and Maintenance of a Traditional Wooden Water Wheel
There are two basic schools of thought on how to start a water mill.
The one method is to start the mill with the millstones together and then
open the control gate letting the water flow from the sluice box over the
chute and onto the water wheel. Once you hear the water crashing over filling
the buckets you gently lift the runner stone that will cause the millstone,
gears (belting), and water wheel to turn. Once the millstone seems like
it is up to operating speed you then tenter the millstones. The other method
of starting the mills is to have the runner stone raised at the full height
of its linkage. Then you open the control gate letting the water flow from
the sluice box over the chute and onto the water wheel. The water wheel
will begin to turn when the weight over takes the balance of the water wheel.
When the millstone begins to pick up speed you then gently lower the runner
millstone to tenter the two stones. Both methods work equally as well. The
main object is not to over speed the gearing and cause harm to it. Another
concern is not to allow a huge accumulation of unground grain to accumulate
between the two millstones. Then they will have to work through that amount
of grain before the millstones they can be properly tentered. If the millstones
were cleaned out the last time the mill operated (between the stones and
around the cribbing under the vat) the millstones will have to grind about
25 pounds (depending upon the diameter of the millstones) before meal (chop)
is flowing at its normal rate down the chute.
At with many things there are also two basic schools of thought on how to
stop a water mill. One method is to simply close the control gate of the
water wheel and gently allow the entire mill to stop. The mill will basically
stop in mid grind or it will grind to a halt. This means there is still
grain in various stages of being ground between the millstones and there
still may be water in the wheel. The problem with this method is the fact
that there still may be water in the buckets of the water wheel, and if
the runner stone is lifted up with the millstone crane to clean between
then you would be in for a sudden terrifying surprise once you slightly
lifted the runner stone. The other method involves closing the control gate
as you slowly raise the runner stone. The motion of the mill and the millstones
will continue until all of the water is exited the water wheel and the balance
of the water wheel is once again equalized. The problem with the second
method is that if someone, something is caught in the machinery, or there
is a problem with the mill, it will continue to turn for several minutes
causing in some cases more harm or damage.
The third method of quickly stopping the mill could be employed. This involves
taking a handful of grain from the shoe and quickly pushing it into the
eye of the millstones. This will begin to choke down the millstones like
an automobile gets too much gas and stalls. Once the millstones have begun
to choke down you then lower the runner stone onto the accumulated bed of
grain that now lies between the two millstones. The weight of the two millstones
becomes one and over takes the weight of the water flowing onto the water
wheel. This acts as an emergency brake. Since water mills do not have brakes
like wind mills. The problem with this method is that it puts strain on
the gears. If the gear teeth are worn too thin they may break like match
sticks, but if someone is caught in the machinery you take that risk. To
start the mill again just simply raise the runner millstone until the system
starts moving again until it gets back up to speed and then gradually work
through the extra grain and then tenter the millstones. This method generally
does not work for millstones that are belt driven, they leather belt with
snap or jump off of the pulleys.
If you constantly have to tenter the millstones, then something is out of
whack. This usually means the millstones need to be leveled and balanced.
The millstones once properly tentered should stay that way and grind constantly
all day unless one of the other factors are changed. A mill is like a machine
in a machine shop. You have "speed," the flow of water more or
less. The more speed or water this would mean the faster the mill should
go and then grind more grain. Then you have "feed," this is the
flow of grain into the millstones, more or less. Then you have "cut,"
this is the distance between the millstones that regulate the grinding of
the millstones. The closer the millstone the finer the grind and the farther
apart the millstones the coarser the grind. The miller or the mill operator
determines the settings for how much he wants to grind and what type of
product he wants to produce. He may want to grind 50 pounds in 10 minutes.
or if he was demonstrating the process of milling to the public then the
may want to adjust the mill to grind that 50 pounds in an hour or more.
