Instrumented Rowing Machine Handle

This handle was born from a desire to measure the force applied to a rowing machine. This effort reached only a prototype stage, and never a production design. My direction was to make a cost-effective prototype as quickly as possible.

Foundation For speed and cost reasons, I chose an aluminum tube and u-bolt from McMaster-Carr as the foundation for this prototype. For the four holes to accomodate the U-Bolt, I decided calipers and marking fluid would provide adequate hole location precision for the two holes which I drilled with a drill press. 

I drilled and tapped two smaller hole in the top of the pipe, to screw on a small plate with more holes I tapped to accomodate a small PCB my EE teammate designed, and a battery holder I specced for the battery my EE teammate required.

Load Cell Coupling For the coupling between the aluminum pipe and the units’ load cell, I decided more cost was necessary to prevent off-axis loading on the load cell from affecting measurments. 

I designed a two-part swivelling coupler comprised of:
 1.  An aluminum coupler designed for turning on a lathe, with one post-process milling  operation. This part includes:

  -- 3/8 - 24 tapped hole for the LCM-200 500 lb load cell used in this design (existing company property)

  -- Flange for retention of a brass bushing

  -- Thru-hole for pass through of U ring



 2. A bushing CNC machined from SAE 660 Bearing Bronze
This bushing requires a complex milling operation to form the sliding interface for the OTS U-fitting
                                               


Other Fittings / Interfaces For cost and speed reasons, I replaced my initial 3D printed grip concept with bicycle handlebar tape. 

For strength and longevity reasons I ordered an aluminum bracket to be CNC machined locally, and used a simple bolt and unthreaded spacer to retain hydrow’s webbing (as shown at right)