V3 Gear System

[Pricilla Igoe]

Istarted with @Math Fiat gears altered with a buffer wheel, and found that zip ties are sufficient to self center and hold the ring gear on tri spoke steering wheels. The zip ties must choke behind the spoke smaller than the diameter of the spoke. using two ties really concretes them in place. Care must be taken that the fat ends are not in a position that can touch the drive motor.

The large gear is printed out of PETG which is very hard. The gear is printed so the teeth are solid in the hopes of never taking it off. 3.6mm wall thickness, 2mm top and bottom, 60% infill. Takes 310g of material and 1.5 days of print time.

The smaller gear is TPU, when printed thick TPU is hard like a hockey puck, but still rubbery. Since it is softer it should be sacrificial and save the larger gear from damage. 2.8 mm wall thickness for solid teeth and 2mm top and bottom 80% infill. Uses 40g of material and takes 5 hours to print.

Added bonus of TPU is during fitment, if too much spring tension is applied the gears will squak. Once they are fully bedded and quiet, tension is proper. In open cab lots of dirt will make the gears noisy. But dirt accumulation seems to be prevented by spraying them with dry silicone lubricant. It does not take much force to keep the gears engaged, the PETG does not try decouple the TPU.

Here are the V3 gear and V1 quick attach .STL (updated Sept 24, 2021) files for those interested. The materials and settings are just a suggestion, but they seem to be working very well. Has large overhangs, support material required.

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Those wondering the benefits of gears vs wheel tire, the main advantage of gears is zero slippage and wonderful repeatability making tuning with them more precise. Also Having the full use of the steering wheel at all times, especially with the cytron freewheel modification.

looks great. I finally went to metal insert over petg for my foam wheel. With just petg the odd one would come loose even though I made it tight enough it took some force to install. Will attach picture of example if you want to go that route.

3D printing strength can very greatly with very with minor setting differences. I just recently got a printer, the guy I used to get them from moved.

I notice a difference in final properties just between the two machines.

The big challenge will be able to make a motor mount that allows the motor to be swapped between machines with minimal time. The motors are reasonable, but if they can travel with the operator the cost per machine falls again.

If it holds up on tractor it will be updated to the same file as the gears. It will require one steel support member 90 degrees to the steering wheel for mounting, but will make installation simpler. It will require a few common nuts and bolts, I tried to make it accommodate either 1/4" and M6 hardware.

Yes the gears will be connected all the time! There is a modification to the Cytron that lets the motor freewheel so no need to disconnect gears during operation. But if you pull the single pin in the location of the hexagon, the steering motor and tension assembly can be removed and taken to another machine with the operator.

All that needs to be reprinted is the side adapter block for each new machine install. But mating that adapter block to an arm would be the only custom fabrication left for the farmer. I think most farmers can fabricate one metal bracket 90 degrees to the steering column very easily. If they are on this forum extremely easily. But adapting and getting spring tension on a motor is tricky multiple times starting from scratch.

Not sure what you mean by this? Put an .stl in Cura Slicer and the magic happens. The adapter has two 1/4"(M6) bolt holes and tilt adjustment. It just bolts to what ever arm you can fab up, but the motor removes with a single pin.

Segmented gears loose a lot of strength are not my first choice, but I will be making one in future. Some steering wheels are harder to get off than others. I have a Combine in my life that requires a set.

Think once I am done oats, I will make a video to show how this setup works. I am converting my friends farm to AOG he has 9 machines and 3 operators. This will save him buying 6 motors, and many hours of motor installation.

The printer is a creality Sermoon D1. Its a direct drive, and has a descending bed kinda like an ultimaker. I really like it its a 9.5/10. Already had the thermistor go, and It really needs a filament handling upgrade to the direct drive.

Once you start using PETG you will just stop buying PLA all together. Its a way better material for functional objects. It prints a little hotter than PLA. I am a 3D novice, have had the printer a little over a month, and had no issues switching.

It is the latest all-rounder co-polyester 3D filament which is made from a mixture of Glycerol and PET. All other 3D filaments were not specifically designed for printing objects in 3D; they were repurposed for 3D printing. Their original purpose was...

