OK - spent hours reading the Clark blank situation. have to see for myself (learned the hard way , form my own opinion from my own real experience) regarding eps foam, SO here I go. I.m thinking I’ll get a block of #2.5 eps, make 3 stringers out of 3/16" basswood, get my 8’ long , 1/4"x 1/4" plastic rod and cut out the rocker and foil on the basswood and glue one piece down the middle of the eps block (after I cut it in half) and one piece o f wood on eachside of the eps . Using the wood as guides I remove excess eps and I’m left with eps “blank” that has my rocker and foil. then I remove side wood pieces, cut out template, and then foil rails. I’m sure I need to be “corrected”- go for it - for me this forum is really where the “little guys” trade advice/support, with occasional support from some of the big guys. SO l’m suggesting we now get to work and share/support an updated approach to doing an , uncomplicated by veneer , simple how to for a first eps board.- I know I’m ready - I just used my last 2 pu blanks and I am not gonna sit on my ass. I know there is stuff in the archives but for me it is too scattered. I don’t mean to be nasty but if you can’t/won’t help/contribute - and you feel the need to be sarcastic - go someplace else - I need to get back to work.–To all the craftsmen out there who may be seriously hurt by this clark thing- my sincere wish things work out for you all.
M10 has started doing at least some of their eps boards with pvc stringers instead of wood. Geoff said it helped the board keep its ‘snap’ longer. Harder to shape pvc, I would imagine.
That’s how I did my first 2 EPS blanks, although without even the side pieces. I did them with a grinder with a grit pad and they came out ok. This was before any block sanding/screening:
Next thing was to try pre-shaping the stringer (a little oversize) and built a hotwire bow. That was ok, but balancing the bow only in the middle was tough. I got a domed deck & a belly bottom, after cleaning up all the wire dips.
Third, I preshaped 2 stringers & hotwired one 12" wide piece of foam at a time. That works great. You don’t need to glue on the stringers, just drill holes at the ends & 1 in the middle and push 16-penny nails through the holes into the EPS. It holds on fine. You glue in one of the stringers after you’ve cut both sides and save the other one as your template for next time. Also, a 15" wire is a lot easier to manage than a 27" one…
Hope that helps.
I’ve also split the blank to 4 6" pieces & cut it out on the bandsaw. There’s a little more dust, but its a lot faster that way 
M10 has started doing at least some of their eps boards with pvc stringers instead of wood. Geoff said it helped the board keep its ‘snap’ longer. Harder to shape pvc, I would imagine.
“PVC” in this application means divinycell or corecell, not PVC like pipe. It shapes a heck of a lot easier than wood.
Makes good stringers for floppy 1# EPS too…
Here’s 3 - 1/2"'ers gluing into a longboard blank.
yes-yes-- keep it up please (I sound like my wife!)
yes-yes-- keep it up please (I sound like my wife!)
if i were you, i wouldn’t divulge that information so freely
All right…but as soon as I finish, I don’t really care if you’re done or not
Here’s the cut from the hotwire with center stringer only. I like making my stringers & rocker cut templates at least 1/4" thicker than I want final. That way I can still ‘skin’ the blank with my planer to smooth it, and add countours if I want them. It also adds insurance space in case the wire gets funky.
Here’s the bandsaw method. The nice thing about this is I don’t have to make any rocker sticks. Just lay all 4 6" wide pieces on edge. Measure out every foot of length, then measure the thickness I want at that spot. Push in little nails, lay a broken bandsaw blade along them, and connect the dots. This board won’t get any stringers - except the 3 glue lines - because its getting a balsa skin. I also don’t really need to worry about cutting in rocker. Whether gluing to a stringer or bagging on a skin, the rocker can all be put in later. So this is all about thickness.
ok- this is good - got my wheels turning - I see ir’s recommended to seal the blank. Seems like the spackle approach, before trying it, would be tough . How about spraying the eps blank with acrylic sealer ?
Great pictures Benny. It’s cool to see evolution happen. I prefer to cut the whole width of the blank though you’re right that it would be easier to cut a 12" wide piece. I use MDF to make templates and put masking tape on the edges. Here’s a picture of a few of my templates. I use screws to hold them on to the sides of the block.
I think it helps to have a hot wire cutter that’s easy to handle. I know a lot of people put springs in theirs but I think a bow under tension is easier to handle. I used to get my wife to help me cut blanks until she got tired of me complaining about gouges on her side. Now I just cut em myself - it’s not that hard.
Here’s a picture of my bow cutter. Pretty simple. The arms are fiberglass rods just cause I had some laying around. 5 ml steel square stock works really good too.
