatedly as long as you do it often enough. Once it really gets loaded up, harder to do. May need to add keeping a spare on hand as a precaution.

You could also consider adding a differential pressure gauge so resistance can be easily observed.

@shoottx, @mdredmond, @cghaly

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Regularly blowing out both filters and vacuuming the canister!


Would plastic nails be of any benefit?

It could be but good luck keeping consumables and the nail gun at DMS for general use.

Sadly that does seem to be the norm…