Hey everyone, I’m trying to CAD a Dr4b for my teams robot and I want help with getting it to have accurate spacing and I don’t know how I would CAD it so that it would be in its resting position instead of having it be in the position where all 4 bars are horizontal. Does anyone know how to do that?? I read other discussions about Dr4b cad but I still don’t know how to do it. Any help would be great!!
Not sure what CAD software you’re using, but any decent program will have rotary joints. Just build it normally, with the bars horizontal, and make sure you get all your joints and gear relations set up right, and then you can move it up and down as you please.
Alright thanks!! I use fusion 360 and I’m pretty sure I can do this with it.
When you are in the joint command you can select the joint type to be revolute
Oh really? Ok cool! I’ll try that! Thanks!!
Just make sure you rigid group all of the components that aren’t jointed, and ground the base part. Then you should be able to click and drag it.
Alright thanks! Ill try that! Instead of rigid grouping the other components, could I just keep them jointed but edit the joints that I want to move to be revolute instead of rigid joints?
Yes and then you can use motion links to link your joints so when you revolve one bar the entire dr4b goes up/down.
Don’t use fusion, but Xdesign and SolidWorks make creating joint relations and mechanizing assemblies simplistic. (Provided you take their assemblies tutorial)
Am I still able to make motion links and movable joints in fusion though?
I have no clue.
Google says yes.
Yes, but I find that it creates less lag when all the parts are in a rigid group than individual joints. I’m not sure whether that’s verifiable, but it sure feels like it.
This is my completed CAD with a scissor lift, 6 bar and Dr4b. This will really help when CADing a Dr4b with vex parts! Thanks!!
I am CADing a Dr4b and I am trying to revolute joint both bars that connect to the c channel that connects to the robot but I can only joint one of them and when I joint the other, it doesn’t work. Every time I joint the first joint, it works, but when I joint the second joint, it says “Selected joint type will result in conflict”. Idk what to do since when I made a model on fusion 360 (that is the only cad software I am using) of a Dr4b, it worked when jointing both bars??
That probably means the c channels are not properly aligned with each other (even if they are off by only 0.1mm such error will appear). Try as-built joint, that will preserve the original position of the c channels but still add a revolute constraint
Thanks, it worked!