2381X Update Thread

Hi Friends,

I’m just gonna put this here mostly so that I can reference my team to it but feel free to look at this whenever. This is just going to be a collection of video updates that I hopefully keep making.

  • sorry for the distortion filming on a chinese knock-off gopro is probably not the best way to do this *

here’s #1: just finished the flywheel (it only took me 5 hours fml)


Can’t wait to see this in action in our Ontario competitions!
Also, I heard you say you’re going to speed up your drive base with a 3:1 gear ratio w/ torque motors. Can’t you just have high or turbo speed motors on the drive for that extra speed?

Lol catch 2381 @…idk yet. Our philosophy is to just…be faster than everyone else. 3:1 torque is faster than 1:1 turbo, so that means that if someone tries to play defense on us we can outspeed them and get back into a scoring position before they can (obviously they can cut us off), but it’s really up to us to out-drive, not to out-push (especially with the amount of talk about 2 traction + 2 omni).

We’re also a ball-focused bot, so being able to get places fast is super important. :slight_smile:


I’ve attached images from today for you guys to look at as well, ok?

Edit: Apparently some of these photos are in the wrong orientation if you’re confused by them just dm me.

Looking really good and solid! Your build quality is pretty good as well, but I have a small simple suggestion. If you are using any 6 tooth sprockets, replace them with anything but 6 tooth sprockets. They cause a lot of friction and occasionally break the chain as well.

Will do…after…I redo all the clearances… XD

Would you be able to provide some reasoning as to why they cause so much friction? We’re using about 16 of them on our robot, so if they are really that big of a problem I’d really like to know why.

@The Electrobotz

You’re in for a lot of broken chain and so much friction you could burn a house down.

1 Like

@375X Robotics has a fair point, but it depends on where you’re using them. In our personal experience, if you get the tension ok, it isn’t too bad (link to last years robot. We used a lot of 6T sprockets on our drive with a 6m turbo drive on 4" wheels. It worked just fine unless you drove it too hard. I think it’s because you’re causing the chain to turn super sharply, so there’s more force. (it’s like you can poke yourself with a needle and your skin will break, with a pencil, maybe not).

Again, depends on where you’d use them.

That’s odd that you’ve had such a bad experience with these little sprockets. I have used them every year since Nothing But Net for at least one aspect of our robot (usually the drive) and never had a single chain link brake or any extra friction caused by these things.

I’ve had links break so many times I often question the load rating - but it’s not just on these sprockets. How much tension is in your chain?

Usually, the tension is similar to the amount you showed in your video. Occasionally, it is microscopically looser, but not by much.
For where we are currently using them, they are exactly identical (as far as I can tell) to what you have shown in your video. Surprisingly, that is the most friction-free part of our robot.

I heard, the bigger the sprocket, the smother the drive :slight_smile:

  • Robot looking good, wanna lend me some Teflon washers? :slight_smile:


So, I…guess this is technically miffy2-1? vexforum: meet miffy2-1

2381X VEX Turning Point 7/2/2018 Update #3. - YouTube

This is definitely a huge improvement over the last iteration of the design, but in my experience, low strength gears are better than high strength on the drive. This is especially true with the metal pinions, which increases friction considerably. Using low strength gears will also allow you to reduce the spacing in your drive, which is currently taking up a considerable amount of space. Also, when using chain on drives, it is best to have one continuous piece to make sure the power transfer is even, a large benefit of chained drives.

Edit: If the c channels are bending outward, that likely means the spacing is pushing out and causing friction. Noticing the extra width in the c channel, this might be the cause of the issue.

Awesome, I’ll see about LS gears (we don’t have any lying around, and the small 12T ones kept breaking last year). We tried using a full length of chain, much like anti did way back in his defense bot, but it … didn’t end very well - lots of skipping, breaking, etc. The C-channel was bending inwards originally, pinching the bearing around the shaft. I bent it back out and now the shaft is free spinning.

If it was bending inward then that means everything should be fine and adding the standoffs was all the fixing needed. I know you said you didn’t have any 18 tooth sprockets, but that would help with the chain skipping. A larger sprocket generally means the chain won’t skip. On another note, have you tried moving the c channel brace blocking the intake to about 10 holes inside the robot? This would save you a lot of trouble messing with the deployable intake and you wouldn’t lose any structural integrity.

hey @Carter quick question. I’m experimenting with different drives and I was wondering what the best way to chain a 6 wheel drive in a single loop would be? I would really appreciate it if you could help. Thanks :slight_smile:

Full disclosure, I haven’t had a ton of experience building these, but I can give you guidance based on what I have seen. You will have two sprockets on the same axle as your wheels, and both of these will be driven by a motor. Then, you will have a motor in the middle driven by the third motor. Make sure that all the motors result in the chain spinning the same way, you should notice if it doesn’t. Also make sure that the tension on the chain is correct. Make it tight enough that the chain never skips, and make it loose enough to minimize friction. I have attached a paint document to ensure you understand what I was saying. It doesn’t look like the chain has much contact with the sprocket in the illustration, but in reality it will be fine.

Next time, it would be best if you start a new thread because you may get better help and ensure that the current thread doesn’t get derailed.