DR4B Tutorial by 333A

Why didn’t you guys show up to Mundelein? It looks like your bot is complete.

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We decided to scrap that bot. We were trying to make too much happen in too small of a space.

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Sweet baby jesus you madman. I love it.
Do you mind editing your post if people provide good additional resources? This is the most thorough and complete dr4b post I have ever seen, and being that vex has HORRIBLE BASICALLY UNUSABLE FLIMSY FRICTION BASED LINEAR SLIDERS we will never see the simpler linear lifts used in most other robotics, so linkage based lifts are here to stay.

Also, I would like to say that using the new 4-post nut retainers as the base of you screw-shaft is a good trick for getting even more consistent geometry with little added parts. I know that centering screws is a challenge and the shaved down bearings are clever, but the nut retainers are super fast, and do a great job both centering the screw and spreading out the force.

If anyone has programming recommendations, I would like to see a collection of resources for that as well. Programmers may not be aware of how necessary learning pids are when creating a lift. The ability to recall preprogrammed lift heights, make small changes to height without running the motors at 100%, changing the acceleration profile of the drive train based on the height of the lift, or even combining actions like rollers or claws automatically running/opening as the lift stacks or unstacks objectives. Additionally, these pids make autonomous routines so much easier and reliable. You can keep it easy, or look into temperature management, and using the brake function upon decent to help reduce the amount of current used. This is one of the easiest ways to get really creative and have a positive impact on your robots performance without needing to know a ton of math.

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Great tutorial @333A!

I am going to print it and give to every team in our club who is building DR4B or DR6B lifts.

Please, keep up this good work making video tutorials, which I’m looking forward to watch!

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I just realized that the thread title has a typo, @Drow can you fix this?

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this is a great resource wish i had it last year, one thing to add always use C-Channel i tried making a lift with angle bars and they are too wide. you want your lift to fold up small and use as little space as possible. If you look at some of the pictures the clearances are less than a centimeter. that is what you want so you can add stuff like a tray to the lift

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The person who made the thread can change t themselves @333A

No need to message drow

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@Drow can we get this post pinned? It is a shining example of the quality content we want to see more regularly on the forum. Furthermore, if it isn’t stickied, it will inevitably get buried by posts including (but not limited to) people asking for help with their DR4B Lifts.

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@333A I have a few suggestions.

  1. Replace the “1-bar lift” with “2-bar” linkage since the tower counts as one in both the 2 and 3 bar linkages.

  2. I recommend using the phrase “screw-shaft” when describing that assembly since it gives that very important building process a proper name that people can call it. I want builders to learn from this techniques that they can apply elsewhere in their builds, and names are good ways to make people remember things.

  3. Investigate the use of the new nut retainers in construction, as they make much of this build way easier.

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We can’t pin every guide, but we can add it to the wiki…

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It would be nice to have some way of nominating or recognizing quality posts as worthy of putting into the wiki. Maybe a regularly (monthly) occurring wiki-nominating post, closed group, @shoutout, or form.

Or just starting a Best-Of thread for sharing the most informative posts you come across. IDK, what do you all think?

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Is there an official parts lists?

There are no official parts lists. Use whatever (almost) you want. Just please dont use steel.

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Steel will make you DR4B bad and very heavy. One of our teams did one out of steel and lets just say that when they tested it… teeth on gears were destroyed.

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someone on our school team is building a half side steel half side aluminum double dr4b with low strength 60 tooth gears with 4 legacy motors…

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I was looking through the post and I saw the part about the raised spacers on the gears, how does that help create stability.

The raised spacers help move the points of contact that the axel has with the gear farther apart. This reduces wobble because the axel has less room to rotate around the gear. If you just use a high strength gear then your two points of contact are essentially the ends of the gear insert. These are pretty close together an allow the axel to wobble more in the gear which translates to wobbling in the entire lift. This is actually a pretty cool way to reduce wobble if you have space in your lift. Another alternative is to use lock bars on your gears.

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If by “lock bars” you mean these, I would not recommend using them, because they go around shafts, and shafts with lock bars aren’t as sturdy as gears and raised spacers.

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Thank you guys. This really helped me out. Especially the K-Bracing!

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This also helped me out on how to figure out good formatting for the digital notebook this year, Thanks!

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