We are relatively new team and have spent quite some time on the forum reading discussions about DR4B and researching, trying to figure out why our lift is not working and only able to lift one cube. We adjusted banding and tested multiple ways of tension, tried to straighten the lift , changed shafts , etc and nothing works. Any help is greatly appreciated!.
What happens when you try to lift more than one cube? Does the lift bend, does it just stall out, does it not lift at all?
At a first glance everything looks pretty good. I see you’re using a reasonable ratio, and screw joints. I couldn’t tell you whats wrong with that lift from that picture. Maybe give use a picture from the back, because if you’re having power issues it’s probably due to friction in your gearbox.
Thank you for your reply. It does not lift at all
Also are you using 200 rpm or 100 rpm motors? Because 1:5 actually might be too fast for 2 200 rpm motors.
A few other things I notice could cause issues:
I see some lopsidedness in your bracing. Try using triangles and x bracing for stability.
You only have standoffs and one c channel bracing the gearboxes, that means you probably have some friction due to slightly misaligned bearings.
Also please don’t mount your motors like that it wont end Well for you.
Don’t use standoffs to transfer power from your gears to the lift arms like that. You should keep all lift arms screwed
Directly to the gears and inside your gearbox.
Thank you. We are using 200 rpm. Here are more pics
First thing I would do is try 100 rpm motors. It will still be very fast and also probably have enough torque. If that still doesn’t work its probably due to all the issues with build quality.
I won’t be able to help that much specifically with your dr4b, because while I can recognize issues with build quality, I don’t have very much experience with dr4b’s, only ever having built one. 333a on the other hand has
an excellent dr4b tutorial that demonstrates fantastic build quality. Give it a read or twenty:
Thank you for your suggestions. I believe we do not have 100 rpm motors , we will try all the rest. If you notice anything else please let us know. Appreciate your help. Thanks again!
Thanks. We did read the tutorial after we built the lift though. Will read again and rebuild!
I notice a lot more that may cause you issues, I can make a full list later.
2m 200 rpm 1:5 isn’t going to be able to lift a heavy load like a tray, tilter, and intakes, even with good build
Quality. Try using a 1:7 ratio (even that will be difficult to pull off, 100 rpm cartridges are pretty important when building a heavy lifting dr4b)
It does not lift at all
Thank you! We have limited parts, but will definitely follow all your suggestions.
from first pic, top 4 bar does not look like a parallelogram. make sure the end-bar is parallel to the lift tower and it should lift a lot better.
@mattjiangThank you for your suggestion, will fix that as well
Instead of two collars on the outsides of your axles, you can place a single collar inside the gearbox. This will let you mount your motors more securely, and still stick to hs axles. As mentioned above, you’ll need a ratio more suited for lifting a lot, so with 200rpm cartridges, the best thing to do is probably a 21:1 ratio. (3:1 compounded with 7:1… pinion to 36, pinion to 84)
The last thing is just try to compact your gearbox as much as possible. You’ve got a lot of unnecessary space being used. Try attaching your arms directly to the gears, and moving everything inside instead of spanning with standoffs.
Lifting the upper arms through the standoffs from the gear is, um, quite brave. Standoffs are not meant to transfer torque like this. The standoffs are also likely to get in your range of movement by hitting the vertical C-channel.
You need to redesign the main joint to have both upper and lower set of arms directly attached to the gears, inside the gearbox structure.
Looks like you could do with a little more bracing and friction reduction. Parallelism and symmetry in a lift are incredibly important as well so really take the time to check nothing is bending, etc.
We actually had 600 rpm motors on the lift, not even 200 or 100. I thought that the blue cartridge was torque for some reason. Thank you so much!