First off thanks to all the other builders who provided useful
guidance before I started this work. Today myself and couple of
teenage helpers laminated up a small test piece (1/2 m2) that will
also form part of my new cabin structure. Took 1 hour from start of
laminating to having it under vacuum. Partly because neither my
helpers had ever touched fiberglass before.

Lessons learned, both positive and negative:

- believe in my software. When it indicates that a layer of 666 gm/m2
triaxial will only be 0.7mm thick, don't make the rebate in the core
1.5mm "just to be safe" where layers overlap. I'd rather fill the
little rebate with bog later than have to fair out a hill, but still I
need to be a little less aggressive with the router.

- a dry test run of my vacuum set up was highly useful. We found that
the bag wouldn't seal well with any folds along the sealant tape

- a digital scale was useful to measure resin/hardener easily. No
mixing cups for this lad any more.

- Corecell is harder than it looks. I made a nailing board (2x4 with
a bunch of nails in it) to puncture the core. Had to really hammer it
down into the core. I thought I would just be able to press it in...

- Olfa rotary fabric cutters are amazing. If you're cutting any
quantity of glass get one.

- A resin with a slow gel time (90-120 min at @ 77F) makes things very
relaxed. Cure time is 5-6 hours at 75F for my particular resin

- pouring on the resin, spreading thinly with plastic spreaders, and
then just working it in worked very well. The particular triaxial
fabric (V2) and resin (Jeffco) wetted out very easily compared to
others I've used.

- yes, it's easy to get a 50/50 resin/hardener ratio. I measured out
the same weight of resin + 10% for bleed. With my complete novice
helpers we wet out 2 layers of cloth with lots left in the bucket,
indicating that we were probably already at 50/50 before vacuum was
applied.

- overall a bit of careful planning made it all go very smoothly.

One hiccup:

The vacuum pump I'm using is a 6 CFM refrigeration tech. type. It
draws a deep vacuum (27-29 in Hg) very fast (like 1 minute). But it
is an oil lubricated type and exhausts an oily mist. We didn't notice
it today with the garage door open, but when I came back after several
hours the garage had a misty oily cloud in it. I figure the best
solution might be to (a) vent the exhaust to a plastic bucket with
some sort of breather material bunched in to capture the mist or (b)
just exhaust it outdoors. Any suggestions??

Thanks all,

Evan Gatehouse

Exhausting the pump into a bucket of rags might be a fire hazard. Better to
exhaust it outdoors. A side-benefit will be that the pump will be quieter
and it'll be easier to find bag leaks. My hearing is such that I need all
the help i can get.

"Evan Gatehouse" wrote in message
...
First off thanks to all the other builders who provided useful
guidance before I started this work. Today myself and couple of
teenage helpers laminated up a small test piece (1/2 m2) that will
also form part of my new cabin structure. Took 1 hour from start of
laminating to having it under vacuum. Partly because neither my
helpers had ever touched fiberglass before.

Lessons learned, both positive and negative:

- believe in my software. When it indicates that a layer of 666 gm/m2
triaxial will only be 0.7mm thick, don't make the rebate in the core
1.5mm "just to be safe" where layers overlap. I'd rather fill the
little rebate with bog later than have to fair out a hill, but still I
need to be a little less aggressive with the router.

- a dry test run of my vacuum set up was highly useful. We found that
the bag wouldn't seal well with any folds along the sealant tape

- a digital scale was useful to measure resin/hardener easily. No
mixing cups for this lad any more.

- Corecell is harder than it looks. I made a nailing board (2x4 with
a bunch of nails in it) to puncture the core. Had to really hammer it
down into the core. I thought I would just be able to press it in...

- Olfa rotary fabric cutters are amazing. If you're cutting any
quantity of glass get one.

- A resin with a slow gel time (90-120 min at @ 77F) makes things very
relaxed. Cure time is 5-6 hours at 75F for my particular resin

- pouring on the resin, spreading thinly with plastic spreaders, and
then just working it in worked very well. The particular triaxial
fabric (V2) and resin (Jeffco) wetted out very easily compared to
others I've used.

- yes, it's easy to get a 50/50 resin/hardener ratio. I measured out
the same weight of resin + 10% for bleed. With my complete novice
helpers we wet out 2 layers of cloth with lots left in the bucket,
indicating that we were probably already at 50/50 before vacuum was
applied.

- overall a bit of careful planning made it all go very smoothly.

One hiccup:

The vacuum pump I'm using is a 6 CFM refrigeration tech. type. It
draws a deep vacuum (27-29 in Hg) very fast (like 1 minute). But it
is an oil lubricated type and exhausts an oily mist. We didn't notice
it today with the garage door open, but when I came back after several
hours the garage had a misty oily cloud in it. I figure the best
solution might be to (a) vent the exhaust to a plastic bucket with
some sort of breather material bunched in to capture the mist or (b)
just exhaust it outdoors. Any suggestions??

Thanks all,

Evan Gatehouse

The bucket of rags, MIGHT be a fire hazard, but, I wonder if maybe that oil
mist might not be as explosive as the grain dust clouds that regularly blow
up silos in the Midwest.