The printer has a heated glass bed. It just prints directly on it, after the bed cools to room temp just pick up the parts no fighting. After two or three prints it gets rubbed down with isopropyl alcohol and regular paper towels, it leaves a dusty white surface. I give the nozzle two white paper thicknesses of clearance for the first layer. Put the folded paper under the nozzle and lower the bed until it still drags when pulled but has minimal resistance, not ripping the paper.

Here is the new holder, It takes a lot less space than the old one and is much easier on the eyes. Still needs an optional finger guard. The big gear got an upgrade due to the tywrap head clearance issue, I really like the green PETG.

The V1 quick attach .stl files have finally been added, other than maybe cosmetics I am not touching this design for a year until I can get more hours on them. Here is the final holder with finger guard, I also added an inset hex to each side of the brackets as it allows for reversible pin placement. I found installing as a wheel motor unit in a Steiger the block needs to be reversed for wheel motor.

Gear teeth are designed to ensure the pitch circles of engaging gears roll on each other without slipping, providing a smooth transmission of rotation from one gear to the next.[2] Features of gears and gear trains include:

The transmission of rotation between contacting toothed wheels can be traced back to the Antikythera mechanism of Greece and the south-pointing chariot of China. Illustrations by the Renaissance scientist Georgius Agricola show gear trains with cylindrical teeth. The implementation of the involute tooth yielded a standard gear design that provides a constant speed ratio.

In addition, consider that in order to mesh smoothly and turn without slipping, these two gears A and B must have compatible teeth. Given the same tooth and gap widths, they also must have the same circular pitch p \displaystyle p , which means

In other words, the [angular] speed ratio is inversely proportional to the radius of the pitch circle and the number of teeth of gear A, and directly proportional to the same values for gear B.

The gear ratio also determines the transmitted torque. The torque ratio T R A B \displaystyle \mathrm TR _AB of the gear train is defined as the ratio of its output torque to its input torque. Using the principle of virtual work, the gear train's torque ratio is equal to the gear ratio, or speed ratio, of the gear train. Again, assume we have two gears A and B, with subscripts designating each gear and gear A serving as the input gear.

For this analysis, consider a gear train that has one degree of freedom, which means the angular rotation of all the gears in the gear train are defined by the angle of the input gear. The input torque T A \displaystyle T_A acting on the input gear A is transformed by the gear train into the output torque T B \displaystyle T_B exerted by the output gear B.

Assuming the gears are rigid and there are no losses in the engagement of the gear teeth, then the principle of virtual work can be used to analyze the static equilibrium of the gear train. Because there is a single degree of freedom, the angle θ of the input gear completely determines the angle of the output gear and serves as the generalized coordinate of the gear train.

A hunting gear set is a set of gears where the gear teeth counts are relatively prime on each gear in an interfacing pair. Since the number of teeth on each gear have no common factors, then any tooth on one of the gears will come into contact with every tooth on the other gear before encountering the same tooth again. This results in less wear and longer life of the mechanical parts.A non-hunting gear set is one where the teeth counts are insufficiently prime. In this case, some particular gear teeth will come into contact with particular opposing gear teeth more times than others, resulting in more wear on some teeth than others.[6]

The simplest example of a gear train has two gears. The input gear (also known as the drive gear or driver) transmits power to the output gear (also known as the driven gear). The input gear will typically be connected to a power source, such as a motor or engine. In such an example, the output of torque and rotational speed from the output (driven) gear depend on the ratio of the dimensions of the two gears or the ratio of the tooth counts.

In a sequence of gears chained together, the ratio depends only on the number of teeth on the first and last gear. The intermediate gears, regardless of their size, do not alter the overall gear ratio of the chain. However, the addition of each intermediate gear reverses the direction of rotation of the final gear.

An intermediate gear which does not drive a shaft to perform any work is called an idler gear. Sometimes, a single idler gear is used to reverse the direction, in which case it may be referred to as a reverse idler. For instance, the typical automobile manual transmission engages reverse gear by means of inserting a reverse idler between two gears.

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