vac bag skateboard build

cbg · December 2, 2011, 6:17pm

this is somewhat far afield from the vacuum surfboard builds, but the gear is about the same, so maybe there’s some crossover even for folks who don’t care about skateboards.

The form is made from a heavy timber base with layers of concrete backer board and modified thinset used to build the depth and shape the concave. The outside is sealed with heavy enamel paint.

[img_assist|nid=1062953|title=gluing maple veneers|desc=|link=none|align=none|width=640|height=481]
Titebond 3 glue is applied to all facing surfaces with plastic squeegees. TB3 is used for its longer open time, allowing for thorough yet careful glue application. As gluing proceeds, the eight individual 1/16” hard maple veneers are progressively stacked in tight alignment.

Once glue application is finished, alignment/registration is tweaked, and the stack is loosely overwrapped with polyethylene sheeting to contain any squeeze-out.

The wrapped stack is placed upon the form and enclosed by a nylon lay-flat tube type bag with simple rod-in-channel end closures. A vacuum port is placed in the top of the bag along with a plastic mesh which helps to assure even vacuum distribution as the bag starts to pull tight. The vacuum pump is connected to the port.

The vacuum switch is adjusted. With this sort of lam, there’s nothing to crush so we’re going to pull it pretty tight. Adjust for about 21 inches of mercury, flip the switch, and let the air begin to evacuate from the bag.

As the bag pulls tight, adjust alignment as necessary to keep the lams square to the form. Tug down and out around the edges at first to keep the bag from being sucked underneath the stack. Pull wrinkles off the edge, so the extra bag is bunched up only around the outside. In this frame the plastic bleeder mesh on top and coarse felt bleeder on bottom are clearly visible.

Pull hard and long. The pump will cycle maybe once or twice an hour for a minute or two each time. The gauge will correspondingly cycle from about 19” Hg to about 22” Hg. Most of the set is finished in an hour or two, but the wise man leaves it in there for another day or so. By the post-cure point, the vacuum is usually rock-solid and the pump is cycling very infrequently.

Are we there yet?

The blank is removed from the bag and form. Layout lines are drawn across the body/nose and body/tail junctions and connected by a center perpendicular. Templates are placed upon the blank and adjusted fore-and-aft to suit the outline.

Do a bit more layout on the ends to assure alignment of the trucks and drill. This one is a modified drop-deck design which places the trucks out on the nose/tail. This allows for variable wheelbase and rise in order to accomodate differing wheel sizes.

Go barge that shit downtown at lunch. Dig the great lines! The drop deck and concave are very evident in this shot.

Hope you dig this. Now go do something!

-cbg

a2tall · December 2, 2011, 6:54pm

looks awesome man, but vac bagging scares me.

NuclearFishin · December 2, 2011, 9:24pm

You look quite the proud Dad , and you’ve got reason to be.

Nice work - great pics and info.

p.s. I hope you wear protective gear when you skate !

ojw · December 2, 2011, 9:41pm

Very cool!

Do you have a picture of the bottom showing the adjustable mounting holes?

cbg · December 2, 2011, 10:46pm

thanks for the feedback folks.

no need to fear vac bagging. it’s just like anything else-- get your kit together, know your toolset, and have your process down and timed out cold.

i’m actually the overgrown hippie in the construction pics. that’s my buddy who motivated the build holding the finished board. he’s so proud he’s about to pop. as a matter of fact, he’s lucky he didn’t get popped screaming through downtown on that thing during square-businessmen’s lunch rush.

you can see the series of mounting holes in the next to last pic, or at least could in some of the full size uncompressed images. my buddy has split town, but i’ll try to scare up some close-ups or other shots that show the variable truck positioning. he’s probably riding the wheels off of it now trying to failure-test it.

i’m probably getting close to doing another one and considering some more extravagant options. early ideas include epoxy, carbon uni up the middle for some added beam-strength/stiffness, and maybe a cork middle lam to try to attenuate some of the foot-numbing vibrations at speed.

-cbg

MikeDaniel · December 2, 2011, 11:07pm

I like it!

here's one of our vac-lam ''skateboards''.

chrisp · December 3, 2011, 12:28am

Bitchin!

That got the marbles in my head rollin’…

Do you have more pics of building the form?

cbg · December 3, 2011, 2:52am

wow. i’m not worthy.

good to know there’s an infintely steep slope ahead of me though-- pressing on.

<<SMILE>>

-cbg

MikeDaniel · December 3, 2011, 3:50am

Looks like your pressing pretty good, no worries :-))

cbg · December 3, 2011, 12:54pm

unfortunately, i don’t have any pics of the form build-up. it’s pretty straightforward though, so i’ll try to explain.

we get all kinds of stuff trucked in at work and end up with lots of interesting starting materials on the pallet pile. i have two big assembly stages and a workbench made of heavy timber skids which came in with equipment on them. anyway, this one had a heavy cast iron pump bolted to it and was a little over four feet long. double thickness two-by, and i just went out with the tape to confirm this but 14.5" wide. what is that-- 2x16? not your average home despot special? it’s just heavy and awkward enough to make your back hurt when you move it.

speeding up…

the doubled boards were spiked and had construction adhesive holding them together. the spikes were mostly near center and everything was nice and tight and square with no warping. i measured and cut to length, then came in from nose and tail, set my depth, and cut off the nose and tail sections square, one board deep.

i took those end cuts and drew a bunch of right triangles of the appropriate rise and nose/tail angle. the nose and tail are symmetrical. i cut out the triangles and epoxied them together into two wedge shapes using pipe clamps, thence down to the ends of the base forming the angled ends.

