On Wood Strip Building Techniques
updated 4/23/08
I met a fellow at a recent show who said to me, "You're
that angry guy who says, you gotta do this and you gotta do that."
I was a little surprised to hear myself characterized as "angry".
Perhaps you might think this when you read information I have written in
capital letters or in bold type.
I am not angry. I'm passionate, about building and passing
on information that will make building easier for you. How I can let you
know I have information that will make your strip building easier and fun?
I've spent the last twenty years unlearning conventional
strip building techniques. I found a lot of the
techniques, passed on in books, that were vague, poorly thought out and
just didn't work. There were parts of the strip building process that were
just not fun. I've spent the last twenty years solving these problems.
My techniques for strip building are fun.
ROB'S RULE: If you're not having fun, something's not
working the way it should.
Yes, some parts of the building process will be more fun
than others, but if you are working with dread, something is wrong. Stop!
Think about it. Ask questions. Look for answers. Too many people struggle
through a task using a poor technique or wrong tool, because they think
that's just the way it has to be. But it doesn't. There are few master
craftsman who are also good teachers AND writers. So just because they
can do it well does not mean they can teach it or communicate it well.
I'm not saying the techniques I suggest are the only way
to strip build. But the techniques I talk about here, used together as
a system make strip building simple and quick.
Novice builder will not realize that many seemingly good
techniques cause problems that must be corrected before progress can continue.
However, I have a LOT of experience and I've tried just
about everything. I've spent twenty years unlearning common strip
building wisdom. The methods I suggest reduce work, period and don't create
problems. I have to do this as a professional builder. Believe me, after
building more than 60 boats, I've eliminated techniques that cause problems
or just don't work. I do enjoy building and have fun doing it. I want
you to enjoy it too.
With the right tool and technique work is fun, work is
magic! Learning the techniques to make things is truly the magic in this
world. Creating a real boat IS fun magic. And that you can take some sticks
and glue and make a little boat that will take you, and support you miles
out to sea, is true magic!!!
Stripping Made Easy
This pages contain my latest thinking on building issues.
I'm constantly adding new ideas and clarifying old concepts to update my
plans and make building easier for you.
If I repeat myself in the following it is because these
are some of THE most important points to your success.
This page includes some of the ideas that set my building
technique apart form other builders and make your task easier. Therefore,
I present these ideas here for you to consider before you dive into the
project, since they will guide you in a different path from other strip
builders, if you choose to use them, which I hope you will.
Strip Building Theory, The
Guiding Principles
The beauty, the genius, of the strip building method is
that IF the wood strips remain in contact with the stations & stems,
AND the edge of each new strip is aligned and glued to the previous strip,
the resulting surface IS FAIR and perfect.
THE RESULTING SURFACE IS FAIR AND PERFECT!
This is the essence and genius of strip building theory.
Everybody kinda knows this, and yet nowhere have I seen
it stated clearly. The assumption is that you will have problems aligning
strip edges and you'll just have to deal with it.
Perhaps I see the beauty of the strip building method,
brightly, because as a sculptor I had to struggle with materials like clay
and plaster trying to impose a shape on these formless materials. Where
with strip building, in a simple stroke, the strips create this perfect
surface for me.
It reminds me of the scene in "Cast Away" when
Tom Hank's character is alone in the banquet room after his rescue from
the desert island and he looks at the butane candle lighter, and lights
it a few times. You know he's thinking about how he struggled and blooded
his hands trying to make fire.
NOTHING YOU DO WILL BENEFIT THIS PROJECT MORE AND ELIMINATE
EXTRA WORK than taking all the time you need to insure each strip edge
is aligned with the previous strip and each strip is in contact and remains
in contact with the forms. If you do this, your hull will start off FAIR
and you will need to do very little work to finish it! I cannot emphasize
this enough.
THE ONLY sanding needed is to round the high points along
the strip joints and to smooth the surface for finishing. Each strip is
perfectly fair, just as a plywood panel on a stitch and glue boat is perfectly
fair.
