i’ve recorded the production of project ASH and am going to describe how to build such a board.
these boards are light, responsive, strong and ugly altho some progress has been made on the last quality
ASH is my acronym for Asymetrically Supercharged Hybrid
the protoype defied conventional wisdom and placed an asymetric shortside rail to Starboard for exclusive use on a right hand pt break. As a result i created myself a lot of fin tuning problems, posted under the thread
i abandonded this for projects 2 and 3, but by 4 i decided that i had learned a lot, wanted to learn more and became fairly convinced that i could succeed. So i’ve come full circle with asymmetry and utelized boxes from LokBox and also grabbed a handfull of Herb Spitzers Superchargers before he discontinued them
… and i reversed the asymmetry
in my hand are superchargers, sailboard drain plug and plastic wallplug. This is a sandwich board and Meecrafty your chance for a virtual look over my shoulder with beer in hand. When in Rome do as Romans do, so when in Thailand I like Singh
very complex bottom shape, features extreme applications of John Mellor Rail Theory, Dave Verall Rail Theory and my own asymmetry findings - lboard style nose concave, into medium deep double concave into panel V. hard nose chines, into tuck no edge, into edge in tail. thick pt of rail forward on toeside, rearward on heelside, shorter asym tail rail on heel. asymetrically supercharged, skewed fins (more toe in on toe side)
testing this is fun, altho i do have some tuning problems to solve
the J- core consists of XPS DOW wallmate (project No 2 used Owens Corning Foamula 250 ) glued flat on top of HomeDepot grade #1 EPS. Both 2 " thick with an XPS block glued on nose to accomodate rocker.
i could have unloaded my entire bookshelf onto the stack, but much easier to put it in the vac bag.
Wirecutting done with overthick masonite rocker templates - overcomes the problems of close tolerance templates flexing. This requires adjusting template position after one side cut. I cut the hull first then the deck. Held in position with nails pushed into foam.
the problems of shaping a rubbery blank are overcome by strapping a piece of EPP to an ironing board. Wedge middle when shaping hull. Wedge ends of EPP when shaping deck - that way can cradle the rocker or deck foil while supporting the planer.
overthick template idea borrowed from KR’s router machine and Sab’s pic of his reminded me.
idea is to make a close tolerance blank - LeeD is right about 3/16 is lost planing it smooth - but don’t forget to subtract a further 1/4" to accomodate 1/8" top and bottom skins!
my method of sawing railbands would horrify most shapers i think, but works for me.
i draw railbands like an excellent pic posted by Carl Olsen some time ago - if anyone can dig that up would be good.
note this method of stacking flat sheets instead bending them gets us a complementary rocker table
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push wire not pull - this way you can watch tv at the same time to alleviate the boredome of wirecutting - its only exciting for blank 1.
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draw rough outlne of board on XPS and mix up a micro-balloon glue for the glue up. Spread on XPS with squeegee - don’t spread on EPS - sucks too much up.
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no bleeder/peel ply needed for glue up - except a small patch on vac outlet.
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i use nylon tubes and quik lok seals
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about 7 Hg is correct pressure - any more will crush #1 EPS.
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my pump has a hysteresis of 2 HG which means that it drops to 5 before going up to 7 again - avoids too much cycling.
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cool pump with table fan.
my belief: i dont think the strenght of glue up is critical - i use about 3oz of epoxy mix. i believe that there is little sheer load at centre with sandwich shell clamping everything tight - whatever result will be super strong.
thats it for today, i’ll post more tomorrow
MrJ
A couple of q’s
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What is the theory behind using XPS in conjunction with EPS?
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Many people have mentioned bonding problems with XPS; what are your thoughts and experiences?
thanks
Darren
Mr J -
Can you hear that sound? I’m smacking myself in the head with my shoe!
After reading the assymetry issue thread, I thought I might chime in on short side/long side theory… I too am aware of conventional thinking on toe side/heel side outline tweaks. I.E. short side of outline should be heel side.
There are different ways to look at that. It makes more sense to me to determine the predominent direction of breaking wave. Rincon, for instance, might be better served with the long side of outline starboard when looking down at deck of board. Backside or frontside, the wave just might be better ridden that way.
Another aspect to consider is human anatomy. I’ve heard it said (and tend to agree) that you can actually exert more downward force directly through your heels as when surfing backside. Frontside, your feet and toes can flex, effectively reducing some of the pressure and perhaps lessening some of the force you can apply to your turn. In that regard, I suppose that there is an argument to have the longer side of the outline on the heel side where you can really punch it.
