Wheels keep falling off the motor shafts

#1

I purchased the Makeblock IR kit. My daughter and I built both the tank version and the three wheeled version.

We are trying to build a robot that can carry 5 pounds of weight. During weight testing, we found that the tracked version wouldn’t turn when the load reached 5 pounds. So we switched to the 3 wheel configuration which turns much more easily when carrying a load.

However, we keep having problems with the wheels falling off! We experienced this is both the tank (tread) mode and the 3 wheeled mode. The problem seems to be that the screws that are supposed to press against the flattened part of the motor shaft keep getting loose. (We noticed the loose wheel initially when the robot started to turn to one side.)

I’ve been tempted to try using superglue to hold the screw in place, but I do not want to end up permantently gluing the wheel to the shaft.

Has anyone else had this issue? How have you solved it?

My other thought was to drill a small hole through the shaft and use a pin to hold te wheel on.

#2

@ChromeTemplar, its the first time we got feedback like this. For better understanding your problem, could you please send us photoes for showing your problem by email, if it was found as quality issue, we would arrange replacement for you. Support@makeblock.cc

#3

I had this problem and i replaced the set screws to rounded head screws. on the drive wheels i had to grind off part of the head with a Dremel tool because it rubbed on on the mounting screws. you can’t really tighten the set screws tight enough because they strip out where the hex wrench goes. i also used 2 screws on each wheel, no problems now.

#4

Thanks Wildwingman. Today I went to Home Depot and bought M3-0.5 x 16mm socket cap screws. Now I will be able to torque down the screw tightly without being concerned about breaking the little allen wrench. If necessary, I will use super glue to hold the screw in place.

I noticed that the screw holes are not perfectly centered. I am sure this is part of the reason that the wheels were falling off, but more testing will be required. Makeblock, I’m not sure how precise you want the parts to be. I’m sure you folks are sampling the parts produced to make sure that they are made according to your specs. But I thought I would mention the centering issue in case you think it is relevant. (I’m a software engineer, not a mechanical engineer, after all.)

#5

@ChromeTemplar Thanks for your feedback. You might check the configuration of screws for driving wheels as shown in the pic.

As @wildwingman suggested, you can use 2 screws on each driving wheel.

#6

I had the same problem and configuration was exactly like in picture above. I used some loctite glue I had from rc-car building to secure the screws. This is not a “permanent” glue, so you can still use the screwdriver and remove the screw

#7