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building giant servos

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Old 01-21-2009, 11:52 AM
  #1  
quadbuggy
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Default building giant servos

hi all.

now i am sure this has been covered before but i would like to try and build one of these bad boys from a wiper motor but most of the info out there is broken, i.e. the author has forgot to write bits down or has changed his mind and used hitec alternatives...

i have been pointed to all sorts of sites to build a giant servo but i and others really want a build guide/ instructions.

when i take on a project i like to use off the shelf parts which anyone can get hold of regardless of world location.
so basic is the key. bit of soldering here and there you know, the more plug and play the unit is the better.

Those who have built a giant servo please could you add your build to the bottom of this thread with the servo build info.

number one person so far for giant servo's is Da Mad Maori

here is a link to the unit i have ordered

http://secure.oatleyelectronics.com/...84e07e9f3e9428

this is my build and i need to make a better servo for the steering

http://www.rcuniverse.com/forum/m_82...tm.htm#8298583
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Old 01-21-2009, 04:15 PM
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bsrman14
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Default RE: building giant servos

A tone servo is all you need. 050 900 oz at 6 volts 1100 @ 7.2 volts. 105 5000 oz @ 12 volts. anything beigger the you don't need a servo.
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Old 01-21-2009, 04:36 PM
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da mad maori
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Default RE: building giant servos

Hey Man
i got your pm sorry for the delay
the kit from oatleyelectronics "should" work fine for a wiper motor... its a kit though, you have to solder it together yourself from a drawing.... but is fairly easy if you have any trouble with it just ask on here

the circuit i used for my servos are having alittle trouble.. i tryed getting too fancy but im now loosing reliability..
and with my build, i dont want to have to worry about the servos... (ill have far too many other things on my build to worry about LOL)

so im currently working on a MUCH simpler circuit that uses componants that "most" elec stores around the world will carry
its a really simply circuit covered in most info you see on the web but your right, noone has really gone from start to finish so once mines built and tested
ill make a vid taking ya though how to make one....

bare with me though it may be a couple of weeks before i can finish it (buzy with work)
until then you should have sucess with the jumbo servo kit

Cheers
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Old 01-21-2009, 07:14 PM
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Default RE: building giant servos


ORIGINAL: bsrman14

A tone servo is all you need. 050 900 oz at 6 volts 1100 @ 7.2 volts. 105 5000 oz @ 12 volts. anything beigger the you don't need a servo.
The PS-050 is actually a great servo for giant scale, 4th scale, even 5th and 6th scales.

http://www.hobbyclub.com/product_inf...0eee42a480748f

This is actually good info, not just for a massive custom built RC, but even our more common 5th scales.
Granted, that 900in-oz is only a starting torque that is rather instantaneous at the turn of the wheel on the radio, even its holding torque, which might be around 600-700in-oz, is still great for keeping the wheels in position even from bumps, hits, and hard crashes. The only problem for 5th and 6th sclaes (and even 4th scales) is finding parts that can survive bumps, hits, and other forces that try to dislodge the steering wheels from the position they are pointing in.
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Old 01-21-2009, 10:58 PM
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rc-cellar
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Default RE: building giant servos

Agree on the PS-050, PLENTY of torque and speed on my 50 lb beast. Got mine for under $200 US at troybuiltmodels.com

Pics and video here: www.rc-cellar.com/pocket.htm I'm currently working on version 2 with scratch-built tube frame.

I tried the wiper-motor route first (external H-bridges, Oatley boards, etc), spent alot of time and money experimenting and got them working on the bench. The BIG drawback I ran into is they use a low-speed motor and about a 60:1 gear-ratio. For a 90 degree sweep the motor only turns about 15 revolutions. That is a very-low resolution for any servo (narrow dead-band, prone to oscillation, no way to tune or adjust gain and damping). In layman's terms, the holding power stinks and it tends to "bounce" back and forth trying. Also the gears are worm-drive meaning they "bite" in one direction but are prone to stripping in the opposite direction. And no ball-bearing support on the output shaft, just a sloppy brass bushing that probably wouldn't last long. Compare to any off-the-shelf r/c servo that has at least a 300:1 ratio, straight gears (bi-directional), factory-tuned electronics, and engineered to take a pounding.

I gave it my best shot and failed to come up with a wiper-servo that would work well in an off-road vehicle. In the end I broke down and got the Toney. No regrets though... I had fun trying, and have yet to see one actually running in a vehicle. (post a link if you know any) Good Luck !

