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View Full Version : Continuation of previous spoil board problem



meatbal80
08-26-2010, 09:54 AM
I had previously had a problem getting my spoilboards to stay flat. I went a head and siliconed the perimeter of each onto my plenum, and it worked great. I have since seen a problem with slight cupping in the spoilboard. I attributed this to the fact that i only glued the perimeter and nothing in the middle. And here is where the problem starts.

I went to put on a new set of spoilboards. When i pulled up the old ones it grabbed my plenum and took it with it (see pictures). To answer the question in my previous thread in this catagorie silicone will hold very well in my case a little to well. I now have to figure out how to install my new spoilboards. The section that was ripped off with the old spoilboard varries in depth from 1/64th to 1/8 and maybe a little more. Here are the solutions i have come up with so far, with problems for each.


Fill void with silicone and dabs on every 4th tower then set pannels in cover with plastic and turn on vacs. I worry that the vacs will just suck the silicone out of the void and into my plenum.
just silicone the edge around by the aluminum channels and on towers. With no support around the edges the board may become squishy, or could cause an initial bow.
Repair damaged plenum, probably with bondo then install spoilboards like before with dabs on towers. Pain in the but to do all that bondo work and also not sure how flat it would be or how to flatten it to match the height of the towers(channel would get in the way).
Between initial calibration and general use with the occasional oopsy i wanted to switch out the spoilboards now while i had a slow couple of days. I want to rebuild the plenum but dont really have the time or desire to do that now. At the same time i dont like the idea of having to worry about my spoil board causing problems with upcoming jobs.

kra
08-26-2010, 10:14 AM
do you have enough depth in the plenum to just resurface it to get rid of bad spots?
looks like this would be the easiest fix

meatbal80
08-26-2010, 10:19 AM
Thats not a bad idea, but then i would have to re-seal the plenum. When made the plenum i had a buddy come over and spray laquer over the whole thing taking up alot of time and then i let it sit for several days (which i dont have right now) to let the finish cure.

kra
08-26-2010, 10:55 AM
you might not need to reseal it since you are just removing material from the top
the inside of the plenum will still be sealed and gluing it down around perimeter should effectively seal the top surface from the outer edge
any small amount of draw through within the plenum will just pull through the spoil board anyway

meatbal80
08-26-2010, 11:00 AM
I think that i will loose a fair amount of vac out the sides and blead through to other zones (not a big problem when i am using all zones at once). i would also need to cut everything at down by a 1/4 or so and i dont think that the finish penetrated that deep.

bleeth
08-26-2010, 12:11 PM
Shellac will seal just as well and you can brush it on. I use a couple coats. Dries quick.

ken_rychlik
08-26-2010, 12:42 PM
I cut the top off of mine on purpose. Then I use yellow glue everywhere it touches the spoil board. Put it in place and throw a sheet of plastic over the top. Turn on the Vacs to hold it till the glue dries and it's good to go.

When the top was fully painted, I never got a sheet to stay on with glue.

Kenneth

Gary Campbell
08-26-2010, 05:30 PM
I agree with Kenneth...
Surface the plenum after sealing to:

1) make sure that it is flat

2) make sure that wood glue can adhere.

ken_rychlik
08-26-2010, 06:57 PM
Gary, You ain't ever supposed to agree with me.

You've been sniffing to much sawdust. :D

Kenneth (the wrong one)

meatbal80
08-26-2010, 09:50 PM
Well since i have not heard any ways to fix the current plenum i have decided to replace the entire thing. I am currently debating using a different material for my next plenum any suggestions?

BTW how does everybody else remove their old spoil boards from the plenum?

ken_rychlik
08-26-2010, 10:16 PM
With a fly cutter for me.

Kenneth

bleeth
08-26-2010, 10:20 PM
bout an 1/8" at a time with my surfacing bit. By then it usually only takes a couple of passes. A lot of dust!

Standard MDF, sealed has always worked for me. The base sheet under it has lam liner on it so I don't have to worry about it bleeding air. Just scuffed up the liner and put the plenum down on it with contact cement. Surfaced plenum, sealed with shellac, scuffed the top, and after skinning and flipping spoilboard used Titebond. On the other hand, the one I have now is only the second one in 5 years. Others may have tried different combinations more.