AW Extra 9/27/12 – 21 Drum Sander Tips

21 Drum Sander Tips

Maximize your drum sander's potential.

By Dave Munkittrick


Click any image to view a larger version.

1. Skip the scrape

Eliminate laborious hand scraping of dried glue: contrary to
popular belief, you can take glue-ups directly to your drum
sander. The secrets are to use a coarse abrasive (24-grit to 60-
grit, depending on the amount of glue and how uneven the glueup
is) and feed the wood at a skewed angle. Set the sander so
it just hits the elevated gluelines. Take light cuts until 90-percent
of the glue is gone, then switch to a finer grit.

Remember, your drum sander’s greatest enemy is excess
heat. This is especially true when you sand off glue. Finer grits
(80-grit and above) and heavy cuts can generate enough heat to
melt the glue and gum up the abrasive. Skewing the work further
reduces heat build-up, because it keeps the gluelines moving
across the drum, rather than remaining in one spot on the
abrasive.


2. It's OK to skip grits–sometimes

It’s OK to skip grits below 100-grit. However, it’s best
to move through finer grits sequentially. It’s harder for
these grits to remove the scratches left by an abrasive
that’s more than one step coarser.


3. Increase belt longevity

Get 20 to 30 percent more life from your aluminum
oxide sanding belts by changing the orientation of the grit.
It’s easy to do. Simply alternate the end of the belt you
install first. You can accomplish this automatically by
removing the belt from the same side of the drum it was
installed on. That way, what was the trailing end of the belt
gets turned around and becomes the starting end.
Switching the abrasive’s orientation changes the direction
the abrasive particles hit the wood. This causes the particles
to wear more evenly, so they last longer.


4. Start with the right grit

The most common mistake people make is to start
with a grit that’s too fine. Here are some good rules of
thumb to follow when choosing a starting grit: For abrasive
planing or glue-ups, start with a 24-60 grit belt; for
sanding boards from a planer or jointer, start with 80-grit
or finer. If you have to make more than three passes with
your starting grit, you probably started too fine. (The
exception to this is abrasive planing where many passes
with a single coarse grit are sometimes needed to joint
the board flat.)


5. Dust collection is a must

Do not skimp! Removing sanding debris quickly and
efficiently is critical to effective sanding. Make sure your
machine is getting all the cfm (cubic feet per minute)
called for in the manual. Be wary of inflated cfm rates touted
by some dust collector manufacturers. Sanders are
cfm hogs because they need to pull dust off the spinning
drum before it gets carried around and deposited back on
the material being sanded. Fugitive dust will load belts
faster, reduce sander efficiency and could cause the material
to slip on the conveyor belt and possibly even kick
back at the operator. If you are getting any residual dust
left on the wood as it emerges from the drum sander, you
need a more powerful dust collector. Note: If your sander
has two 4-in. ports, you will need a 6-in. line to carry the
required cfm to the machine. Divide this 6-in. line into two
4-in. lines. It’s a mistake to divide a single 4-in. or even 5-
in. line in two because it will starve your machine of the
airflow volume it needs.


6. Start at the right height

Heavy cuts are hard on both your machine and the abrasive.
The first cut is the hardest to get right. Here’s the trick.
Unplug the machine, and slide the board into the sander so
the thickest portion is under the drum. Then lower the drum
as you spin it by hand. Stop when the sandpaper starts to
make contact with the wood. You’re good to go. Remember,
it’s much better to have a very light first cut then one that
bogs down your machine.

Once you have the initial setting, subsequent adjustments
between passes should be very small, especially with fine
grits. Shoot for cuts that are less than 1/64-in. for fine finish
work and up to 1/8-in. for abrasive planing. Also, keep in mind
stock width; glue ups that approach the machine’s capacity
require lighter cuts than a single 8-in. board. It’s a good practice
to occasionally run the stock through a second time without
adjusting the depth. If you still hear the abrasive cutting
on the second pass, the sander was probably set too deep on
the previous pass.


7. Clean paper works better and lasts longer

Use a rubber belt cleaner whenever the dust build-up
on the abrasive can’t be swept off with a brush. A loaded
belt will not cut efficiently, because the abrasive particles
are partially buried. Loaded belts build up heat rapidly,
making them prone to scorching the wood. When a
loaded belt hits a pitch pocket or a knot, the excess heat
can melt the pitch and leave a hardened streak of bakedon
sanding debris on the abrasive.

