Model Boat Mayhem

Mess Deck: General Section => Model Boating => Topic started by: AlanP on August 15, 2019, 03:46:02 pm

Title: Servo motor
Post by: AlanP on August 15, 2019, 03:46:02 pm

I have just taken an old servo to pieces to use the motor for a radar ( hopefully) on a boat, but there is a very small brass cog on the motor that I cant prise off. Any help with this problem would be most welcome  :-))

Regards Alan

Title: Re: Servo motor
Post by: Netleyned on August 15, 2019, 03:56:38 pm

i have removed them by gentle application of a dremel cutting disc
between the cogs. Sometimes the heat generated loosens it before
cutting through the cog.


Ned

Title: Re: Servo motor
Post by: minimariner on August 15, 2019, 04:31:33 pm

Alan,
           You may find the motor on its own will be to fast for a Radar,
           Unless you use it with the original gears in the servo and a 1.5v
           battery connected on the motor.

                  Bryan.

Title: Re: Servo motor
Post by: AlanP on August 15, 2019, 04:59:25 pm

Thanks for the replies lads, all set for a bit of messing/trials in the workshop now.  :-))

Regards Alan

Title: Re: Servo motor
Post by: Stan on August 15, 2019, 07:54:43 pm

HI Alanp how about this small unit runs on 2 volts I may a spare one. Just checked my box of spares you may be out of luck. :(( :((

Stan. :((

Title: Re: Servo motor
Post by: roycv on August 16, 2019, 08:35:33 am

Hi, you can use fine piano wire to take the drive to the radar scanner and have the servo lower down in the s/s.Roy

Title: Re: Servo motor
Post by: malcolmfrary on August 16, 2019, 10:14:12 am

To remove the cog, either a slit applied by dremel as suggested earlier, or use a large vice and a pair of side cut pliers and a nail and a hammer.  Mount the motor spindle gently between cog and bearing in the cutting jaws, sit the motor and pliers in the vice jaws so that the pliers lie across the jaws and the motor dangles between the jaws, but is not gripped by them. Then using the nail as a punch, tap on the end of the shaft.  The motor will separate itself from the cog.  Just a case of catching the motor when it does.
Both of these are a waste of tme for a radar, whatever voltage is used, it will spin far too fast.  It does need a gearbox, handily provided by the servo makers between the motor and the output shaft.  Leave the cog, remove the mechanical end stops (or the lump on the output cog) and remove the position sense pot.
The servo motor minus cog is ideal as power for small displacement boats, the main problem being getting drive from the stubby shaft.  Flint springs fron dead disposable lighters work well for this.

Title: Re: Servo motor
Post by: JimG on August 16, 2019, 12:20:43 pm

Quote from: malcolmfrary on August 16, 2019, 10:14:12 am

The servo motor minus cog is ideal as power for small displacement boats, the main problem being getting drive from the stubby shaft.  Flint springs fron dead disposable lighters work well for this.

Easier to keep the gear on the motor and use a short length of silicone tube which will fit tightly on the gear.
Jim

Title: Re: Servo motor
Post by: AlanP on August 16, 2019, 02:07:37 pm

Well it was well worth posting my question, lots of useful information has come from it  :-))

Alan

Title: Re: Servo motor
Post by: Stan on August 16, 2019, 03:22:39 pm

Hi alanp I have sent you a pm will check again to see if I have one those small units. All you need then is a small voltage regulator from component shop jobs done. Put the old servo in the bin to much hassle. I have been trying to find a picture to show you from one of my last builds

Stan.

Title: Re: Servo motor
Post by: Stan on August 16, 2019, 04:18:38 pm

HI Check this out. The unit is fitted to the top of the mast no wires from the superstructure or bits of silicone tube

https://www.modelboatmayhem.co.uk/forum/index.php/topic,40665.msg521589.html#msg521589

Stan.