Author Topic: Planetary gearbox - an attempt to make sense of how it works  (Read 6520 times)

Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #45 on: April 27, 2019, 12:05:37 AM »
Don, my bad. I must have been mixing Simplify3D with some of the freeware ones that I've tried. I don't have Simplify3D. I have only read about it. Sorry for the confusion.
Information, that you have provided, is much appreciated, though.

Hello sorveltaja

Congratulations for getting this far. A noisy three speed and reverse epicyclic gearbox using printed gears is a real achievement. With any Wilson gearbox, all the epicyclic stages spin at different speeds, The speed of the output shaft is dependant on which gear band brake is selected. First and Reverse gears will the worst as the overall reduction is the highest and reverse has a direction change as well. Some of the epicyclic stages will be spinning really fast.

What's you reasoning for going from 1.0 Mod to 1.5 Mod?

My instinctive reaction would be to increase the tooth count to reduce the tooth meshing noise, unfortunately reducing the tooth size also increases the precision required.

It is normal practice to have three planet wheels, instead of just the two. This will have the effect of increasing tooth count as well as improving the load distribution and concentricity of the sun and  planets, as they spin inside annulus gears.

Do you have an end use for your epicyclic gearbox or is it simply an exercise in design and 3D printing?

My Merritt-Wilson transmission system was designed for use in a 45Kg 1/6 scale, all metal, model tank (AFV) driven by a 2HP four stroke petrol engine. The Sturmey-Archer bike gear hubs provided the epicyclics for both the Wilson gearbox and for the Merritt double differential track steering. The S-A bike hubs selflessly donated their internal organs for scientific purposes. They proved to be a strong and very robust solution. They were also quite noisy, but then, so is any tank.

Mike

Mike, the reason for going to 1.5 mod was simply to see, how much more there is room to play with offsets. When printing gears, they will not be as accurate as machined ones.

So all kinds of eccentric defects are always present. To overcome that, I increased the tooth size, so there is bit a better chance to avoid the collision of one gear's teeth's outer diameter(slightly eccentric), with other gear's root diameter(also slightly eccentric). I wish I could explain that better.

Instead of just two planet gears, I have added two more. With 21 teeth ring gear, and 7 teeth planet gears, to my surprise, four planet gears seem to fit, or mesh together with sun gear and ring gear.
But I'll have to confirm that, by printing them out first. I have even drawn 1.5 mod helical gearsets, but wouldn't hold my breath for them to be less noisier.

What comes to my take on epicyclic gearbox, It's more like an exercise to realise a model, that could hopefully end up as a usable project for others, that are interested of planetary gearbox, and its magical movements.

Of course, the gear changing mechanism is an open question so far. But I'll get back to that, after I get the gearset problems sorted out.

And Mike, that tank project seems quite interesting :praise2:. What could be better, than putting the four cycle engine, coupled with an automatic transmission to actual use??
Do you have a build blog of that tank?

And thanks for the additional pictures of the Sturmey-Archer gears.

Online Vixen

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #46 on: April 27, 2019, 04:45:47 PM »

Mike, the reason for going to 1.5 mod was simply to see, how much more there is room to play with offsets. When printing gears, they will not be as accurate as machined ones.

So all kinds of eccentric defects are always present. To overcome that, I increased the tooth size, so there is bit a better chance to avoid the collision of one gear's teeth's outer diameter(slightly eccentric), with other gear's root diameter(also slightly eccentric). I wish I could explain that better.

Instead of just two planet gears, I have added two more. With 21 teeth ring gear, and 7 teeth planet gears, to my surprise, four planet gears seem to fit, or mesh together with sun gear and ring gear.
But I'll have to confirm that, by printing them out first. I have even drawn 1.5 mod helical gearsets, but wouldn't hold my breath for them to be less noisier.


What comes to my take on epicyclic gearbox, It's more like an exercise to realise a model, that could hopefully end up as a usable project for others, that are interested of planetary gearbox, and its magical movements.

Of course, the gear changing mechanism is an open question so far. But I'll get back to that, after I get the gearset problems sorted out.

And Mike, that tank project seems quite interesting :praise2:. What could be better, than putting the four cycle engine, coupled with an automatic transmission to actual use??
Do you have a build blog of that tank?

And thanks for the additional pictures of the Sturmey-Archer gears.

Ok, I understand your reasoning; bigger gear teeth will potentially have less percentage error. Let's hope the extra planet wheels do not make the clearances too tight again. You could always revert to two planets if necessary.

