Our team is building a DR4B lift for the very first time. We just tested our prototype and found out that as the lift goes up, it slightly leans back. At full extension, our intake is 5 inches further back than at the starting position. We were hoping to make it go straight up without any lean. Has anyone else had this problem? What causes the problem and what are possible solutions? Thanks.
If the two 4 bars on your dr4b are not exactly the same length, it will not lift linearly. It they are and it’s still leaning, than the lifts are either not aligned correctly or there is some play. To check if they are aligned, move the lift exactly halfway up so the bottom 4 bar is perfectly horizontal, if the top 4 bar is not also horizontal, than you need to change where your gears mesh so it is.
Thanks for the feedback. The lifts were not aligned correctly. We fixed that and it eliminated most of the lean. However, there’s still a little of it. What are things that can be done to eliminate the play that’s causing the last bit of lean?
@stevehoaim in order to eliminate as much play as possible you want to use single rotating bearing joints. Basically, you should firmly attach a screw to one of the bars with a tightened keps nut. This will keep the screw perpendicular to the bar and in turn remove play. Then, run it through a bearing on the other bar with a Nylock nut so that it is tight but able to rotate. The reason this joint is so great is that it is very strong but also only rotates in 1 bearing instead of 2 which takes away the majority of play.
If you go to 2:23 in this video you can see it https://www.youtube.com/watch?v=rhfNeMwAKnI
Speaking from personal experience When you’re designing your dr4b, make sure that at some point, both 4 bars are completely horizontal. In other words, try making the bottom 4 bar horizontal, and see if your top 4 bar is horizontal as well. If it is not, shift the gear of the top 4 bar upwards or downwards. This was what helped us a lot.
bearings + screws. every bit of looseness and play adds up