An off season project involves 20:1 gear reduction on some 775 motors (BaneBot, Vexpro, or random other). These will then be used as drive motors with the expectation that at times they might have survive outputing the stall torque (roughly 20N-m) at times with long run times at fairly high power output.
The Magnum Planetary looks good but its $90 which is more than I can justify for the project. Thus I’m left with options like modifying a DeWalt gearbox or finding Globe motor/gearboxes.
Does anyone know the pinion info for those?
Is there any place to buy a Globe motor to take the gearbox off? I’m willing to hit junkyards but I’m striking out on finding the part numbers of suitable ones to look for.
Are there other options that I’m missing to do 20:1 reduction?
I hate to reply to my own post but I have a related question.
Is there any way to tell how much a given gearbox could be expected to survive? There are loads of 12 and 24V gearmotors sold for less than $20 that could have their motors replaced, if they would survive much higher rpms and torque than what was expected with the original motor.
RS775 motors are mostly selected due to cost and the fact that I have RS775 motors and lots of motor controllers that can deal with them. There is no need to be FIRST legal on any of this; in fact I’m leaning towards 24V operation. Heat, especially near stall, is a serious issue but I’m looking at ways to add extra fans independent of the motor fans.
The project started as a test bed vehicle for our programmers -
Create a mecannum drive platform since we’ve never done that in LabView.
Integrate sensors and vision processing to allow for better autonomous actions
However its also been handed to me, as the slightly more mechanical sponsor, to see if it can be expanded to either a ride on or at least able to complete a 20 minute drive time in autonomous mode. So I’m looking at figuring out if we can reasonably move around 100kg (it might be much less but the first pass at the design is for the worst case ride on situation) with all 4 wheels independently powered.
Unfortunately I can’t contribute more to this discussion of inexpensive COTS gearboxes, but the Globe motors aren’t 775 motors… They’re conduction-cooled (like the window motors and CIMs) and closer in size to a 550 motor.
I joined FIRST after the Globe motors; I had just assumed that they were 550 motors. Probably doesn’t matter as what I’ve seen says that they aren’t strong enough for my uses but their gearbox might be.
No need to use COTS; yes I’m looking for off the shelf stuff to modify but its an off season task for the team so we can use pulled stuff from junkyards, surplus stuff or whatever.
If I was looking looking for cheap and high reduction, Banebots planetaries, VPs, and custom gearboxes would be my first choices in that order.
Some places like Robot Marketplace sell drill gearboxes.
Robot Marketplace’s DeWalt gearbox was a possibility but it needs a pinion gear and I can’t find any information on ordering them (Robot Marketplace does not sell them it seems). At one point FIRST teams would order them for the NBD idea but the links I can find are dead and no one seems to have posted the details (tooth, pitch, pressure angle) so that I could attempt to find a source.
The P60 is possible although the specific reductions they offer are so so (16:1 is not enough but the next step up is too much). The VP is my best option sticking with normal FIRST parts but it gets rather pricey for 4 of them. Both of these are good thoughts but I want to see if anyone has any off the wall ideas before I commit $300.
Here is a thread I posted a while back on this subject.
There is some discussion on the use of 775s. I would not be too worried about them now. The manufacturing process has been straightened out and they seem to be fairly reliable now.
In the thread I show how I adapted a Globe transmission to a RS 395 motor. The same approach can be used for 550’s and most likely, 775’s.
Thanks Billbo911, your thread was one of the reasons I started thinking about modifying something instead of buying a P60.
As I mentioned I was not involved with FIRST when the globe motor was around. Nor was my team. Do you have any idea of a part number or a source of such motors so that I can experiment with them? A quick Google search has turned up tons of hits since Globe is just the company name.
DeWalt gearboxes like in the Nothing but Dewalts paper would be cheap and relatively easy to use. I was working on a prototype of adapter the VP input C-colars to use them and the input plates for the Dewalt gearboxes. I never got around to making the custom parts (just 3D printed prototypes so far) or testing it or anything.