Backroom balsa compsand

I just finished my second compsand, just rode it yesterday, and thought I would detail it’s genesis for the record. Disclaimer-if you try any of this sh!t, don’t blame me if it doesn’t work. I don’t know what I am doing.

So anyhoo, I am presently working with an 8x12 room with closet, and a back deck roughly 10 x 12 or so, and a landlord who lives downstairs with his family. Basically, I would be able to use this setup in a well appointed prison cell (although smuggling some of the items in the usual way just woldn’t work). The space constraints have led me to create a fairly compact system, and I thought some pics and a description might be helpful…

My first compsand was made with a rocker bed that slid into a vacuum bag. the room I have now is too small to back the board up and load it into the bag, and I didn’t want to deal with trying to wrestle some rolled up arangement over my board as the resin hardened, so I came up with the idea of using a box with a vac-bag lid that sealed around the edges, basically a veneer press. Or coffin.

The bag material is 20 mil vinyl, the yellow stuff is vac sealant tape (sticky-tack on crack) and the top of the coffin is coated with 100% silicone caulk–nothing sticks to it. The vinyl is wrapped up and over the wooden frame of the lid, so that when the vac is applied, it pulls itself down harder, helping the seal. Also, I left enough slack in the bag so that it could be used without the rocker bed, for flat laminates (pre-formed skins) and such…A major advantage is that work can be done right on the surface, then pumped down with less chance of shifting layers. For test runs I used a wet-out table and some cardboard tubes cut to just fit the bed, and I would wet out the cloth and roll it onto the work all wet out, but I found it’s easier to simply wet it out in the bed. (more detail on that later…)

Problems include the fact that the yellow tape squeezes out a little each time I seal the lid. I had thought that a wide enough strip would just stop, but it keeps going. So every few pumpdowns, I have to pull it off the edges toward the middle, to reset it.

The box itself is made with two 2x4’s laid on edge for the sides, and a base of 3/4" plywood, very sturdy. The inside working area is 7ft. by 22", designed for anything up to 6’10" and 20" wide. The board I want to focus on is more like 6’3" x 19". Vacuum inlet is simply a hole drilled through one end-wall with a barb fitting screwed in and sealed with yellow goo. The box itself is sealed using an old vinyl bag glued up on the sides to just under the lid, on the outside of the box. This arrangement is quite airtight, and “takes in” very slowly, not much faster than just my pump and reservoir. It falls from 28" to 24" in about three to five minutes.


After I had built the table , the box, and a prototype lid, I reasoned that this system would benefit from a more robust pump than my old fridge compressor, so I bit the bullet on a pump from fiberglass supply (, reasoning that it would give me faster pumpdowns and seal more quickly. in retrospect, maybe overkill, but better than underkill, huh? (more later…)

So my pump comes, and it’s frikken loud, and farts oily smoke out of it’s rear end. Fine. Build an enclosure and venting system. Oh, and it gets hot. fine. include blower in enclosure design.

there it is, sitting insie an old army footlocker (check the east coast stickers, most of those are from when I was a grom, some twenty years ago (!!)) the foam is acoustical dampening foam, great stuff. I used the excess on a set of shaping stands. vac inlet tube exits one side, cord and exhaust the other. on the side, I have a blower that points in, slightly pressurizing the box, ensuring the oily exhaust moves out the hose I have that runs to the window, and helps cool the pump.

Unfortunately, I couldn’t get a seal for a while during one of my runs, and the pump malfunctioned, so I had to drag out my old fridge pump (talk about a frantic, cursing frenzy, changing pump oil, looking for a fuse, trying anything to resussitate, then switching over to ol’ sucker, all while my project is slowly hardening…AAAAGH!) which worked fine. whew.