The less you do to this surface the more it will remain
fair!
Of course, the above assumes you have strips of regular
thickness, if B&C, it must be correctly centered, and that your station/stem
set-up is correct.
The random orbital sander allows the builder to take advantage
of the strip building method in a way no other tool can. The random orbital
sander uses the FULL FLAT SURFACE of the sanding disk to ride on high spots
and level and round the surface TO the lowest point of VISUAL REFERENCE,
in this case, the surface down the center of each strip which is perfectly
fair.
You cannot create a fair and regular surface with random
tool use.
You must carefully define the areas to focus tool use.
Imagine working on a stitch & glue boat using a aggressive
edge cutting sander or a plane on the plywood surface. You would quickly
cut through the top veneer, destroying the fair surface naturally created
by the plywood panel .
It just doesn't make sense to work a fair plywood surface
with a plane or edge cutting sander. It should make just as little sense
to work a well stripped, fair hull with a plane or edge cutting sander.
It will be counter productive.
If you take the time to align your strip edges your hull
will be nearly perfect.
I understand that quite a few builders have difficulty
in aligning strip edges.
Traditional strip building techniques use 1/4" strips
and staples or brads to FORCE strips into place. This method creates real
problems in the most difficult areas around the keel/stems. While this
worked reasonably well for simple football shaped hulls, for more complex
modern hull shapes, kayak shapes and stapleless stripping methods, 1/4"
traditional force stripping, makes perfect alignment of strips at the hull
stems very difficult.
I've developed a number of modifications to the traditional
stripping technique to solve these problems.
The three big differences in my stripping technique
that make stripping 3X easier than anyone else are:
First, use 3/16" thick strips instead of 1/4". 3/16" thick strips are more flexible
and are easier to twist, bend and align. The strength of stripper construction
is in the fiberglass sheathing.
Second, use northern white cedar
to strip below the waterline. The area below the waterline is the most
difficult part of the hull to strip. Northern white cedar is more flexible
than other softwoods and has always been the preferred wood for canoe building
for hundreds of years because of it's bending properties.
You can buy northern white cedar strips from kit makers
or buy boards from companies listed
on my web site links page.
Third; Use a heat gun to apply
dry heat to bend and twist strips into place instead of relying on force.
A heat gun boils the water in the wood to bend without
having to wet the wood. This allows you to glue immediately without having
to wait for wood to dry as you would if you used a wet/steam heat method.
The heat gun applies local heat to a small area so you
don't need a large box or other apparatus. There is no waiting, no clamping,
or drying time, as in wet bending.
Northern white cedar is the best wood to utilize the heat
gun method of bending for the already stated natural bending properties.
But also, because NWC is typically air dried, the natural glue (lignin)
which holds the wood fibers together can be reactivated by heat. Kiln drying
wood alters the lignin and it will not respond as well to heat/steam bending.
3/16" Plus
Using 3/16" strips RELIES on the proper use
of a random orbital sander to level and smooth the strip surface.
A random orbital sander works like no other surfacing
tool by riding on the high spots and utilizes disk speed and disk grit
instead of high motor power and tool weight. The round pad and random stroke
will not cut deeply into a surface as long as the full pad is held FLAT
against the work surface. These features make the random orbital sander
ideal for sanding the complex curves of a stripper.
The round pad and random stroke will not cut deeply into
a surface, as long as the full pad is held FLAT against the work surface.
IF the ROS is HELD FLAT against
the surface, it will produce a fair surface.
THIS IS CRITICAL TO SUCCESS.
The ROS is moved over the surface until a uniform sanded
surface results.
You must assess the progress VISUALLY.
The original unsanded surface is your visual reference
letting you know when to move on. This will happen JUST as the lowest center
of each strip is sanded in each area. Then you must move on. This sanding
method takes off very little wood.
Rough sand the surface with a random orbital sander and
60 grit paper. Then WET, I mean WET the surface to raise the grain. The
cut marks from the 60 grit paper will disappear. All dents and staple holes
will raise and close. After the wood dries you can sand with 120 grit because
the soft wood needs no courser grit to proceed to finishing steps.