this establishes the backbone and profile.

the entire thing was planked full-width with a layer of 1/2" hardy-board (high quality concrete backer board, not that cheap durock shit). a small height drop is allowed in the body flat to accomodate the center rise for concave.

a strip of hardy-backer (thin glass reinforced concrete backerboard for tile countertops and such-- cheap and already has a grid on the face for layout) goes down the middle to build up the ridgeback that will become the concave. construction adhesive and screws hold it down just right, because i love a deep yet flat-floored concave that works with my shoe size.

mix some thinset. it’s not worth buying a bag-- scrounge some. color’s not an issue, and you don’t need much, but grout or mortar will suck. mix it super dry and stiff, maybe even a few chunks left. then modify the shit out of it with future polish or some other cheap acrylic additive. it should now be just fluid enough to move when you push it, but then just sit and not slump or run. i think they call that physical state a bingham plastic.

anyway, fair out your center strip to the edges with trowel or stiff squeegee. if it’s super messy you mixed it too thin, didn’t modify it enough, or maybe you just suck with the trowel/squeegee.

given a couple of days to dry, do about 90 seconds of artful grinding, mostly around the join where the concave goes flat into the nose and tail ramps. use a brick as a sanding block if you need to fair the long lines a touch. if you have to use the grinder on the body section, you suck with the trowel/squeegee.

deep breath…last part.

you fair out the uglys with about five bucks worth of bondo and knock it down again once it dries. if you use more than one lid full of bondo or have to use the grinder again, then you suck with the trowel/squeegee.

smooth everything out, and make it all rough with abrasive-- everything fair but dull, then paint. just use some cheap paint, but if it doesn’t stink, it stinks. no water base latex whatever for me. i used some leftover oil base enamel which flows out nicely even with a chip brush, seals well, and has reasonable resistance to glue adhesion down the road.

finis.

-cbg

Ultimats · December 6, 2011, 9:32am

[quote="$1"]

I like it!

here's one of our vac-lam ''skateboards''.

[/quote]

Mike, is the orange stuff a fabric or printed paper ?

Thanks.

MikeDaniel · December 6, 2011, 1:39pm

It's a fiber, certainly not paper.

brian_cab · December 6, 2011, 4:50pm

Looks great!

Building skateboards by vac bag opens your options up to some pretty unique builds that can carry over to almost every other kind of boardbuilding.

I deliberately jumped into composite skateboards to proof every concept now used on larger projects but at better than 1/6th the cost.

Go make some foam or garbage core boards.

dpicton · December 7, 2011, 10:53am

Thats cool. I almost a month ago bought a simple kit for a rudimentary vac system from roarockit.com, they make and sell kits for maple veneer vac projects with a focus on skateboard decks, also advocating titebond 3 as their preferred glue, but they sell a little hand pump for it, looks like it does the trick with some elbow grease…didn’t get it yet but its on my toy list for one day, might be a good simple intro to the ins and outs of baggin

lawless · December 8, 2011, 3:15am

The nice thing about skateboards vs. surfboards is working with solid wood you can use hydraulic presses for your clamping force.

Check out these skate molds: http://www.snowboardmaterials.com/pages/skateboard%20molds.html

With those you can lay up 4 boards at a time and put it all in a big-ass hydraulic press. Same way snowboards and kiteboards are built.

Some other DIY skateboard press ideas:

http://www.diyskate.com/mold_01.html

http://diyskate.com/press_01.html

HerbSpitzer · December 8, 2011, 3:19am

cool! go my man go !

herb

brian_cab · December 8, 2011, 2:04pm

[quote="$1"]

cool! go my man go !

herb

[/quote]

Go my man. GO!

Bwahahahahahahaha

Nice.

You can solid press foam surf/skim boards much like wood veneer skateboards on a small scale for little cost with very good results. The investment in setup is not for everyone but once you get it dialed in it's pretty slick.

There's a 22" x 96" adjustable rocker cradle press that's able to handle up to 100psi across the entire surface lurking in Virginia Beach that was used with very good results.

HerbSpitzer · December 8, 2011, 5:18pm

for brian and crew,

just a few years behind ............like 9 or 10.

http://www.quivermag.com/node/920 or http://www.quivermag.com/node/boards/hyperedge-racing-boards

herb

cbg · February 26, 2012, 9:54pm

another one out of the archive, but i finally got around to doing another core on the longboard form. this one is maple top, bottom, and center, but it’s got a double corecork sandwich on either side of the (purple dyed) maple centerply. i know it’s a bit afield of normal core/shell theory, but i was thinking about the vibration isolation potential of the cork, and i wanted the idea of “doubly decoupling” the top and bottom, vibrationally speaking, almost like a double sprung floating body.

i know some of that vibrational decoupling will be compromised when it’s bagged over, as i intend to full bag it such that the perimeter seam will be fully encapsulated by glass. i’ve got 9 oz stitched biaxial e-glass and 4" carbon uni tape. it’ll get a blackstripe top and bottom with top and bottom biax-- cut oversize, bagged flat, and trimmed post-cure. i’m going to do a raw cork deck and probably leave the bottom clear on this one. if it looks messy, i’ve got some odd ends of interesting fabric to do a coverup overlay.

I’ve got it cut out and faired up, but no pics of that yet. just waiting now for some extra time and warmer, dryer conditions more amenable to glasswork. updates to follow.

-cbg

cbg · July 2, 2012, 1:44am

-cbg