making a blank with perimeter stringers
making a blank with perimeter stringers
i picked up about ten sheets of eps from a warehouse that was getting rid of a bunch of packaging material. i cant let that go to waste now, but it is 1.0 density eps so it needs some support. i was thinking that instead of sawing them in half and adding a stringer to all 10, i would try making perimeter stringers out of balsa wood (at least on some of them). ive been looking at alot of threads and had a couple primary questions.
1) For glueing balsa wood to EPS, should i use gorilla glue? people were mentioning elmers glue, but that seems weak and i think that was between two sheets of foam, not between balsa and EPS.
2) Is it worth it to invest in bar clamps? I was seeing everybody glue up their blanks with bar clamps and i was looking on the internet and 24" clamps run at about 7 to 15 bucks each. Can I cut this corner by just wrapping the board in masking tape or something else when i glue the balsa pieces to the rail of the board?
Ive never done something like this before, usually just order blanks and make boards. Any advice would be really helpful.
Re: [scboy4382] making a blank with perimeter stringers
Hey
Search the archives
here's a start and there's more
http://www2.swaylocks.com/node/1017338
http://www2.swaylocks.com/node/1018416
Re: [scboy4382] making a blank with perimeter stringers
Hi Scboy,
I did one last year, just used gorilla glue, worked well. Pretty low tech but was easy and effective , I just used some bricks and weighted down the separate pieces of EPS until the glue went off!
heres the post if you want to check it out,
www2.swaylocks.com/forums/need-some-glassing-advice-someone.
not really sure how to post a proper link!
Re: [nocean] making a blank with perimeter stringers
Hi Scboy,
I did one last year, just used gorilla glue, worked well. Pretty low tech but was easy and effective , I just used some bricks and weighted down the separate pieces of EPS until the glue went off!
heres the post if you want to check it out,
www2.swaylocks.com/forums/need-some-glassing-advice-someone.
not really sure how to post a proper link!
try this one: PROPER LINK
'I visualize my boards as a wire frame floating in space where I can see each line and how it relates to the next as the whole shape blossoms into full view...The key is in the accuracy of visualization....... and then, the translation of that into foam...' - Bill Barnfield
call me Huck http://surfersover50.blogspot.com/
Re: [scboy4382] making a blank with perimeter stringers
Gorilla glue and this wrap work good.
Re: [scboy4382] making a blank with perimeter stringers
Thanks Huckleberry!
Re: [scboy4382] making a blank with perimeter stringers
You can also use a good quality marine grade five minute epoxy and tape the balsa around the rails. That can be a quick method. I prefer bagging them on with epoxy all in one go (does take a bit of practice)
Re: [scboy4382] making a blank with perimeter stringers
Perimeter stringers? Maybe not all twisting is bad. Sleep on it.
1. Elmers glue is ok. Gorilla is better but expands, you just need to keep the pieces from floating apart. It depends on if the seams will show, and many other things.
2. It's up to you whether you think you need to buy clamps. Prolly depends on how many more you think you will do. Remember, a carpenter is only as good as his tools. It's a personal decision if you want to try and get away on the cheap.
Re: [scboy4382] making a blank with perimeter stringers
Do like I do, dumpster dive your local bike shop for blown out inner tubes, cut them at the valve stem, split then length wise, once for racing tires, twice for balloon, cinch them around the blank, you can pull them good and tight, as tight as bar clamps and they are free
Former gremmie, who followed his dream to do the best job possible
Re: [scboy4382] making a blank with perimeter stringers
How thick are the sheets?
What we do is take a 2" sheet and a 1" sheet or how ever many sheets you need to make the thickness you want then cut out the outline shape about 1/2" narrower. I like to use a 1" piece on the bottom and thicker piece on top.
Then we epoxy the sheets together with the top side of the blank on the bottom side of a board that has the rocker you want to use. Sometimes we'll strips of wood between the sheets for springers. Other times we just place reinforcements for the fin boxes.
