From The Young Mill-Wright and Miller's Guide, by Oliver Evans, 1795
Published by The Oliver Evans Press, 204 West Rose Valley Road, Wallingford, PA 19086, and is used with permission.
To lay out the Arms
To Dress the Shaft
To lay out the Mortises for the Arms
To put in the Gudgeons
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Directions for constructing [Undershot] Wheels
- Dress the arms straight and square on all sides, and find the center of each. Mark 2 lines across each arm, on both sides, 6 inches each way from the center. Then scribe each arm lengthwise into 4 equal spaces at the center.
- Set up a truckle (caster) or center-post, for a center to frame the wheel on, in a level place of ground, and set a stake to keep up each end of the arms level with the truckle, of convenient height to work on.
- Lay the first arm with its center on the center of the truckle, and take a square notch out of the upper side 3/4 of its depth, wide enough to receive the 2nd arm.
- Make a square notch in the lower edge of the 2nd arm, 1/4 of its depth, and lay it in the other, and they will joint standing square across other.
- Lay the 3rd arm just equidistant between the others, and scribe the lower arms by the side of the upper, and the lower edge of the upper by the sides of the lower arms. Then, take the upper arm off and strike the square scribes, taking out the lower half of the 3rd arm, and the upper half of the lower arms, and fit and lay them together.
- Lay the 4th arm on the others, and scribe as directed before; then take 3/4 of the lower edge of the 4th arm, and 1-4 out of the upper edge of the others, and lay them together, and they will be locked together in the depth of one.
- Make a sweep-staff with a gimlet hole for the center at one end, which must be set by a gimlet in the center of the arms. Measure from this hole half the diameter of the wheel, making a hole, and another the depth of the shrouds towards the center, making each edge of this sweep at the end next the shrouds, straight towards the center hole, to scribe the ends of the shrouds by.
- Circle both edges of the shrouds by the sweep, and dress them to width and thickness. Lay out the laps 5 inches long. Set a gauge to a little more than 1/3 of their thickness and gauge all their ends for the laps from the outsides. Cut them all out but the last, so that it may be made a little longer, or shorter, as may suit to make the wheel the right diameter. Sweep a circle on the arm to lay the shrouds to, and while fitting them, put a small draw-pin in the middle of each lap, to draw the joints close. Strike a true circle for both inside and outside the shrouds, and one 1 1/2 inch from the inside, where the arms are to be let in.
- Divide the circle into 8 equal parts, coming as near the middle of each shroud as possible. Strike a scribe across each to lay out the notch by, that is to be cut 1 1/2 inch deep, to let in the arm at the bottom of where it is to be forked to take in the reminder of the shroud. Strike a scribe on the arms with the same sweep that the stroke on the shrouds for the notches was struck with.
- Scribe square down each side of the arms, at the bottom of where they are to be forked; make a gauge to fit the arms, so wide as just to take in the shrouds, and leave 1 1/2 inch of wood outside of the mortise. Bore 1 or 2 holes through each end of the arms to draw-pin the shrouds to the arms when hung, then mark all the arms and shrouds to their places, and take them apart.
- Fork the arms, put them together again, and put the shrouds into the arms; drawbore them, but not too much, which would be worse than too little. Take the shrouds apart again, turn them the other side up, and draw the joints together with the pins. Then lay out the notches for 4 floats between each arm, 32 in all, large enough for admitting keys to keep them fast, but allowing them to drive in when any thing gets under the wheel. The ends of the floats must be dovetailed a little into the shrouds. When one side is framed, frame the other to fellow (match) it. This done, the wheel is ready to hang, but remember to face the shrouds between the arms with inch boards, nailed on with strong nails, to keep the wheel firm together. Top
Directions for Dressing Shafts, &c.
