Re: Vacuum Bagging
That is the reason for the four 1/4" holes, they let air go through.
If you put a vac guage on one of these shop vacs, the vac level is
pretty low, about 2 pounds. But it doesn't vary much, even with
fairly titanic leaks in the bag, or holes in the hose. This has its
advantages over low volume high pressure systems. You can vac using
epoxy any flat materials like ply, or fabrics. But you may not have
the pressure to really push excess resin around, not always
desireable anyway. You don't have the pressure to flatten out stuff
like floppy birdseye veneers that have micro iregularities that are
really quite difficult to get out. There are other issues, but I am
sure my time is up by now.
If you put a vac guage on one of these shop vacs, the vac level is
pretty low, about 2 pounds. But it doesn't vary much, even with
fairly titanic leaks in the bag, or holes in the hose. This has its
advantages over low volume high pressure systems. You can vac using
epoxy any flat materials like ply, or fabrics. But you may not have
the pressure to really push excess resin around, not always
desireable anyway. You don't have the pressure to flatten out stuff
like floppy birdseye veneers that have micro iregularities that are
really quite difficult to get out. There are other issues, but I am
sure my time is up by now.
> One point the author of the WOODEN BOAT article makes concerninguse of
> non-displacement vacuum generators such as Shop- Vacs and householdOnce
> vacuum cleaners is that they rely on air flow to cool the motor.
> they are hooked up to a well sealed vacuum bag, the air flow stopsand
> the motor becomes toast in a short while. Shop-Vacs can be used in arelease
> small setup using a "space saver" bag made for storing clothing,
> fabric, soft open cell foam for breather material, and a one-wayvalve.
> After the vacuum is achieved, the valve is closed. Then the theShop-Vac
> is switched off to cool. The foam is compressed against thelaminate by
> the 3-5 psi of the typical Shop-Vac and stores energy. It slowlyrelaxes
> as vacuum leaks out, but maintains pressure on the laminate. Thevacuum.
> Shop-vac is switched back on every 5-10 minutes to restore lost
>
> Vince
An acquaintance of mine Jim Dory of Nome built a Kurt Huges Cylinder
molded catamaran using Vacuum bagging
http://home.gci.net/~jdory/boat.htm
He used a shop vac and let it run the 8-10 hours needed for each hull
half. He just punched some holes in the suction line so it would keep on
pulling air.
Its a pretty neat site, he cranked out a 30 ft catamaran hull from start
to floating in 10 months over a Nome winter.
Aussie site using refrigerator compressors
http://members.ozemail.com.au/~flyingwing/vacbag/
HJ
Vince and Mary Ann Chew wrote:
molded catamaran using Vacuum bagging
http://home.gci.net/~jdory/boat.htm
He used a shop vac and let it run the 8-10 hours needed for each hull
half. He just punched some holes in the suction line so it would keep on
pulling air.
Its a pretty neat site, he cranked out a 30 ft catamaran hull from start
to floating in 10 months over a Nome winter.
Aussie site using refrigerator compressors
http://members.ozemail.com.au/~flyingwing/vacbag/
HJ
Vince and Mary Ann Chew wrote:
>
> The latest issue of WOODEN BOAT has a detailed article on vacuum
> bagging. I haven't tried it yet, but I just purchased a W.E.S.T. vacuum
> bagging kit from Jamestown Distributors and plan to use this method for
> taping the chines of the Dakota. By-the-way there are detailed
> instructions furnished with the kit.
>
> One point the author of the WOODEN BOAT article makes concerning use of
> non-displacement vacuum generators such as Shop- Vacs and household
> vacuum cleaners is that they rely on air flow to cool the motor. Once
> they are hooked up to a well sealed vacuum bag, the air flow stops and
> the motor becomes toast in a short while. Shop-Vacs can be used in a
> small setup using a "space saver" bag made for storing clothing, release
> fabric, soft open cell foam for breather material, and a one-way valve.
> After the vacuum is achieved, the valve is closed. Then the the Shop-Vac
> is switched off to cool. The foam is compressed against the laminate by
> the 3-5 psi of the typical Shop-Vac and stores energy. It slowly relaxes
> as vacuum leaks out, but maintains pressure on the laminate. The
> Shop-vac is switched back on every 5-10 minutes to restore lost vacuum.
