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Author Topic: Where to get continous servos?  (Read 735 times)
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Norway
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Or, where to get ones that are easy to mod?

Just want a few that has the limit removed.
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I don't think you connected the grounds, Dave.
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I've modded Futaba servos in the past.
Dead easy - simply snip off the pot shaft, or shorten the pot leads, and cut off the mechanical stop.
Try not to saw, as this tends to leave too much dust which can get into the gears - you may think you've got it all, but some usually gets stuck in the grease.

Hint: don't buy all of the servos you need at once!
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Norway
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Hint: don't buy all of the servos you need at once!

How come?
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I've modified a couple of Futabas and some HiTechs.  I found the Futabas easier.

ServoCity has a chart about how easy/hard it is: http://servocity.com/html/rotation_modification_difficul.html
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I don't think you connected the grounds, Dave.
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Don't buy all your servos at once because:

If you can't modify the one you've bought, you haven't wasted the purchase price of the other five.
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Norway
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That listing is only for Futuba?

I've only bought cheap-china servos atm. Is futuba that much better?
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Rather precariously, I modded a S3003. It was pretty easy assuming you have the tools..

The best way to do it is cut the pot shaft and remove the little stoppers.

In my opinion, you *need* to remove the shaft, whether you cut or use a resister otherwise, as I'm finding, it catches just enough to unset the "zero" reading.

In all seriousness though, if you're in the US you can pick up a Parallax server for like $12-13 dollars (sadly in the UK it's 1:1). Considering a new servo costs around the same, I'd avoid the mod.
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Hey, I'm just curious what is the purpose of a continuous servo?  Why wouldn't you just use a motor with a gear head?
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A modified servo is an easy way to get a compact motor and gear-head.  It seems strange to me, too, but modified servos are very popular as motor drives for small robots.
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The Big Smoke
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Pretty much what Maker said.

Yeah a motor is a far more suitable form or propusion but servos "just work"™. They are easy to install and get working and dont require controllers or various other supporting equipment.

...and in all honesty, how fast does a robot really need to go. The Arduino isn't a far processor by any stretch smiley-razz
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A R/C servo converted to continuous rotation is indeed just a variable speed/direction DC motor driving a gear train. The reason most likely they are popular for modification is economical as the large volume of servo sales means there are lots and lots of sizes, gear material options (metal, plastic, etc) at good prices. Also interfacing to a modifed servo is a lot simpler then having to design or build a motor driver board.

I do think that a few of the major servo manufacture do sell servos already modified for continuous rotation but you will have to search out or you can ask around at the below R/C forum link. The modification can be botched so be careful on how you proceed selecting one and what procedure you use.

http://www.rcgroups.com/forums/index.php

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DC Gear motors OTHER than RC servos are hard to find outside of the surplus market.  By modifying a well-known brand of servo, you get an easily reproducible gear motor (plus electronics that make it "easily" reversible.  Plus standardized mounting, mechanical, and electrical interfaces.  Plus a wide variety of mechanical attachments...)    And the price tends to be comparable to surplus gear motors with NO electronics even if you're buying your servos at retail hobby stores (and lower if you're buying cheap imported servos.)
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Man, that's a long list of good reasons!   smiley

I haven't done anything motorized yet.  So that's good to know for when I do.
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Norway
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Wrote an easy guide for making Mystery 9g servos continous.

Since these servos are very cheap off ebay, or dealextreme.com

http://www.dealextreme.com/details.dx/sku.20023

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=150302752989

Heres the link for the guide:

http://stigern.net/blog/?p=96

Easy, no need for extra components. Only glue and cutting tools smiley
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