Reaching out for knowledge…
EPS.
Done a lot of repairs and most EPS I have observed in others shaping bays, have been CNC’d.
I’m told no big deal. I doubt…
I am gonna through my hat over the wall.
Questions at this time:
Shaping tips
Spackle?
Epoxies that work well with Poly.
Although I spent a long time running an EPS molding plant, I didn’t
have any shaping experience until the Clark shut down. I learned a
few tricks and I know that guys like Greg Loehr have many more.
Here’s mine. First, I have a whole set of tools specifically for EPS,
from planer to blocks. I have found that you need to reduce the
grit on your sandpaper by a lot with EPS. While I use a 120 grit
hard block on PU, I use a 50-60 grit for EPS. Also, do not block an area
or rail for any extended period of time as it will heat up the bead
and give you problems like collapse, bead shedding, pukas, etc…
I don’t use screen on EPS, but use a whole sheet of sandpaper instead.
I don’t use dragon skin, but don’t use it on anything, so…
I use super-sharp planer blades and slow down my planer with a
reostat. I also use a grit barrel on a second planer for smoothing.
I always blow out my planers from one use to the next so I get less
gumming up from dust. I hope you are asking about bead EPS, XPS is a whole
different animal. Even with a stringer, EPS flex is floppy compared
to PU so use a lot less pressure with all your tools. There’s lots of
good techniques and advice here, so do a search about specifics like
rails, etc. I have used spackle, but prefer epoxy & balloons. Just my 2 c…
Just move slowly with EPS. You’ll get clean slices with the planer when you move slowly. Same for XPS, slower is better. I use spackle, but the stuff I use is now greyish. I don’t do white boards, so it doesn’t matter, heck a lot of the time my blanks are dirty by the time I’m done. I’ve done epoxy sealer coats instead of spackle, but I didn’t like the way you have a hard surface to sand. If you sand through, you will mess up the blank. I guess I’m not very good at doing the sealer coat with epoxy.
I don’t know about epoxy for PU foam, but the boards I’ve done that way seemed soft. I prefer doing PU/PE when I use a poly blank.
I use cheap EPS, so spackle is good to fill the small pockets. Marko blanks are great, they don’t have those small air pockets, and they finish off real nice. When you use the Marko blanks, scuff up the inside of the fin box holes so the resin has good bite
EPS and XPS… when you sand the board with a power sander, move around a lot. Once the foam heats up it expands and you’ll have a sand through. I also use course grit home made sanding blocks. 36 grit up to 50 for shaping and then blocking the laminated boards. 100 grit would be enough for finishing the blank. I use drywall screens, 150 and 220, for the rails. My blocks go up to 120 then I use the 6" rotary sander or a 5" RO with vacuum attachments.
Epoxy seems to sand better if you let it cure longer or if you have a oven curing system. Here in Hawaii my car does a good job for post curing, but I have no idea if that causes twists. Never checked.
You can get a really light board using a 1lb EPS core and thicker shell (more glass or composite skins).
Custom hotwires for most cuts. Specifics surfoam blades. High grit sandpaper. Resin seal. Hot box before sand, sand only full cured resin, sanding Green resin is healthy be carrefull when You have to do it, use an effective vaccum sanding system. For Nice flex use more glass in skins and less to no stringer. Work resin in at least 20°c dry space.
I tried 1lb Eps with spackle.
I did 2 layers of 4oz and it wasn’t enough for heal dents after 2 weeks curing. It also delaminated very easily with light grey paint on the blank.
After getting a lot of heel dents and losing foam near the foot side I reinforced the deck a lot and added a foot pad. This added a lot of weight. The epoxy is still a bit spongy. People say I couldn’t have mixed the epoxy right but I was very paranoid about that, counting to 100 every time. The only thing I might have gone wrong on was when I ran out of epoxy once and topped up the same cup rather than use a new one… With a fee ml left in the cup only
I know 1lb Eps should be possible though. I think the spackle and paint also was a problem. I’m not sure 3x 4oz would have really made much difference… I cut the deck off at 2x4oz and it was very flexible. I guess I’ll have to try some test panels.
The price difference here to better foam is 5x more so it would be nice to figure it out. I also like the easy hotwire. The next one I’d like to put in a stringer… Maybe an epoxy stringer… If it’s in the middle that shouldn’t mess up shaping too much
Solid advance surfteach!
Sorry but I’m thinking you "prehaps suffer " as I do with dyslexicia.
" I have found that you need to REDUCE the
grit on your sandpaper by a lot with EPS. While I use a 120 grit
hard block on PU, I use a 50-60 grit for EPS.
Visa versa yeah?
Love the epoxy µ balloon solution…
Thanks!
lemat, and sharkcountry.
Eh sharky, if I am not mistaken, you one kine recycler, yeah?
Trying to keep this simple.
My reason?
Light…
Fed up with PU "orange foam!
With my glassing schedule of 4oz WARP 2,5/1, the shit does not snap, it just rebonds and buckles.
Right now I am thinking a USB 6-5A EPS Rawson fish thick and good rocker for what i’ll make.
Thinking of this as a challenge.