Other sanders, or the ROS itself, CAN be very aggressive
if weight and power is applied with an edge, or only part of the sanding
pad. This will result in an irregular surface. Don't do it! If you must,
know you are creating a potential problem spot.
It is common for people unfamiliar with sanding to use
a sandpaper grit of 80 to rough sand their stripper. When it does not level
the surface quickly, they use an edge of the sanding disk, LIKE AN ERASER,
to aggressively remove a blemish, cutting a low spot. This is a mistake
and will leave an unfair surface.
Most woodworkers will tell you to use 80 grit because
this is the coarsest paper grit they use.
BUT they are only removing machine marks from flat boards that have had
defects and irregularities of the surface removed by a thickness planer.
On a stripper, the wood strips often have deep saw blade
marks on the surface and strip joins that are high and must be leveled.
This calls for 60 grit sandpaper to shape and level the curved surface
of the boat.
This is why I use the ROS and a courser 60 grit paper
which will level and fair the surface quickly. If you are concerned with
the aggressiveness of sanding cedar with 60 grit paper, try sanding all
the way through a strip panel while holding the sanding pad flat. It will
take a long, long time. Then sand using an edge. It will cut much faster.
It is important to use a soft backing pad on the ROS because
this will conform better to the curved surfaces of a boat. Most ROS come
with a medium/hard backing pad for designed for flat surfaces. Buy a soft
backing pad and buy an even softer "interface" pad that goes
between your backing pad and the sandpaper. This "interface"
pad will allow you to sand in the deep concave sections of the hull bilge.
After rough sanding with 60 grit, WET down the wood surface,
with a wet sponge, to raise the grain, raise dents and close any staple
holes.
These stripping techniques and the random orbital sanding
method I describe above are the foundation of my stripper construction
technique. Each step is interlocked into the next. If you can't bend strips
you can't align the edges. If you can't align the edges, you will have
to sand more, or plane to establish a common surface and you will destroy
the natural fair surface created by using wood strips. If your strips have
not naturally created a fair surface the ROS will follow the irregularities
of that poor surface.
I urge you to focus your attention on pre-fitting each
strip.
Test fit each strip. Totally clamp the strip in place
BEFORE GLUING using spring clamps. If you cannot get the strip to fit in
a test clamp up, it will not fit with force once you apply the glue. Dry
fit, clamp, and use a heat gun to bend strips so they fit perfectly before
applying glue. This will reduce work on every future step.
If you work to align your strips the surface will be nearly
perfect and you will have less work smoothing the hull.
Any stapleless method that does not tack your strips
firmly to the stations can not keep the strips from warping out of alignment.
AFTER you have stripped your hull, if you have strips
that are mis-aligned 1/32" or more, then fix the strip alignment before
sanding.
Use a new blade in a utility knife and cut on the joint,
apply glue and realign the strip edges.
If you use 3/16" strips they will be more flexible.
If you use northern white cedar it will be even more
flexible.
And if you also use a heat gun to bend and twist strips
into place you will find it very easy to strip a perfect fair hull or deck.
Any one of these suggestions will make stripping easier.
If you will use all three suggestions you will find stripping
a totally painless dream.
By understanding the basic theory of strip building, by
looking at WHY we are doing something, we can focus our labors in areas
that are most productive and eliminate random and counterproductive steps.
I hope you will find this useful.
Random Orbital Sanders
The random orbital sander allows the builder to take advantage
of the strip building method in a way no other tool can. The random orbital
sander uses the FULL FLAT SURFACE of the sanding disk to ride on high spots
and level the surface
The beauty of the ROS is the control you have over the
aggressiveness of the cutting action. You have five levels of control which
are: disk grit, disk speed, pressure, flat or edge sanding with the disk,
and finally visual input. The last is most important. You can and must
observe the surface being sanded to tell exactly how much material is removed.
ROS use must be totally visually cued.
