Comedy, like beauty, is in the eye of the beholder. I find humor less in the frantic arm wavings and screechings of sitcom actors than I do in the infomercials that plague nearly every TV station from time to time. My favorites, hands-down, are those shilling the head-spinning diversity of exercise machines, in which spandex-clad pituitary cases shoutingly suggest that if you buy their $399 "Ultimo Gym, "your business, love, and dream life will take on magnificent proportions.
We sat around thinking these thoughts at a meeting at which several of the best woodshop projects of the past month were put through their paces. Graeme Knight's simple and clever homemade rowing machine won, not least because it's getting cold and chopping wood once a week just isn't going to keep those holiday drones from taking permanent residence on our haunches. Rowing works virtually every muscle group in the body, and it doesn't require an "Ultima Gym " to do properly. The rest of these words are Graeme's, and begets a round of kudos from we tinkerers.—Matt Scanlon
With about $70, a single sculling seat, a pair of sculling grips, and a number of 10-pound weights, it is possible to build a rugged and dependable rowing machine. Refer to the 171-homemade-rowing-machine-diagram pdf as you follow the instructions below.
Rear Frame Construction
The seat is constrained within two parallel wood strips screwed on top of 2 x 4 lengths. The space between the strips should allow 1/8" clearance outside the seat wheels.
Two 1 1/2" x 7/8" x 3/8"-thick pieces of wood are used to stop the sculling seat from sliding off the back of the rower.
Drill four 3/8"-diameter holes at the front of the frame to enable the rear frame to be bolted to the front, using 3 1/2"-long coach bolts, spring washers, and nuts.
Front Frame Construction
Cut all of the 2 x 4 and the 5/8" x 4 1/2" material to length.
Cut a 3/8"-diameter steel shaft to length (6", by these plans), so that it passes 1" into one of the 24 1/2"-high pieces and protrudes 1/8" outside of the opposite 24 1/2"-high piece.
Assemble the two side frames using coach bolts, spring washers, and nuts. The two frames should be carefully aligned before drilling the holes for the lower pulley shaft. After drilling the holes, place the steel pulley shaft in position to keep the two side frames aligned. Then position the two 20"-long top pieces and drill the 3/8"-diameter holes for the top pulley shaft (use a 5"-long coach bolt for this upper shaft).
Bolt the two side frames on either side of the rear frame and install the pulleys with a suitable number of 1"-outside-diameter x 3/8"-inside-diameter packing washers, as shown on the plan view drawing. (I used six 3/64"-thick washers on each of the two pulley shafts.)
Cut two 9 1/2"-long foot rests from 2 x 4 material and screw them to wedges mounted on the 54"-long inclined pieces.
Assembling the Weight System
Cut a 9 1/2" length of 3/8"-diameter rope and tie it to a 1 1/2"-diameter dowel. Feed the other end of the rope over the two pulleys and attach to the desired number of 5-pound and/or 10-pound weights.
If four 10-pound weights are used and the distance through which they are raised is 41", then the work per stroke is: 41"/12 x 40 Ibs = 137 ft-Ibs. If this work is done in 1.08 seconds (which corresponds to 120 strokes in 4 minutes, 15 seconds) the power is 137 ft-lbs/1.08 secs x 1.356 = 171.6 watts (or 0.23 hp). To calculate other powers, use the following equation: power (watts) = 0.113 x distance load is raised (inches) x total weight (lbs)/time (secs).