When you put the epoxy on the foam, don't go out to the edge, leave a small space so that when you start foiling the board, you don't have to cut through epoxy. You can hot wire the foil after the epoxy is hard, the blank should hold the rocker shape for a little while. Or, you can add strips of perimeter rails with the foil pattern, then bring the foam down to match that . If you cut out the strips for the rails with the foil thickness, you can use a 1/8" piece of plywood. Cut out both sides making sure they are the same shape, then glue them onto the blank. I like to use 5 minute epoxy and cheap masking tape to glue the first piece of the rails to the foam. Be sure to work out the rail's shape so that you don't have to shave down the plywood. Plywood will give you a strong one piece rail, and then you can have anything you want on the outside of that. If you can get balsa long enough to make a one piece rail, you can use balsa. Otherwise, you just have to use several pieces of wood to get the length you need.
Once I have the rails on, I profile the deck and finish adding the rail bands, then shape out the rails.
1lb EPS is very soft, so you'll have to do a heavy glassing. You may want to seal the blank with an epoxy microballoon mixture before laminating the blank. We only use 1lb EPS for wood composite sandwich boards. Those have either 1/8" of balsa with a normal glassing schedule, or thin veneers with glass under the wood and then normal glassing schedules over. Having a durable skin seems to work OK with the light EPS. The skin absorbs the impact of your feet weighting and unweighting, and doesn't end up with small indentations like a regular board.
Re: [scboy4382] making a blank with perimeter stringers
Bike inner tubes work good, also some duck tape is "stretchy" and is easy to use for glueing up stringers. Definitely go with a gorilla glue or similar, Elmer's glue won't dry with foam.
Kevin
www.SpirareSurfboards.com
kevin@spiraresurfboards.com
Re: [kevincc] making a blank with perimeter stringers
yeah, I couldn't gt elmers glue to dry on EPS. Not enough air?
Remember: it’s all fun and games until someone looses an eye. Then, it’s a challenging scavenger hunt.
Re: [scboy4382] making a blank with perimeter stringers
Slash- thats basically the idea i had as of now
ozzy- the perimeter stringers are just an experiment, when the foam is free and each blank comes out to about 15 bucks i really have nothing to lose and who knows, i could discover something cool in the process. i was thinking of making like 3 of them with perimeter stringers and the rest with regular center stringers. just a little pet project i guess you could call it.
jim- great idea! the things that we do to save a buck here and there are amazing. ill run down to cycle werks and go searching.
sharkcountry- each sheet is 4 inches thick. so i was thinking about just making a hotwire (seen some internet tutorials) and carving rocker with that. if i were to make rocker by taping it to another board i assume i would leave it overnight? then put the rails on it in the morning before it regresses back to what it started as flat? and the density was the only bummer about coming across all this foam. since i have perimeter rails on some of the blanks and no support in the center i was having nightmares about maybe putting a foot through the eps or having sasquatch sized knee pressure dents. i was thinking that i would go with 2 layers of 6 oz on the deck and bottom or maybe 2 or 3 layers of E glass. think that would help slow that process? i dont have the technology to vacuum bag veneers onto the deck (i wish)
Re: [scboy4382] making a blank with perimeter stringers
"each sheet is 4 inches thick."
yup that's too thick for our flat sheet bend technique
we did a bunch the way you described using 6" wide 2lb
at 4" you have alot of glue lines to shape through so think about that.
Certain PU glues and epoxy can be difficult to shape without messy up the soft foam next to it.
lookup roo glue or something similar that doesn't dry so hard
also PU will want to expand and if the compression is not even you will get wavy lined glue ups
Roo and Sumo PU don't dry so hard and crusty there's even some waterbased contact cement you can use just gluey on you blades when shaped.
i would cut rocker profiles like you said less waste in the end
and they are parabolas not parems (inside joke)
Live Aloha Always...
