VEX Differential Guide

[Sylvie]

@technik3k

The fact that you didn’t link to any of the previously posted tutorials, videos, or robot reveals - boo!

Well I mean I did shout out your team

Point taken, will keep in mind

@technik3k

Lol, this is the most important part of this design that prevents additional friction losses. Without managing ridiculously large friction in your configuration - you will be much better off not doing differential at all.

Yeah, I get that, and I understand why that should be the case, but when I was playing around with my robot I didn’t find it to be significantly helpful at all. I had similar power on both mechanisms when I tried both. I completely understand the idea behind this, and it’s a nice thing to show off to the judges, but from what I tried there really wasn’t a significant decrease in friction.

I would be interested to try a 2-motor version of this design with turntable gears to see what would happen, but I only have one set of them, and I’m not about to spend $20 for a one-off experiment.

@technik3k

lso, using chain to close the differential loop makes it tricky to tune - in this case all gears design is much more smooth and robust.

Had to make mine different from @Codec’s somehow . Also as I said above, it really didn’t cause any issues. I am frankly shocked by how smooth that robot is.

@technik3k

The flip side is that those two motors will only contribute power in one direction, depending on which end of the range they are parked. They cannot contribute any power while not at the end of the range.

1. Could you not set it up to apply power moving the indexer forwards when the hood is fully closed? It might theoretically work a little bit if you did this.

@technik3k

Therefore this is not a viable design for the variable position hood.

2. I do agree with this. Simply an example.

@technik3k

However, @Kyle1’s innovative way to build differential core without bevel gears offers some very interesting design opportunities, if friction losses could be reduced and input torques are properly balanced.

@Kyle1

Here’s the clearest picture of my favored gearset. This current application is continuous power sharing, but its what I used for the multispeed drive designs too.

If Kyle could share the CAD file for that with me I might give it a go. I didn’t see this one before, but I really can’t see enough from the image to build it. My brain can only visualize so many gear trains at once.

@technik3k

Taran, you could improve your topic by a lot, if you offer readers who are interested to further study this subject, some easy to follow links to: vexforum, chiefdelphi, or external resources like this one:

Good point, I’ll take that into consideration whenever I next make a guide like this. This was definitely supposed to be more of an intro than a full-out tutorial, so I see why that could be useful to add.

@technik3k

The fact that you CADded

I would lastly like to add that my CPU quite literally hates me at this point. I think I broke something in the process of all this modeling and rendering because my computer now struggles even running Chrome. I dunno what happened, but it’s kinda annoying. It takes longer to render a single frame on my ASUS laptop with a gen8 i5 CPU (built-in graphics, using the CPU for rendering) than my 80 dollar Chromebook running Linux with Blender installed.

I think I need a new computer. Supposedly building a computer is one of the suggested options for the IB MYP personal project, so maybe I can convince my parents to fund that.