by Nigel McCarter

Unhappy is the amateur boat builder that completes the hull, orders the sails and then discovers the price of blocks. Even single blocks, with simple sheave bearing cost $5 - $15, and more complex bearings will empty your wallet.

But for light rigs, blocks are simple to make, and look 100 times better than stainless steel and plastic. You need, appropriate size acetyl sheaves, hardwood, (elm, oak, maple) either stainless steel bolts or rod as sheave shaft.

In the illustrations below, the sheaves are 32 mm (1¼ inch) diameter, bored to 6.4 mm (¼ inch). For strength and proportion the long axis of the block should be about 1.5 times the maximum width (sheave diameter) , so in this case a block length of 50 mm (2 inch) is about right.

1. Choose quarter sawn wood if feasible; the grain should run parallel with the cheek faces.

2. Cut a 130 x 32 mm (2½ x 1¼ inch) strip of hardwood about 1 mm thicker than the sheave (10 mm; 3/8 inch) ensuring the sides are parallel and square.

3. Cut into three pieces – two cheeks 50 mm longer, and a spacer piece 20 x 32 mm. The smallest piece acts as a spacer. The spacer grain should run at right angles to the cheek pieces.

4. File a groove with a round file in the long axis of the spacer piece

5. Measure and mark centre lines and ½ sheave diameter (16 mm) up from bottom of the two long pieces.

6. Centre punch, and then drill pilot holes, then 6.5 mm holes to 6 mm depth (¼ inch) holes or to fit the shaft. Use masking tape to indicate the depth on the drill. Don’t guess.

7. Cut the shaft (from bolt or rod) 10 mm over size (5 mm into each cheek).

8. Mark the glue line on both inside surfaces of the cheeks and dry assemble to check the cheeks lie parallel, and the sheave rotates easily when clamped.

9. I spray the sheave with silicon to ensure it won’t stick to excess glue. Candle wax will also do the job.

10. Make up about one ml of epoxy resin; before you add the glue fiber, put a drop of resin into each shaft hole. This will seal the wood fibers and glue the shaft. Add the fiber, spread the glue on mating surfaces and clamp overnight.

11. Make a template from light card. Tip: Measure out a rectangle (32 x 50 mm) mark the centre line, shaft position (+16 mm from the bottom) and the spacer position (- 20 mm from the top); cut two notches top and bottom, draw a smooth curve on one side to produce a pear shape, fold in half and cut both sides together. That way you end up with a symmetrical shape that can be centered on the long axis of the blanks.

12. Drill a 6 mm hole through the top of the blank. Tip. Centre punch, then drill pilot holes from both sides before committing to the full size bit.

13. Mark the shape on the blank, cut, file and sand to shape. I use a fine Japanese saw followed by a belt sander with 60 grit to get to rough shape, working up through the grades to 240 and sand smooth.

14. Finish as you will: I soak the blocks in 50% Danish oil ( or linseed) : mineral turpentine for a couple of hours followed by two or three coats of neat Danish or Teak oil to finish

The blocks cost about NZD $4.00 or what ever the sheaves cost in your currency and with a mass production set up I make four in an hour. The blocks look better than stainless steel, and are quite strong enough for standard use. If you wish to make larger or stronger blocks you can reinforce the cheeks by using hidden pins or through bolting through the spacer.