Anyway, still to be added are a vac switch and relay (my old switch was busted, and that size pump needs a relay, it will fry the switch by itself) and I just put that together last night.


ive got a vacuum controller on my setup

it only runs for 5 seconds every 5 to 10 minutes

noise isnt to much problem when it runs intermittently

thats an interesting setup there Wells

have you though about gluing a melamine or plastic sheet to the rockerbed

then you only need to tape a sheet of plastic over the top of the board onto the melamine

far less complicated

and no leaks

The rocker bed…

I had an old rocker bed from my previous fit of shaping. it was made out of dow blueboard (the “real” styrofoam) left over from a previous board made out of same (I’ll have to do a short writeup on that one too…Mr. craftee has already enquired, and the fact that he remembers that old thing or me for that matter blows my mind…grin) and it wasn’t wide enough. In a rush to try my new system, I tried filling the sides in with spray foam, but the vac crushed it, breaking a piece of toughened 1/4" hardboard (and a full scale test piece that wasn’t a test piece until just then) down one side, sounded like a rifle going off, crack crack.

See, I knew I was going to have to make a bed anyway, but I was chomping at the bit…

So I had to fashion a hot wire cutter. I got a cheapie battery charger from the local hardware store, and some sizes of stainless steel wire. I messed around with settings, until a 24" piece of 19 AWG wire worked with the 2.5 amp setting. the 10A setting was faster, but left melty gobs of foam behind.

I got a few 4"x2’x8’ pieces of the foam, cut one of them to fit the coffin, epoxied it to a piece of hardboard, epoxied extra blocks for the nose and tail (making sure not to epoxy where the wire would pass through) screwed on a pair of templates I had made to the sides, and cut out the bed with the cutter.

The cut went very smoothly, I did warble in a few spots, but fixed them with lightweight spackle. Next time I will make reverse templates, so that I cannot cut into the bed. It’s alot easier to sand down ridges than to fill dips. I then flattened the surface with a sanding block, and shaped the corners round to better fit the bag.

This rocker is the result of taking a few rockers from some shortboards, taking out about 1" from the tail and 1/2" from the nose, kind of a standard relaxed shortboard rocker with a very flat tail. (hopefully a little tail flex will fix that nicely?) I drew the lines on a piece of masonite, attached another, then cut and shaped them both to a smooth curve thast best fit my rocker survey, withg what looked like a smooth curve. As I smoothed it with a sanding block, I tried to let the block do the curve, walking smooth cuts from end to end. seems to have worked, my roomate had a demo firewire in here the other day, and I dropped it into the bed sans fins. to my surprise, it fit really well. maybe just a hair more tail rocker. I extended the curve out past the nose and tail, so that I could adjust the position of the board and do some shimming, and obtain a wide variety of rockers. The blue foam works well, it won’t crush or even sag under vac, and can take moderate temp. increases.

here’s the bed, an offcut, the twin templates, and my hotwire setup. The bow is joined with bolts and wingnuts, and is tensioned from the side opposite the cutting wire.

here’s a photo of the wire attachment. the wire itself wraps around two screws, and the juice is introduced right next to where the cutting starts-this keeps the attach points from getting hot.

here’s how I attach to the battery charger-the bent plugs make it impossible for some parboiled moron to plug it straight into the wall (me). a rubber band holds everything together.


An oven…

After the coffin came together, it occurred to me that I could make a top that would function as an oven. I got some light fixtures, some foam insulation with foil surfaces, and a couple of hairdryers, and cobbled this thing up. it was after it went in that my friends started to look at me funny, and avoid the house.

disclaimer-a setup like this is dangerous. I never run it unless I’m right there, All other times the power is disconnected, and my smoke alarm works. the room is vented with a fan that creates an airflow out of the building, as heating almost anything creates fumes. the oven is powered by lightbulbs only-the hairdryers are for fans only, and have their heat coils disabled. 4 100 watt lightbulbs can do 185F (85C) no problem with this setup. please use caution and do research before building and operating an oven like this.

so the basic sequence goes:

1 prepare work (backing, layup, bleeder, etc.)

2 drop and clamp lid, turn on pump

3 supervise pumpdown, straightening, etc.

4 lower oven and apply heat

other permutations are possible, such as getting the stack hot before pumping it down, so that for example still curing laminates could be softened and molded to shape more easily…


Wow - I have a garage, you have a laboratory.

