1webby1
General Category => My stuff => Topic started by: webby2 on July 11, 2026, 07:42:23 pm
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This is an offshoot and is the build I am working on right now.
This is an exploded view of the parts so far,, more to design and print.
Maxwell's little demon is sitting in the slip of the gears and its logic places one force this way and the other force that way,, it is all pre-programmed into the physical parts relationships.
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I made an adapter so I could try this in my existing frame,, this frame has no feedback system so it is a test between the input drive gear and the pivot shaft.
My system has new bearings still filled with grease so they are stiff and I have some friction within the system so there is some force that will transfer.
First test,, spin the drive gear, the upper gear turns, the lower gear turns and the whole system turns,, very little effort to spin.
Second test, I stuck my finger in and stopped the lower gear from turning,, I then spun the input drive gear and it was a little stiffer to turn and the upper gear rotated but nothing else turned.
Third test, I stuck a TT motor on the pivot shaft, it can spin but has a force required, the input drive gear felt the same as the finger test and the only thing that moved was the upper gears.
Fourth test, I used my finger to let the pivot shaft "slip" past my finger with varying amount of force,, the input drive gear changed with the amount I was pushing on the pivot shaft but only went up to the point where it was the same as the stopped test.
It would appear that the physical distance relationship has been decoupled and the "magnetic coupling" then would be a constraint force only,, that coupling will be 3 TT motors running in series and across a 50 ohm resistor.
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This is the inside of the TT motor reduction unit
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The gear reduction for the TT motors was way too much, at the low RPM I want to run some basic tests at they were barley rotating so I am going to jump that to a gear up, so a 22T gear on the TT motors and a 66T gear on the lower gear to drive them.
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3:1 is to far the other way so now I am going to try a 1:1, 44T to 44T
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force flow,,
[1. Input Drive Gear]
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[2. Outside Ring Gear] (On the main rotating housing)
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[3. Internal Ring Gear] (Inside the housing)
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[4. Upper Gear]
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[5. TT Motor Case]
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(Magnetic Coupling Bridge)
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[6. TT Motor Rotor]
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[7. Lower Gear]
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[8. Fixed Internal Ring Gear] (The rigid anchor point)
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[9. Arm Pin]
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[10. Arm]
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[11. Pivot Shaft]
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[12. Pivot Shaft Gear] (The 80T gear)
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[13. Idler Assembly] (The compound 40T/60T step-up)
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[14. Input Drive Gear] (Loop Complete!)
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this is the frame stack I am building for this test bed,, not all the gears and shafts are included.
It will use 4 8mm shafts that are vertical and lock to the frame level pieces and 2 8mm shafts mounted n bearings for the pass through.
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starting to do all the test fit so I can make all the right shims,, this is the lower section and you can see my 2 speed gearbox on the left :) The upper middle piece is high so you can see where the 20T mod2 gear is.
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the build so far
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printing off parts that should be the final parts,, should be because so far I have messed up a few print changes,,,,,
An interesting observation is that the "pin" when only between 2 pivot bearings can twist out of alignment, meaning that the pin is not 90 degrees vertical to the pivot bearing face,, good thin I built in a gear sync system for that part.
With all of the test fits so far the system actually can spin very smoothly which, with all of these gears,, is a little surprising but very good.
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I still need to print out some more spacers, cut 2 shafts shorter, build the electronics package, build the motor holder and the motor coupler.
It is coming along and so far it all spins fairly well.
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an inside look with the 80T upper gear and the TT motors removed to expose the lower 30T internal ring gear with its 20T mate
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here are some premature test runs for setting a base line,, with this run however the Blue TT motors are geared down 4:3 to the input drive gear.
Configuration / Setup,Input Voltage,Total Input Current (Iin),Net Current over Motor Tare,Generated Output / Status,Bench Notes
Yellow Motor Alone (Tare),6 V,0.11 A,0.00 A,N/A,Baseline internal motor + gearbox friction.
Yellow + Bare Frame Stack,6 V,0.22 A,0.11 A,N/A,Frame bearings (8 mm shafts) & structure add just 0.11 A drag (no 80T gear).
1 Blue TT Motor (Direct Drive),6 V,0.35 A,0.24 A,5.0 V Open Circuit,Smooth single-branch baseline; yellow motor stays cool.
2 Blue TT Motors (Direct Drive),6 V,0.54 A,0.43 A,—,Linear load scaling up to 2 direct-driven gearheads.
3 Blue TT Motors (Direct Drive),6 V,0.70 A→0.95 A,>0.59 A,Stall / Thermal Limit,"Torque limit exceeded; armature back-EMF collapses, cooking motor windings."
3 Blue TT Motors (In Planetary Loop),6 V,0.31 A−0.34 A,0.20 A−0.23 A,Feedback Loop Active,Key Result: Loop force cancellation drives all 3 motors for less current than 2 direct-driven motors!
1 Blue TT Motor (Under Peak Short-Circuit Load),6 V,0.78 A,0.67 A,0.110 A−0.120 A Peak,Measured across DMM 200 mA range (∼0.5Ω shunt load). Heavy magnetic back-torque.
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the yellow motor was not going to cut it so I changed it up for a blue body all metal TT motor,, well then I got a little carried away with doing some silly testing and this pdf sums it all up fairly well.
a reduced cost is pretty cool when it matches the math to the bench.
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there seems to be an error on the calculated TT motor turn ratio,, so those conclusions are wrong. Sorry for the confusion.
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The printer I used for the frame sections had an issue that I have now resolved. I reprinted those parts and also made the dual ring gear, or hybrid ring gear, a little stronger so it is less prone to deforming under load. I also found two bad pivot bearings and replaced them.
As tested:
28 bearings
17 gears
Blue motor alone: 0.07 A
1:1 direct head-to-head, 1 Blue driving 3 Yellow:
0.48–0.50 A
2:1 system, no load motors:
0.16–0.23 A
1:1 system, no load motors:
0.18–0.24 A
2:1 head-to-head through the system, 1 Blue driving 3 Yellow:
0.45–0.54 A
All tests were run at the same 6 V power-supply setting and allowed to run until reasonably stable.
These are the measured numbers from this build. They are not being presented as evidence of gain; they are simply the results from the current configuration.
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something that has been bother me with this is that the math only shows 1/2 of the input coming back to assist and I did not see why that would be, well I finally figured that out and it is so silly that it is embarrassing that I missed it.
There are 3 systems lets say,, there is the upper input section, the slip and then the lower return section. The upper and lower share a physical connection on one side and a force connection on the other and it is that force only connection where the slip is.
Now if the input goes in on the upper and it spins the upper and then the upper goes across the slip and spins the lower and then the lower comes back to assist the upper,, the simple thing is that the slip boundary has the upper traveling at say 100 RPM and with the 2:1 return gearing the lower is traveling at 50 RPM, so the same force but at half the rate means half the return work,,, and that is why there is only 1/2 of the input returned to assist.