The factor that compounds this is how much moisture is in the grain. Too
much or too little and the grain won't grind or bolt properly. It is much
easier for the miller to add more moisture to temper and condition the wheat
than to eliminate moisture from the grain. This then arises the problem
with grinding grains in the United Kingdom, it is too damp there most of
the time and it makes it difficult to grind and bolt meal. One solution
is to mix grain with the opposite amount of moisture together and then grind
them together. One time of wheat that may have too much moisture may be
soft wheat mixed with hard wheat which tends to be too dry, once mixed together
in equal amounts produces all-purpose flour.
Another important issue facing many restored mills is "to idle,"
or "not to idle." In other words it could be taken to mean, "to
die a slow death," or "live to grind another day." In many
grist mills open to the public they cannot operate continuously like a real
mill, so many have taken to idling the water wheel when not grinding to
show some motion of the machinery. The average traditional wooden water
wheel weights 4 thousand pounds (you add water and moisture then it can
weigh up to 10 thousand pounds), and that water wheel is mean or designed
to be pulling about the equal weight inside of the mill. If the water wheel
is allowed to turn with out the load and the process of grinding, then the
water wheel will use is energy to destroy itself. A water wheel is designed
for one propose to grind grain. If it is not used for that propose then
the energy it creates will be used to slowly destroy itself over time.
Some historic mills I have observed the policy that they idle the water
wheel with the runner millstone raised on the spindle. Never raise the millstones
and idle the water wheel in this manor. This is not a good policy or activity.
The entire weight of the upper runner millstone is on the bottom millstone
spindle bearing. This bearing is not meant to take the weight of the millstone
and it will die within about a year or less. When the millstones are grinding
grain the weight of the upper millstone is transferred to the action of
grinding. The turning millstone is floating on a moving sheet of grain and
there is no weight upon the bottom bearing. The millstone spindle bearing
of properly cared for (kept fill of oil, clean of debris such as wood chips
and metal shavings) if the babbitting is good there is no reason it should
not last over a hundred years or more. Also with no grain flowing into a
turning millstones this invites a visitor to toss something in between the
millstones when he is not looking like metal coins. This could severely
damage the millstones, create sparks which could blow up the mill or cause
the runner millstone to jump the spindle.
This one was rebuilt by the foundry in Fredrick, Maryland, after one
installed originally by the Fitz Water Wheel Companies restoration of Peirce
Mill during the 1930's. The bearing mounts in the center of the water wheel
on a shelf underneath the water wheel and on the inboard side of the mill
wall. Behind the bearing is one half of the main vertical bearing that mounts
on a cross beam just above the great spur wheel. Inside of the bearing journal
is a coupling where the basment shaft is coupled to the shaft on the first
floor. The same sort of coupling is inside of the journals bearing on the
second and attic floors.
A traditional wooden water wheel has two bearings, the outside or "outboard"
bearing and the one inside of the mill, the "inboard" bearing.
The inboard bearing usually give no problems even if it is flooded by the
stream once and a while. It is the outboard is the one that offers problems
because it is exposed to more wetting by the water wheel. The wall behind
the water wheel or its wet shadow should be either stone or covered with
waterproof material such as tin sheeting. Because of the turning motion
and the weight of the water wheel the water wheel wants to turn in one direction,
and because of the weight or the resistance effect of the grinding machinery,
it wants to drag backwards. This sometimes causes strains in the center
of the water wheel shaft in about the location of where it passes through
the wall of the mill. This problems can be helped by building a water wheel
shaft carriage bearing. An iron band is wedged in place above the bearing
around the water wheel shaft and made to run on three rollers at three separate
points. For a drawing of this bearing see my drawings of the water wheel.
A welding shop can easily fabricate one of these bearings. The roller bearings
should be made adjustable so they can be made to move in and out so they
make contact with the iron band around the water wheel shaft. The three
bearings can be easily aligned and should be heavily greased. Another band
outside of the wall is sometimes helpful to stop the flow of water along
the shaft and damaging this bearing. The minute one of the rollers lock
up it means trouble, but if properly cared for it will gives years of service.