Variable speed is important because it allows you more
control. Fast speeds for large open flat sanding and slower speeds for
small close quarters. If you are worried about the aggressiveness of a
courser grit, you can slow down the disk speed to have more control.
The Dustless feature is important because it removes debris
from the paper, so the paper works longer and better and won't clog as
fast.
And if you hook your ROS to a good quality shop vacuum,
you'll have almost no dust in your lungs. I would not consider using
a ROS without a hook-up to a shop vac.
Light-weight is important because you must hold the sander
over internal and external curved surfaces which are often angled or vertical.
The light-weight ROS will allow you to work for a long time without getting
tired of holding the tool weight.
The heavy more powerful, 6" ROS are intended for
large mostly flat surfaces. More weight and power are important when you
are working on large flat surfaces because the weight will help in material
removal as will the power. This is the intent behind belt sanders which
are designed for flat surfacing. The combination of heavy weight and high
power remove material fast. Too fast and too hard to control for the finesse
needed to keep a stripper hull fair.
ROS come with a hard disk pad for sanding flat surfaces.
The first thing you want to do it buy a soft disk pad which will conform
better to the curved surfaces of a boat.
For the mostly curved surfaces of stripper boats, especially
the interiors, a light-weight sander is much easier to handle for long
periods of time and more control is available because material removal
is more dependent on disk speed and grit size than weight and power.
A very important accessory for interior sanding is a soft
but firm "interface" backing pad. This is attached to the regular
backing pad and the sanding disk is placed on top. This soft interface
pad allows the sanding disk to conform to tight interior curves without
the edge of the sanding disk cutting ripples into the soft wood. Unfortunately,
I've had a hard time finding one for my 8 hole Bosch sander so I made my
own. I used an old worn disk backing disk from my ROS and glued 1/4"
thick piece of the L200 foam I use for my kayak seats to it. Then I glued
some hook material so I'd be able to use my loop sanding disks. I cut holes
in the pad for the dust removal. It work's great. If you buy an interface
pad or make your own make certain the foam backing is quite firm or the
sanding will not be effective.
The ideal ROS for strip building is light-weight, variable
speed, and dustless, 5" disc with hook and loop paper. If I had to
choose one from the current crop I'd go for the Makita BO5020, Porter Cable
333VS or DeWalt DW423Kat about $85 at Tools on Sale - 800-328-0457 (free
shipping). If you really want cheap, Grizzly makes one for $25 - see www.grizzly.com
Update 4/08
Time to buy a new ROS as my old faithful Bosch died. I
figured after twenty years and all the sanding I do I'd get the best, so
I started looking at the highly touted highly priced Festool systems. But
after many test runs I could not see or feel a marked improvement over
my old Bosch ROS teamed with a Bosch triggered vac.
So, I replaced my twenty year old Bosch ROS with the Makita
BO5021-K 5" variable speed sander. I choose this 5" sander because
it has a D handle design like my old Bosch. I like this because it allows
me more one or two handed holding positions which helps relieve vibration
fatigue. Plus the dust outlet is a round tube that could be easily connected
to a shop vac. And when this style is connected to a vac the balance moves
to the D handle because of the weight of the vac hose. Plus, the Makita
uses the same 8 hole pattern 5" hook and loop sanding disks I had
stock piled for my Bosch ROS.
An interface pad is mandatory, because the Makita has
only the standard hard backing pad available. The Makita 743022A 5"
contour surf backing pad is required. At the same time I bought the Fein
Turbo I trigger activated shop vac to use with the Makita ROS. The Fein
vac is very quiet and very strong. Fein makes a stepped hose adapter that
mates the Fein hose to the Makita ROS dust port perfectly. I also found
the Fein hose and the Fein stepped adapter allowed me to connect to other
sanders and tools I had that I could not do so before. I upgraded the standard
cloth filter on the Fein vac to the 1 micron filter kit and paper dust
bags.
This grouping of the Makita ROS and the Fein vac is great!
This is the best I've used. If you are in the market for ROS and vac I
recommend this pair.
