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wooden dummy construction
by dan lucas
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overview
mook yan jong - (pronounced moohk yàhn jàng) literally translates from cantonese into english as "wood man post," but is usually just called a "wooden dummy" in english. the most commonly used dummy consists of a body with two removable upper arms at shoulder level, a lower arm at stomach height, and one leg; all suspended on a framework by two crosspieces. this style was created in hong kong, where crowded apartment living no longer allowed the post to be buried in the ground. the following descriptions are loosely taken from the wooden dummy my instructor brought with him from hong kong in the 1960s.
here are plans:
front view, without arms and leg.
top view
side view
materials
teak was often used for all parts of the dummy but, since solid blocks of this exotic hardwood are increasingly hard to get, you can use almost any strong hardwood--one thatâs heavy, strong and dense, but not brittle. softwoods may be used, but some may not have enough strength to withstand the forces applied to a dummy, or have the proper weight. another problem with softer wood is over time, as the arms and legs are struck repeatedly, they become compressed and more "sloppy" in their movement.
avoid pine--it has pitch in it. be sure the wood is well-seasoned--dry all the way through--to avoid cracking. try to use wood native to your area, as transporting it from a different climate, especially with different humidity, can also cause cracking. even with these precautions wood will still sometimes check or split. in this case, patch it with wood fill and band it to help hold it together.
because itâs difficult to get hardwood in one piece large enough for the body of the dummy, you can also try lamination. plastic pipe comes in the right size for use as a dummy but, though it's nearly indestructible, it doesn't give the same response as wood.
body
i suggest hardwood for the body so the weight will correspond to that of a human body. this way if you can move the dummy you can also move a person.
the body has a round cross section of about nine inches in diameter. anything smaller may not give the needed weight and will require adjustments in the length of arms and leg. the height of the body is roughly five feet.
make the cross section as close to a perfect circle as possible. irregularities in the surface can cause damage to hand or foot. for the same reason the body should be smooth, to avoid splinters. you can also slightly taper or round off the top and bottom of the body to remove rough edges.
one of the hardest parts of dummy construction is cutting the square holes needed for the arms. first drill circular holes, then square them with hand chisels. in order to give both arms room to pass through the dummy, the left arm (facing the dummy) is slightly higher than the right. the holes intersect at their outer edges where they cross in the exact center of the dummy. another advantage of hardwood is that youâre less likely to tear up the center of the dummy as you cut these overlapping holes.
arms
it's more important to have the arms made of hardwood, since they're more likely to break than the body. the arms receive the most stress at the point where they enter the body.
i recommend turning the arms on a lathe, rather than making them by hand, since a smooth even surface is essential.
all three arms are identical in that each is twenty-two inches long, divided into two sections: one eleven inch half goes through the dummy body and out the back, the other eleven inch half sticks out from in front of the dummy. all three arms are set parallel to the floor.
the visible half of the arm, extending from the dummy, is a tapered cylinder--wider where it leaves the body and tapering smaller towards the tip. the widest part, closest to the dummy, is two and a half inches in diameter. the amount of taper differs, but a loss of about an inch, down to one and a half inches in diameter at the tip, is average. round off the tip end so there are no sharp edges.
the inner hidden half of the dummy arm has a square cross section. though itâs far easier to make the inner half cylindrical, this would allow the dummy arm to spin on contact--unlike a real opponentâs arm. this half of the arm can be either in line with the outer half, or offset from center so one corner of the inner half touches one edge of the outer half while the opposite corner of the squared inner half is inset from the edge of the rounded outer half. while this offset is more difficult to make, it allows the dummy arms to be adjusted to different angles simply by switching or turning the arms. the distance between the upper arms at their tips depends on your own body--the upper arms point at your shoulders when you stand at an arms length from the dummy; the average is about eight and a half inches.
the topmost arm is nine inches down from the top of the dummy. the lowest arm is eight and a half inches down from the upper arms, extending straight out from the center of the body.
the holes cut in the body for the arms should provide a fairly tight fit, but not too tight or too loose. your technique on the dummy can be judged by the sound of the arms moving in their holes: a dull thud indicates tension in the arms, caused by holding back power, while a sharp "clack" shows power has been properly passed to the dummy without force being reabsorbed into your own arm.
extend the dummy arms through the body and out the back about two inches. secure the arms in place with a removable pin or wedge inserted into a hole drilled from the top down through the arm, close to the dummy body.
leg
the leg has two sections: one extending through the dummy and out from the front center of the body to a "knee joint," the other extending down from here towards the floor.
the leg is the least standardized piece of the dummy. the upper part of the leg may come straight out from the dummy, parallel with the floor, or it may extend downwards at an angle towards the front. the lower part of the leg may go straight down, at a right angle to the floor, or it may extend forward at an angle. it is meant to correspond with your own leg, as if you were standing with one bent leg forward, so keep this pattern in mind when making your wooden leg. use the knee joint as your guide and have it roughly at the same height as your own knee. the leg can be all one piece, or it can be made in two pieces connected at the knee. some people shape the lower section of the leg to appear like a calve and ankle.
