Just vacuum bagged balsa bottom onto first vacuum board, when i took it out of the bag pressure from the vacuum has sucked some of the air out of the eps core and left it with a crushed appearance also my super flat bottom is no more and i have a slight convex? can anyone help…?
That really sucks !
Can you remove the foam and glue on some new foam ?
Dont think it would be possible… just had another look now its out of the bag and its starting to mellow out a bit. I was gonna vacuum a carbon fibre deck on, but at carbon prices beginning to get a bit worried if its gonna happen again…
ouch Sounds like your vac was up too high.
10"Hg is maxing IMHO if it’s 1/2lb foam. Others will disagree on the exact number, but it’s around there.
If you have more foam you can pull the skin off and bag it to the other core.
The archives are loaded with entries of the light foam vacuum distortion problem, don’t know if there are any solutions mentioned. Have you done test runs for the fabric lamination vacuum idea? I did some tests and found it was very easy to suck out too much resin leaving the lamination very starved, that would be a major bummer if you messed up a whole $carbon side by not getting it right.
On 1# EPS, I set the vac switch to go on at 5" Hg… it runs to about 9" and shuts off until it drains back down to 5. There’s about 4" of slop in my system, but its fine. On 2#, the top setting is about 14". HTH
I run the same pressures as Ben. I use to bag at 12-14 for the 1 lb eps, but I’ve gotten better results with the lower pressures. I don’t think that I would bag the 2 lb stuff at higher pressures either.
7" vacuum Or whatever the gage reads (7 psi negative)
any more than 10 and your flirting with disaster (been there done that)
basicly more that 5 , less that 10
you can turn it up till the bag draws down
wanta have some fun… take a finished board (POS) and tap a tube fitting in it and hook up the V pump, turn that sucker up to 25 and give her a little heat gun action and watch it implode.
Hi Ken -
Maybe you or Benny can help me out with this one. A friend’s brand new EPS/Epoxy (not compsand) developed 4 big bubbles - one on each side of the stringer, top and bottom at the nose. The board was left on top of a car with another board on top but the nose was sticking out.
It’s a drag because he paid a lot of money and this board looks like new otherwise.
I’m wondering if I could install a vent with a vacuum fitting in place of the plug and after injecting some epoxy, suck those bubbles down? The board is all new and shiny with a nice paint job so I’d like to minimize any “surgery” required. I’m hoping to just make a couple of tiny injection holes that wouldn’t be too noticeable.
Of course, if I can suck those bubbles down and get the epoxy to stick, I’ll leave the vent, replace the vacuum fitting with an o-ring seal and directions to use it.
Do I stand a chance on making this work?
Thanks!
I’ve done the same thing. Left it in the corner of the shed thinking I stuffed it.
After a couple of weeks I looked at it again and it had flattened out.
EPS breathes with temperature fluctuations and has good memory properties (to a point).
5" hg is enough, get yourself a gauge to measure the vacuum pressure if you haven’t got one.
John,
I’ve been repairing lots of bubbles and delams on epoxies for several shops down here. The problem is that you’ll need to heat the bubble (to get the glass pliable again) and pull a high vacuum at the same time. This combination will probably implode/crush the core, and the heat gun action may create other problems.
My recommendation is to remove the glass around the bubbles to where it still is adhered to the foam (diamond wheel in a dremel), and reglass. On some of my repairs, I removed additional glass to form a symetrical outline and put in some printed fabric. I use a couple of layers of cloth to fit inside the opening, and another piece to go over the whole thing. This method is for boards where weight isn’t an issue, and the delam/bubble damage isn’t wrapping around the rails.
All styro boards need to be vented.
Quote:
All styro boards need to be vented.
I agree. With a vent I can permanently store my boards in my van, get water out of the board in case of a ding, and safely drive over the grapevine. The only minus is they don’t look beautiful, but you quickly get use to them.
John, too bad about those bubbles.
I pulled air & water out of a board recently by tapping a hose barb / 1/4" NPT fitting right into the skin. Just drilled a 7/32 hole, screwed the 1/4" side halfway in, gooped some silicon around the threads, and sent it home.
Next day, shoved on a tube & pulled vac. Make sure you add a trap chamber in case there’s water - a mason jar with 2 holes in the lid for 2 more 1/4"/barb fittings works great - you don’t want moisture going towards your pump.
I used a long tube to move the board far enough away from the pump. Then, its just a matter of going around the board with your ear close to it until you find & mark all the whistles 
I taped them off (there were almost a dozen) with aluminum tape which stands up to vac. You’ll know when you’re done, because all of a sudden your vac system goes way up in pressure. (If you’re getting water, wait for that to stop before taping over the pinholes & dings.)
I’d say to go ahead & try that and then try your injection trick. I agree that you won’t get the glass to lie back down without heating it…and heat guns are dangerous for the underlying EPS. Know any electricians who work with PVC pipe? One of them probably has this little tool that’s like a mini-electric blanket. You can put a piece of PVC pipe in it, roll it up, plug it in, pull it out a minute later and bend it to any curve you want. (It also works great for pre-bending PVC foam rail pieces - hint, hint 
). I bet if you just laid that on the bubbles for a couple seconds they would lay back down while under vac.
Heck, if it doesn’t work, you can still grind 'em off. You haven’t lost anything by trying. And the hole you drilled to let in the vac fitting - that’s where your new vent will go http://www.swaylocks.com/surfshop/Detailed/1986.html
Thanks will try lower vacuum should sort it… Almost compltely flattened out now, just laminated carbon top on seems to have done job…Cheers
John
This is what I would do…
Like Benny said, just drill a hole and tap a barb fitting into the tail of the board where the vent plug will soon be, I used a 1/8" npt fitting.
I know people use holes to inject resin or epoxy but holes dont allow you to spread the stuff around under the bubble and you dont want it to puddle cause then you get the thermal heat happening,sooo,what I would do is in this case would be to slice along the stringer so you can swash some epoxy under the bubbles then lay some thick tape on the slice’s and pull a vacuum, keep the vacuum low under 5 hg
heet up the bubbles with a hair dryer the epoxy wont need much to soften it up as soon as it lays flat turn the vacuum realy low or maybe off and hold the vacuum at below 3 hg’s till it cures
I think the stringer will hide the slice marks
remember too much heat and the foam will melt and cave in
and too much vacuum can cave in other area’s that may be weak
keep us posted
mike sabins method on compsands was to drill the hole from the other side of the board
through to the delam
pour in some resin and give it blast with compressed air
to distribute the resin
then bag it
i guess you have the hole to deal with then
id fill that with GG foam and then cap it with some white foam or whatever