Peoples views on our lift ...

hi, the image attached is a cad design of the lift that i built, can anybody see any problems with this, because the lift was having problems

thanks in advance

-393 motor (high torque)

(note with the second axel bar down, it is a c channel, and the washers go upto the plate … not a mistake)

Does your robot’s lift tower look like this CAD exactly, screw for screw? I get the feeling you’re missing a motor on the bottom, and some bearing flats are missing.

Put a few washers between your bottom 12, 36, and 60 tooth gears and the c channel the motor is mounted on. You could have trouble because they’re too close and hitting the screwheads you mounted the bearing blocks with.
On a similar note, add some horizontal space between your bottommost two 60-tooth gears so they don’t contact eachother - might help.

I’m also not sure on how well putting bearing blocks on the insides of c channel works because the bearing blocks aren’t always skinny enough to fit properly- I’ve always put them on the outside or the center holes of the metal so they reduce friction as they’re supposed to.

If there’s no power going directly to your topmost c channel arm, remove the gears on it-they serve no purpose.

Does your arm lift properly without a feed attached to it?

You should turn you channel sideways that way your axles are shorter and it takes up less space … also make sure the last gear is screwed directly to the arm so your axles aren’t transferring the torque.

Also what’s with the bottom most 36 tooth gear… I don’t see its purpose… and a 1:25 gear ratio seems a little strong… might be an axle bender…

But you should make all your axles shorter…

It all looks much larger than it really needs to be. My recommendations:

Do you need the lowest 36T gear? If it is there to stop the 12T attached to the motor from skipping, maybe look at a different solution.

Do you need two 60T gears in the 12T:60T -> 60T -> arm part? Could you find a way to go straight 12T:60T -> arm?

Using c channel mounted in the orientation you have means that you need much longer shafts. In my experience, try to keep the shafts as short as possible, because twisting and bending problems are far more common in situations where the shafts need to be long, and especially when the shafts are long without enough support. So I would try and rotate the metal to be in the other orientation for the piece that is between the motor and the gears (the one on the left in the picture). Not so important for the other one.

I completely agree with the other suggestions, make sure the arm is bolted securely to the gear, make sure every shaft has a bearing on it wherever it goes through metal, maybe remove the gears on the upper arm if they aren’t being used, make sure no gears or moving parts are scraping along other moving parts or screws.

Also, maybe you could give us some more information as to what issues you are having? It would help us out a lot. :slight_smile:


Yes I see problems, can you post some more views, it’s really hard to see how it works at all.

I came back to look at it again with a clear head, just noticed you may want to put some collars on there too :wink:


What is the purpose of the 2 thin gears on the center arm? If the axle through them is also going through the 2 side tower rails, this will prevent the arm from moving. (I’m assuming that the center rail is bolted to the topmost HS 60-tooth gear).

Also, as mentioned, the 36-tooth HS gear on the bottom is extraneous. Are you planning to put another motor under it (attached to a 12-tooth gear) for more torque?

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Please describe what “problems” you are having, post photos of the actual lift and describe exactly what your lift is supposed to do.

It’s very difficult for someone to offer help if they don’t understand the problem.

Hi, i dont have access to the robot until January 14th, but this is a different view, basically the top section with standard gears is screwed into the top part of the arm … with axle bars, we dont have any shorter axle bars (ex. clutch posts)

  • with the problems, it couldn’t lift our intake which is about 1.5kg (that has a sack in it) … it got about half way up, and just didnt wanna go up anymore.

  • with the small 36 tooth gear at the bottom, it keeps the main drive gear steady, it is not essential, just helps

  • motors, we only have 1 393 per side because of lack of motors

  • with the second 60 tooth gear, i dont know why it is there, could this be causing problems …

  • 1:25 gear ratio, we increased it because it couldn’t lift the intake, but it may not be the lack of torque that is causing it not 2 lift, that is why i have posted it here…

  • locking nuts (collars), there will be collar nuts, but i have not finished the cad yet, working progress … (there will b 12 collar nuts on it)

These are more views:

Where, exactly, is the intake mounted?

What is the purpose of the 1:3 at the bottom?
2 motors total at 1:25 correct?
What is the purpose of the like 6 flat bearings, they look like spacers or some sort of weak axle support?

there are two of the arms (AS DISPLAYED), and it is bolted onto the arm, with the 1:3 has no purpose (supports the drive axle) …

there is 1 motor per side, for lift in total 2 x 393 motors …

Ok, now I see.

Obviously a work in progress, looks like nothing is constrained in the CAD, lots of axles not aligned with the holes in the structure. However, my general comments are.

  1. Distance between axle support is too large, this needs to be minimized.
  2. The stacked bearing flats supporting the main drive needs to go, this would all be part of reducing the distance between the axle supports.
  3. The 36 tooth gear supporting the 12 tooth drive should not be needed, if the drive gear is needing that extra support then it just reinforces the fact that the axle is too long and needs reengineering.
  4. The two 60 tooth standard gears on the upper arm perform no useful function as that axle is not driven, bearing flats on either side of the C channel would work as well.
  5. How are the two tower supports joined together? Right now the axles are the only support between them, this will not work.

I’m not sure on the exact numbers, but my team’s lifted greater loads with the same amount of motors at a smaller gear ratio (1:25 is quite the powerful ratio). So I really don’t think it’s a power issue.

How did you connect the pieces of metal for your arm? Did it go Screw -> Metal -> Washer -> Metal -> Lock nut (and not that tight?)

Has your team ever used the arm before you put it on the robot (like powered it by hand, not by motors)

Also, I can only see four motors on your robot. Do you have 6 motors on your intake?

I’ve found that having more than two support points (stack of bearings) only increases friction due to slight variations in attachment.

Correct me if I’m wrong, but I remember bearings not fitting on the insides of c-channels in the configuration you have.

I would rotate the c-channels as others are saying, remove the bearing stacks, and remove the excess gears at the bottom and top of the lift.

Regarding the attachment - there should be a metal piece holding the towers together. if those flex outward it could be bending the axles and hurting your lift weight. I also recommend adding a bar from the towers to the base of the robot to create a truss - if you rotate the bars and they are only attached to the back of the base you may have flexing issues.

connection of arm to gear, 4 screws with kelp nuts (very tight) …

config of motors atm: 2 on drive, 2 on lift, 2 on rotation, 4 on intake …

holding the tower together … ok we didn’t think of this, because there are like 10 screws connecting the c channel to the base, and it doesn’t seem to move …

also with c channels, i will look into it, i am gonna scrap the entire prototype and start again using everyones feedback … THANK YOU ! :smiley:

Why so many on the intake? You should have at least 4 on your drive… I don’t know what kind of intake you plan on but it should not require 4 motors…

Unless Its some crazy new intake no ones ever seen before… and what’s this rotation you speak of?

the rotation is the entire system can rotate around that works fine, basically 2 x 393 motors can rotate the entire intake system around, it can score in all goals, and desc ore all goals, plus when rotated to a certain orientation can completly block the trough … so could take out the sacks from a trough, move them to our trough then cover them up (defensive strategy)

and our drive seems to work fine, it drives fine with intake/sacks mounted … drives reasonably fast, i am considering trying to convince the other guys to add 2 393s from the intake to the lift, because intake is pretty useless without lift …

Have you tried moving it down so that you won’t worry about building to the floor but building up and this might help as well I know it did for me. Good luck