Hollow Pot?

Projects General Guidance
1

I'm going to attempt yet another monster servo from a DC motor and Pot and motor controller.like this: http://arduino.cc/forum/index.php/topic,10836.0.html
My problem is I dont have a good way to mount the pot to the motor's final drive shaft.
As I see it i need to attach the spinny part of the pot to my shaft and then mount the base of the pot to something that doesnt move.
I dont have room for that plus I dont see a way to do it without it being hacky and glued on. In fact I havent even seen it done online where it looks like it would last for more than a proof of concept.

Is there a Pot that is somehow hollow and could slide over the shaft? I can see it in my brain but I dont see one online anywhere.

On another note I havent seen a spoon feeding of how to do this. I thought monster servos would be of enough interest to have a DIY with buy this this and this and do this and you have a servo out of a motor.

I'm planning on using a Uno + Dual VNH2SP30 Motor Driver Pololu - Dual VNH2SP30 Motor Driver Carrier MD03A + some pot.

any thoughts?

2

well obviously my googlefu was broken earlier.

http://www.automationworld.com/information-management/small-hollow-shaft-potentiometers

3

holy !@#$. they want from $60-$400 for a pot. LOL Looks like that one company is the only one that makes them and the rest are reselling or just talking about them.
bleh thats way out of budget.

4

I have no idea what sort of motor you're dealing with. Can you give some idea of the shaft dimensions, is either end exposed/accessible, what sort of travel/speed are you expecting and what else will be connected to the shaft?

5

windshield wiper motor. something like this:

I will have a sprocket and chain attached to the shaft. The shaft is extended about 6 inches from whats in that picture. No more than 120 degrees of movement is what im looking for.
But where I have to put it the sprocket is nearly flush with a backing plate and no room to stick a pot on the other side of the sprocket.

6

Actually this is a better picture. I have a 6 inch rod threaded on the shaft here with a sproket on the end of that which drives a chain. (which drives a sprocket which steers a rov)
http://www.google.com/imgres?imgurl=http://www.bigmacktrucks.com/store/images/Wiper%2520Motor.jpg&imgrefurl=http://www.bigmacktrucks.com/store/index.php?main_page%3Dindex%26cPath%3D13_46&h=428&w=552&sz=29&tbnid=m4P3iV65qd-abM:&tbnh=98&tbnw=126&zoom=1&usg=__JR8gQCWmaqKUQmG5M4j7jYqDg6k=&docid=Ipp_tplQgOlFlM&sa=X&ei=1soZUODvCcGLrgH0soDgCQ&ved=0CIIBEPUBMAY&dur=141

7

What's on the far end of your shaft extension? If the shaft is exposed, you could couple that to a pot. For such small amounts of travel, you may even be able to use a pushrod+crank to turn the pot. If this is ultimately driving some sort of mechanical linkage, connecting the pot to the far end of the linkage (rather than the motor end) would enable you to control the position accurately regardless of any flex/backlash in the drive mechanism.

8

Maybe look at a pot and see how it's put together. Perhaps re-purpose a regular pot by removing the shaft and drilling a hole in the center.

It may be possible to build what you need.