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Drum Building Tutorial - Veneering a Drum Shell with a Vacuum Bag System
Veneers, Vacuums, and Volatile Organic Compounds
As promised, here is my method of doing veneer on snare shells. You method and mileage may vary.
Shown below are some of the goodies that you will need. While it may be messy and sticky,
polyurethane glue dries very hard and actually will expand into any cavities. Because it expands
we must use a vacuum bag to put clamping pressure on the entire surface. I have tested
this stuff against other adhesives and have found that using a hard drying glue keeps the
shell more resonant and keeps the pitch of the shell higher.
This shell will be finished with a high gloss polyester finish and given away in a
GN contest that is to be determined.
Of course you also need a piece of veneer. I am using a piece of paper backed Tamo Ash. No I won't
tell you where I got it. Cut the length of the veneer so it has a 1" overlap. In this case I cut it 44" long.
The overlap will be cut off later so the seam will butt up against one another.
Prepping the veneer for gluing
Mark where the overlap area of the veneer begins. Apply 1 1/2" of tape to either side of that mark on
the overlap end of the veneer, for a total of about 3 inches. Notice you need to tape the veneer to the
paper so it is easy to apply the glue.
On the opposite end, just put 1 1/2 of tape starting at the very end of the veneer.
Prepping the shell for gluing
Strike a vertical line on the shell (not shown). Tape 1 1/2 inches on either side of the line.
There is a mark on the tape shown that shows where the line on the shell is.
Spreading the love
Throw down some glue on the veneer
Polyurethane glue is a little bit more difficult to spread evenly than other glues. I first spread it out with
a piece of plastic, or in this case, a scrap of white marine pearl wrap. Then I use a rubber brayer to
work out any lumps or thick spots. If you have any thick spots with the glue these will turn into lumps
in your veneer later.
I can't stress enough that you need to work the glue and get it as even as possible.
Next apply the glue to the shell. Even even even even.
Peel off the tape
Peel the tape off the shell and both ends of the veneer. Polyurethane glue has a mind of its own and
wants to spread its influence everywhere, so take care.
Slap that sucka on the shell already!
Poly glue uses moisture to setup and cure. Spritz a light mist of water on either the shell or veneer.
In low humidity conditions you definitely need to do this. In high humidity conditions you may not
need to do this because the wood and veneer might already have enough moisture in them to cause
the reaction. In either case it will not hurt to do this, but be aware that the more moisture there is
the faster the glue will start to set up. The glue will begin to foam and expand. When you see this
happen you better get you rear in gear!
Have plenty of our friendly blue painter's tape available, and it's even a good idea to have a bunch
of strips precut and ready to grab. Begin by aligning the veneer (non overlap end) with the line you
scribed on the shell. As you work your way around the shell, tape the edges as shown. One nice thing
about the poly glue is that it lets you move the veneer (unlike contact cement). Also, the veneer bag
sometimes wants to pull the veneer to one edge or the other and this keeps it aligned on the shell.
The seam does not have to be pulled super tight. Once in the vacuum bag, the pressure
of the bag will take out all the slack.
Another word of warning about the poly glue. If you are planning on using a stain, you'll
have to sand thoroughly any part of the shell that gets glue on it or the stain will not penetrate.
Time to Suck Sucka
Never send a boy vacuum pump to do a man vacuum pump job.
Actually many people here have good success with the smaller units. We use this
one for our CNC and need more super suction for that.
Here's the rig I use to support the shell. The platform at the bottom and the "hat" for the top
is to let the vacuum bag sit as flat as possible from the top of the shell to the bottom.
This bag is 3 ft. x 4 1/2 ft.
As the vacuum forms inside the bag, you have to check all around the circumfrence to
make sure the bag isn't bunching up anywhere, and the folds are forming cleanly.
In this next picture you can see a problem spot at the bottom of the shell.
To remedy this, I had to let a certain amount of vacuum out of the bag and adjust the bag
as it drew vacuum again. Here is what it should look like:
Once the bag has drawn full vacuum, I go over the entire surface to push down
any bubbles in the bag, and check all the folds that they are tight.
Here is how it looks when the vacuum is fully drawn.
Finishing the Veneer Seam
After your shell is dry, you will have two flaps, one overlapping the other.
Time now to cut the seam so the ends are flush against one another. Secure the shell and clamp a
square to the shell at the spot where you will be cutting off 1/8" to 1/4" of the underlying veneer.
The red arrow points to where you can see the edge of the underlying veneer.
Cut the seam using many light strokes until you have cut through both layers. Using an Exacto knife or
similarly thin blade will result in a tighter seam. Using a utility knife will result in a more open seam.
Once cut, this is what you will have. A beautiful seam. Mmmmmm.
Tape both sides of the seam to protect from glue spooge. I then spread polyurethane glue on the shell
underneath the flaps. I did not put glue on the veneer.
Using two pieces of shell scrap and a straight piece of wood, I clamped the seam and allowed it to dry.
I also put tape on the side of the shell scraps that face the seam.
NIRVANA
A beautiful seam.
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