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Author Topic: Help with wheel mount for improved structural integrity of servo/wheel  (Read 2929 times)

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Offline LIONS*LEADERTopic starter

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so i understood the basic way of just attaching the servo to the wheel for the most part. there is a picture of that in this post
http://www.societyofrobots.com/robotforum/index.php?topic=2227.0

but i wanted to have basically a shaft in which the weight of the robot rests on which is attached to the servo mounting bracket, then a pole attached to the wheel  through the shaft, which the servo turns.  if necessary two ball bearings one for each side of the shaft.  this way all of the stress of the weight is on the pole which would bend or break  long before the servo would snap. 

i was also thinking of keeping the wheel the wheel from being moved sideways (i.e. jamming the pole in toward the servo or pulling the wheel/pole out away from the servo.
i figure the design of this would basically mean i needed a pole that was threaded on both ends but smooth in the middle. so that i can just attach a nut and a washer.
 
this is what I'm trying to figure out first mostly just where i would get the parts or what they would be called.

i have the websites for where i would probably buy most of the stuff, i just don't know what is what. for instance.


http://www.servocity.com/html/mechanicals___accessories.html

http://www.servocity.com/html/shafts__rod___tubing.html

http://www.servocity.com/html/ball_bearings.html

http://www.robotshop.us/rbban77-banebots-bearing-block.html

http://www.pololu.com/catalog/product/602

http://www3.towerhobbies.com/cgi-bin/wti0093p?&C=QDB

http://www.robotshop.us/servo-brakets.html

http://www.robotshop.us/tubing-hubs-connectors.html


so basically I'm just not sure which parts to buy to do what i want. nor could i find a smooth pole with threads on both ends.

has anyone else done had this type of idea in mind? to take the stress off the servos?  how did you guys do it? what is a good way?

thanks for your input guys!


secondly

i also wanted to be able to use servos to be able to turn the wheels like in a Taurus 2 design. having the servos facing down at a 90 degree angle to the floor in order to turn the pole that the wheels are attached to.   


are these along the lines of something i might use?

http://www.robotshop.us/lynxmotion-ball-link-set-4-40.html

http://www.servocity.com/html/ball_bearing_turntables.html


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Offline Ro-Bot-X

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Re: Help with wheel mount for improved structural integrity of servo/wheel
« Reply #1 on: December 06, 2008, 08:03:29 AM »
The robots that use continuous rotation servos are small and light enough so the double ball bearings inside the servo are enough. For larger robots, the servos are too slow and weak so DC motors are used. In this case, a shaft like in the picture you attached may be used, especially in Batle Bots. People use chain and sprockets to transfer the motion from the motor to the shaft when they need to lower the speed (and increase the power) or they are using shaft couplers to connect the motor shaft to the wheel shaft. If you need to eliminate backlash, you may use toothed belt and cogs instead of chain and sprockets. But you have to take into consideration that they are reducing the efficiency.
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Offline Admin

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Re: Help with wheel mount for improved structural integrity of servo/wheel
« Reply #2 on: December 09, 2008, 08:11:21 AM »
I *strongly* recommend you using 3D CAD to design what you make before you buy anything.

Quote
i also wanted to be able to use servos to be able to turn the wheels like in a Taurus 2 design. having the servos facing down at a 90 degree angle to the floor in order to turn the pole that the wheels are attached to.
Not that I recommend this method, but I used super glue to attach those rods onto the servos for Taurus 2. It held so well that the servos still have the rods attached to them after 5 years or so.

 


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