Have you considered ‘pre-curing’ your wired blanks to try & exotherm the trapped gas that XPS supposedly has, before sealing them up with the gas inside?

Do you vent your boards?

Alright, I promised myself that I would do 1 hour of taxes for every hour spent doing this. As it is, I’m booked till midnight, hehe. Tomorrow, I’ll post a rundown of how the first board went together.

6’1" x 19" x 1 7/8"

cant wait

Hi benny,

Actually, I’m just using the blue stuff for making the rocker beds. hopefully, I’ll only need to make a couple to cover the range of shortboards…I’ve made one board with the blue stuff, and in spite of some efforts otherwise, had trouble with delamming and gassing. I’m so enamored with this balsa stuff, I have little interest in going blue again…

the one I’ve finished was made with 1 lb. white insulfoam EPS, 1" thick, courtesy of my local home depot. I stack two layers to get 2" thickness. Also, 1/8" balsa for the skins and 3 x 1/4" to wrap the rails. I’m gonna cover it in detail in more posts tomorrow…

as for the room, hehe, yeah it is kind of a freak show in there, especially now that everything’s all out of place after finishing the board…Necessity of fitting the space has made some interesting possibilities arise, now that I have it all more or less built. Particularly with regards to repeatability, and using heat.


WOW… and the pic at the end is such a cliffhanger.

just one more question(sorry im a pain)

did the blue foam board have a sandwich skin on it

or just glass?

oh, dont be silly…you’r not a pain…

nah the blue board is just glass and epoxy. it was my third board…no stringer, really thick, with rail channels, and LOTS of glass. I can’t remember how much was on the deck but I think it might have been as much as 4x4oz, with some patches. Also, I scored the foam with xacto blades and squeegeed in epoxy before I glassed. It still delammed under my back foot, so I cut open the deck and squirted in some expanding canned foam, then sealed it back up, kind of a freak show. it lasted for a couple of years, then I creased it it in some decent size, and haven’t ridden it since…I’ll snap some fotos of it tomorrow…

ah, sheesh, no drama intended with the cliffhanger, just ran out of time…

A couple Q’s

  1. What’s your height and weight?

  2. What is your level of surfing ability?

  3. Is your deck concave? flat? domed? I can’t really tell from the picture.

Thanks, Fosta

the compsand you built looks great man

sic as

im a big fan of round noses like that

would like it as standard personally

much safer and prettier as well

wrt to blueboard

2 years isnt to bad though

a lot of my experiments look pretty freaky by now

cool thing with compsands they can look like shit

but still go like a new one

Very impressed…

very out of the box thinking… or uhmm… in the box thinking???

Great setup and very nice compsand board! You seem to have put a lot of thinking in all that.

wells … how are ya ,man … nice stuff …

didnt you move to thailand (i could be wrong there )for a while ??

i had a set up that looked almost identical to that once …

watch the dust with that yellow stuff and watch resin getting on it to …

with your set up and the volume , it will work , but for an industrial setting , 2 weeks and your replacing seals or the yellow sealer , and its not cheap … or you get some glass fibres fall across the sealer and start acting like a straw after you pull vacy and create leaks …

good to see you around again …

you always had some real techy stuff going on and great feedback on techniques and results …

your like the model swaylocker …

look forward to your stuff and nice work so far …




you should be proud of yourself when you look at the retail cost of buying a pre-fab version of what you just built for a pittance of the cost of these…

Like Paul said…

if you can get a copy of the “Vacuum Bag Board building with Tom Sullivan” video from Victoria Video Productions, you see that with a melamine or acrylic surfaced adjustable rocker table you can do the same thing for an infinite variety of rockers. If you make the bed removable then you can use other types of beds (pegboards/ or simple bars) to clamp all your rails to the boards on at the same time or use it for building out hollws as well. DanB showed an excellent example of a portable version you can attach to a tabletop awhile back. If the table is portable instead of a workbench like Dan used that would be even better. A combination of aportable shaping table Paul Jensen showed us way back, DanB’s rocker table jig and Bud’s shaping/glassing rack jig would be the perfect combination for a short of space environment…

