Unidirectional Windmill

1. Foundation

Requirements: 4 concrete foundations (4 bags cement, cbm sand, cbm gravel, 4 pieces post straps, and L angle for foundation boxes).

Procedure: Lay the foundation as shown in fig 2. Dig the holes making sure they are longer at the bottom than at the top (fig 3a). Construct the forms for the concrete around each hole (fig 3b). Mix the concrete in the ratio 1 bag cement + 2 bags gravel + 4 bags sand. Pour the concrete and set the post straps inclined towards the center as shown in fig 3c & 3d.

2. Construction of Blade Frame Assembly


Axle 1piece - Round bar 19.05 x 2031.4 mm

Spokes & Braces 3 pieces - Round bars 12.7 x 6096 mm

Ribs 3 pieces - Round bars 6.35 x 6096 mm

Bearings 2 pieces - 19.05 mm ball bearings

Crank 1 piece - Flat bar 9.525 x 50.8 x 812.8 mm

Angles 1 piece - Angle bar 3.175 x 19.05 x 19.05 x 3048 mm

For Spokes 10 pieces - Flat washer 12.7 mm

For Ribs 20 pieces - Flat washer’s 9.525 mm

For Spokes 20 set cap screws with nuts 9.525 x 25.4 mm.


Construction of the axle

1. Cut the 3.175 x 19.05 x 19.05 x 3048 mm angle bar into five pieces 0.6 m long (fig 4a)

2. Weld one of these 0.6-mm angle pieces across the 19.05 x 2031.4-mm round bar (axle) as shown fig 4b.

3. Weld the second angle 4318 mm from the first and 45 degrees to it (with respect to the centerline of the axle). Weld the third angle, 431.8 mm from the second and at 45 degrees to it (90 degrees to the first angle). Continue the procedure with the fourth and the fifth angles progressing at 431.8 mm and 45 degrees each.

4. Cut each of the three 12.7 x 6096 mm round bar into halves, so that you get six pieces at 12.7 x 3048 mm pieces. Cut one the 12.7 x 3048 mm piece into five pieces 600 mm long.

5. Weld a 12.7 mm x 600 mm round bar in place under each angle (see fig 4c).

Place Bearings and spacer rings on each and of axle as shown in fig 5.

Note: The spacer should be placed on the side of the bearing with the locknut, when bearings are already in their respective positions, tighten lock nuts and bend washers.

3. Construction of the Crank fig 6

1. Cut the 9.25 x 50.8 x 812.8 mm flat bar into four piece 203 mm long (fig 6a).

2. Take one of these pieces, round off the corners and drill as shown fig 6b. All holes should be 12.7 mm.

3. Weld crank in position on axle (fig 6c).

Note: Crank to be welded to 177.8-mm end of axle.

4. Construction of the Spokes fig 7

1. Weld two 12.7-mm washers on each of the five spokes (12.7 x 3048 -mm round bar) as shown fig 7a.

2. Weld two 9.525-mm cap screws to each spoke as shown in fig 7c.

5. Construction of the Ribs: fig 8

1. For the outer ribs, weld five 9.525 mm washers on 1244.6 mm centers to each of two 6.35 x 6096 mm round bars. Cut off the excess.

2. For the inner ribs, out the remaining length of 6.35 x 6096 mm round bar cut into halve, weld five 9.525 mm washers on 641.35 mm centers to each of the two 6.35 x 3048 mm round bars. Cut off the excess.

6. Construction of the connecting rod ends fig 9


2 pieces Connecting rod ends

2 pieces 9.525 x 50.8 x 203.2 mm flat bar


Round off the corners and drill the two pieces of 9.525 x 50.8 x 203.2 mm flat bar as shown in fig 9.

Note: Take two pieces.

7. Construction of the Tower: fig 10


Complete axle with bearings

Posts 4 pieces 50.8 x 101.6 x 4876.8 mm Longer M.S. "L" angle

End braces 8 pieces 25.4 x 101.6 x 4267.2 mm M.S. "L" angle

Foundation bolts 8 pieces 12.7 x 63.5-mm bolts with nuts and washers

Bearing mounting bolts 4 pieces 9.525 x 127 bolts.


