Pots, encoders, and bearings....

Hi,

I have yet another vague question. Basically, I wish to build a concentric encoder, that is, two incremental encoders, on different shafts, same axis. With an inner shaft for one, and an outer shaft for the other.

I originally thought taking apart a concentric potentiometer, using the bushing/mounting, and to two original shafts, but they are awfully hard to find, and provide a fair bit of resistance.

Hopefully, someone here is mechanically minded, and knows what 'bushes', 'bearings' and 'sleeves' are. To make things a tad more complicated, the 'outer shaft' should be connected to a wheel, and the inner to a large knob. I have no idea how to control 'friction'. I like the 'feel' of potentiometers, but I don't know why they aren't that easy to turn (have you ever spun a pot?). All I'm really after is some form of assembly, that can be mounted on a panel (through a hole) that allows a wheel/disc to turn, without spinning, and having a fairly large (4-6mm) hole all thr way through, for a centre shaft.

I'm not really up on mechanics, so any help would be appreciated.

BuriedCode.

Instead you can :
- attach button (metal membrane based) to the wheel.
- or make the wheel clickable as mouse wheels but in axis direction .

Hi artem,

Thanks for your reply.

Instead you can :
- attach button (metal membrane based) to the wheel.
- or make the wheel clickable as mouse wheels but in axis direction .

Click to expand...

Good point. Making one of the buttons 'clickable' is something I would like, but I thought I'd just get the rotary mechanics out the way. I'm currently machining up a piece of nylon, as a bush. The middle shaft will go through the centre, and the outer one will fit over th outside of the bush. Making things fit nicely is difficult though, which is why I'm not working with metal. If anyone has some idea's, heres a pic of the sort of thing I'm after...

https://www.usb-ware.com/dv-keyboard-4100.htm

Dispite the fact that these things seem to be everywhere, and the 'inner/outer shaft' thing is in almost everything machanical (clocks, engines, motors) I'm having real trouble actually finding information on how these are designed. Thankfully, the outer wheel doesn't need a shaft, it will be an optical encoder, the mount is just to allow it to turn, and provide some form of resistance (lot a standard metal shaft potentiometer).

Maybe I'm over-complicating things, I've been thinking of 'thrust bearings', but I don't think ball-bearings are necessary. God I hate mechanics, I should stick to electronics :/

Thanks again,

BuriedCode.

I see what you mean . You can try aso fiberglass , though it is expensive but good to work with .
If wheell on picture is what you like to achieve then you need either good handwork abilities or/and good mechanical shop.

I suppose that you can try to fnd something usable from other design - have a look to toys shops - those are cheap and may already contain the whole or part of what you are designing .

Hi again,

If wheell on picture is what you like to achieve then you need either good handwork abilities or/and good mechanical shop.

Click to expand...

yep. I have neither :/ But, I have 'some' tools' and I don't like to be beaten, so I'll stick at it. In the mean time...

have a look to toys shops - those are cheap and may already contain the whole or part of what you are designing .

Click to expand...

Good call! I've been going through all the crap in my garage (old appliances, tools etc..) and I haven't found something which can be used...but toy shops? Oh yes. I didn't think of that at all. I mean, I'm always looking for parts in ready-made products, since its usually cheaper and easier, but toy shops are something I've never thought about, thanks, great idea!

Cheers man,


BuriedCode.