Double reverse four bar V5 motor placement

[Teresa_53A]

I’m playing around with a few lift designs but I’ve never made a dr4b. I got the concept but where is the best place to mount the motors? Is it better to put them on the bar connected to the chassis or on the lift. Is the weight of the motors enough that I should worry about putting it on the lift?

[DrewWHOOP]

the motors are more than capable of lifting their selves. This is how I usually see dr4bs built:

 /
/
|
M
|
\
 \
 |
 |

The motor is on the part where it reverses

[Codec]

What software did you use to make that

[DrewWHOOP]

The vex forum <20 chars>

[technik3k]

@Teresa_53A, yes, just like @DrewWHOOP said the best place to put motors on the full size DR4B is in the middle section.

The weight of the motors is not going to be a large factor, given the total weight of the rest of the lift.

That is usually taken care of by rubber banding the lift such that when there is no game objects it would take almost no force to bring it up, because rubber bands would counteract the gravity.

To make full size DR4B stable there are few more things that will help:

1. You need to link the 12T pinion gears on the left and right side with the axle, so that lift doesn’t lean to one side (those are gears that are driven directly by the motors).
2. You will need to cross brace (X) the sides of the lift to make it more stable (see linked pictures below).
3. It is highly recommended to make connections between lift stages not with axles, but with the screws fixed with nut to one side and having minimal slop on the other moving side (tighten nylocks just enough for it to freely move but not to have any free play sideways).

How to rubber band a DR4B

So im trying to rubber band my dr4b, but i dont understand how to perfectly rubber band a lift using triangles

DR4B Tips

I’m currently building a DR4B, and I am encountering many problems. my lift keeps leaning, but it isn’t because of weight, since it sometimes leans left, and sometimes leans right. The lift is also generally unstable, and wobbly, despite multiple, tight screws into the base, and support bars wherever I could put them. Are there any particular tips for these kind of issues?

How to rubberband

How do you rubber band a DR4B? I know that you should make a triangle and I know that @antichamber made an online rubber band calculator tool but the tool is in 35 hole C channels when I’m using 25 holes 1 x 1 cut c channel. So do you just randomly pick places? Or is there a way to use the online rubber band calculator for this too? PS. How do you use the calculator? I didn’t want to “revive” old threads because people seem to not like that.

Reconsidering DR4B Rubber Banding

I haven’t worked with one in a while, but I was thinking about the standard advice on applying rubber bands to a DR4B. I think it’s a little bit off. The whole triangle thing is clever, and I’m not saying to avoid that. I’m saying the targets seem to be incorrect. Why? Maintaining uniform force on the lift is not desired, nor is uniform torque. Aiming for this is incorrect to begin with. What we really want is to provide the most torque when the bars are horizontal and less as the bars are more…

Example of the well crossbraced and rubberbanded DR4B from this thread:

full res

[Xenon27]

Lol it’s always funny for me to see a post made by the ghost of xenon past…
I solved the issue btw it turns out I was just terrible at building.

But back on topic I hear its better to mount motors towards the middle, because the weight is negligible and it reduces slop between the stages, so that’s what I would do.

[josh_siegel]

Lol that robot looks familiar!