THE shaft for a water-wheel with 8 arms should be 16 square, or 16 sided, about two feet diameter, the tree to make it being 2 feet 2 inches at the top end. When cut down saw it off square at each end and roll it on level skids, and if it be not straight, lay the rounding side down and view it, to find the spot for the center at each end. Set the big compasses to half its diameter and sweep a circle at each end, plum a line across each center, and at each side at the circle, striking chalk lines over the plum lines at each side from end to end. Dress the sides plum to these lines; turn it down on one side, setting it level; plum, line, and dress off the sides to a 4 square. Set it exactly on one corner, and plum, line, and dress off the corners to 8 square. In the same manner dress it to 16 square.
To cut it square off to its exact length, stick a peg in the center of each end. Take a long square (that may be made of boards) and lay it along the corner, the short end against the end of the peg. Mark on the square where the shaft is to be cut, and mark the shaft by it at every corner line, from mark to mark; then cut it off to the lines, and it will be truly square. Top
To lay out the Mortises for the Arms.
Find the center of the shaft at each end, and strike a circle. Plum a line through the center at each end to be in the middle of two of the sides. Make another scribe square across it, divide the distance equally between them, so as to divide the circle into 8 equal parts, and strike a line from each of them, from end to end, in the middle of the sides. Measure from the top end about 3 feet, and mark for the arm of the water-wheel, and the width of the wheel, and make another mark. Take a straight 10-foot pole, and put the end even with the end of the shaft, and mark on it even with the marks on the shaft [so that you have a “story board” for the shaft]. Use these marks to measure for the arm at every corner, marking and lining all the way round. Then take the uppermost arms of each rim, and by them lay out the mortises, about half an inch longer than they are wide, which is to leave key room. Set the compasses a little more than half the thickness of the arms, and use them to lay out the width of the arms, on center. This done, lay out 2 more on the opposite side, to complete the mortises through the shaft.
Lay out 2 more square across [perpendicular to] the first. These must be one quarter the width of the arm, longer inward, towards the middle of the wheel. Take notice which way the locks of the arms wind, whether to right or left, and lay out the third mortises to suit, else it will be a chance whether they suit or not: these must be half the width of the arms, longer inwards.
The 4th set of mortises must be 3-4 longer inwards than the width of the arms, laid out as above. The mortises should be made rather hollowing then rounding, that the arms may slip in easily and stand fair. Top
Strike a circle on the ends of the shaft to let on the end bands, make a circle all round 2 1-2 feet from each end, and saw a notch all round half an inch deep. Lay out a square round the centers the size of the gudgeons, near the neck; lay the gudgeons straight on the shaft, and scribe round them for their mortises; let them down within an 1/8 of an inch of being in the center. Dress off (trim) the ends to suit the bands. Make 3 keys of good seasoned white oak, to fill each mortise above the gudgeons. To key them in, those next to the gudgeons to be 3 1/4 inches deep at their inner end, and 1 1/2 inch at their outer end. The wedge or driving key should be 3 inches at the head, and 6 inches longer than the mortise, that it may be cut off if it batters in driving. The piece next to the band should be so wide as to rise half an inch above the shaft, when all are laid in. Then take out all the keys and put on the bands. Make 8 or 12 iron wedges about 4 inches long by 2 wide, 1/3 inch thick at the end, not much tapered except half an inch at the small end. On one side next to the wood, drive them in on each side of the gudgeon exceeding (very) hard at a proper distance with a set. Then put in the keys again, and lay a piece of iron under each band, between it and the key, 6 inches long, half an inch thick in the middle, and tapering off at the ends. Then grease the keys well with tallow and drive in well with a heavy sledge. After this, drive an iron wedge half an inch from the two sides of each gudgeon 5 inches long, near half an inch thick, and as wide as the gudgeon. Top
This text is from The Young Mill-Wright & Miller's Guide, by Oliver Evans, Reprinted from the First Edition, 1795. Published by The Oliver Evans Press, 204 West Rose Valley Road, Wallingford, PA 19086, and is used with permission. The spelling and grammar have been slightly modernized to make it easier for contemporary readers to understand.