So picture ur standard dr4b with a claw. Obviously the height of the dr4b or the angle at which its at cause the ends not to be perpendicular to the ground and anything mounted there to also not be parallel to the ground. As of right now we have a poorly designed wrist motor that sits on the inside. Any alternatives to keep the claw parralel to the ground within the current 18x18 frame we already have?
wait what ? The whole point of DR4B is to go up vertically while keeping it parallel to the ground sooooo
The bottom bars will end up shorter than the top. They’re only even at when the bars are parralel the the ground as well.
that means you need to properly build a DR4B cause its not supposed to happen like that
@The_Original_Kev is right. A 4-bar is a parallelogram, so the opposite sides remain parallel to each other. Throw another parallelogram on top of that that maintains the same angle relative to the horizontal, and your fronts/backs should remain vertical. Maybe your gears in the middle of it don’t match so they two parallelograms rotate different amounts as the dr4b goes up and down? Look at some pictures of robots online and check to see that you’ve built it properly. Or post a photo of your arm and let people here check.
When building a dr4b, you have to align the middle set of gears when the top and bottom 4 bars are parallel to the ground. That can cause the whole lift to be limited to less than its maximum height and cause it to drift as it moves up. The top-most vertical bar should still be vertical though in this case. The top and bottom bars of either the top or the bottom half of the dr4b have to all be the same length, or else it will no longer be a parallelogram, like @callen said.
There are multiple guides on YouTube.