A metal water wheel can have problems and its shafts can become twisted
A wooden and even a metal water wheel can suffer from balance problems.
Some have said that millwrights would design a mill so the water wheel would
be on the side of the building that faces the moving path of the sun. Why?
So during the winter months the sun would melt the ice buildup on the water
wheel. If a water wheel is allowed to stand in the sun, the sun will try
out the side and faces the sun while the part that remains in shadow remains
water logged. This will cause the water wheel to become out of balance by
several thousand pounds. To lessen this effect of the sun a water line can
be placed under the sluice box and chute with a series of holes to allow
a sprays of water to cover the water wheel. This is a good practice for
the summer months but should be shut off during the winter months at about
the same times as when ice would form on puddles around the mill. If a water
wheel becomes out of balance by the sun it should be locked down in place
by the weight of the two millstones together and run water over the dry
side of the water wheel until the wheel becomes equalized. A metal water
wheel has to be balanced like an automobile tire with the adding of metal
If water is directed upon a water wheel not in the direction the water wheel
rotates a phenomenon will develop known as "shock" which will
retard and in many cases the water wheel to stop from turning especially
with a water wheels that is out of balance. Generally only wooden water
wheels suffer for being out of balance but rebuilt metal wheels sometimes
also have this problem. The balance of the water wheel will greatly effect
if ability of the wheel to rotate properly. An out of balance water wheel
will not rotate properly and cause more strain on the gears. If shock is
effecting a wooden water wheel it will sit there for hours without turning
unless it is given a "kick" start. An out of balance water wheel
will slow in its rotation when it reaches an imbalance point. When you stop
the mill you can also see that the water wheel may be out of balance wheel
with out an internal load will sometimes it may begin to turn backwards
and seesaw back and forth until it stops with the heavy end of the water
wheel downward. This can also create a problem when pulling one millstone
out of gear to engage another one. A simple solution is to engage the other
millstone (with the two stones together) before disengaging the first one
so you always have the weight of one pair of millstones stopping the out
of balance from turning the wheel wildly.
An out of balance water wheel will cause strain on the bearing, gear teeth
and gear faces, and become hazardous when pulling stone nut gears out of
mesh or lifting the runner stone for dressing.
Ice build up on a wooden water wheel can create operation problems in the
winter months. I have operated a traditional wooden water wheel through
many a winter with no ice buildup. Some winters I have operated a water
wheel with an even coating of ice with no problems while other winters the
ice has prevented me from operating the water wheel for months. When the
water wheel becomes covered in ice the trick is to test it first (like during
the summer months) find a place that you can turn the water wheel to check
it for balance. If the wheel is in balance operate you can operate the mill.
You know that the wheel is in balance when you turn it and stop the wheel
it will not continue to turn in either direction. If a wheel is out of balance
the thing to do is lock it down with the weight of the millstones and run
water over the water wheel. This is the best means of removing ice buildup
on a water wheel is to run ice over the wheel. An ax, pick, and other tools
can damage the wood of the water wheel besides where you are standing may
be covered with ice there is an additional danger factor. Not to mention
standing of ladders propped against the water wheel or siting on an ice
Too much water in the stream can be a bad thing when the stream floods.
The first parts effected seem to be the rising waters in the tail race.
If a mill is operated regularly the mud and silt should be kept flushed
out of the tail race. It may be helpful to have a screen or trash rack across
the mouth of the tail race to prevent floating debris from coming back up
the tail race and damage the water wheel. I have operated a wooden water
wheel with the lower one third of the water wheel covered with back water.
You can hear the sounds of water being sucked and trapped in the buckets.