The Wilson gearbox was not an automatic gearbox. The next gear was preselected by the driver, when the clutch pedal was pressed, it engages the brake for the previously selected gear. My model uses a centrifugal clutch (automatic-ish) and for the Wilson gearbox, I intended to use a four lobe camshaft operated by a single servo. The cams would have been located 90* apart and each cam would operate one of the band brakes to select that gear ratio.

I have not posted a build log in the MEM website. I did not think a scratch built, model tank with a multi speed transmission and double differential steering system was appropriate for this forum dedicated to Model Engine Making; I did not expect there would be much interest in the subject matter. There would probably have been more interest if it had been powered by a boiler and steam engine built from castings.

Mike
« Last Edit: April 27, 2019, 04:52:24 PM by Vixen »
It is the journey that matters, not the destination

Offline Kim

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #47 on: April 27, 2019, 05:43:02 PM »
I would have been (am!) interested! Sounds like an engine powered vehicle to me!
Kim

Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #48 on: April 27, 2019, 10:08:01 PM »
Here are the first parts of the mod 1.5, helical gearset. Reverse brake spool with an 'orphan' sun gear, to see how they fit together:


Ring gear has 0,3mm offset, planet gears 0,1mm, and the sun gear was scaled down to x 0,95. When fitting them together, there were still some tight spots.

So I turned 0,2mm off of the planets- and the sun gear's outer diameters, and tight spots went away. There are relatively big gaps between the gears, but still enough meat in them to mesh together(although loosely).

Now the reverse brake spool and its gears rotate freely. No more crackling, only rattling. But as there is a play between the gears, which also have somewhat rough meshing surfaces, noise is to be expected.

With previous version of the transmission, which had plenty of friction, and some serious bindings and tight spots, I applied plenty of white vaseline to gearsets.

Messy stuff, but it seemed to dampen the noise to some extent.

Due to the printed parts being partly hollow, they act like acoustic amplifiers. I have printed the parts with 50% infill for some time now, in hopes to reduce the noise factor. 

But once I manage to make a low friction version of the transmission, I'll print all the parts once again with 100% infill.

Offline ddmckee54

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #49 on: April 30, 2019, 05:56:07 PM »
3D printers, at least the AFFORDABLE ones, will never give a smooth surface finish so that is going to contribute to your noise also.  Your statement that your printed gears bind in some spots make me think that not all of your axis are printing accurately.  If your X and Y axis are not printing the dimensions you tell them to print then you're not going to get circular gears.  They'll be elliptical, which will contribute to both binding and noise.  Z axis dimensional accuracy will always be a problem, unless you are so lucky or good that the top of your part always corresponds to the top of that layer.

I've found that even though both my X and Y axis were originally set to the same steps/mm, when I printed my 20mm test cube, the X and Y axis did not print a 20mm object.  On one printer they were within a couple of tenths of a mm, on the other it was more like 0.6mm.  That error will only increase as print size increases, that's why I "tuned" my printers.  Now when I print my 20mm test cube I consistently get values of around the 20.02mm for both the X and Y axis, Z is holding at about 19.98mm, that's good enough for me at this point.  In the future I may try to squeeze another decimal place out of it, but for now it's close enough.

Don

Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #50 on: April 30, 2019, 11:32:42 PM »
Don, how do you actually do the tuning of the printer(steps/mm)? I haven't found any information, of how to tune the one, that I have.

What comes to the 1.5 mod version of the transmission, I think I'm going to redraw the parts, that have bearings, to add some more, and maybe extra bushings, if needed.

Some of my ancient projects just might have practically unused 13 x 6(od x id) ball bearings to donor for the cause. I'll have to check that out, though.

So far my take on the original drawings has been rather clunky, as I wanted results as soon as possible.

I know that

I'll be posting pics of the progress, as it proceeds.

Offline ddmckee54

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #51 on: May 02, 2019, 10:52:59 PM »
Like I said in Reply #39, I cheat.  I documented the steps in that reply.  A couple of things I didn't say was that I printed a 20mm test cube with X,Y, and Z on the appropriate faces so that I would know how the cube was oriented  when it was printed.  Also you need to use a micrometer for the actual measurements.  A digital caliper will get you sorta close, but you need more accuracy than that.

Don

Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #52 on: May 03, 2019, 12:17:56 AM »
Don, yes I had to look again, and there it was in the reply 39. I started to wonder, how to make the information, that moves between computer and the printer, visible.

As it is through usb, it was easy to find a software, that shows a 'raw data view', from https://freeusbanalyzer.com

The only way so far, that I've managed to send M503 -command to the printer, is to make a new .g-file(actually a text file), which consist only that command. Then opened it with Flashprint, and hit the print -button.

