Experimenting with brushless out runners and planetary gear reduction units

[Subculture]

Worth looking at LiFeP04 batteries. they have a lower energy density than lipo/li-ion, but are more stable and very long life. The cell voltage is 3.2-3.3v, so 2s gives 6.6v, current capability of the cells linked is 60A, although best to use half that for best longevity- still more than sufficient for model use. e.g.

https://www.ebay.com/sch/i.html?_fro...0-M1B&_sacat=0

[gantu]

Very good company

https://www.i-tecc.de/shop/einzelzellen/lifepo4/a123/

[Monahan Steam Models]

Thank you very much Andy and Gantu for sharing those links.

I will certainly have to take a look at those cells as an option and get an idea for what the energy density is compared to a similar sized LiPo pack. At first glance I’m assuming these are the same types of cells commonly used in back up battery systems for homes and some electric vehicles?

[SubDude]

Does anyone make a planetary gear reduction unit that will fit a 40mm dia. motor?

[Monahan Steam Models]

I haven’t looked for one for a motor that size yet. If you get a chance, post the motor specs such as shaft diameter, mounting pattern, kv, inrunner or out runner. Or if you have a link to the motor. I will do some research. I’m noticing the robot building crowd uses a lot of brushless motors and planetary gear reduction units. Everything from little stuff to big stuff

[SubDude]

Mtronicks.

[Subculture]

That's a whopper! What's that earmarked for?

[SubDude]

That's a whopper! What's that earmarked for?

Yeah, they are powerful but I run the Mtronicks G2 Hydra 50's in my 66" Nautilus, 1/72nd Columbia and soon to be completed 1/48th USS THRESHER. I like how they perform and run them in the wet. Dialing down the end points helps but it would be better if they had gear reduction of some kind even if I had to custom make something.

[Subculture]

Why not print your gearbox, bush the planet gears them with DU bearings. That should run very well in the wet.

[Monahan Steam Models]

Steve,

Could you measure the threaded mounting hole spacing on the face of the motor and let me know the thread size? I could not find those details on Mtroniks website. I’ve been looking at various planetary gearboxes this morning. Did you have a rough idea of what sort of reduction ratio you would prefer?

[SubDude]

Why not print your gearbox, bush the planet gears them with DU bearings. That should run very well in the wet.

I have been thinking more about that lately. Not sure if my CAD skills are up to the task but I won't really know unless I try right? Please pardon my ignorance but what are DU bearings?

[SubDude]

Steve,

Could you measure the threaded mounting hole spacing on the face of the motor and let me know the thread size? I could not find those details on Mtroniks website. I’ve been looking at various planetary gearboxes this morning. Did you have a rough idea of what sort of reduction ratio you would prefer?

Yeah, the specs on the motor are not that great. Hole spacing center to center is 25mm. M3 and M4 threads. Not sure about a reduction ratio.

[Subculture]

Please pardon my ignorance but what are DU bearings?

To be specific, you'd want DU-B. https://www.ggbearings.com/en/why-ch...re-du-bearings

[He Who Shall Not Be Named]

To be specific, you'd want DU-B. https://www.ggbearings.com/en/why-ch...re-du-bearings

A form of 'Oilite' bearing?

David

[Subculture]

Yes, but they're not oil impregnated, and water acts as a lubricant. Perfect for use in the drink. there are alternatives if you have trouble finding them. Norbert Bruggen sells them in quite a few sizes, but postage may be costly to the US.

Lead teflon bearings are another similar item.