Just because somebody did it one way is no reason to accept it as gospel. Once again, I’m amazed at your creative independent approach! With your out of the box fin tweaks and personal test piloting experience, I’d say people should be headed your way for answers rather than telling you that you’re doing it wrong.
PS - Have you considered using your hotwire device for cutting your rail bands?
Welcome back J-man…
What density is that Dow Wallmate?
I’ve been xperimenting with 1.6lb and it doesnt shape smoothly…I actually find 1.0EPS easier to shape…Im slowly making progress on my comp…its got perimeter stringers…the shaped blank weighs 1.25lb!!! Next step is to press the d-cell on the deck…I should easily acheive my goal of <6lb finished…proly closer to 5.5lb.
PS - nice shirt(s)
yes John, i’ve tried wirecutting the rail bands - its a favourite technique with the sailboard builders. Some use just masking tape as guides - i tried that and produced a more wobbly line than the handsaw. however i think the best railbands would be produced with the wire and using thin strips of masonite or flexy laminate as guides. one of the problems is that i got very bored wirecutting the railbands, whereas the handsaw method literally brings a smile to my face.
seven tenths, not really theory behind my combo core, more a line of wobbly reasoning which went something like this:
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100% XPS core would be great - my spyder foam unicore was full of pinholes but absorbed zero water. home depot #1 eps aborbs heaps.
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trouble is result would be too heavy for sandwich construction (wallmate is 1.8 lb/cu ft i think)
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so combine them both for the best or worst of both worlds
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hmmm no 1 worked really well that way so lets not fix what isn’t broken and carry on with the combo core.
i have found that 12 oz of glass over spyder foam (it does have a compression resisiting vertical grain) and there will be no dents or delams.
vacuum sandwich the much weaker wallmate with superstrong corecel and there will be dents or delams either.
all other methods i don’t know about but I reckon what you are doing sounds better Meecrafty, you are already ahead of my shaped weight of 1.9 lb altho my boards are quite big 6’ 9" x 20" x 2 1/2" +, the t-shirts will get an explanation on one of the anti popout threads which can be found littering swaylocks, but some time in the future coz i want to finish this thread first
before i launch into an explanation of vacuum lamming, i’m going to dump much of what i have learned about epoxy here coz i think its important.
Its important coz epoxy is the only reasonable way for me to vacuum. Its also a skin sensetizer.
polyester resin is totally unsuitable for the following reasons:
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The only reasonable way to sandwich is with a light styrene core - polyester resin melts this stuff.
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The way epoxy goes into a sticky phase rather than kicking quickly allows a good bond to be achieved with the skin. So although it will be setting in the pot, its still fairly liquid in the vacuum bag and will work its way into the surface of the sandwich skin. Polyester would run the risk of Gelling and resulting in a very poor bond. Vacuuming is more elaborate and things sometimes go “slightly wrong” causing a delay in achieving full vacuum. The resin setting properties of epoxy help overcome delays immensely.
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polyester just isn’t strong enough to protect a vulnerable porous eps core.
unfortunately i developed an allergy to it
some symptoms and useful advice here
The frightening thing about epoxy allergies is not so much the severity of my symptoms but rather the way i could take all sorts of precautions and protection, get zero epoxy on my skin yet still break out in the rash.
thankfully i’m able to continue using di-amine based Resin Research with not a hint of the rash. I’m unable to get/understand definitive answers on why aliphatic based resins such as SBS-112 is a high sensitizer, although a web search did mention this undesirable property. Anyway my strongest advice is do not use System 3s resin if epoxy building is important to you. Start with a product known to be safer (from historical use) such as Resin Research.
Some interesting background info from student Chemical Engineer and surfer Ryan Shade. - aka LabRat on surfline
I found an excellent link for epoxies also. I’m less
familiar with the engineering specs of this than the
chemistry but if you want me to try to explain
anything let me know.
http://www.psrc.usm.edu/macrog/lab/epoxy.htm
Well, it’s hard to say what makes the amines an
irritant. Amines are basic compounds, and organic
amines have a lone pair of electrons on them and are
what we call nucleophiles, basically they react well
with things that have a positive charge on them. If
you noticed in epichlorohydrin where there was the OH
group next to the chlorine atom, well you see that a
minus charged chlorine falls off in the reaction. The
amine nitrogen hits that carbon with its electron pair
and then has a positive charge on it, while the
chlorine falls off and takes a negative charge. You
start with two neutral molecules so the charge has to
balance at the end. Epoxides are basically the same
thing…for example, if you took epichlorohydrin and
added base (NaOH or draino in the example) the base
pulls the proton (H) off the OH group to make O minus,
which then attacks the adjacenbt carbon and knocks the
Cl off as Cl minus to form the epoxide, which is the
two carbons bridged by the oxygen, also called a 3
membered ring. This is all second year chem stuff, so
don’t feel bad if it’s fuzzy at first. This chem is
the bane of doctors and dentists everywhere.