The water wheel will reach the point that you can not put enough water onto
the wheel to make it turn. The best policy is not to operate the water wheel
when the stream is flooding to keep silt and small debris from damaging
the water wheel. Operating a wheel in back water you can suck in logs into
the wheel and damage and destroy the buckets. Also not to mention loosing
loose bucket fronts in the rising water. An overshot water wheel suffers
more from the problem of back water because it is turning in an opposite
direction to that of the rising water against the wheel. A breast water
wheel has much less problems because it is turning in the same direction
as the water is moving out of the water wheel. One solution is to vent your
water wheel. A metal water wheel will have holes in the buckets to vent
out air or allow all of the water to drain out of of the wheel when it is
stopped. A wooden water wheel may sometimes have round holes with leather
flaps that open and close to allow air to escape when the buckets are filling.
Every day the mill is operated the inboard and outboard bearings should
be lubricated along with the wooden gears mounted on the inboard end of
the shaft in the mill's basement. Hey it is a wooden water wheel, once built
nothing should be done with it until it needs replacement? Wrong assumption.
A wooden water wheel needs regular maintenance to increase its life time.
The average wooden water wheel will last 10 to 20 years and possibly 30
years or more. To keep a water wheel in long years of service means that
it should be regularly maintained. This means crawling into the water wheel
to check the wedges that hold the arms tight in the water wheel. As the
water wheel rotates a water wheel will tends to pull itself out of round.
This will in time cause the arms of the water wheel to become loose and
move in and out of their sockets. The wedges should be regularly checked
and tightened. If the water wheel wedges become split or water logged they
should be replaced with new wedges. A wooden pounding block should be used
to pound in the wedges and directly by the head of a hammer. The bolts that
hold the sandwich sections of the cant and rim boards should be tightened.
The rods that pass through one side to the other side should be replace
when rusted and broken. It these rods suddenly begin to break on their own
they you know you have movement in the wheel.
The rim plate or shroud plate the outer covering of the sandwiched sections
of the felloe, cant and shroud boards should be kept in place and tight.
A piece of either wooden or metal plate molding that cover the outer edges
to protect the wood and its layers from damage by water and ice. This covering
is either screwed down or bolted down tight against the circumference of
both rims of the water wheel. This covering also keeps the front bucket
board in place. The bucket boards should be kept nailed down and square
nails work best (if driven in the proper direction) to prevent the wood
The old saying goes something like: "The old wheels creak the most,"
but they don't have to. When a water wheel starts making a creaking sounds
this means that there is something wrong with the wheel and it is trying
to tell you something, "like fix me." The water wheel that creaks
the most is the one that is not properly maintained, and age has nothing
to do with it. I worked in one mill where when I began working there I picked
up a bushel basket of wedges from the gear pit in the mills basement. The
old miller just was not able to climb down and pick up wedges. It was easier
for him to constantly add now ones. Wedges and bucket boards that fall out
of a water wheel tend to get carried down stream by the tail water and disappear.
You need to put on your coveralls and climb into the water wheel if need
be. Always lock down the machinery with the millstones. A board or planks
can be placed on one side of the arms if a platform needs to be created.
The bearings should be regularly maintained and the shaft of the water wheel
should be checked once and a while to check it for level and trueness. If
you have to lift or move a water wheel shaft a hydraulic jack should be
used with a piston separate from the pump crank by a long hose. This will
save lives and limbs if the jack pumping action does not take place under
the heavy shaft in case if falls. If you buy a mill or go to work in a mill
this should be one of your first purchases and the second should be a grease
gun. The first thing you should check is the condition of the millstone
crane. This means take off the iron hardware and walk the crane out of its
foot pad and head plate and check the crane's top and bottom post pins for
A water wheel really needs less maintenance and attention than other parts
of the mill but that does not mean it should be ignored. The water wheel
should be locked down at night to prevent turning. As soon as you go home
people and kids will come along and climb into the inside of the water wheel
or onto the buckets to have their picture taken. Signs and fences don't
really matter if someone is hurt, killed or injured this will lead to a
court case. The best preventive means is to lock down the water wheel when
it is not turning operating the mill. If you let a water wheel turn or idle
during the time in which the mill is closed people will come along and stick
boards into the turning wheel just to see what would happen. If you spend
50 or 100 thousand dollars on car you don't let it sit there with the doors
unlocked and the key in the ignition to let someone go out and wreck it
and get killed. There is a lot of power behind water and it does not discriminate
between grinding grain or grinding up people.