1. Assemble two "A" frame (fig 10a)

2. Stand "A" frames on edge with the bases 3 m apart and tops in position to accept the axle (brace temporarily) (fig 10b)

3. Drill the necessary holes and belt axle in position.

4. Lift tower into standing position (fig 10d)

5. Trim bottoms of posts so that the tower sits in a level position and fits the foundations.

6. Check axle to make sure it spins freely, if not make the necessary adjustments.

7. Drill necessary holes and bolt the posts to the foundation posts straps (fig 10f)

8. Nail the permanent braces in position as shown in fig 10e

9. Remove the axle and sit it upon temporary supports (at left 1.5 m high) for assembly of the blades.

Note: Because the tower slopes toward the center form both ends, the bearings will not be bolted squarely to the post fig 10c.

8. Assemble of Blades: fig 11





Inner ribs

Outer ribs

2 gals coat tar


1. Place spokes in position on the axle. Fasten tightly with wire. (Fig 11a)

2. Bolt inner ribs to spokes (fig 11b)

3. Bolt outer ribs to spokes (fig 11c)

9. Assembly of Connecting Rod: fig 13


2pcs Connecting rod ends

2pcs 25.4 x50.8 x 4267.2 mm M.S. "L" angle

8pcs 9.525 x 50.8 mm bolts with nuts and washers

2pcs 12.7 x 50.8 mm cap screws

4pcs 12.7 mm nuts

4pcs 12.7 mm flat washers

2pcs 12.7 lockwasher

76.2 mm nails.


1. Nail the two pieces of 25.4 x 50.8 x 4267.2 M.S."L" angle together to form the connecting rod fig 13a

2. Cut away the front side of the connecting rod as shown and drill the necessary holes and bolt the steel end piece in position as in fig 13b

Note: 3. Prepare only one end.

3. Bolt connecting rod to crank as shown in fig 13c.

Note: Tighten the nuts securely against the crank and make sure the cap screw spins freely in the end of the connecting rod.

4. Rotate the windmill until crank is in a horizontal position. Place the pump handle in a horizontal position and mark the connecting rod through a hole in the pump handle place.

5. Remove the connecting rod from the crank and put the second end piece, with the hole over the mark made in step above.

6. Drill the necessary hole, bolt the end piece in position and cut away the excess material.

7. Reattach the connecting rod to the crank and fasten it to the pump handle plate.

8. Release the windmill and stand clear to avoid getting wet as the water flows out.

Note: Grease all joints well.

Tighten the nuts securely against the pump handle plate, and make sure the cap screw 3 pins freely in the end of the connecting rod.

Materials Needed:

4 bags Cement

cbm. Sand

cbm Gravel

2 pieces Self-aligning ball bearings, 19.05 mm with housing (Light duty)

1pc round bar 19.05 mm x 383.2 mm

3pcs round bars 12.7 mm x 6 m

3pcs round bars 6.35 mm x 6 m

1pc flat bar 9.525 x 50.8 x 812.8 mm

1pc Angle bar 3.175 mm x 19.05 mm x 19.05 mm x 3 m

8pcs Bolts, Nuts and washers 12.7 mm x 63.5 mm or longer if necessary to hold post straps

4pcs Mounting bolts 9.52 x 127 mm or longer and with nuts

14pcs flat washer 12.7 mm

20pcs Flat washers 9.525 mm

20 sets Cap screws with nuts 9.525 x 25 mm

8 sets Bolts, nuts and washers 9.525 x 50.8 mm

2pcs Cap screws 12.7 x 50.8,

4pcs Nuts 12.7 mm

2pcs Lock washers 12.7mm

8pcs FRP nails

1pc Hand pump or ordinary pump cylinder

4pcs M.S. "L" angle 63.5 x 6.35 mm x 5.3 m

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