the upper section of the leg is twenty-two inches long: one half of which extends through the dummy and out the back, the other half visible out in front. the part passing through the dummy must be smaller than the part visible, so the leg wonât slide back up into the dummy body. the lower "hanging" section is about thirteen inches long. as with the arms, the leg is secured in back with a removable pin or wedge.
the section of the leg extending through the dummy should be made with a square cross-section, to eliminate rotation of the leg in its hole.
the leg leaves the dummy at a point roughly sixteen or seventeen inches up from the base of the body. because the angle of the leg can vary, the hole may be raised or lowered as needed. the bottom of the leg should line up with the bottom of the body, about six inches above the floor.
the diameter of the leg is not standardized, and was often made from a hardwood branch with a knot and bend where the knee would be. this makes a functional and decorative leg, but suitable tree limbs can be hard to find. a square cross-section leg with a joint at the knee is much easier to construct, but round all edges so kicking the leg is easier on the feet. anything less than two by two inches will probably be too weak to stand up to steady use.
stress points are at the knee and where the leg passes into the dummy.
use a strong hardwood, since the leg must withstand a great deal of kicking force. you may want to reinforce the leg and, as with the arms, itâs a good idea to have a spare leg on hand.
crosspieces
the dummy is suspended above the floor by two crosspieces or slats, each one inch wide by two inches high.
no matter what wood is used for the rest of the dummy, these crosspieces must be a strong hardwood, since they absorb most of the force given to the dummy. on the other hand they must not be too brittle, or they will crack rather than flex under stress. stress points are at the spot where the slats pass into the dummy. itâs a good idea to have an extra set of crosspieces on hand for the inevitable day when one breaks.
the crosspieces should be no less than five feet long, so they are long enough to flex when the dummy moves forward or backward, and long enough to extend a few inches from either end of the framework.
the top crosspiece is six inches down from the top of the dummy, the bottom crosspiece is nine inches up from the bottom of the dummy. at this distance apart they provide support so the dummy does not tip too much forward or backward. if the top crosspiece is too close to the upper dummy arms it will get in the way of the neck-pulling movement.
the crosspieces must be mounted parallel to each other, the top directly over the bottom, otherwise they will bind, and not slide, in the supporting framework. they should also pass directly through the center of the dummy for best balance and to minimize torque on the crosspieces.
attach some kind of stops near the dummy body so it wonât slide on the crosspieces--the body and slats should move together. put another set of stops on near the end of the crosspieces to keep everything from sliding all the way out of the framework on either side.
framework
mount your dummy on two sturdy parallel upright posts (4x8 is a good size) about five feet apart, or on any framework that adequately supports the weight of the dummy while allowing for itâs movement.
attach these supports securely to floor, walls, or ceiling. set them far enough out from anything behind them to allow for forward and backward movement of the dummy.
there are two kinds of dummy: "alive" and able to move in all directions, or "dead" and set into the ground or on an immovable frame. [as i typed this, my wife corrected me, "there are two kinds of dummy: the ones who teach wing chun, and the ones who learn wing chun."] the live dummy was an innovation necessitated by life in crowded hong kong apartments, where there was no place to plant a dummy in the ground. the advantage to the live dummy is that it gives a sense of the movement of a real opponent and lessens the chance of injury; any force given to a dead dummy canât be passed to the dummy, but is reabsorbed back into your own body.
"life" in the dummy is provided in two ways: by flex in the cross slats when you move the dummy forward or backward, and by these slats sliding in the framework when you move the dummy side to side. this movement only needs to be a few inches in any direction.
although the dummy should be suspended about six inches above the floor, the actual height of the dummy from the floor depends on your own height: the upper arms point at your shoulders; the lower arm points at your stomach; and your knee is the same height as the dummyâs "knee."
you can make the dummy portable by cutting upside-down l-shaped slots in the uprights to hold the crosspieces. you can then lift the dummy in or out of the top of the slot and let it drop into the bottom of the l to keep it in place. these slots also provide a way to adjust the height of the dummy. cut the bottom of the slots at the lowest height needed for the dummy, then to raise the dummy, insert wooden risers in each slot. this is just one way to support the crosspieces, there are many other possibilities.
finish
while you can finish the dummy in any way you like, you donât need to use anything on the arms since the natural oils from your hands and arms will eventually seal and color the wood. don't kick the arms, it's both unsanitary and your shoes will damage the finish and scratch the wood.
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if you've changed your mind about making your own, try buy for sources on where you can buy a wooden dummy. and check books for more on the history and use of this unique training device.
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發表於 2004-9-16 06:21:39
發表於 2004-9-17 08:48:30