Spintronics Community Forum

Junctions with matching sized gears

First of all, love the kit, it’s well thought out and beautifully made and what follows is a teeny tiny gripe that shouldn’t been taken as a big criticism so much as an observation.

The current arrangement of the 3 gears on the junction all being different sizes adds a lot to the fiddlyness of the chains.

I guess maybe it helps you see that they are moving at different speeds, but you can see that from the chains.

The problem is a loop of chain around 2 components or 3 components varies in size quite a bit depending on the sizes of the gears involved.
Aside from the transistor and the junction most of the gears are around the same size, so you can rearrange components without needed to change up belt lengths so much.
The transistor isn’t used so much, but the junction is used all the time.

If the gears were all a standard size then you would largely just use the same 2 component and 3 component chain loops over and over without having to redo chain lengths hardly at all.

A good example is something like tutorial 15 where you have a bunch of resistors in series and you want to measure the voltage across one.
You want to pop out the resistor and replace it with a junction, then loop the capacitor and resistor off that junction.
But because of the different sized gears on the junction you likely need to adjust the size of the main chain. And you might not have suitable chains lying around to loop around the other two components.
And you can’t just go long because then you get issues with droop in the chains and there’s not a lot of clearance between the 3 levels.

If I had a do over on the design the two changes I’d make would be
1: as much as possible use a single gear size
2: a little more vertical spacing between the 3 layers so that long chains have a little more space to drop before catching on another chain

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There is a technical reason for the gears being different size on the junction. Currently, all three gears rotating as a unit is a valid motion of the junction, since the number of teeth on the gears is in ratio 1:2:3 and 3=1+2. If you do almost anything else, this is no longer true and the internals would almost certainly get more complicated on this already finicky part. But it is annoying, in particular when you try to do the voltage doubling thing and connect both upper levels to a single other part.

That last one would be easier if the number of teeth on the three levels were in ratio 1:1:2, which would also at least make the different levels closer in size; currently the bottom level of the junction can be inconveniently large. (But getting the ratios to work might be difficult.)

100% agreed on point 2, just a little extra vertical space between the levels would help any potential catching.

I agree the junctions are the reason chains need to be adjusted that often.

One other consequence is that the big wheel has far more resistance than the other wheels.

Just attach the battery to the middle wheel of the junction and a 500 Ohm resistor to the other two gears and you will see the bottom resistor turns slower.

Could you have a poorly assembled junction? Does this behaviour happen with all your junctions? (The other thing to check is chain tension, of course.)

One of my junctions arrived with the planetary gears not meshing great and substantial friction. After a few tries reassembling it, that one works great like my others, with very negligible resistance. (You can see by spinning the gears freely that there is mildly more resistance the more the planetary gears turn, but it’s really small.)

technicaly the “wheels” or “gers” are caled sprochets