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. The instructions below are the *plan* for how to build the unit, not documentation of a fabrication procedure. The actual fabrication procedure will also be documented, and deviations from the plan illuminating.
Note: The dimensions will be added in the next draft.
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 to said pipe sections.
Cut a hole with a torch in the wall of the pipe, and a nut welded on such that the end of the bolt passing through the hole and nut tightens against a flattened section of the main steel shaft, which passes through the pipe. 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 there is already a hole provided through the collar of a standard coupler. A bolt rather than a pin passes through the holes, preventing relative rotation. This bolt is intended to be small enough that it will shear in the event the rotor gets stuck, saving the rotor some damage. There is also a bypass valve on the hydraulic motor, which also helps with this.
Fabrication of the Tine modules:
Cut pieces of the pipe into 3 inch sections with a cold cut saw. Cut the holes for the bolt to pass through using a plasma or oxy-acetylene torch.
The tines can be manufactured with the metalworking machine and/or a torch easily, or with a CNC torch table, plus, in either case, a monkey wrench to bend the tips with.
With a metalworking machine and hand torch:
Use 2" wide, 1/4 thick steel strips, cut into sections 5" long with the metal worker, then cut a roughly 1.5 inch slit cut in the end of the tine with the torch, to allow the splitting of the ends seen in the photos. The use of the iron worker to both split and bend the ends of the tines may be an option.
The tines are currently attached individually by welding them to the pipe sections (the collars).
Important note: The tine modules are not all identical. The position of the hole and associated nut welded to the pipe sections is not the same for all of them. There are 2 kinds. On one kind, the position of the nut is rotated 45 degrees relative to the other kind. That is the only difference. This is so they don't all collide with the mass of soil simultaneously, rather half collide, then 45 degrees later, the other half collide. They are of course interleaved. This may or may not be reflected in the 3d models.
If we have access to a CNC torch table, cutting a cross, like a plus sign, from 1/4 steel sheet, which includes all 4 tines and slits, and a hole in the center for the pipe section to pass through, may be used. The crosses can be tessellated, or packed together, to waste less metal when cutting them out of the sheet of 1/4 in steel, as well as cutting time, as some of the cut lines overlap.
After all welding is completed, bend the tips of the tines using a monkey wrench by hand to roughly the state shown in the 3d models.
Shaft fabrication:
Modify the circular main shaft by milling down one side flat, about 1/4 inch deep, to provide positive locking of the bolt against the otherwise circular shaft.
Drill the hole in the shaft for the spline coupler bolt.
Final assembly with the bucket:
The main shaft then goes through the bearing on the side of the bucket which does not have the motor mount, and through all 14 tine modules. Unlike in prior versions of the pulverizer, do not weld the tine modules to one another.
Secure the shaft to the bearings by tightening the bolts integral to the bearings. Now secure all the tine modules to the shaft by tightening the bolts.
Attach the motor coupler and motor, with the hydraulic connections pointed towards the tractor. Go back over and ensure that all bolts are suitably tight.
images: For now, consult the 3d and 2d drawings on Dozuki.