What is it?
http://culturalkapolei.honadvblogs.com/2009/04/01/oneula-hau-bush/
Where is it?
http://www.inter-island.com/eva.html
Re: [scboy4382] making a blank with perimeter stringers
yeah i figured. thanks a bunch for the advice
Re: [scboy4382] making a blank with perimeter stringers
If they are 4" thick and wide enough, you might be able to just draw out 2 profile jigs and hot wire a solid slab. I make stringers from 3" and 4"balsa wide balsa. To get more rocker, I just move the tail up as far as I can and keep the low point as close to the bottom. You should be able to get an extra inch may be more of nose rocker this way. When I can't get enough nose rocker, I cut out the front part off then glue it to the top. I've been able to get a lot of nose rocker and even extend the nose out several inches that way. The profile templates will also help you to make the perimeter rails.
Hot wiring a solid slab would be less work especially when you start foiling the top. Also you might want to look as using a layer of Kevlar and glass on the top to get a flexible top shell, I don't think 2 layers of 6 oz glass will be enough to stop the top from getting a lot of dents. The perimeter rails will give you strength, but the foam is still soft. That's something to think about when you glue up several sections of foam. With PU foam the tops of boards will dent and rip along the stringer if the foam is soft. Whatever you use to glue up the sections will probably create a hard line and the glass will be pushed between those hard lines and the softer foam.
Give it a go, you have 10 sheets, so you can try different techniques and by the third board, you should have it figured out.
Re: [scboy4382] making a blank with perimeter stringers
Cool. Experimenting is the best way to learn. I know I've made my share of experimental pigs. They worked good to a degree, but were never the break through I hoped they would be. Learned a lot in the process though.
Re: [scboy4382] making a blank with perimeter stringers
If you use glues for the stringers, then the blank won't hold rocker if you bag it later - the vac will pull the rocker flatter - you'll need a rocker table. My experience, anyway.
I used masking tape to hold the rails on and long pins to keep them aligned correctly when I put epoxy/cloth perimeter stringers in (because the rails can creep during the drying time). Just pull the pins out after the epoxy hardens - can't even see the holes.
Now I just use wood glue and put a bead down the middle of the join and try to keep it away from the edges. (I had the rails already cut off and decided perimeter stringers were not the go). Gets rid of much of the sanding problems.
My veneers sucked down in the foam around the hard epoxy stringers, so after bagging you could see a faint line where the stringers were (don't know if you're using veneers).
Re: [scboy4382] making a blank with perimeter stringers
One more option for you. I made a board last year from 6" thick 2lb EPS slabs using the technique you started this thread with. I cut out rocker slices and glued them together with elmer's white glue, the same stuff that kids use in school. I didn't do a good job of cutting the slices, so I had to do a lot of planing to get the blank trued up. The glue didn't dry in some spots so the blank started separating, so I stuck long bamboo barbeque skewers into the foam to hold it together. I used a bunch about 2" apart, and I cut them with wire cutters. I used a razor to cut a sharp point on the shorter pieces that were left over. This worked for me and it held the sections together. If you shove them in enough, you won't see anything after shaping the rails. Just draw out the outline before gluing up the blank, so you know where the edge will be. If you do this be sure to keep them where you know there will be foam after shaping out the blank, or they will pop out. With the white glue shaping is not an issue because the glue is not hard like epoxy, but it doesn't always dry, so the skewers will hold things together. I always use epoxy to hold the first band of wood for the rails, and I use cheap masking tape to hold it in place till the glue dries. I use wood glue and masking tape for the rest of the rail bands. I cut out as many layers as I need for one side then glue it all up at one time to conserve tape. I also size the bands so I don't waste as much wood. Each band gets narrower as it gets closer to the edge, and the final shaping is also easier.
The board I'm working on now is a 1lb EPS compsand and it has the first band of balsa rail, a piece that is 3/16" thick. I used a belt sander to get it profiled down because the sanding block took so long. If you're good with a disk sander that should work, but I feel more comfortable with the belt sander right now, and I didn't want to mess up my planer cutting through epoxy.