Model Boat Mayhem

Mess Deck: General Section => Chit-Chat => Topic started by: C-3PO on December 23, 2017, 01:24:24 pm

Title: Linear servo - where to buy?
Post by: C-3PO on December 23, 2017, 01:24:24 pm: Linear servo - I had a quick Google and didn't get any positive results

Are they still made? Can you still but them?

Thanks in advance

C-3PO
Title: Re: Linear servo - where to buy?
Post by: bfgstew on December 23, 2017, 01:31:06 pm: https://www.robotshop.com/uk/actuators.html
Title: Re: Linear servo - where to buy?
Post by: Subculture on December 23, 2017, 01:35:10 pm: You can get very small linear servos. They're low torque and designed for very light aeroplanes. e.g.

https://hobbyking.com/en_us/hobbyking-ultra-micro-servo-1-7g-for-3d-flight-left.html (https://hobbyking.com/en_us/hobbyking-ultra-micro-servo-1-7g-for-3d-flight-left.html)

If you want a standard size linear servo, the cheapest and easiest solution is the EMS kit, which adapts certain Futaba servos to a very nice linear servo.

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

Becker in Germany did sell linear servos in various sizes, not sure on current availability.

Other than that, it's a case of searching on ebay for old Linear servos from the seventies by the likes of Futaba, Skyleader etc. Or DIY.
Title: Re: Linear servo - where to buy?
Post by: Brian60 on December 23, 2017, 04:24:54 pm: I have a couple of the hobbyking type and to be honest, unless you are building a quadcopter for inside use they are too small and too feeble to move anything but the lightest load - I attached a sheet of A4 paper to one and it struggled to lift it when free hanging. They do larger types though, or they did for outside aero use.
Title: Re: Linear servo - where to buy?
Post by: Neil on December 23, 2017, 04:39:42 pm: please excuse my ignorance guys, but what are they and what do they do.
Title: Re: Linear servo - where to buy?
Post by: Brian60 on December 23, 2017, 04:45:05 pm: Quote from: Neil on December 23, 2017, 04:39:42 pm
please excuse my ignorance guys, but what are they and what do they do.

A standard servo makes a rotary movement.

A linear servo converts the rotary movement into a back and forth movement similar to pulling open/closed a drawer, it does this by using a worm drive and toothed track.
Title: Re: Linear servo - where to buy?
Post by: C-3PO on December 23, 2017, 04:56:20 pm: Linear servo - sort of like this

The ones I used many moons ago had 2 attachment points that traveled in opposite directions to each other

(http://modelboatmayhemimages.co.uk/images/2017/12/23/linearservo.jpg)

C-3PO
Title: Re: Linear servo - where to buy?
Post by: C-3PO on December 23, 2017, 05:53:59 pm: Possibly a neat 3D printed solution - thanks Tim Garrod

https://hackaday.com/2016/03/31/3d-printed-case-turns-servo-into-quality-linear-actuator/

(http://modelboatmayhemimages.co.uk/images/2017/12/23/LinearServo2.jpg) (http://modelboatmayhemimages.co.uk/image/8HMPv)

C-3PO
Title: Re: Linear servo - where to buy?
Post by: timgarrod on December 23, 2017, 06:17:45 pm: No Problem C3po, Will print one off next week a give it a go. not a neat as the adaptor that go on top of the servo but a option .
Title: Re: Linear servo - where to buy?
Post by: The Old Fart on December 23, 2017, 07:25:14 pm: I have one of these, works well,

https://www.ebay.co.uk/itm/Linear-Actuator-Stepper-Motor-4-Arduino-Raspberry-PI-micro-Rack-and-Pinion-NEW-/282363055991?var=&hash=item41be264f77 (https://www.ebay.co.uk/itm/Linear-Actuator-Stepper-Motor-4-Arduino-Raspberry-PI-micro-Rack-and-Pinion-NEW-/282363055991?var=&hash=item41be264f77)

works better than a servo, easy arduino program.

Dave
Title: Re: Linear servo - where to buy?
Post by: C-3PO on December 23, 2017, 07:56:27 pm: Hi Dave,

I guess an enhanced version of Tim's initial suggestion - I will consult Tim (shapeways) Garrod to see what his rates are as I don't have a 3D printer and my piggy bank currently is ear marked for a sub...

C-3PO
Title: Re: Linear servo - where to buy?
Post by: derekwarner on December 23, 2017, 09:27:26 pm: C-3PO..........this is Servo City in the US....... they have a range of linear servos...................Derek

https://www.google.com.au/search?sourceid=ie7&q=Servo+City&rls=com.microsoft:en-AU:IE-ContextMenu&ie=UTF-8&oe=UTF-8&rlz=1I7NOOH_enAU530&gfe_rd=cr&ei=Ui7OVuTgM8Tu8weF8JWAAg&gws_rd=ssl
Title: Re: Linear servo - where to buy?
Post by: C-3PO on December 24, 2017, 11:05:57 am: Hi Derek,

Thanks for that suggestion - I am familiar with the "linear actuator" they are widely availbale in the UK - I discounted these as I didn't want to sell a body part to facilitate purchase.

I can only assume it's the limited production/ more involved engineering (gear box) that determines such a high price of these actuators - some of them are eye wateringly expensive £60+

I think Tim/Dave's suggestion have merit at an affordable cost... - I also think this "travelling nut" could work well and is simple to hook up to

(http://modelboatmayhemimages.co.uk/images/2017/12/24/Stepperandtravellingnut.jpg)

Cheers

C-3PO
Title: Re: Linear servo - where to buy?
Post by: The Old Fart on December 24, 2017, 12:21:34 pm: Are yes, these are used for the Z axis on my 3d printers.
Title: Re: Linear servo - where to buy?
Post by: Brian60 on December 24, 2017, 01:59:10 pm: Does it have to be a servo Threepio? What about these linear stepper drives, I have two of these in my ship at the moment, just needs a bit of arduino code ok2

AliExpress or Banggood is your friend for them.
Title: Re: Linear servo - where to buy?
Post by: steamboatmodel on December 24, 2017, 03:59:57 pm: Quote from: Brian60 on December 24, 2017, 01:59:10 pm
Does it have to be a servo Threepio? What about these linear stepper drives, I have two of these in my ship at the moment, just needs a bit of arduino code ok2

AliExpress or Banggood is your friend for them.
If you have any old cd/dvd drives you may find some of those small steppers with the traveling mechanism in them.
Gerald.