Again Congrats…



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…that’s what I get for not paying attention…Just read up on the adjustable rocker table, sheesh, wish I had seen that one when it happened…I dunno, had just been a little intimidated by getting one to be completely accurate and solid, given my limited construction capacity…That would be awesome, though…as soon as I get a garage. ok, how about this, make it out of clear hi-temp plastic, and get a couple banks of big infrared lamps, one the top and one under, and flash-cook that sucker…20 minute flip times! you could use hi-temp prepregs…just kidding. in case you haven’t noticed, I have a penchant for the esoteric, even if it’s done in a lo-tek way. totally useless stabs in the dark, but fun nonetheless.

Thanks to everyone! and cut it out. I’m going all red.I Thought at best people would think the whole thing kind of amusing…grin

fostachild said

"1) What’s your height and weight?

  1. What is your level of surfing ability?

  2. Is your deck concave? flat? domed? I can’t really tell from the picture. "

  3. I’m 6’0", 195 lb’s (88kg) shoe size US11. (11 inches) with an enormous big toe that has dented every board I own.

  4. Uh, I guess experienced? well rounded? I started when I was 11, i’m 35 now. grew up surfing east coast US (teaches you how to travel), then made my way to san francisco 6 yrs ago. I like it when it gets some size, and my favorite aspect of the experience (other than getting tubed) is g-force in a turn. I like hard turns. Grew up watching Tom carrol, sunny garcia, alan sarlo, occy, and the big hawaiians et. al. put it on a rail, and it stuck. so I carve a lot. don’t really go for big moves, just like to link up turns and get speed. besides, bigger guys like me have no place trying flicky little airs and stuff. It just looks wrong. besides, I broke my ankle a couple of years ago trying to land some floater-out-too-far thing on a chest high wave, so for now, I’m gonna keep it in the water. I like where I live (SF) because while rarely perfect, it can be quite raw and adventuresome–alot of time is spent here trying to outrun waves and reacting to unpredictability rather than repitition on a perfect machine… that speed is intoxicating…

  5. concave deck. a bit more than I intended, actually, I’ll elaborate in a bit…


“im a big fan of round noses like that”

Yeah, me too. just makes more sense. Actually even my storebought boards end up with that nose, there are a couple kinda rocky breaks around here, and, well, you can only be so careful…My friends call it “the euro-nose”. To tell you the truth, I’d much rather get hit in the bean with one of these…sure you could use a noseguard on a pointy thing, but you just added a couple ounces you don’t need to a couple inches you dont need. Also i’d like to see someone be able to tell the difference.

Bert said

“didnt you move to thailand (i could be wrong there )for a while ??”

no, but one of the other composite guys did, cause I remember that too, was it MrJ?


"i had a set up that looked almost identical to that once …

watch the dust with that yellow stuff and watch resin getting on it to …

with your set up and the volume , it will work , but for an industrial setting , 2 weeks and your replacing seals or the yellow sealer , and its not cheap … or you get some glass fibres fall across the sealer and start acting like a straw after you pull vacy and create leaks … "

Chuckle yeah, all of the above. Dust, glass fibers, bits of rubber glove and hair and breather felt…and I’ve had to reset it once, by pulling off the edge and folding over the middle, took about 15 minutes, pain in the butt. I’m still on my original application, though, two six-dollar rolls for about twelve pumpdowns so far…wouldn’t you have to use almost a whole roll every time on an adjustable rocker table? or could you reuse it? one of the most important features to me of my setup (ideally) is to minimize consumables. generally, for a whole board, all i use and throw out right away is about 3 21" x 7ft. pieces of breather. the cover sheets and homebrew peel-perf are all polyethlyne sheeting, and can usually go round a few times. but your right, I think as it is, the top will end up being a maintenance nightmare.

Thanks again, and let me reiterate that there’s no way any of this could be done without all of the helpful info on this site that you guys have taken the time to share over the years…

OK, I’ll post this, and start a description of the board and how it all came down…