Hi.
So my team has a DR4B and because it’s our first year competing, we only have steel. We know that aluminum would be better for our lift, but as I said, we don’t have any. So our lift is pretty heavy and our motors can’t handle it. We know that rubber bands will help. But if we add motors to the second tier of gearing, will that help to take some strain off of the motors which are at the bottom of the lift?
Thanks.
I am sorry, but I have not heard of any metal DR4B that works. I am sorry, but you could try a four bar or a chain bar. And do not underestimate the power of mobile goals, they are the easiest way to score a lot of points
You can try 6 motors but… you will never get the speed and efficiency, and that is mainly why people choose to use the DR4B design
I can see how it can be done, trimming 2 wide c channels in half, or using slide rails(lighter than c channels, proper rubber banding, it could work. We do SkillsUSA (8 motors, all steel, 20 small vex rubber bands). It’s not impossible. We built a all steel bot capable of dumping two cubes at a time over the center and a high hang with only 8 motors last year. It can be done with good build quality.
So what is Skills USA?
Also, I do think it is possible to do an all steel DR4B, because we have done it while waiting for our aluminum to come in. Just needs a ton of rubber bands and good build quality, though ours could lift itself (albeit slowly) without any rubber bands.
Definitely use rubber bands or it wont work, and gear it down a lot. Four motors would help a lot.
I think there was another team that had the same issue. They said they had an external ratio of 1:5 with torque motors, so try it with a 1:7 outside ratio.
It’s a large CTE student organization, similar to TSA, they have a VEX based contest where the build is limited to only what is in the Classroom and competition super kit.
It’s an interesting competition due to the 8-motor limit
That sounds pretty fun
This is an interesting challenge. With only 8 motors I would strongly recommend not using a dr4b. Instead I would go with a 4 motor drive, 2 motor mogo lift, and a 2 motor four bar for cones.
Two motor DR4B’s are a thing
(If you were not using full steel.)
Our old DR4B was ~50% steel (and our chainbar was almost entirely steel). We had two torque motors geared at 1:7. With enough rubber bands it was functional, but it still died somewhat often and in total we had 36 bands, 8 of them doubled. Even with enough bands to make the lift pretty much weightless, inertia is a thing. The motors still had to move the full mass of the lift. Once it was moving, it was no problem, but starting and stopping motion of the lift really strained the motors. With a game like this, where the lift will constantly be going up and down, I can’t see a full steel DR4B working consistently enough with only two motors.
I was refering to Carter’s post
And I was referring to the general “not with two motors” trend in the thread and giving data to back that up.
I understand 2 motor dr4bs are a thing. I am recommending a design based on a teams resources and constraints.
technically aluminum is metal
Let me rephrase, I meant steel not metal.
Four motors geared at about 1:5 or 1:7 should help.
If you are really desperate, you could become the first people in all of history to attempt a one bar DR4B.