Find a board you like, lay a long straight piece of wood along the bottom (touching at midpoint) and take some measurements from the wood to the bottom of the board for your rocker specs. Shortboards typically run around 5" and 2" at nose and tail. Take some other intermediate measurements too - maybe every foot. Make marks corresponding to your rocker measurements on a piece of masonite or luan door skin using one of the edges as baseline. Connect the dots with a flex batten, freehand it or use a “rocker stick.” Using calipers, take some thickness measurements of the board and measure and mark those using your rocker line as your baseline. Cut a bit outside the lines with a box cutter or jigsaw. Spend some time getting fair curves with a hand plane and sanding block - this is your profile pattern and time spent here will pay off later. When the profile pattern is to your liking, make an exact copy. The second one will be easier. Follow Benny’s lead on attaching patterns, hotwire cutting and inserting stringer. If you have fine tuned your patterns and used the hotwire correctly, very little profile shaping will be needed. Hopefully you’ll end up with something like one of these…
Patrick - many ways to skin a cat again. I spackled once but I think I used junk stuff & it discolored.
I’ve sealed with epoxy & cabosil. Takes very little time & material. You can also then lay on your cloth a couple hours later while its still tacky and it doesn’t move around as you cut it & wet it out. Jim Phillips uses epoxy & microballoons, but my microballoon bog is gray.
I’ve done 'em without sealing. On 1#, this is a very good way to make a mushy, heavy, expensive board. Jim P says on 2#, this is the strongest, but also a little heavier & more expensive.
When I bag on skins, I don’t seal anything. I wet out the inner glass on a wet out table or folded up in a square and then pull it out over the blank. No direct resin application to foam, so no soaking in. Then the balsa or d-cell (so far) goes on, and into the bag. Even that small layer of relatively dry resin is plenty to form a very strong bond between the skin & the EPS in the vac bag. I’ve done break tests with offcut pieces.
I also sprayed one board with white Krylon h2o (masked off the stringer) because I was doing a pattern on the deck & a tint on the bottom. The spray on the deck was great, the tint on the bottom still shows some pukas because spray paint doesn’t fill in holes as it seals like epoxy or spackle does. That’s the yellow, red, white, and brown one in another thread.
So…one of these should work for your materials experience & comfort, yeah?
If you guys need rocker or outline templates,
I can CNC very clean rocker and outline curves
based on your specs or almost any Clark core
in the catalog. I can also do matching stringers
in a variety of materials.
Hot wire away…
Thanks,
Hein
PS. months ago I asked whether or not Shapers
knew about smooth C2 continuous curves. I
guarantee that I can produce a cleaner better
flowing curve with software than anyone can by
hand. I have curve analysis tools that that
I can use to clean up any curve. And the CNC
machine reproduces them exactly time after
time. Your boards will glide better because
of it.
Hein - great idea. What material? UHMW PE? Wood? (I suspect aluminum would be a shocking material choice for hot wire guides 
)
Rough cost for a 10’ pair?
Where are you located?
This sounds cool! Could you give more information - cost, material, timeframe? I’m ready to make a good quality template for my 9’1 shape and would like options.
I actually just machined some material from Dupont
called DIBOND. It’s ABS clad with thin aluminum on both
sides and cuts real nice. It’s .160 thick. I guess
you would have to be careful about not grounding
them so you don’t short out your hotwire.
I have a large CNC router and can machine lots of
materials. Some cut easier and cleaner than others.
MDF is also real nice for templates and other tooling.
The real magic is in what I can do with the curves.
I’ve digitized hand made rockers for several production
brands and cleaned them into much higher quality
curves. Same curve, just smoother.
Email me directly for quotes. I am located in Hood
River, OR. Across the river from Fiberglass Supply.
I’m a regular customer over there and I’m actually
getting some of the last 6-4R Clark blanks to machine
for a client. I wonder if that guy will want me to cut
some EPS?
Thanks,
Hein
P.S. Didn’t mean to highjack this thread. Just
thought what I am offering is relevant.
I’ve been highacked by a salesman !
I’ve used aluminum templates before and there’s no shock problems, well I never had any. The only problem was the metal sucking a bit of the heat out of the wire, but wasn’t critical.
Another really good material for hotwire templates is formica or laminex. With the edges fine sanded and a little rounded the wire just glides.
I really like the idea of your curve smoother Hein. I’m a tech fan when it comes to logical quality over possible human error.
tip:
“microplane” surform blades are much better on EPS than the standard blades. Foam-EZ among others sell them. Get both the 10" and 6"(?) as they have different patterns and cut differently. They are also much better for wood and PU than the standard blades. These were great for shaping my wood nose block.
question:
what are you guys using for longboard hotwire cutting guides? i.e. how are you getting 10’ boards. I’ve only found 8’ material for making guides.
I’ve only found 8’ material for making guides.
I make a giant paper template then cut it a little short of 8’. After I cut them out I join them together with a little wood splint and some pvc glue. The splint allows the wire to ride over the gap.
However, Airframe buys 10 ft lengths of mdf. This is the route that I’m going next time. My shapes are getting good enought that I might actually want to recreate them