Building our first DR4B

So, my team is building our first DR4B. We understand very well how it works and the mechanics of it. However, we do not know everything, having never done it before. We’d like help with some of the smaller more specific things, mainly:

  1. Reducing Slop
  2. Reducing Friction
  3. Reducing Friction on joints specifically
  4. Anything else you can think of that could help

Thanks in advance.

Use screw joints. Those will help a lot with slop. If you power your lift from the midsection, that will help with slop as well. I would recommend using standoffs in your middle section as well It helps a lot. And don’t forget, always use bearings when it is absolutely necessary. For friction, just space all your gearboxes appropriately. Make sure nothing is hitting something else. I would also recommend looking at other threads made by people asking the same questions. Those threads probably have more in-depth information.

So what is the ideal configuration for making a screw joint? Our second team is also making their first DR4B and I help occasionally, and I feel like the way we use screws for joints is not ideal. What we do is have a long screw with bearings on both pieces of metal, and 2 teflon washers between them. Then a nylock on the end of the screw. But this seems like not the best way to do it. Is there a better way to use screws as axles?

The way that I make joints is as follows:
Screw the bolt to one piece of metal in the joint with a kep’s nut, as tight as you can make it.
The other piece of metal gets the bearing block mounted in whatever orientation fits best in your case.
Then make sure the spacing is what you need to line up with the other part of your robot, and nylock on the end of the screw.

Very minimal slop, and the kep’s nut means you don’t need a allen key to tighten the nylock, the screw stays put and the nylock just tightens. Hope this helps.

Thanks, I will pass this on to our other team!

Him can someone please help me and my Team? We have a very bad robot and slk of our pieces are steel. Nomsluminum. But I think we don’t hsve enough pieces for the dr4b. However, we have enough for s Danny lift. Can you guys please help me on how to build it?

Well first off if you understand a “danny lift”, then you know it requires pretty much all the pieces needed for a DR4B. Also people (me included) are willing to help, but broad and vague requests like “can you please help me” are kind of hard to answer, as we don’t know what kind of help you need. Can you ask for something more specific like “What are some good gear ratios for a danny lift/DR4B?”

I’ve been trying to, but the search system for the Vex Forums is hideous. If you could help me find some that would be much appreciated.

The best way to search for forum posts is on google, search “ (insert your search words here)”

Make sure that whatever metal contains the gearbox, make it as close together as you can in order to avoid the axles bending away and the gears skipping.

I have a question about picking up the mobile goal. Whenever, we pick up the mobile goal, our two motors that control the slider bar aren’t strong enough to lift it. And the back of the robot is floating off the ground, do you know a solution? It is two c channels connected by another c channel. The two c channels slide the mobile cone right into it. Then, the slider bar will pick it up. However this design has multiple flaws and we can not brainstorm a better solution. Do you know a more effective way to pick up a mobile cone?

You are 31st in the world as of 12/9/2017? Is there a video of your robot in action on YouTube?

I would recommend doing some tests and figuring out the solution. But don’t ask new questions in an existing thread. All it does is derail the thread.