Engage The Rack & Pinion!

Spent some time installing the nyrod and fabricating a linkage set for the rack. The nyrod is Sullivan Precision Rod, 91.4 cm diameter, with a carbon fiber 2-56 pushrod. I drilled a hole in the control deck upright and inserted a length of brass tube to stabilize it as it passes through the bulkhead. The final turn is rather sharp so this keeps it from angling upward. Brass rod was cut to length, threaded to 2-56, bent into a Z-bend and screwed into the end of the control rod.


A control linkage tab was cut from brass stock along with a spacer of the same thickness. Both were clamped in place on the end of the rack and soldered. The spacer gave the tab the proper height to engage the control rod. A hole was drilled in the tab to accept the Z-bend in the rod.

One side of the rack housing (a square piece of brass tube) was opened to allow the rack tab to travel inside it. Keeping as much length of the housing as possible prevents slop when the rack moves. At present the housing is set in place. Ultimately it will bolt to the deck.

A close shot of how the rack engages the pinion gear. The shaft is not quite finished but the gear will ride just proud of the deck. The pinion shaft serves as the pin which holds the rudder in place. Another tab will be installed to keep the shaft and the gear from working upward during operation. While holding the rack housing in place, the control rod works easily inside the boat, turning the pinion back and forth. I can almost see the rudder wagging!

The results are very satisfying. This is the first model engineering project of this complexity I've ever attempted and it's pretty cool when it comes together. So far, the only fabbed items I've purchased are the rack and pinion gear. Everything else was made from stock K&S brass items using basic hobby tools (Dremel, disc sander, files, solder). And it all fits within the footprint of the upper rudder piece!