PS - google for halloween/christmas animated displays. There are forums and info on the same subject.
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Old 01-21-2009, 11:08 PM
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SAVAGEJIM
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Default RE: building giant servos

LOL! That is the VERY same RC I've been watching on youtube the past few nights! Very nice build!
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Old 01-21-2009, 11:42 PM
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Default RE: building giant servos


ORIGINAL: rc-cellar
I had fun trying, and have yet to see one actually running in a vehicle. (post a link if you know any) Good Luck !

its not a great vid... he's more steering with a locked diff
but still... its running a wiper motor servo
http://au.youtube.com/watch?v=tRjvUD...eature=channel
found another one too a better one but cant find it

your right the wipermotors arent designed to run backwards and are not the most effient way of doing it however these arent competesion class rcs... and its cheap

i saw your buggy vids the other day VERY cool cant wait to see the new version..

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Old 01-22-2009, 04:15 AM
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Default RE: building giant servos

thanks guys, i would like to give the servo building challange a bash but might have to use the seiko / tone servos later as they are just so dam expensive.

the wiper motor i want to use is off a fiat chinqucento and it is the rear wiper motor. i am thinking it might be abit better as it is designed to go back and forth.

i have placed an order for the oatley boards but i have to confirm it over the phone, looks like i staying up late to night!!! dam time zones!!

best price for the seiko / tone servos... anyone?
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Old 01-23-2009, 08:07 AM
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Default RE: building giant servos

I am not familiar with that car does the motor actually reverse or is it a mechanical linkage like all other cars that I know of.

What kind of ratio does a normal servo use?

Drewcrew6
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Old 01-24-2009, 12:03 AM
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Default RE: building giant servos

The 050 will put out 1800ozin at 11.1v and if you get an oddified one it'll be plenty quick enough. there was an oddie one on ebay a couple of months back that went for $140...they come up on ebay .co.uk now and again
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Old 01-24-2009, 10:15 AM
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Default RE: building giant servos


ORIGINAL: mooman007uk

The 050 will put out 1800ozin at 11.1v and if you get an oddified one it'll be plenty quick enough. there was an oddie one on ebay a couple of months back that went for $140...they come up on ebay .co.uk now and again
The MFg ratings for a 050 the servo are 4.8-8.4 volts only.[8D] Good luck trying to find a oddified aytwhere????[]
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Old 01-24-2009, 05:01 PM
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Default RE: building giant servos

Instead of using wiper motor why not use a elec window motor as these are designed to go both ways? and a lot smaller than wiper mtrs but just as powerful!
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Old 01-25-2009, 12:26 PM
  #13  
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Default RE: building giant servos

I will take a tone 050 any day. Smaller, lighter and plenty of power. If I need any more power then a tone 105!!!!! The end.
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Old 02-09-2009, 02:07 PM
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Default RE: building giant servos

i like the tone 105 but i am currently designing a off road 2wd buggy on the computer and its rather a lot larger than a childs quad!! im talking somthing along the size of the yamaha yfm 350r thus i need some big ass servo motor. which reminds me there is here in the uk a club that take normal automatic cars and race them via the usual r/c transmitter. i will post the link when i find it.
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Old 02-09-2009, 03:36 PM
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Default RE: building giant servos

The tone 105 is the most expensive servo @ $650.[X(]
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Old 02-12-2009, 12:11 PM
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Default RE: building giant servos

mad maori hows that servo write up going.

waiting to dig into this beasty servo motor building
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Old 02-12-2009, 09:49 PM
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da mad maori
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Default RE: building giant servos

hey man im still trying different drivers to find the easiest way. the problem is alot of the drivers (hacked small servos) ive tried are not designed to run big motors so they overshoot often coz they dont know about the big motor causeing the hbridge to heat up fast.... and widening the dead band is difficult coz the board is so small lol

im currently trying a digital driver that adjust its own parameters to suit what ever motor you using... (apparently )
ive got working servos here!! but i dont want to write up how to make them as the way ive done it is not very dependable

so if the digital route works well, ill let you all know

i pmed ya
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Old 02-13-2009, 10:28 AM
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thanks dude. yes please let me know if this works as I am now travelling down the hydraulic route!!

thinking of using a water pump and 2 original Austin mini radiator on and off valves (for the internal heater) and 2 house radiator drain valves for bypass release valves and another for excess pump pressure dump to tank and control the valves using 2 jumbo servos I have. the return to centre will be by 2 springs on a second link.

first I have to build a cylinder actuator from 1 and half inch drain pipe (about 45mm say)

problems with hydraulics is the speed the actuator works
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Old 02-13-2009, 05:00 PM
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Default RE: building giant servos

if ya cant wait, this method is proven and works well... i have a working one here.... i had two but one blew up though my fault

http://www.fieroaddiction.com/servo.html

the driver boards are quite cheap... very easy to hook up.... i just found it abit bulky but it does work

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Old 02-14-2009, 04:59 PM
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Default RE: building giant servos

yea no worries just would like to know what i am dooooing. lol.

lynxmotion have a unit fot 6volt 2 amp motors which you can run the wipermotor on but only on low speed. however i will wait for your out come.


cant wasit.. hehe
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