Soil Mixer - Rotor Module - Build Instructions

March 12 2013

The latest version of the soil mixer/pulverizer unit is past the high level design stage.

Overview: The tine modules are pieces of pipe cut into sections 3 inches long, the tines made from 1/4 inch steel plate welded on. They are slid onto a steel shaft and secured in place in a removable way for easy replacement: they have a hole cut with a torch in the wall of the pipe, and a nut welded on such that the end of the bolt passing through the nut tightens against the steel shaft. Detailed measurements are found in the design files.

The coupler to the 6 spline motor shaft consists of a standard 6 spline coupler attached to the main shaft by drilling a hole path along the diameter of the shaft, and through the collar of the coupler. A bolt passes through the holes, preventing relative rotation.

Fabrication of the Tine modules:

Cut pieces of pipe into 3 inch sections with a cold cut saw. Cut the holes for the bolt to pass through using a plasma torch.

The tines can be manufactured with the metalworking machine, and a torch easily. The current model of pulverizer used 2" wide, 1/4 thick steel strips, cut into sections 5" long, then a roughly 1.5 inch slit is cut in the end of the tine, to allow the splitting of the ends seen in the photos. The tips can then be bent by hand with a monkey wrench.

The rotor turns at 600 rpm, but the shaft and bearings are sturdy enough that vibration caused by poor symmetry of the tine modules is not a problem. The tines are currently attached individually by welding them to the pipe sections (the collar).

Cutting a cross, like a plus sign, from a sheet of 1/4 steel, using the CNC torch table, which includes all 4 tines and slits, and a hole in the center for the pipe section to pass through may be used in the future.

The separate tine modules, 14 per rotor, are slid onto the shaft of the rotor. In a prior version of the soil pulverizer, the modules were then also welded together with spot welds. We do not expect this approach to be used in the latest prototype.

The rotor module has it's own 2 bearings, bolted to the side of the bucket. It does not depend on the bearings integrated into the hydraulic motor.

images: Neither the dozuki nor the wiki's file upload features are functional right now, so the images will have to come along later.