Inspect the shaft, water wheel and attached master or greater face gear
from time to time. If you see mold growing on the wood that means the roots
of the mold on the surfaces is effecting the wood you do not see. A pocket
knife is a good tool to check the condition of the wood. Open the knife
and try and stick the point of the blade into the wood. If it sinks in the
the wood like butter you have problems with the condition of the wood. Also
watch for water running out of cracks in the shaft and socket openings for
the greater face gear. If you have water coming out that means you have
rot on the interior of the water wheel shaft. Wooden water wheel shafts
can presents some interesting problems but a wooden water wheel bolted down
to an iron hub on an iron shaft will present even greater problems. Wood
is a living and breathing thing. It does not matter that is no longer a
tree. It is still a living thing and effected by the seasonal and climatic
conditions or changes. You may not have a calendar or date book the mill
will tell you when the calendar changes and it becomes winter or spring.
There are some times of the year that every time you turn around the wedges
are always falling out of gears and arms on shafts, and there are other
times of the year that (the wood is so swelled up) the wedges could not
be pulled out if your life depends upon it.
I should mention water wheel shaft gudgeons. Their installation is discussed
on another page, "The Construction of a Wooden Water Wheel." If
the gudgeons were not installed properly they will cause you to have maintenance
problems before too long. They should be inspected. Gudgeons should be installed
with the wedges pounded in a saw cut one inch way from the saw cut made
for the wings of the gudgeons. This will then press the wood of the shaft
tight against the wings and hold the gudgeon in place. Problems arise when
the gudgeons and there wedges are placed in the same slot. The wedges become
water logged and they will slide across the metal plate surface of the wing
of the gudgeon. I have seen where people have mistaken installed gudgeons
incorrectly, had problems with them, and then added a metal plate in the
slot with the wedges and wings. Once the wedges become wet or water logged
it will act as a roller sliding between the two metal surfaces and the gudgeon
will come out for sure.
I should say something about wood preservatives. On one of my many mill
trips with the late Charles Howell we came across an old wooden overshot
water wheel inside of an old mill in Perry County, Pennsylvania. The reason
that the old water wheel was in a perfect state of preservations was (1)
it was located inside of the mill structure, (2) it was not in contact with
the water, (3) and the water wheel had not been used in decades. Later on
the same trip we saw an good example of how not to build a water wheel.
We came across a wooden water wheel that was built on a Fitz Water Wheel
shaft and hubs. The wood was pressure treated (green) lumber. One of the
warnings on the label is that the wood should "Never be in contact
with water, used on docks, and it is extremely harmful to aquatic life."
On another trip later I saw a sluice box that had been also rebuilt with
green pressure treated lumber. Don't they realize that the wood is treated
with arsenic. That is why they say don't paint it for so many years for
the arsenic fumes to be given off. If anyone has ever worked with green
lumber they should know that it is a poor grade of fast growing timber with
poor quality to the structure of the wood grain. There are a number of wood
preservatives that are on the market (that has been approved by the environmental
protection agency) that is not harmful to aquatic life. They are available
in 5 gallon to 55 gallon drums. "Raw" linseed oil can be used
as a wood preservative on water wheels but it does not seem to be long lasting.
It needs to be retreated from time to time. It does give off a sheen the
first time it becomes in contact with water after the treatment. Maintenance
of the water wheel and regular usage is perhaps the best way to preserve
a wooden water wheel.
Return to Home Page