Hi all,

I'm building an 8' x 12' formica toppped mold table. I will be using
this to lay up foam/E-glass panels for a bridgedeck cabin for my 40'
catamaran. It's being build inside a garage.

I'd appreciate a bit of feedback on a few questions:

1) How high off the floor? I was thinking of either 2"x8"'s on the
floors (with resulting back pain from lots of bending other) OR on
sawhorses to have a nice working height. Generally I'm concerned that
the table might be too flexible or harder to make it if level on
sawhorses (5/8" plywood substrate)

2) I'm thinking of building a "bridge" (for lack of a better word) to
get to the middle of the panel more easily. Any construction hints?
Maybe some 2x8's with ply top and bottom to form a box beam. It has
to span 9'+ and have 220 lbs in the middle.

3) What's the best method (short of proper resin impregnator) to
apply epoxy resin (1000 cps) to a triaxial fabric. I'm thinking of
pouring and then plastic spreaders as the most efficient way. I've
never used fabric rollers to spread resin, though I know lots of
production builders that do use it.

Oh, it's vacuum bagged and the triaxial fabric is 90/45/-45 20 oz (666
gm/m2).

Thanks very much,

Evan Gatehouse

Been to this movie.

Contact me off list next week to discuss.

Tonight is a bad nightG.

HTH

Lew

My table is 8x12 melamine clad MDF available at any cabinet maker's supply
for a lot less than the Formica alone. It is joined with biscuits and the
joints are filled with epoxy/silica and sanded smooth. The table is mounted
on a cross braced 2x8 frame bolted to sawhorses and carefully leveled. I
have a concrete floor but if you locate the legs over joists it will stay
pretty stable. The tablet is a little below crotch high so I can brace my
thighs against the edge and lean over to the middle. I am 6' tall and can
easily reach well past the center. Glues don't stick to Melamine well and
if you can keep it clean with an occasional light coat of carnuba wax cured
epoxy just flakes off. My first top lasted 2 years and when it got to
groaty I just sanded it down smooth and put another layer of melamie MDF on
top. Because it is used for cutting and wet out as much as layup I built a
rack for peel ply glass and breather at one end. A roll of 12' x 6 mil
poly for drop cloth/ bag material is hung on the wall to one side. There is
a picture of the original 6x12 table here
http://www.rutuonline.com/html/laying_glass.html

I just came in from laying up about 120' of 50" wide A-130 uni with Proset
125 for the traveler arch. Started just after Car Talk and finished half
way through Prarie Home Companion. It was split to 25" and cut at 20'. I
weighed a piece to get an idea of how much epoxy I needed to get about a
50/50 ratio and added 10% for waste. When I am doing this large a batch I
cover the table in poly to make cleanup easier. The plys were folded in
half to fit on the table and stacked with a bit of stagger so that any resin
running off the edges will soak into the lower plys. I weighed out and
mixed enough resin for two plys at a time and poured about 1/4 of it down
the center of the pile. Then worked it in with a 4" plastic spreader . I
get the spreaders by the dozen from a body shop supply house for about 20
cents each. Be carefull with the spreading. Uni can take a lot more
handling than tri-ax. If you work tri-ax or bi-ax to much you will end up
with a tangle of binder threads. Work it just enough to get it evenly
spread and then stop and let capillary action pull it it. Inspect and
dribble on a little more resin on the dry spots. Again, work it very
lightly.

If you are using it as a wet out table as I was, fold the cloth up to an
easy to handle size. Wet knitted bi-ax will stretch out of shape very
quickly.

If you are laying up a flat panel, place the core material on a piece of
plly at least 6- 12" from the edges. Lay the vacuum tape around the
perimiter of the table surface and cover it with blue masking tape. Cut
some 6 mil poly sheet to fit over the table and get your peelply and
breather/bleader ready.

Some people wet out the core material but if you are bagging that is not
really needed. The tendency is to use to much resin so the bag is going to
push it into the core anyway. Lay up one side, apply peel ply and
breather/bleader and turn it over. I use spring clamps to hold the glass in
place during the turn. Lay up the other side and apply peelply and
breather/bleader. Decide where your vacuum ports will be and add 4 or 5
extra patches of breather to minimixe sucking resin into the ports. Remove
the blue masking and lay the poly sheet over the table evenly. I start
removing the vacuum tape backing in the corners and lightly stick down the
bag. You want all four side even so you don't have to tape up a pleat
unless absolutely necessary. Set your ports and finish sealing the bag.
Don't start stripping the peelply and breather for 2 or 3 days to let the
epoxy get past the brittle stage or you will pull up some fiber.

I have a length of 2x2 oak that I use to strip the peelply. I pull off
enough to get around the board a bit more than one time, put a hand clamp on
the end of the board and just roll it up.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

On Sat, 22 Jan 2005 16:28:08 -0800, Evan Gatehouse
wrote:

Hi all,

I'm building an 8' x 12' formica toppped mold table.
//

2) I'm thinking of building a "bridge" (for lack of a better word) to
get to the middle of the panel more easily. Any construction hints?
Maybe some 2x8's with ply top and bottom to form a box beam. It has
to span 9'+ and have 220 lbs in the middle.
///
Evan Gatehouse

I made a double take on your bridge suggestion.
I made a strong beam 18 feet long supported either end on perimeter
walls, to support a wide ceiling with screw rod hangers, whose rafters
were sagging a little.

This could easily take me jumping up and down on the middle.
With me aboard, the static deflection was less than 0.45 inch.
It was an upper and lower member of 18 ft X 2 X 4in,
with 1/4 in ply webs of 12in X 18 feet to make a stiff box beam. I
used internal struts ot 2 X 4 X 8.5 in on 2 ft centers.
External dimensions 12 X 4in X 18 ft. The longer cross section was
vertical, of course.

Use two beams like this, with a ply platform between.
Or if you choose another structural plan, put the meat of the
structure vertically spaced as two spars, and use ply just for the
sides as a compression/shear web.....

Brian W
p.s. For table heights, higher is ofter better.... how about waist
high?

Evan, email Joel. He will send you pics of the table he built last
year: 5x10. We used 1" thick melamine faced particle board on 2x4's.
We also experimented with different wet out methods and to simply pour
the resin then spread with squeegees works best.
We also experimented with cheaper vacuum bagging materials with
success: duct tape and breather made from garden supply store canvas.
I assume you are going to vacuum bag?

Jacques from bateau.com