As greybreads go,
Challenge is all you really have to live for…
1lb EPS with 3 layers of 4oz glass is still not going to be tough. A wood skin or carbon fiber is best with 1lb. I have 1lb eps boards with 3 layers of 6oz glass and they still get pressure dents on the deck. 1/8" balsa with 4oz on each side of the balsa will make it solid. I think the composite wood skin spreads out the impacts. I have balsa skinned PU boards that will not get pressures. You can punch the board with your fist hard enough to break through a PU board, and it won’t be dented.
Matty, I haven’t done PU with a “real” blank for a long time. The last 4 or 5 were very old longboards, stripped and reshaped. They were much heavier than the EPS or XPS boards I’m doing. I don’t have a clue what the newer light weight PU blanks are like. If costs were not an issue, I’d probably try them, but I’m still working with foam I got very cheap.
1lb or lighter EPS with a balsa skin makes very tough and light boards. A perimeter stringer adds more strength. We put a 1/8" thick stringer about an inch in so it’s at least an inch high. Then we add XPS rails because XPS is supposed to be more waterproof. Having the hard glue line, or a wood perimeter stringer in an inch helps making shaping the rails easier.
Crappy foam is crappy foam, why bother. Might as well build hollow boards. Good EPS is ok, almost fun to work with. Still a lot of extra work but can come out sweet if wanting a light light board. Better pu blanks are close in weight but tons less work. Your mileage may vary…
I just shaped a paddle board out of 1.5# eps and pretty much hated every step of the build.
Blank glue up sucked, shaping sucked, glassing was ok until I had to sand it.
Nothing about it said “shape this stuff again”
Yup… Keith is right, crap is crap. But my build costs run about $150. Almost all of that is glassing and fin boxes.
On the bright side, learning how to make a decent board from really crappy foam makes it soooo much easier with good blanks.
Best and simplest way to make good boards is with good PU blanks and PE resin.
For a very light yet durable board, composite skins with light cores seems to work at the cost of way more labor and sometimes way more cost. From what little I’ve seen, the windsurfer/kitesurfer guys using vacuum bags are light years ahead on durable builds.
Like US Blanks? I have three boards built on US Blanks with epoxy resin that are 2-3 years old and going through massive shrinkage. Very disappointed. Maybe you can recommend a ‘quality’ PU blank source? That shrinkage never happens with EPS. And I agree, PU is easier to shape and require less overall work. But I just will not go back to PE resins (even though they were great and easy to use).
In 20 years I have never shaped a PU blank. Really.
I used to use 1 lb foam for experiments and under timberflex builds but the weight savings were not enough to warrant the pain. Good surfboard specific 1.75 to 2.0 lb faom is so much better in the short and long run.
I put up with 1 lb on my carbon SUPs because it can really save some weight on such a big board. It just takes a tender touch when shaping, and extra support until you get some fiber on it.
ONe thing not mentioned previously here is the problem with color. I make it a point to never do vanilla boards, but that is a challenge. I am reduced to doing wood veneers and foam stains. You can spray them before glassing too. But color in epoxy resin is always a compromise. Because epoxy wets out so much easier it also blurs the color separation on acid splashes and makes them muddy. Resin tints will look spotty given the inevitable pocks on the surface. But I am very happy with epoxy overall.
One more note. The new super fused EPS blanks are really nice and really strong/tough. I think perhaps better than comparable PU. So much so that I don’t use stringers on short boards anymore.
teach is correct. I use 60 grit on EPS, where I would use 150-120 on pU. Grits like 120 on EPS don’t remove foam, it just polishes the foam.
Check and thank all!
Willing to step away from USB.
My question is which outfit has the better EPS.
Oh shit did I just do that?
How much do you pay for 1lb Eps vs a decent eps blank? If it was $30 vs 140nzd would you still make the same decision?
Basically, how cheap does it have to go before it’s worth it, even it’s free it’s still a waste due to waste of epoxy and Paulownia right? Backyarder point of view
Matty, I would try a Marko blank first, then whatever else is out there for a comparison. I’ve used Marko from when they first started making the molded blanks and then a few years ago I got a couple newer blanks. They’ve been working hard on their product. I got blanks made by the local EPS foam manufacturer here, and they are very different. I have not used a US Blanks EPS surfboard blank.
If you can make deal with XTR, I’d definitely check them out. They have a good XPS product. I like the XPS for the lower water absorption properties. There’s an epoxy out there that is available in Hawaii for about half the cost of Fiberglass Hawaii’s aluzine. I’m planning to try it the next time I need to get epoxy. I can’t remember the name, but others here have posted it in epoxy threads. The Epoxy XTR used to sell was good, not sure what it costs.
I’m down to enough foam for one more board using foam that cost me $10 or less per board. Then I have blanks the local EPS manufacturer sold for $60 for 10’ 2" and $35 - $40 for smaller boards, I got one 12’ SUP blank for $120. These are rectangular slabs with rockers cut and stringers and either 1lb or 1.5lb. They sold all their stock inventory and now only cut them on order.
If I was building boards for customers, I’d probably use Marko EPS for standard builds. For compsands, I’d stay with the 1lb EPS and wood skins or Carbon Fiber in a vac bag. Just charge them accordingly.
Marko pressure molded. Although USB has a limited catalog of pressure molded too I have not used USB.
Man do I ever agree with Keith. It’s just plain old practibillity. If you like making mountains outta mole hills; Get some construction grade crap foam from Home Depot or Loews and put hours and hours and hours into making a surfboard out of it. Ce Le Fi…