>
> Vince
>
Another trick is to use a small hole in the line to the vacuum
cleaner to let in a little extra air. I did this while pumping out our
basement with a wet vac (real pumps all sold out of course). Seemed to
pull harder that way, even. Maybe blades less stalled.
Another trick is to make a vacuum regulating switch out of an old air
door vacuum actuator from a car (available at junkyard from air
cleaner snorkel). It's set up to pull against a spring with a threaded
rod in the middle which has a little cam to trip a switch. Easy to
adjust vacuum by moving cam up and down rod. I have'nt bothered with
this, but I've seen it.
cleaner to let in a little extra air. I did this while pumping out our
basement with a wet vac (real pumps all sold out of course). Seemed to
pull harder that way, even. Maybe blades less stalled.
Another trick is to make a vacuum regulating switch out of an old air
door vacuum actuator from a car (available at junkyard from air
cleaner snorkel). It's set up to pull against a spring with a threaded
rod in the middle which has a little cam to trip a switch. Easy to
adjust vacuum by moving cam up and down rod. I have'nt bothered with
this, but I've seen it.
--- In bolger@y..., Vince and Mary Ann Chew <vachew@v...> wrote:
snip
> non-displacement vacuum generators such as Shop- Vacs and household
> vacuum cleaners is that they rely on air flow to cool the motor.
Once
> they are hooked up to a well sealed vacuum bag, the air flow stops
and
> the motor becomes toast in a short while. snip
> the 3-5 psi of the typical Shop-Vac and stores energy. It slowly
relaxes
> as vacuum leaks out, but maintains pressure on the laminate. The
> Shop-vac is switched back on every 5-10 minutes to restore lost
vacuum.
>
> Vince
Whoops! I guess I shouldn't talk about "vacuum leaking out". Actually,
it's air leaking back in.
Vince
it's air leaking back in.
Vince
The latest issue of WOODEN BOAT has a detailed article on vacuum
bagging. I haven't tried it yet, but I just purchased a W.E.S.T. vacuum
bagging kit from Jamestown Distributors and plan to use this method for
taping the chines of the Dakota. By-the-way there are detailed
instructions furnished with the kit.
One point the author of the WOODEN BOAT article makes concerning use of
non-displacement vacuum generators such as Shop- Vacs and household
vacuum cleaners is that they rely on air flow to cool the motor. Once
they are hooked up to a well sealed vacuum bag, the air flow stops and
the motor becomes toast in a short while. Shop-Vacs can be used in a
small setup using a "space saver" bag made for storing clothing, release
fabric, soft open cell foam for breather material, and a one-way valve.
After the vacuum is achieved, the valve is closed. Then the the Shop-Vac
is switched off to cool. The foam is compressed against the laminate by
the 3-5 psi of the typical Shop-Vac and stores energy. It slowly relaxes
as vacuum leaks out, but maintains pressure on the laminate. The
Shop-vac is switched back on every 5-10 minutes to restore lost vacuum.
Vince
bagging. I haven't tried it yet, but I just purchased a W.E.S.T. vacuum
bagging kit from Jamestown Distributors and plan to use this method for
taping the chines of the Dakota. By-the-way there are detailed
instructions furnished with the kit.
One point the author of the WOODEN BOAT article makes concerning use of
non-displacement vacuum generators such as Shop- Vacs and household
vacuum cleaners is that they rely on air flow to cool the motor. Once
they are hooked up to a well sealed vacuum bag, the air flow stops and
the motor becomes toast in a short while. Shop-Vacs can be used in a
small setup using a "space saver" bag made for storing clothing, release
fabric, soft open cell foam for breather material, and a one-way valve.
After the vacuum is achieved, the valve is closed. Then the the Shop-Vac
is switched off to cool. The foam is compressed against the laminate by
the 3-5 psi of the typical Shop-Vac and stores energy. It slowly relaxes
as vacuum leaks out, but maintains pressure on the laminate. The
Shop-vac is switched back on every 5-10 minutes to restore lost vacuum.
Vince