Eps and epoxy questions

General Discussion
1

I have shaped several eps blanks and have just recently considered purchasing a block and hotwiring my own. my question with this is; is it feasible to hotwire my exact rocker and foil in order to minimize the hand-shaping process, and to obtain a precise and perfect rendering of my desired rocker? what approach do you guys take to hotwiring your own blanks?

Also, i want to add color to my epoxy boards. What i’ve pondering is to glass them in solid, completely opaque colors. Can i achieve this with an epoxy and pigment combination? Experience with this?

2

Yes,

Depending on…

How good your hotwire works…

And how experienced/talented you are at hotwiring eps.

3

Yes you can use opague colors in your epoxy lam w/o problems,providing you use a quality color product…Tints are a different ballgame all together.

4

Hey Tedd,

This summer was my first time hotwiring EPS, here are some things I learned. Yes, just like Herb said, you can dial in exact rocker, and it does depend somewhat on how good you are with it, some test runs are essential. But, once you are decently good at hotwiring, you get very precise rockers, or as precise as your templates are. I used a slightly low voltage setting, and went very slowly. To clean up any mistakes, I made a 26" long sanding block out of a 2x4 and a beltsander belt, and took the hotwire crust off with it and leveled everything out.

Problems, though. If you plan on using stringers, be prepared to figure out the hard way how hard it is to glue up a blank. There are several ways to avoid the mistakes, one is to cut your entire foam block and glue in a pvc foam stringer that the hotwire can cut through, or cut your hotwired blank and make wood stringers from your rocker templates with a router and flush cutting bit, and see how you can glue them together without making mistakes (not easy).

Whenever you glue 2 large flat areas together, problems in registration usually occur, as the two surfaces can slide on the film of glue (turns out I used too much glue, and more sliding than necessary occurred). I used dowels, hobby pins, and toothpicks, the pins and toothpicks worked best. Then you find out that you need proper support so that the weight of the clamps wont introduce some concave you didn’t want somewhere, especially near the nose and tail. Any mistakes in glue up means more sanding/planing to fix, and you original rocker template in no longer neing followed.

You could also build without stringers, and with a stronger glassing schedule, something I plan on trying for my next one.

I have some pics I need to dig up to show you what I mean. I’ll post them up when I find them.

5

Here are the pics:

Hotwiring with rocker template

Rocker done:

6

Getting everything lined up…

Putting in the hobby pins to prevent slip and slide…

Clamped in place…

7

Here you can see the ‘concave’ in the tail caused by the weight of the clamps. When the clamps came off, it was less, but still there. What I need to do next time is get 2 more sawhorses to support the nose and tail so this doesn’t happen again. Hobby pins get pulled out when glue sets, with pliers.

after correcting the concaves, ready for outlining…

There’s the template. I hotwired using the the half-tempate as a guide about 3mm outside the pencil line I drew with the half-template in the middle of the board, because I am not good at hotwiring. In the future, I will do this with a router, to ensure an edge perpendicular to deck and bottom.

8

cleaning up the outline…

These are the marks I make to ensure my rail bands are the same sie to side. I have an excel spreadsheet that gives me all of the measurements based on 3 cross-sections of the board. The spreadsheet morphs the cross-sections into one another, so I don’t have to shape with the ‘minds eye’ that I do not have. I just place 3/4" strapping tape on the marks, and sand to the tape.

Here’s the first 2 bevels/bands on top…

9

I use 4 bevels top and bottom, at 45, 60, 75, and 85 degrees from vertical. After all of these are in, it’s just finish sanding, and I was fortunate and ended up with this…

My method takes a ton of time to do the marking and layout, and you go through around 2 rolls of strapping tape, but it is easy to do, and does not require tons of skill. Works great for a first-timer like me.

10

just wanna say nice work

u could try this way if your in a hurry

if you use narrower molded blocks that have flat surfaces

so you cut two slices off .1 for each side

glue stringer to one side with 5 min epoxy. clamp wih tape

trim stringer down to rocker

use your offcut to support your next glue up

and do the other side put some weights on the whole shebang to keep your rocker

minimise clamping as they dont do much

cheap, less wastefull stringers can be glued up in pieces that overlap

11

Paul, very clever. I like it. You’d probably find it easier to hotwire a 12 inch piece than a 24 inch piece anyway. and to ensure you ended up with a full bed rocker bed, you could just glue your two off cuts together for a full 24 inches.

12

Thanks so much! I would have never thought of using the offcuts, but it makes perfect sense. Will have to do that on the next board… I’m actually putting graphics on the board pictured above today, so far looking pretty good.

13

thats right greg!

actually thought bit about it some more today

if you had some sheet eps you could use slices of that for the foam insert in between the stringers

and bend the rocker into the insert

and that way you would have two clean faces for gluing

i think if you made a few of them you could put them together pretty quick after a while.

i would suggest that clamps would be overkill to some extent cuz of there weight they are more likely to distort things

i havent tried it though

i only make compsand blanks and basically just use masking tape for clamping (one of those annoying disposables)

double sided tape can be helpful as well

but next week im making up 5 close tolerence eps blanks for standard glassing

and i dont really want to distort the rockers

cus basically i want to just shape the rail bands and that it

the other alternative is to set up a fence system for your hotwire and cut the blank in half after the proflie is cut

a hotwire fence table saw thing would be cool

i think most guys use a bandsaw or table saw

actaully has anyne tried a table saw

is that what u used maxmercy or a a bandsaw

that would work sweet as

my blanks are comming precut at full width from the foam suppliers

i think i might ask for some at half width for stringers

and full width for stringerless!

i dont know how people traditionally make stringers.

but i would think that butt joints in short pieces would be okay if you used two or three staggered layers

ill let you know how i go and post a few pics in a week or so

im using paulownia btw

contact adhesive might work

thers some great instant glues on the market these days

i could be way out here btw