Q.V.P. VAKUUM BAGS WITHOUT BASEBOARDS - Manual (Page 4)

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ADDITIONAL VAKUUM BAG
VENEERING TIPS
4/7/98 - Electric Bag Instructions.cdr
Always dry test the system before trying something new
like a fast setting glue, a large item or a new form. This way
you can be sure that the work piece will fit in the bag and
you have sufficient time to do all that needs to be
accomplished in the time allowed.
If the object in the bag is large, like hollow columns or a
box, you can use a shop vac to evacuate the bulk of the air.
A shop vac moves large volumes of air quickly, however, it
does not get a very high vacuum level needed to supply the
pressing force required for a good bond. Turn the VAK
Pump on, then insert the shop vac in the open end. It will
quickly pull the bag down and tight against the workpiece.
Remove the nozzle and close the bag, this will allow the
VAK Pump to finish the job.
A word of caution about continuously running a shop vac in
a closed system. Any electric motor needs an air flow to
cool it. If it is run continuously while attached to a closed
system, like the bag, the motor can burn out. Running it for
10 - 20 seconds to evacuate the bag is not a problem.
Any time a form is used inside the bag, make sure it is
strong enough to withstand the pressure of 1800 lbs/sq.ft.
Make a dry run!
Also, do not make a form or veneer a piece that has only 2
contact points with the baseboard. For example, think of
an inverted U shaped piece that is 2' wide, 5' across at the
base and 6 - 8" high at the top of the arch. If this were
placed on the baseboard and VAKuum applied, it would
snap most baseboards and possibly cause the bag to
implode (explosion pushes out, implosion pulls in). First,
all the pressure from the top area (2' X 5' = 10 sq ft X 1800
lbs/sq.ft. = 18000 pounds of force) is on the 2 contact
points. Since the base of the inverted U would have less
than 1 sq.ft of surface area to distribute the load, the 18000
lbs is distributed as 9000 lbs on two .5 sq.ft. areas. The
baseboard is seeing 1800 lbs/sq.ft on the underside and
since the top side is only supported by in two small .5 sq.ft.
areas (5' apart) it will snap most baseboards in the center.
Even if the baseboard was strong enough to withstand this
pressure, the bag would not. We have a situation where
the bag gets pushed in, under the arch, (roughly a 6" x 5'
area). The bag will stretch until it hits something or will
burst after a certain point. The open area must be blocked
to prevent the stretching. A strong form to fit under the arch
will not only prevent the bag from stretching but will also
support the arch and baseboard.
If for some reason you are not able to fully protect the bag
from sharp corners or excessive stretching, consider
purchasing an extra sheet of vinyl material and use it as a
protective layer. The double thickness will help extend the
life of the bag.
After the bag has been used and stretched, it will develop
pin holes which will cause leakage. Turn the bag over,
plug the hole and reinstall the VCA (VAKuum Connector
Assembly). The bottom side will be fresh and un-stretched
for the most part. With the top side now on the bottom, it
will be pressed against the bottom of the baseboard.
Since the bottom does not contain any saw cuts, the pin
holes will be sealed when pressed against the baseboard.
Excess glue must be cleaned from the bag as the hard glue
could puncture the bag. To make cleaning easier and to
add protection to the bag, order a length of vinyl material
and use it as a cover over the workpiece. The vinyl sheet
can be removed and easily cleaned. When used it will also
cover pin holes that have been created if the bag has been
overly stretched.
CAUTION: Some glues will stick to the bag: urea
formaldehyde, polyurathane and resorcinol are known to
stick to bags. Use wax paper or some material that will
isolate the bag from the glue.
Avoid, if possible, having the seam pulled tight against the
baseboard as shown below. This can be the cause of the
material ripping at the edge of the seam. This is
different than the seam delaminating. Leave some
space between the bag and the baseboard so that the bag
can flatten out against itself and not put any stress at the
edge of the seam.
Always fully support the bag, do not set-up on saw
horses without complete support.
Base Board
Base Board
Here it can rip due to stress.
The bag flattens out against itself and does
not stress the edge of the seam.
Seam
74 Apsley St. - Hudson, MA 01749
Tel: 978-562-4680 - Fax: 978-562-4681