With the dust collection on, hold the cleaning stick
against the spinning drum. The soft rubber scrubs out
the embedded debris. Be sure to sweep off any debris
left on the drum and conveyor belt. Always wear eye
protection when cleaning a belt.


8. Clean up stubborn streaks

Use a length of 1/4-in. Plexiglas to remove
streaks of fused sanding debris. These
streaks are typically caused by pitch pockets
or knots and can ruin a belt. A rubber abrasive
cleaner won’t touch these baked-on rings.
Instead, hold the Plexiglas edge on the
streak. If that doesn’t do the trick, try soaking
the belt in mineral spirits or a product like
“Simple Green”, overnight. Note: Always
wear eye protection for cleaning operations.


9. Choose the right feed rate

There’s no foolproof formula for calculating optimal feed rates. A
good rule of thumb is this: the coarser the grit, the faster the feed
rate. Slower feed rates yield more drum rpm’s per inch and that helps
create the ultra smooth finish you’re looking for from the finer grits. If
you start to get some burning on the stock, bump the feed rate up
until the burning stops.

Heavy stock removal with coarse abrasives does not benefit from
a slow fed rate so it makes sense to go as fast as the machine can in
order to get the job done quickly.

When in doubt about the right speed, set the feed rate between
40 and 50 percent for your first pass. This will get you safely in the
ballpark where you can fine-turn the optimal speed for the task at
hand. Finally, listen to your machine: it will tell you if it’s working too
hard and you need to slow down.


10. Don't skimp on abrasives

Use high quality abrasives; you’ll avoid all kinds of headaches and in the long run, save money.
Look for a backing material made of cloth, polyester or a combination of the two—cloth will stretch
a bit more than polyester. Avoid paper-backed products; they’re too fragile and tear easily.

Besides selecting the correct backing material, you should also select the correct backing
weight. For a drum sander, look for an X, Y or XY weight rating on the back. This weight
range is the best compromise between durability
and flexibility.

Inexpensive abrasives tend to
use lower quality bonding
material (the stuff that holds
the grit to the paper) and
won’t last as long. Also, the
grit on inexpensive paper can
be inconsistently sized, which
can cause annoying scratch
marks on an otherwise
smooth surface.

It’s best to stick with reputable
abrasive brands like
3M, Norton and Klingspor.


11. Sand really thin boards

It’s easy to make your own veneer from resawn boards with a drum sander. Furniture repair shops love this feature because it
allows them to match the thick veneer used on period furniture. Some drum sanders can sand wood all the way down to 1/32-in.
Note: Drum sanders that use compressible materials such as hook-and-loop fasteners, soft backing under the abrasives or a soft
rubber conveyor belt cannot sand this thin.


12. Avoid burns

Burn-prone woods like cherry, maple
or pine need special care when sanding
to avoid burn marks on the wood. Try the
new zirconium or ceramic abrasives.
Both abrasives are harder than aluminum
oxide and run cooler, to help minimize
burning. This is especially useful
during abrasive planing, when heavy
cuts and coarse grits are more the norm.
As you progress to the finer grits, take
very light cuts.


13. Always finish with an orbital sander

Don’t expect a sanding machine to
give you a surface that’s ready for applying
a finish. Always finish the sanding
sequence with an orbital or random-orbit
sander. It’s best to back up one grit size
when you start your orbital sanding. So, if
you drum-sand to 180-grit, start your
orbital sanding at 150- or even 120-grit.


14. Skew the work for best results

Feed the wood through the sander at an angle. This creates an
efficient shearing cut on the wood fibers that generates less heat
than a cut that’s parallel with the grain. Less heat means less belt
loading, and that means less burning on your wood or melting of
glue lines.

A 30-degree angle gives the best shearing cut. If the work is too
wide to skew 30 degrees, do what you can; any amount of skew is
better than no skew. Finish with one or two straight-line passes
with your final grit to eliminate any cross grain scratches.


15. Sand box sides

Drum sanders work great for sanding assembled boxes
and drawer sides. People pay a lot of attention to the width
of their machines, but often ignore the depth capacities. In
general, wider machines have larger depth capacities.


16. Hold the gap

When you install a belt, it’s important to leave a gap in the
take-up slot at the end of the drum. The take-up pincher
inside the drum is spring-loaded, so it’s always pulling on the
end of the belt. The gap allows the belt to be pulled further
into the drum as it stretches during use. This keeps the belt
tight on the drum. Failure to provide this gap locks the belt in
place and renders the take-up pincher ineffective. It’s OK to
leave a slight gap or no gap where the belt winds around the
rest of the drum.