Roger

http://derbyrm.mystarband.net/default.htm
"Jim Conlin" wrote in message
...
Exhausting the pump into a bucket of rags might be a fire hazard. Better
to
exhaust it outdoors. A side-benefit will be that the pump will be quieter
and it'll be easier to find bag leaks. My hearing is such that I need all
the help i can get.

"Evan Gatehouse" wrote in message
...
First off thanks to all the other builders who provided useful
guidance before I started this work. Today myself and couple of
teenage helpers laminated up a small test piece (1/2 m2) that will
also form part of my new cabin structure. Took 1 hour from start of
laminating to having it under vacuum. Partly because neither my
helpers had ever touched fiberglass before.

Lessons learned, both positive and negative:

- believe in my software. When it indicates that a layer of 666 gm/m2
triaxial will only be 0.7mm thick, don't make the rebate in the core
1.5mm "just to be safe" where layers overlap. I'd rather fill the
little rebate with bog later than have to fair out a hill, but still I
need to be a little less aggressive with the router.

- a dry test run of my vacuum set up was highly useful. We found that
the bag wouldn't seal well with any folds along the sealant tape

- a digital scale was useful to measure resin/hardener easily. No
mixing cups for this lad any more.

- Corecell is harder than it looks. I made a nailing board (2x4 with
a bunch of nails in it) to puncture the core. Had to really hammer it
down into the core. I thought I would just be able to press it in...

- Olfa rotary fabric cutters are amazing. If you're cutting any
quantity of glass get one.

- A resin with a slow gel time (90-120 min at @ 77F) makes things very
relaxed. Cure time is 5-6 hours at 75F for my particular resin

- pouring on the resin, spreading thinly with plastic spreaders, and
then just working it in worked very well. The particular triaxial
fabric (V2) and resin (Jeffco) wetted out very easily compared to
others I've used.

- yes, it's easy to get a 50/50 resin/hardener ratio. I measured out
the same weight of resin + 10% for bleed. With my complete novice
helpers we wet out 2 layers of cloth with lots left in the bucket,
indicating that we were probably already at 50/50 before vacuum was
applied.

- overall a bit of careful planning made it all go very smoothly.

One hiccup:

The vacuum pump I'm using is a 6 CFM refrigeration tech. type. It
draws a deep vacuum (27-29 in Hg) very fast (like 1 minute). But it
is an oil lubricated type and exhausts an oily mist. We didn't notice
it today with the garage door open, but when I came back after several
hours the garage had a misty oily cloud in it. I figure the best
solution might be to (a) vent the exhaust to a plastic bucket with
some sort of breather material bunched in to capture the mist or (b)
just exhaust it outdoors. Any suggestions??

Thanks all,

Evan Gatehouse

A cheap stethescope (sp?) truly helps here, especially if the pump is in
a different room (or outside) from the bagging room...and, yes, I can
attest to Jim's poor hearing, as well mine, as we once worked together
on several significant bagging projects ;-)

- paul

Jim Conlin wrote:
My hearing is such that I need all
the help i can get.

I believe I would find a different vacuum pump. HVAC pumps are designed to
run a long time with almost no flow. With the constant flow from even a
well sealed bag you run the risk of blowing all the oil out and burning up
the pump before the epoxy kicks. You also don't need that high a vacuum.
When you get much above about 15" Hg you run a risk of squeezing to much
resin out of the layup. A pump rated at 24" Hg will give you plenty of
headroom.

--
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

"

Glenn Ashmore wrote:
I believe I would find a different vacuum pump. HVAC pumps are designed to
run a long time with almost no flow. With the constant flow from even a
well sealed bag you run the risk of blowing all the oil out and burning up
the pump before the epoxy kicks. You also don't need that high a vacuum.
When you get much above about 15" Hg you run a risk of squeezing to much
resin out of the layup. A pump rated at 24" Hg will give you plenty of
headroom.


I know but this pump is quite quiet (quieter than a vacuum cleaner).

The first thing I did was check the oil level in the window on the
pump when I went it and it hadn't budged. I suspect that a little oil
goes a long way when it comes to making a mist.

I did keep the vacuum level at 10-15" during the time the pump was
running but thanks for the thought.

Evan Gatehouse

Vent the pump into a bucket 1/2 full of water. Put a couple of drops of
dishwasher detergent in the water to aid cleanup. You should test for
foaming, but machine detergents shouldn't foam.

John


"Evan Gatehouse" wrote in message
...
Glenn Ashmore wrote:
I believe I would find a different vacuum pump. HVAC pumps are designed
to
run a long time with almost no flow. With the constant flow from even a
well sealed bag you run the risk of blowing all the oil out and burning
up
the pump before the epoxy kicks. You also don't need that high a vacuum.
When you get much above about 15" Hg you run a risk of squeezing to much
resin out of the layup. A pump rated at 24" Hg will give you plenty of
headroom.


I know but this pump is quite quiet (quieter than a vacuum cleaner).

The first thing I did was check the oil level in the window on the pump
when I went it and it hadn't budged. I suspect that a little oil goes a
long way when it comes to making a mist.

I did keep the vacuum level at 10-15" during the time the pump was running
but thanks for the thought.

Evan Gatehouse