Staples or Stapleless Stripping
I think the use of staples over the whole boat
is the best way to go on your first stripper.
You can focus on aligning your strip edges, which will
give you the best results.
Then if you build another boat (of course you'll build
another boat even if you don't think so now) you'll know how the strips
should fit and if they don't do so, you will know it is a problem with
the stapleless method you are using, not your stripping ability.
When you work on your boat you spend most of the time
with your nose about three inches from the boat. You see those staple holes
and they look big.
A lot of energy and time have been spent hiding filling
and figuring out stapleless stripping methods. The only time I notice staple
holes on a boat is when I'm talking to someone about how to strip without
them.
I've seen many stripper boats that looked great with staple
holes, and I never noticed them when we weren't talking about staples.
I don't have confidence in any stapleless stripping method
that doesn't somehow keep each strip in contact with the stations and stems.
Most stapleless stripping methods use clamps to hold strips
in place and against the forms until the glue has set. Then when the clamps
are removed to add a new strip, the previous strips are free to move away
from the forms. If they can move, they will move, and cause mis-aligned
strips and improper hull shape.
This is not acceptable to me. If there is nothing continuously
holding each of your strips to the stations and stems, how can you expect
them not to move, shift and come away from the forms?
The only stapleless method I know of that really works
is the hot glue stapleless method I use.
Rob's Hot Glue Tips for Fast Stapless Stripping
I like hot glue. I learned to use hot glue in
working as a professional wood worker to make all kinds of jigs. Most woodworkers
know what a great tool hot glue is for the temporary holding of pieces
of wood.
The trick to hot glue is that it will release cleanly
when it is sheared off by a blow from the side.
I use hot glue for the deck and hull sides on my kayaks
and I use staples for the hull bottom.
I use 3/16" strips, which are more flexible than
1/4", on all my boats.
Hull bottoms are the most difficult to strip having the
most twisted and bending of strips. I use northern white cedar for my hull
bottoms because northern white cedar is the most flexible and easily bent
wood for strippers
Hot Glue
Pros Hot glue leaves no holes. Hot glue
has good holding power if the glue has enough time to harden thoroughly.
A good option is to use hot glue for the deck even if you use brads or
staples for the hull. Get the Right Hot glue, one specifically for bonding
wood. I currently use HS-300 ,10" x 7/16" sticks from Hotstik.com
I currently use their HS300 HP Clear Glue Sticks designed
for gluing hardwood and softwoods.This glue has all the right characteristics
for strip building.
Cons Strips must be held in place by hand or with
some type of clamping method for at least a minute for the glue to achieve
full holding power. The process is slower than staples.
MAKE CERTAIN the hot glue you buy is intended for use
on wood.
Western red cedar is the best wood to use with hot glue.
The glue holds well and releases without pulling a chunks of wood.
White cedar works well also, with some tear-out if too
much glue is used.
I use northern white cedar on ALL of my boat hulls.
I use plywood stations and leave the wood bare and unsealed
where I will apply hot glue. This insures maximum holding power for the
hot glue. On my hull bottoms I use staples. Here I apply masking tape to
the station edges. On the stems I apply duct tape so the stems will be
easy to remove later.
NOTHING YOU DO WILL BENEFIT THIS PROJECT MORE AND ELIMINATE
EXTRA WORK than taking all the time you need to
insure each strip edge is aligned with the previous strip and each strip
is in contact and remains in contact with the forms.
If you do this, your hull will start off FAIR and you
will need to do very little work to finish it! I cannot emphasize this
enough. If after you are done stripping your hull and a strip is as much
as 1/32" high, cut through the joint with a utility blade and align
and re-glue the strips.
PRE-FIT EACH STRIP holding
it in place with spring clamps. At the stems or any place that needs more
holding power drive a sheetrock screw into the station (about 3/16"
in from the edge) behind where the strip will lie and clamp the strip in
place with a spring clamp. This will also later hold the strip in place
while the hot glue sets.
