keef said...

ok so you wet the glass onto the divicell, then stick it onto the blank and bend the rails with a heat gun or have i got it wrong

Yes you've got it wrong.

"PRE"- bend the dcell, while it is dry, naked, virgin. Lay it aside somewhere, then I punch holes in it about ever 10cm with a compass point, (actually easier to do this before it's bent.)
Then cut out the internal layer of cloth and laminate it to the board, place the prebent dcell over the top of this, tape in place and vacuum. any extra resin or air comes out thru the holes, and makes sure of a very good light bond.

i have only used a vac on the outer laminate and i use a bleeder and a breather then the vac bag so its the same right

is bleeder another term for peel ply?

Thanks Keef, I've been hearing satin weave a bit now, I'll have to check it out.
I've used "crows foot" and "herringbone", they both conform very well, but still won't wrap 90deg without lifting.

I use the same resin as Decrepit which cures to 100% if heated to between 65>80 deg C. for two hours. Over time with fatigue the epoxys matrix breaks down and the foam squashes a little giving the board a softer feel, the resin can be rebaked but the foam stays as is..

how do you bake it other than wrapping it in black plastic and leaveing it in the sun, and tell me are the blanks a square block or do they have rocker,the only ones we could get were square blocks and i had to bend the nose rocker and use a preshaped carbon 8mmclegacellx80mm deep stringer, the blank was as stiff as a honeymooners pr-ck
if anyone out there is haveing trouble with pinholes in there filler coat i can give you a tip, have a look in my pics and check out other photos of that race board and check out how flat and how sharp those rails are (keef)

[b]
No messing about trying to bend it, I've tried that sort of thing once or twice over the years, and I usually end up with rocker where I don't want it.

(if the board is 150mm thick how thick does a block have to be to get a 300mm rocker)i dont think you have been paying attention decrepit,the only way you can make a raceboard thats 650 wide&300 rocker is to get 2 blanks 400 wide,or hotwire 800, make 1/2 your dagger case and carbon stringer, bend your blank and resin and cure, repete the other side what you end up with is a square blank with rocker and dagger case, you shape the board from there, a slalom board is the same the only thing is you dont have to do is hotwire just preshape the laminated a 60mm stringer bend the blank and resin it in & dont forget to use some microballoons, so what youve got is a square blank thats as stiff as a honey mooners, just shape it and when you bag it you dont have to worry about the board changeing the rocker line, as well you dont need all that glass you guys are useing, and if you do a dry mix of balloons to fill the cells and sand before the last laminate you can get away the 3oz of carbon and 3oz saturn weave in the stress areas then filler with balloons
now im talking about a slalom and race board not a wave, just incase you guys are going to take the piss out of me for useing less glass

i thought i said it was 650 wide from two 400's
you still havent told me how you bake your boards

decrepit said...

Sorry, my blank is 600mm wide, you'd need to add another 50 to make your 650.[/quote
and youve made 9 boards useing a template for the rocker that block must have been at least 8ft high where did you store it
the bleeder is that peelply

"the blank was as stiff as a honeymooners pr-ck[":D] with the same amount of rocker?
The block was around 2400x1200x480 which is hot wired as Decrepit does . this will give me 6 to 8 blanks without having to bend them. I use the outside off cut as a rocker bed when bagging, just needs to be placed on a flat surface.
" But I haven't noticed my boards getting a "soft feel", is it very pronounced??? " Mainly with production and lightly glassed customs which have had a hard two or three seasons. Under the heels would be first then in front of the fin box and overall a little more flex. It's something that's not really noticed until riding a brand spanking new board that's a bit stiffer giving it a lively feel, but that's just what I find, anyone else?
For baking , if it's cold weather I'll use foam and cardboard sheets for an oven with a room heater and fan to circulate the hot air. If it's warmer the car will will get over 65C. on a hot day. In both cases it's baked before sanding the epoxy filler to prevent sink back later on, then once again after painting. I tried the black plastic method but found it hard to regulate the heat evenly .
Yours truly, The Humpty Dumpty Board Construction Company.

have you ever had the hotwire breaking , i use the thickest element wire from the electrical supplys, and if theres too much heat and too much load it will break,so tell he what do you guys use

thanks nebbian for the addvise my hotwire is from an old B&W TV with a light dimmer to control the heat so im not sure what the amps are

your rite 240V,a friend made it im not sure about the earth leakage system the light dimmer seems too work ok, i think the problem is as you said going to quick i havent used it in the last 15years and if i need to ill get some NICHROME wire
i probabley will make a board but i dont think ill need the hotwire

I used to use nichrome but now use stainless mono-strand trace wire from the tackle shop ( size #5 "HOLDFAST") and works great and at around $1.50 for a 3mtr pack I bought one of each size . The gauge wire depends on the current, if the amps are down use thicker wire. My variable power supply pumps out up to 16amps and up to 16volts but will also work quite well with a 5amp battery charger. The hot wire frame is a timber 'H' shape with cutting wire at the bottom and an occy strap for tension at the top. When the wire just starts to glow it's good to go.
I can post some pics and info on the supply tonight if you like.

I've built a CNC foam cutter - it's not big enough for board blanks, but does RC plane wings perfectly with some insane precision (0.005mm in theory)..

I use an old electric-blanket transformer from the 60s to power my wire. It's still A/C but seems to have tonnes of current available (they used real copper, and decent gauge wire to make stuff back then). Like someone said before, I have an extra length of wire pinned under the bench with an alligator clip to vary the wire temp. Wire tension is built into my bow - a broom handle with a piece of piano wire sticking out on an angle on either end. The combination of the springiness in the wood, and the piano wire is plenty to allow for the expansion and contraction in the ni-chrome wire.

Stainless wire doesn't stretch with the heating, so you can tighten that sucker right up to avoid any wire sag as you're cutting, although it's only really necessary if you're using a really long wire, or there is some harmonic in the mechanism pulling the wire through. (like stepping in a CNC setup - caused ripples on my wings until I figured that one out!)

Technically, the wire should be cutting by 'radiance' and never actually touching the foam. The foam melts away as the wire gets close.

For best temp control you need to have as little wire outside the block as possible, or at the very least minimise any sideways movement of the wire, because the resistance of the wire changes with the heat of the wire, and you get messy cuts at the edges. The wire inside the block is insulated to an extent by the foam, while any wire left outside will be cooler because the air can circulate. Also be aware of the material used for the template because some materials act as a heat sink, and you end up with a cooler wire at the edges of the block, and bigger kerf (the melted bit) in the middle - especially if you're feeding it by hand..

If you're up for the challenge, you can build a 'chopper' circuit to control the current (not that hard), and hook up two car battery chargers in series to give you around 30V DC. VERY nice setup which will happily run a 2m Stainless wire, at feed rates up to 20mm/s.

hoop said...

Yeah some pics would be good. I'm mainly interested in the adjustable power source. I've got a couple of bows that work well but I need to have more control over how hot it gets and stop it from cutting out.
thanks.

I looked all over the place for a decent power supply and this was the best option that gave enough variable amps (up to 16).It's an Avair model av-815m from Alltronics in Perth(next to Metros night club) for $130 1 1/2 years ago. Not the cheapest option, but for the cost of a fin it was worth it.