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The Raven


Well now, there has been no update on this project for some time. Most of the work quieted for a few months while I attempted to work out the steering motor operation. Finally, and after many years of agonizing over how to get the system to behave as I had envisioned, I made a breakthrough. The issue restricting the motor's number of revolutions as well as proper positioning control was nothing more than the feedback system. Nowhere in the documentation nor the web forums did I find the proper connections for the pot. The manner in which the software sees the 5v reference is quite simple, yet elusive. The reference is actually on the controller and all three terminals from the pot must be connected there in order for it to adjust the voltage accurately. Once I had the connections with the correct placement on the controller, the motor began to position itself according to the input (PWM signal from the receiver). Of course, the rotation of the motor and feeback pot must match or it will rotate continuously.

That hurdle was the single most annoying and frustrating aspect of developing this crazy steering system. Shortly thereafter I wanted to learn if the big gearmotor would actually have enough torque to push and pull as I need. So, back to the garage.

With a bit of measuring, I created a small block of aluminum from my old stock and drill it to accept the motor's mounting bracket. Thanks to SDP-SI I was able to connect the motor to the steering shaft via a 2" universal joint. Their parts are very nice - great machine work and extremely tight tolerances. Of course, being me I had to go over it with a fine-tooth comb upon receiving the part to ensure their drawings matched my ridiculous standards for tolerance. Perfect.

I was able to correct the diameter differences between the motor shaft, steering shaft and universal joint with bushing and shim stock, and once everything was aligned the steering worked quite smoothly. The motor seems to have more than enough power to turn my crazy system without flinching.


...and another long period of time passes.

Soon after running repeated tests on the new steering operation, I decided to oust the old chassis plate and design something less convoluted. Considering all of the changes which took place since first machining the original plate many years ago, the multitude of cuts and holes is not surprising. Measuring everything which needs mounting holes as well as forecasting the primary drive brackets was difficult to say the least. Everything is critical and hole locations would need to be absolute. I slowly drew and edited the new plate over a two month period and then had emachineshop.com do the actual fabrication. I must admit their work is impeccable. Upon receiving the plate, I was able to mount everything related to the steering, and the FB pot was then moved off the motor itself and mounted directly upon the plate. I had to fab a small angle bracket to hold it, and the connection was moved from the motor shaft to the steering shaft via small pulleys. With this new setup, the relationship between motor and pot is much more stable and accurate. I used a silicone o-ring for the belt itself, and as such it is readily available and easily replaced if necessary. Some tweaking of the input numbers in the software have resulted in smooth operation with decent range.

Such is the present condition of the steering. Right now there are no wire ropes linking the steering block and bellcranks, nor any tubing. Routing must change due to the location of the motor.

On the other half of the mechanical front, the primary drive has progressed, regressed, and progressed yet again. I regret so much back-and-forth but these things take time.

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Content Updated: Sunday, September 04, 2016 at 10:25 pdt

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