Mark the alignment of each
new strip to the previous one with an X with a pencil so you won't confuse
marks from one strip with past ones.
Use spring clamps between
stations to align strips. The strip must fit PERFECTLY. If not, do what
you need to do to make it fit.
Use a heat gun to bend or
twist stubborn strips.
Make certain there is nothing
keeping the strip from fitting tightly like hard hot glue drips or other
debris on station edges.
Starting at the center stations apply hot glue to two
stations and press the new strip in place.
Use as small an amount of hot glue as possible usually
about a 1/8" diameter drop. Small amounts of hot glue set up faster,
release more easily, yet hold very well.
Work toward each stem.
Holding the strip in place while the hot glue hardens
is okay in the middle but is not the best choice at the stems.
It is easy to become impatient and let go too early. You
may come back to this spot and find the strip has moved out of alignment.
Apply the hot glue and clamp the strip in place with a small spring clamp
to the previously installed sheetrock screws in the stations.
By the time I've worked toward the second stem the first
stem end's hot glue has set and I can remove the spring clamps. By the
time I remove these clamps the second stem's clamps can be removed and
I can go on to applying the next strip.
Clamp strips between stations with spring clamps and use
beads of hot glue on the strip joint to hold after the clamp is removed
in 60 seconds
The beads of hot glue are used like a clamp to hold the
strips in alignment and tightly together BETWEEN stations. I use the hot
glue beads on the hull and deck.
Once I've applied the strip to the station, with hot glue
(or staples on the hull bottom) I use spring clamps to align the strips
and tighten the strip joint BETWEEN stations. By applying beads of hot
glue on the strip joint (like stitches) I can remove the spring clamps
in about a minute and apply my next strip.
These beads (use the low setting on glue gun) must be
thick, so when they cool, the thickness of the bead will be hard enough
to hold the strip edges in alignment. To get an idea of how well these
beads can do this try placing two scrap strips together and tack along
the joint with beads of hot glue. You will be impressed with how well they
hold.
When you buy a glue gun try to find one with a high and
low heat setting. The low setting will allow you to make beads easily.
All the hot glue beads are easily removed with a paint
scraper along with other traces of glue.
You are unlimited in the number of new strips you can
apply since all clamps are removed after 60 seconds.
Go over the newly applied strip to make certain all edges
are aligned and snug against the stations and stems. If your strips are
tight and aligned you will literally save yourself hours of work down the
road. I cannot emphasize enough that nothing you do during your strip building
project will pay off more, than taking the time now to ensure each strip
fits perfectly and all edges are aligned.
In spots that need a lot of holding power use hot glue
with a piece of 3/16" X 3/16' strip.
I cut 3/4" strips to a 1/16" thickness and use
to bridge strip gaps anywhere I wish I had another station.
All the beads and strip pieces can be easily removed with
a paint scraper.
The trick to removing hot glue beads is to hold the scraper
so the scraper handle is nearly perpendicular to the hull surface.
THIS WILL POINT THE SCRAPER BLADE EDGE AND THE FORWARD
FORCE OF THE SCRAPER, TO SHEAR OFF THE HOT GLUE CLEANLY.
If you have any trouble with large glue blobs or strip
bits held with hot glue, use a chisel to pare away glue or wood before
scraping
To remove deck and hull from hot glue, start removing
the deck from the stations by wedging a putty knife at the outside edges
of the stations. Lift the edge of the deck JUST ENOUGH to insert a large
screw driver blade/shaft or flat pry bar.
Do not pry because this could crack the fiberglass on
the deck.
CAUTION Please only use this knock out technique on the
stations by hitting them from the side.
DO NOT PRY!
Use a very large screw driver to reach the stations through
the gap between the deck and hull. Lay the flat of the screw driver blade
against the station. RAP VERY FIRMLY on the middle of the screw driver
shaft with a mallet or dead blow mallet to knock out the stations without
damaging the deck. Hit stations toward the center of the boat where the
larger beam will facilitate removal. You will be surprised at how easily,
quickly and cleanly the stations will pop out.
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