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Why servos are so expensive?

pit09

Im a 16 years old Electronic Technician and i wanna make a robot ... the problem is i cant have a Job ... because of my age, and the college. i was seaching on Amazon i saw some prices like 9,10,15,20 Dollars ... i thought that the price was good until i realize i need more than 1 to make a decent robot. Then i saw  0.40 dollars Micro Servos ... i was excited ... but i read the comments like: it broke too fast and that kind of stuff.

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  • in reply to michaelkellett

    Actually that idea , about fix them,  is not bad ... Thank you very much ._. ...also ,have any idea about where i can find Failed ones on internet?

  • in reply to pit09

    I've had the same issue, and took to eBay. There's often lots of used servos on there in the RC toys category.

     

    For working lots they'll often sell for about half to a quarter of new price. Even less for ones that are actually broken, but don't expect much in the way of details on why they're broken.

    The best finds are ones that aren't listed as servos but as mixed lots since less people tend to bid on them. If you have the time, go into the category and just set it to only display "used" and/or "for parts or not working" items. Sort by price ascending so cheapest display first and view as gallery. You should be able to spot cheap lots containing used servos quickly.

     

    Servos that have had their wires cut tend to sell very cheaply, so if you're fine with the solding iron and shrink-tubing then you can get some nice ones. I've used the 3-pin connectors from PC fans to replace the missing wire on sets like this, since they'll still connect to standard 0.1" header pins even if not regular servo connectors.

    Similarly people tend to avoid servos with broken casings, removed mounting lugs or lots of glue covering them. All good for savings if you don't mind their visual appearance or some custom mounting needs.

     

    As a note, repairing servos will most often mean replacing the gears. Sometimes you can upgrade to metal gear sets, but sometimes you'll run across servos that are old enough that parts intended for the model no longer fit because manufacturing tolleraces have changed. Plastic gears are cheapest to replace at least, but if you're tight on cash you may wish to look up the cost of new gears for that model before bidding. Lots that contain multiples of the same servo can be good if there's enough good parts to assemble a couple of good gear sets out of the parts of many, but most of the time the same type of servo will fail in the same way so they'll be a shortage of one or two particular gears.

     

    Broken RC cars can be a good source of servos, but the cheap ones won't be ones that are easily usable in other things. The motors are cheap and the position encoders tend to be wafer switches without any actual control electronics. I'd steer clear of these.

     

    Another useful tip is to keep the electronics from inside even mechanically wrecked servos. They can be wired up to pretty much any other tiny DC motor, and the ones from old analogue video cameras and wrecked digital cameras will often have their own tiny gearboxes attatched. Not much good for standardised applications, but good if you need to make a one-off item.

    I've personally used a zoom-control motor wired to a broken stepper's control board to turn a large plastic gear from a printer, with the position-pot reading off via another smaller gear. Gave a nice slow rotation on a robot head of about 100degrees. Just an example though.

     

    Also, try to get some tiny sealable containers for storing the parts in. They'll go everywhere otherwise. And try to work cleanly; a tiny speck of grit can jam these small gear trains very easily.

  • in reply to pit09

    Hi Pablo,

     

    I pick up my servos at garage sales.

    You would not believe the number of devices I have picked up from unwanted RC vehicles, usually for about 1 USD each.

     

    Look around, people are throwing these things in the trash.

     

    DAB

  • in reply to DAB

    Thanks for the advice! i really cant go to an garage sales because... that things doesnt exist in my country but was a nice information about RC vehicles image Thanks again

     

    Pit

  • in reply to Former Member

    That probably was the best advice that someone who ever told me about electronics, was clean and completly helpfull... Thanks alot for the advice! i cant wait to get money to start looking some servos on ebay image

     

    Pit