Extruder and the plate made some moves. After they stopped moving, I ended the capture.

That usb-analyzer was already running, and capturing the usb traffic only for selected device, which was the printer. It was possible to export both 'read' and 'write' -data to text files.

Here goes the 'read' data:
Code: [Select]
CMD M602 Received.
Control Release.
ok
CMD M601 Received.
Control Success.
ok
CMD M602 Received.
Control Release.
ok
CMD M601 Received.
Control Success.
ok
CMD M650 Received.
X: 1.0 Y: 0.5
ok
CMD M115 Received.
Machine Type: Flashforge Finder
Machine Name: Flashforge Finder
Firmware: v2.2.7.299 F2.12.2 20181203
SN: FFF215029
X: 140 Y: 140 Z: 140
Tool Count:1
ok
CMD M114 Received.
X:-64.9991 Y:-64.9991 Z:70 A:0 B:0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: READY
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M28 Received.
Writing to file: 0:/user/testi.g
ok
CMD M29 Received.
Done saving file.
ok
CMD M23 Received.
File opened: testi.g Size: 5
File selected
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:1 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:1 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:1 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:1 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:1 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:1 Y-max:1 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:1
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: BUILDING_FROM_SD
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M26 Received.
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: READY
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:27 /0 B:0/0
ok
CMD M27 Received.
SD printing byte 0/1000
ok
CMD M119 Received.
Endstop: X-max:0 Y-max:0 Z-max:0
MachineStatus: READY
MoveMode: READY
Status: S:1 L:0 J:0 F:0
ok
CMD M105 Received.
T0:26 /0 B:0/0
ok

And the 'write' data:
Code: [Select]
~M601 S0
~M602
~M601 S0
~M650
~M115
~M114
~M27
~M119
~M105
~M28 5 0:/user/testi.g
~M503~M29
~M23 0:/user/testi.g
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M119
~M105
~M27
~M26
~M119
~M105
~M27
~M119
~M105

The printer seems to respond to M503 -command, but I can't figure out, what it does with it.

In Slic3r, there is an option to add a custom gcode to the start and to the end of the code. I haven't been able to connect it to the printer, though. The usb/serial connection box is always empty:



   



Offline ddmckee54

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #53 on: May 03, 2019, 03:33:17 PM »
From the files that you sent I have no clue either, I'm seeing what appear to be mcodes that I've never seen before.

I've got a feeling that our printers are using different communications protocols, so let's start with the basics:

1) What printer do you have? (Make & model)
2) How do you get the gcode file to the printer, sent from PC via USB, loaded from SD card, or something else?

I've got a feeling that I'm telling you to send Apples to your machine and it's reading it as Oranges.

Don

Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #54 on: May 03, 2019, 07:49:52 PM »
The printer is Flashforge Finder V2.0.

I send the gcodes, using the bundled Flashprint, through usb cable to the printer.




Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #55 on: May 05, 2019, 11:29:53 PM »
A bit of a progress. The reverse spool got an extra cover, that also holds the brass bushing:


While fitting reverse- and first spool together, all went well, until it was time to fasten the grub screw of the carrier inside reverse spool, to the output shaft.

After some head scratching, the solution was easier, than I thought. I Drilled 2,5mm hole through the rev. spool, so the hex wrench could be used through that hole, to fasten the carrier.
Needed only to dial in the position, and the job was done. The 2,5mm hole was then tapped for M3 grub screw, to keep the lubrication inside:


And here was another puzzle, of how to connect the second spool's inner spool to first spool. Obviously, both ends of the carrier stubs couldn't be threaded ones.

Stubs have 4mm blank ends, while first spool's cover has 5mm holes in it, to allow less critical operation:


Now the second spool's cover has a brass bushing:


First spool's cover will also have one. Not sure, if they are of any help, but hopefully they make the construction more rigid.

Last but not least, is the dirty trick, that I tested on one of the scratchy gearset. In fact, they are all scratchy straight out of the printer.

I have tested it only with PLA. But here it goes. When running a single gearset at a time in the lathe, or any other power source, holding the brake spool, instead of applying lubrication first,
squirt some acetone to rotating gears:


Not much is needed. When the gears are rotating, you can hear, after applying acetone, change of the sound(or noise) they make. At first, it smoothens, then, quickly after the acetone evaporates,
they get really sticky.

Just before that, apply some lubrication. Otherwise you'll end up prying the gears apart. If successful, gears should have less noise. Repeated treatments, that's something I'm still working on. 

The idea for that came from Youtube video, where a guy tested, if it's possible to glue PLA parts together without glue, using only acetone. He managed to get rather positive results.

