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Pager motors: Removing weight and driving wheels

hello fellow life forms,
I am currently working volunteerily at a local school, teaching young kids a bit about telescopes and astronomy.

One topic I am currently planning is the mars rover(s) and I am planning on building a simple line follower as activity.

As the budget is very low but I still want the kids to be able to build something to take home I am trying to keep it as simple as possible.

After I ordered a pager/iphone motor a year back or so, I now ordered 100 vibration motors for $28.50 at aliexpress.
http://www.aliexpress.com/snapshot/6020160679.html
They work fine but are smaller then the one I had before, a rubbery encasing makes them the same form factor.

http://www.ringohr.de/tmp6//motorbadpic001.jpg
 http://www.ringohr.de/tmp6//motorbadpic002.jpg  (excuse the horrible pictures, I just have a older android phone)

1)
The first problem is removing the weight.
I have searched and found several tutorials (for example http://www.robotroom.com/TinyMotor.html) and aproaces, heat and regular pliers failed, for everything else I lack smaller tools.
 
I consider ordering those grip pliers here in germany, which one would be better?
http://www.ebay.de/itm/Gripzange-extra-kurze-Baulange-100-mm-Neu-nur-3-95-505-incl-Versand-/151165386645?pt=DE_Baby_Kind_Baby_T%C3%BCr_Treppenschutz&hash=item233228bf95
or
http://www.ebay.de/itm/Mini-Schweisser-Gripzange-125-mm-mit-Feststellzange-Klemmzange-NEU-OVP-/261407967637?pt=DE_Baby_Kind_Baby_T%C3%BCr_Treppenschutz&hash=item3cdd210995

I also considered a watch wrist band tool as I have only a limited set of tools,
 http://www.ebay.de/itm/Stiftausdrucker-Armbandkurzer-Stiftentferner-Uhr-Federsteg-Uhrenstift-Entferner-/370981549407?pt=DE_Elektronik_Computer_Haushaltsger%C3%A4te_Staubsaugerbeutel_PM&hash=item566039355f
or
http://www.ebay.de/itm/Armbandkurzen-Stiftaustreiber-Stiftausdrucker-Werkzeug-/131084177829?pt=Uhrmacherwerkzeug&hash=item1e8539d1a5
or
http://www.ebay.de/itm/1x-Stiftaustreiber-Stiftausdrucker-Zange-Uhrenwerkzeug-Uhrmacherwerkzeug-/310765191716?pt=Uhrmacherwerkzeug&hash=item485b0c8224
But I don't think I can adapt them to hold the motors.

Any other tricks?

2)
The second problem is to drive small wheels with those motors.
With the vibration weight attached I can't drive a small foam or cardboard wheel, neither via friction nor a rubber band/belt.
I hope it will work once the weight is off.

I hope I can solve this issue, else I am stuck with 100 motors that are only suitable for bristle bots ;-)
The vibration is strong enoug to move something, also attaching the motors to a cardboard square and directly touch the ground seems to have enough power.

I could use a 3d printer to print a gear, but I would like to keep it as simple as possible.
Also the groove bearing + shrink tube drive I have seen on another project would not be ideal to build with younger children.

I initially was thinking of using bottle caps as wheels and wrap the motor axis with shrink tubing or isolation tape to drive the bottle cap by friction.

Thanks for any ideas, advice or suggestions!

-Marcus

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Kiteman3 years ago

You might be able to mangle them off with a vice. Clamp the weight in the jaws, then slowly build up pressure until the part around the shaft splits enough that you can then use a pair of pliers to rip it off.

Or you can clamp the weight in the vice, and knock the shaft through with a hammer and (very) narrow nail.

Screenshot_2014-03-02-09-27-15-1.png
Kiteman Kiteman3 years ago

Oh, and for the wheels, you can just add a big blob of hot-glue (or Sugru?), and mount the wheel at a 30º-45º angle.

Screenshot_2014-03-02-09-35-19-1.png
schorhr (author)  Kiteman3 years ago

Hello Kiteman,

thank you for your replies and the sketches!

I tried something like the angled motors yesterday night (but still with the weights), this would be a perfect and simple solution. With weights it's more a random movement of course. Initially I had something like

http://elm-chan.org/works/ltc/report.htm ln mind.

I think I will go with your suggestion and the vice. Can't find it after we moved though :-) I tried with pliers and a nail, but the nail was too soft. I suppose I should try finding a hardened steel bolt then in the hardware store.

as the weight has an open slit and is not closed around the shaft completely I thought of using pliers to split it there or similar, but it's hard steel and trying to bend or cut it failed so far.

I also discovered slightly larger motors for 16 cent, even cheaper, but I am still trying to figure out a way with these motors.

motorweightdoodle.PNGmotorweightdoodle2.PNG

you need a nut remover but you will spend more than what a new set of motors cost. It is essentially a hardened anvil wedge that is forced into the piece held in a collar by tightening the bolt on the other side. Look up nut remover.

caitlinsdad3 years ago

Have you tried to stick the shaft into a wheel and then try to counterbalance the wheel with a stick on weight or nut and bolt?

Vise-grips(brand name) or locking pliers are pretty common all purpose tools for mangling something. The second set you show is more for clamping two pieces of metal or wood together so you can work with it, no teeth on jaws. I think the problem is still grabbing on to the small exposed bit of shaft so you can yank off the weight.

I don't think the watch drive pin is steel hardened enough since it only needs to press a spring loaded watch pin on the clasp. I'm not sure where you can really get a good drive pin unless you reuse another driveshaft pulled from another motor and held with pliers. Good luck.

schorhr (author)  caitlinsdad3 years ago

Hello Caitlinsdad,

I have considered it but the tiny motor is too weak to drive a wheel directly.

Yes, the locking pliers will be tricky to get tight on the round weight without damaging it, but at the price I guess I will try as it seemed to work for the person who made the tutorial :-)

Thanks for the thoughts on the watch tool, yes, I suppose it won't be sturdy enough. Butchering another motor is a good idea though...

Another thing I could try is to cut or pinch the weight above the shaft and try leavering it apart...I'd better put smaller hands + smaller tools + the strength of an elephant on my shopping list.

It was probably a bit naive ordering 100 motors without knowing the dimensions and specifications, but I hope I can figure out something.

The weight is glued on. Heat is the best bet. What where you using to heat it?

schorhr (author)  mpilchfamily3 years ago

Hello Mpilchfamily,

it seems like it is crimped. I tried with a simple lighter as I tried to avoid heating the whole motor too much :-)