Unfortunately, it’s how the body works, so they have
to learn it.
As far as which compounds are going to cause which
allergic reaction, it really is hard to say and you’d
likely need to know a lot of things about structure
vs. reactivity, such as amines with more things
attached to them are likely to be stronger bases,
whihc would probably make them more of an irritant,
but I just don’t know what the predominating cause is.
Hope this makes sense,
Ryan
i have however became very neurotic about it and an example of this is where i returned to my apartment and believed i could smell vampire urine (or what i imagine it to be - never had direct experience with it) damn, damn, damn [:/} must be epoxy contamination which i didn’t realise was building up.
and then it occurred to me - i had made a trip north to San Francisco beachbreak ealier that day and purchased Durian fruit in Cupertino asian village. It was purchased frozen and stored in its shell in my freezer but still the smell escapes. Monthong Durian is a weird imported fruit - tastes like heaven on earth to me, but it stinks and most ppl don’t like it.
as a result of this neurosis i have developed a procedure from which i never deviate - not even for the smallest fin procedure. As a result I get NO DETECTABLE RESIN ON MY SKIN at all
here is my resin use system:
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Pumps avoid dribbles of epoxy down the sides of the bottles. Trying to tip without spilling accurate quantities of resin directly from the neck of a 1 gallon container is a challenge that should be avoided. Pumps are too innacurate for measuring tho and careful not to press to hard or air can be sucked causing the cheap ones i use to spit.
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For measuring use electronic scales, mine are accurate to 0.1 of an ounce (what a ridiculous unit of measuring, but i’m in the US). I’d like more accuracy.
BTW when using weight Resin Research 2000 does not mix exactly 2:1, the correct ratio is 100:45, so i tend to use standard quantities produced with the aid of a calculator. eg. 2oz resin :0.9 oz hardener producing 2.9 oz of total mix.
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Polypro suit.
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Tyvek suit over this.
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Smother arms in waterproof moisterizer (vaseline intensive care brand)
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Full face mask with organic cartridges.
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Turbo Fan
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Waxed paper on all surfaces
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Cling film on scales.
10 Ceiling Fan
- Air-con
12 Heating
- Mix ratio Sanity Check
also copes with resin setting anxiety - no more going to bed worrying if its going to set - never had a failed batch yet.
for dealing with additive F i used a 1/4 tspn size cooking measure to fill a disposable dropper from TAP plastics with water to figure out the droppers capacity.
i can then use a dropper to suck some F and add at cc’s per ounce accuracy. i then throw away the dropper. the cooking measure was used only once with water so gets to stay in the kitchen
thats it for today
J sorry to hear about your sensisitation…
I forgot to ask earlier…how are you finishing with color?
Are you painting the outer shell?
Epoxy paint?
oh, no more rash now Meecrafty, with Resin Research epoxy. But regardless i think everyone should take precautions to minimise exposure, although how far we take the measures to avoid is a personal decision, none of us know if we have a predisposition to sensetization.
btw on another conventional building topic what i think is happening with chipfish and wildy on the itch thread when they stop building and break out into dermatitiisL is that they are taking in polyester resin and acetone toxins when building then start detoxing when they stop - the body says ok so i’m not being bombarded anymore i’m going to get rid of all the toxins lodged in my tissues and to hell with any reaction that occurs in the process. This is my theory anyway - there is no way i can believe that regular handling of poly and acetone is good for a builder!
grey rails on my board were done with 3 coats of brushed on LP-U crosslinked paint - i;'ll cover the rest of the colouor procedure later
btw my sanity check consists of taking the total of the resin weight + hardner + weight of mixing pot and writing it under the mix ratio weights. I measure out the mix using my electronic scales, then reset my scales and weigh the whole lot pot and all. If it matches the total (approximately coz mix pots vary a little in wt) then it passes sanity and gets used for the lam. There would be very little chance of 2 mistakes cancelling to produce a passed sanity test - allows me to relax while job cures.
you can see that i have standard mixes - all figures in ounces on my US bought scales - all of which come close to 0.1 of an ounce exactly in the 1:45 ratio - not all figures do this and my scales can’t cope with 0.05 of an ounce etc.