There are also some videos, where acetone vapours are used to smoothen out printed PLA surfaces. Not very convincing, though.

As far as I understand, PLA is not soluble in acetone, but it seems to have some factor in it, that softens the surface of the printed PLA part, making it just slightly more 'malleable'.

Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #56 on: May 08, 2019, 10:53:33 PM »
So the Wilson gearbox is mostly completed, although I haven't made the brakes for it. Brass bushings seem to reduce wobbling quite well, and add some rigidity, but otherwise making the whole construction stiffer to rotate.

If I had an extra machine, I would run it for days, or long enough to 'break in' the transmission, to smooth it out:


Especially the reverse gear needs more torque, when compared to other gears. But that was also the case on previous version, which didn't have any extra bushings.

I wonder, if the Wilson gearbox was originally intended for slow rotation only, as on some gears, the planets rotate at wildly high speed, when compared to input shaft speed.

Anyways, thanks goes to Mike, who provided the drawings for Wilson gearbox :ThumbsUp:

Journey continues, and I looked back to the original sources(or at least one of them), and found Pol Ravigneaux's patent 2,631,476, from 1953. It includes some variations of this:


I've done sketches to 3d-model the above transmission, to figure out different 'organs' better. To me, the text on the patent is plain, and understandable.

Just as if that wasn't enough of challenge, I found a very highly detailed 3d-model of "Mercedes Classe CLK kompressor 200" automatic transmission at: https://grabcad.com/library/mercedes-speed-automatic-transmission-by-solidworks

It is an absolute overkill, but what the heck. I'll crop out all the outer parts, to the bare bones, just to see if I can find any similarities with Ravigneaux transmission.

Of course there must be plenty of 'flavors' other than Ravigneaux. But one at a time, as it goes.


Online Vixen

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #57 on: May 09, 2019, 12:04:10 AM »
Hi sorveltaja

I am pleased you managed to get my Wilson gearbox design to run with 3D printed components.  :ThumbsUp: :ThumbsUp: I had intended to build mine from hardened steel Sturmey Archer bike gear sets.

Have you measured, counted, or calculated the gear reduction ratios for the three forward gears and the reverse gear? I would be specially interested in the reverse gear ratio.

Mike
It is the journey that matters, not the destination

Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #58 on: May 09, 2019, 10:59:59 PM »
Mike, I put a on mark on both input and output shaft to count the ratios.

1st gear ratio is ~0,33. For one revolution of output shaft, input shaft rotates 3 times (1/3)
2nd gear ratio is ~0,25 (1/4)
3rd gear ratio is ~0,44 (1/2,25)
Reverse gear ratio is ~0,125 (1/8)

All the sun- and the planet gears have 7 tooth in them, and all the ring gears have 21 tooth in them.

But on the other hand, I got an idea of how to measure the ratios bit more precisely, without math calculations. If one had a 360 degree protractors attached on both input- and output shafts, the result could then be more easily read.

There is some slack between the 3d-printed gears though, so it might make the result again less precise, after all.

But then again, to get the exact results, one has to use the underlying mathematics, which makes me feel dizzy.


Offline sorveltaja

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Re: Planetary gearbox - an attempt to make sense of how it works
« Reply #59 on: May 14, 2019, 11:44:03 PM »
It's been quiet for a while, but in the meantime I have looked at some different types of transmissions.

As mentioned earlier, the Mercedes transmission was one of them. But it is way too advanced for me to make sense, although I can distinguish sun-, planet, and the ring gears, and their carriers.
Even when most of the outer parts are stripped out, it looks like this:


Then it was time to take a deep breath, and go back for simpler models. I reread this thread from the beginning, and thanks for Ade, who posted(reply #3) link for the page, which also has a video of an animated operation of a gearset.

I simply looked the video many more times again, and counted all the teeth of the involved gears, and modelled them. Result:


I took screen captures from the video to compile a single picture, of how the different elements work together. To me, it explains more than thousand words:

 

As explained in the video, the gears are engaged by using corresponding clutches. There is probably a very good reason for that.

But then I started to wonder, if there was a way to use brakes, instead of (complex?)clutches.

Adding a single planetary gearset for each gear just to engage them by using brakes - not sure at all, if it's any simpler. I might try it, anyways.

I've also revisited the transmission, that was in my first post in this thread. Had to re-draw most of the parts, mostly to add 3 or 4 planet gears, instead of just two.

Other modifications, so far, include something as obvious like this, where the ring gear Z isn't supported in any way:


Here the ring gear Z has an additional supporting part(highlighted):