17. Save your fingerprints

Avoid skin abrasions by wearing leather
gloves whenever you handle the abrasives. I
learned this lesson when I first started using a
drum sander. At the end of a job that required
several belt changes, my fingertips were really
sore. On closer inspection I saw that my fingerprints
had been completely abraded away.

A pair of tight fitting leather gloves really
does the trick.


18. Joint wide boards

Use a drum sander to joint boards that are too wide for
your jointer. Unlike a planer, some drum sanders (typically
ones with adjustable pressure rollers) exert very little
downward pressure on the board. That allows them to
take the cup or crown out of a board (Photo A) without a
sled or support. Take light cuts and run the board concave
side down.

If your board has a severe twist (Photo B) use some
hot melt glue to attach skids to keep the board from rocking
as it passes through the sander. Once one side is
planed flat, knock off the skids and plane the other side.


19. Surface figured wood without tearout

Run a bookmatched, quartersawn oak panel through your
planer and I can guarantee you’ll be dismayed at the nasty
tearout. Try the same thing on a drum sander – perfect
results. You just can’t beat a drum sander when it comes to
surfacing figured wood. It does a great job no matter which
way the grain runs.


20. Decipher the back's alphabet soup

It’s best to know what you’re buying. Most of us
are familiar with the grit number on the back of an
abrasive, but what about all those other numbers
and letters? Manufacturers use proprietary codes
on the back of their abrasives. Some of the codes
can be cracked by visiting their website. For the
Klingspor belts in the photo at left, for example,
I went to www.klingspor.com/products/
MtlAvail.html and found that the CS311
belt is a Y-weight polyester-backed belt, open
coat, resin bond, with aluminum oxide abrasive,
and is available in 36P- to 180P- grit
sizes.

The CS411 belt is an X-weight clothbacked
belt with a resin bond and a longer
lasting alumina zirconia abrasive, available
in 24P- to 120P-grit sizes. There’s lots
more info on Klingspor’s website and on
other manufacturer’s websites as well.


21. Sand multiples to a uniform size

Drum sanders excel at surfacing to a precise dimension. Face
frame parts can be clamped together and sanded at once. The drum
sander removes all the saw marks and leaves you with parts that are
exactly equal in width.


Here are some other dust collection tips:

• Ground your machine to a plumbing run
or a ground screw on an outlet. Sanders
can generate a lot of static electricity that
cause the sanding dust to cling to the
machine and hamper collection.

• Be sure to use at least a 2-micron filter on
your dust collector. Many single stage
collectors come with dust spewing 35-
micron bags.

• Use the least amount of flex-hose possible
for more efficient airflow.


Do-It-All
Combo
Brush and
Drum Sander

The SB13’s dual contour/flat-sanding
capability is popular with small shops
that specialize in products such as
moldings, picture frames and musical
instruments

A variable speed lever lets you set the
brush speed from 400 rpm to 1200 rpm.
Variable brush speed combined with variable
conveyor speed allows the operator to set the
optimum brush strokes-per-inch for the task
at hand. The SB13 is equipped with a 1-3/4-
hp motor that runs on a standard 20-amp,
120-volt circuit.

Like its larger SuperBrush stablemates,
the SB13 can be equipped with a number of
different brush heads. The heads most commonly
used for woodworking include a flatter-
style head (Photo 2), an abrasive-impregnated
nylon brush head (Photo 3) and a
wire brush head (Photo 4).

1. The ability to mount
a drum sander
head
in the
SB13 sets it
apart from other
brush sanders.

2. A flatter-style brush
head
has strips of
serrated sandpaper
backed by bristle
brushes. This
brush excels at
sanding profile
or contoured
wood surfaces like
moldings, or frame
and panel doors. The
brush is available with 60-grit
to 400-grit abrasives.

3. An abrasive-impregnated
nylon bristle
brush
is primarily used to
scuff sand sealer coats on
moldings. This brush practically
eliminates the need for timeconsuming
hand-sanding between
coats.

4. The wire brush head is
used to distress wood
surfaces. It can make new
wood look like weathered
barn wood or like the
boards used in Southweststyle
furniture.

Source

(Note: Product availability and costs are subject to change since original publication date.)

SuperMax Tools, supermaxtools.com, 888-454-3401,
SuperBrush 13, SB13, (Includes Nylon Or Wire Brush
Head);
Flatter-style Brush Head;
Wire or Nylon Brush Head;
Drum Sander Head.

This story originally appeared in American Woodworker May 2008, issue #135.

May 2008, issue #135

Purchase this back issue.