6bar motors clicking

Can anyone tell me what we did wrong? I am using a 6bar linkage with 4 393 motors a 12 tooth metal gear on the axel hooked to the motors and the largest high strength gear on the arms. Everytime we raise the arm we hear a licking in the motors. They click even when we raise the arm manually. Any suggestions?

try check the motors internally. you could have a broken tooth of a gear. or if you recently opened it up you might just need to take out and replace the gears in again. were having trouble with 269s right now and trying to figure them out. but i think you could just have a broken tooth on the internal gear.

I agree, it sounds like it could be the internal gears. A lot of 269s come ceased, and will click badly when moved by hand to start off with until they are used a bit :stuck_out_tongue:

Another thing you should check is how far are your towers apart? And i assume the axles arent cantilevered? Because if the two sides of one tower are too far apart the axles can bend slightly and click (ie, the distance between the two bearing blocks on one axle is too wide)

Yeah, my team broke two internal gears at worlds somehow on our 393’s. One time it was a broken tooth, and the other time was that the gear broke in half.

iv seen on the forum they use the metal lock bars round holes to act as a make shift tower there was still a bar on the other side. i guess the arm was putting so much stress on the tower the gears slipped.

Can you post a picture? My guess is that your arm gears are slipping, and when the gears slip they make a clicking noise.

It’s not their robot but this is how you can solve gear skip. Our guys ran into something very similar and by the third time around they got it. Answer: use shoulder screws! The shoulder screw has pretty much a direct contact with the metal causing less room for wiggle which causes the skip. A slight variation in distance caused by excessive froce will pop that sucker out of the gear train.

You may be putting a fair amount of force through these gears on your 6 bar so keep them locked into place using the shoulder screws. You may need a piece of metal here or there to sandwich it deep enough for the shoulder screw too.

Notice the rounding out of the corners on this steel bracket. That’s from all the force of a big lift.


Notice the extra layer of metal here on the shoulder screw… It just makes the fit work. On the down side only one layer of metal plus the Delrin bearing block is all you can get with the Vex shoulder screws. Getting the shoulder screw through the Delrin block requires a little persuasion a hammer at the vice can assist with. But remember you want the thick end on the metal, not the top of the bearing block. Your goal is to have the screw set against the metal directly versus the plastic which causes the skipping via screw wiggle room.


sorry maybe im still stuck on the internal gear slipping but where would you appy this to the robot?

Those were just pictures from another robot lift type, but the concept is the same. Slack bolts means the axles can shift out a touch causing gear skip. See the rounded edges of the square holes? Does not matter if it’s a c channel or a motor bracket - it’s the warped holes that show the axle movement which caused the gear skip/click. These were 12 tooth HS against 12 tooth HS metal gears, so I guess the bracket gave in before the gear did.

A picture of the motors and axles would be very helpful too to diagnose. Where are these gears placed relative to the big gear? Are you trying to go right from a 12 tooth to a 84 tooth gear? Stepping up to the 84 tooth seems to have worked well for others rather than going right for a 7:1 ratio off the bat.

Open the motors up just to see what’s inside, but it may be the 12 tooth gear skipping on the larger gear (they did not say if it was 36, 60 or 84 it was attached to). If it’s just happening on one spot of the 6 bar lift over and over again, it is probably the 12 tooth with the big gear slipping out of alignment since the motor would have revolved around quite a few times across that skip point with a clicking sound. Check out the plastic on the big gear to see if you have any rubbing or wear on the teeth indicative of skip. Also check the connection point to the tower or even axle bending. More likely that plastic big gear will wear down than a metal 12 toother. Or are you using a plastic 12 tooth gear? (Try switching to metal HS 12 tooth gears too)

You’d hear clicking a few times before you got to the top of the raising of the 6 bar if it were a busted tooth inside the motor since they revolve around a bit. So that makes me think that axle is moving a bit and one or more of the 12 tooth gears is slipping out of alignment.

Lastly, your elastics were not mentioned. Do you have any? If you do, the elastics at the top of the arm motion may be slack. So at the top the elastics may not be helping the lift forces much any more. Your motor now sees the full load of that arm in the raised arm position if that makes sense. More load on the gears is a higher likelihood to cause a skip.

Have fun!

Well, he said this:

I assume this means the 60-tooth gear, putting him at a 5:1 ratio, which is not as extreme of a jump.

I don’t see how stepping up to the 84-tooth gear would make a difference. It seems to me like that just adds friction.