Author Topic: Planetary gearbox - an attempt to make sense of how it works  (Read 4737 times)

Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #75 on: June 11, 2019, 12:34:47 AM »
Don, yes I tend to calibrate the build plate rather close to the nozzle(under 0.10mm). I do it manually, as I've found that the automatic calibration in Finder is useless.

As you mentioned the bed adhesion, it is indeed quite good, even though the Finder doesn't have warmed build plate. I might do some testing about the top layer and 'elefant feet'. Thanks for the tips.

What comes to the transmission, it is still far from perfect, but here is the mock-up of it with middle support:   


There is something strange between 3rd and 4th gears though, which I haven't been able to trace so far. It feels like they are missing. Maybe it is too obvious for me to see:


At the lower left corner there is a diagram of 'kraftfluss'(power flow?), but I'm not sure, how to interpret it.

Anyways, here is the drawing of current version of the transmission:

Offline jtrain

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #76 on: June 11, 2019, 05:16:25 AM »
This is not a transmission but someone that made planetary gears for a different purpose.


John

Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #77 on: June 11, 2019, 09:09:41 PM »
John, that's a wonderful video. Too bad he doesn't show details of that broaching device. Not that I have a mill or lathe sturdy enough to attach broaching machinery, but it would be interesting to see his take on it.

 

Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #78 on: June 13, 2019, 12:19:54 AM »
Here is the test setup for the transmission so far. Even if there are missing gears (third or fourth), I'll give it a shot, and continue testing:


The steel rod axle on the front will have cams for each brake. When turning the axle, there should then be a sequence, where one brake is locked at a time.

I have no idea, does that concept work, but as always, there is only one way to find out.

The brakes are to be held in position with screws, that are attached to the front 'post', or that's the plan anyway:


There are six brakes(one being 'neutral', as I found out) to fit in, and i'm sure the idle friction between the brakes makes it already quite tricky challenge. But then again, there are plenty of possible alternative options to test. 

Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #79 on: Today at 01:07:31 AM »
Testing of the 0.6 mod transmission proved again at least one thing: multiple stages of gearsets multiply any, and all possible, even minor defects, which the printed parts have.

The result was (yet again) a grinding machine, with lots of friction and wobbling.

So far, what I have experienced with my entry level printer, it is highy unlikely to make such complex contraption just by printing the parts out and assemble them, and expect it to work smoothly.

The printed gears must be machined after printing, or formed by other means, to ensure better meshing.

One last thing, that came to my mind, is to 'roll' the printed gears, using the same module metal gear with some heat.

I don't have any 0.6 mod metal gears, so I'll have to skip the current version, and go back to the 1.0 mod one.

I have some mod 1.0 steel gears, that came with lathe. This one has 40 teeth, which I used to form the 12 teeth planet gear:


The heat source:


Result after 'forming'. Left one is straight out from the printer, while one on the right is also printed, but post-formed: