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[pipster]

Hi,
I'm after a linear servo with a throw of 20mm and torque of 3.0 kg-cm.  Does anyone have any suggestions of where I could get one?


Cheers
Phil

[derekwarner]

Phil.....3kg & 20 stroke appear just outside the run of the mill available in Kellogg's Corn Flakes type linear servos

Try Servo City in America.........they appear to have an extensive range of linear servos............. ]......Derek

https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwiCntvJwffcAhUHQd4KHQn5DPkQFjAAegQIAxAC&url=https%3A%2F%2Fwww.servocity.com%2F&usg=AOvVaw0qgfkocPrk02xtt4Tn5gQF

[pipster]

Thanks for the tip Derek,


I've had a look and it looks like they only have linear actuators as opposed to linear servos.  I'm tight on space so I think a linear servo is the only solution.  I could probably get away with a little less torque if that opens up some more options?


Phil

[Subculture]

These are good-

http://www.emsjomar.com/linear.aspx

[Andyn]

How limited on space are you? Savox do micro servos with more than that amount of torque...


https://www.servoshop.co.uk/index.php?pid=SH0256&area=Servo - See specs - 4.6kg at 6v.

[Subculture]

Are they linear motion? Afaik the only company producing new linear servos above micro size, was Becker in Germany. A heck of a price too.

The only other alternatives would be to scout about for old servos e.g. skyleader used to make linear servos. Not sure their servo amplifiers would work with modern radio though.

[richald]

pipster

Either of these any good ?

1 Pair Goteck GS-1502 1.5g Analog Micro Linear Servo For RC Airplane Sale - Banggood.com

Scisky 1.9g Ultralight Digital Linear Servo For RC Helicopter Airplane Sale - Banggood.com

Richard
 

[Umi_Ryuzuki]

Firgelli products? PQ-12 L-12

https://www.robotshop.com/en/micro-linear-actuators.html 

https://www.robotshop.com/en/firgelli-technologies-pq12-actuator-20mm-100-1-6v-potentiometer.html .

pq-12-20-63-A
https://www.robotshop.com/en/firgelli-technologies-pq12-actuator-20mm-63-1-12v-potentiometer.html .
 
 Firgelli on ebay
https://www.ebay.com/sch/i.html?LH_CAds=&_ex_kw=&_fpos=&_fspt=1&_mPrRngCbx=1&_nkw=firgelli+l12&_sacat=&_sadis=&_sop=12&_udhi=&_udlo=&_fosrp=1

[pipster]

Thanks all for your suggestions. 
I've tried a mini/micro servo, which is where I've got the torque figure from.  The issue is that it's to lift a mast via a Bowden cable (if that's the right term as its a twisted wire) and the cable is tending to kink rather than lift.  I think the circular motion of the servo is contributing to that.  So my idea was to shorten the length of unsupported Bowden cable and use a linear servo.
I may give a micro linear servo a go, just to see one is torquey enough and also try the micro servo with a shortened cable. 

The EMS servo converter looks like an option too - I'll have to contact them about payment though as I don't have a credit card!!

The firgelli pq12 rc looks like an interesting option but not cheap!!
Phil

[barriew]

Pipster,


I used standard servo to operate the drop down loading ramp on my Calmac Ferry. I found that the cable had to be supported over as much of its length as possible.


Barrie

[malcolmfrary]

Twisted wire is great for pulling, useless at pushing, especially if a change of direction is involved.  Most things that use twisted wire have a return spring to work properly, think of bike brakes and gear changers. 
A servo raising a mast might need something to slow it down to avoid it looking like a trebuchet arm.

[barriew]

True Malcolm, although my ramp does work.    The other alternative is a 'snake' as used by the model aero guys, although I found that still tended to flex. I used an Arduino to slow the motion and limit the throw.


Barrie