Author Topic: Stipping a servo  (Read 6652 times)

0 Members and 1 Guest are viewing this topic.

Offline richardabeattie

  • Petty Officer
  • *
  • Posts: 15
Stipping a servo
« on: 12 December 2013, 13:26:23 »
The Bronington instructions advise me to use the motor and speed controler from a servo to drive each prop.

I have opened up a very old servo possibly it came with my ancient Macgregor R/C.  Inside is a motor fixed to a printed circuit and fed by the cable from the receiver.  On top and attached by 3 wires is the upper plate with the plastic gears.  So I have three questions. 

1. Do I simply cut the three wires and discard the gears?   
2. What is the small round drum shaped molding under the gears into which the three wires feed?
3. In its original role as a servo the motor spins fast and the gear train cuts down that speed.  But how does that translate into making the actuator arm just turn a bit one way and a bit the other?

Offline richardabeattie

  • Petty Officer
  • *
  • Posts: 15
Re: Stripping a servo
« Reply #1 on: 12 December 2013, 13:35:22 »
I should add that when I connect the opened up servo to the receiver (without cutting the wires to the gear train) the motor runs well but the working the transmitter controls does not slow it down let alone reverse it.  What am I doing wrong?

Offline ship's doctor

  • Lt-Commander
  • *
  • Posts: 159
Re: Stipping a servo
« Reply #2 on: 12 December 2013, 14:38:51 »
Hi Richard,

As I remember the small drum moulding should be a potentiometer? You need to detach the gears from this, leaving the potentiometer and the three wires intact. Then with the tx stick in neutral, you turn the potentiometer to a point where the motor stops turning. The tx should then work in forward and reverse.

I think this should work but could you post a photo of what you have so far?

James




Offline richardabeattie

  • Petty Officer
  • *
  • Posts: 15
Re: Stripping a servo
« Reply #3 on: 12 December 2013, 22:15:53 »
How's that?

Having posted this I cannot see that my attempt at attaching a photo has worked!

Offline richardabeattie

  • Petty Officer
  • *
  • Posts: 15
Re: Stripping a servo
« Reply #4 on: 12 December 2013, 22:23:04 »
The forum keeps telling me my photo is too big.  But I'll have a go at tuning the potentiometer.  I am better at explaining heteroskedasticity than the workings of a servo.

Offline radio joe

  • JOE
  • Admiral
  • *
  • Posts: 816
  • Gender: Male
Re: Stipping a servo
« Reply #5 on: 13 December 2013, 10:29:24 »
Hi, personally I would go for a small motor and esc,  I believe I'm right in saying that with a servo motor set up you only get a forward and reverse drive with no control over the speed,

Offline ship's doctor

  • Lt-Commander
  • *
  • Posts: 159
Re: Stipping a servo
« Reply #6 on: 13 December 2013, 17:59:17 »
You can get some speed control with a servo- I've used them to motorise a 1/350th KGV by tamiya which worked OK. However, if the potentiometer moves slightly whilst 'at sea' you then end up stuck in forward or reverse, which happened a few times!

However I agree with Joe that a small ESC and motor (Action electronics?) is a much better way to go!

 

Offline mikearace

  • Captain
  • *
  • Posts: 378
  • Gender: Male
Re: Stipping a servo
« Reply #7 on: 13 December 2013, 20:02:14 »
Have to agree with James and Joe and in your original thread I suggested action.  Action also do a small mixer for their P68s which does work a treat.  I used two small 1amp actions and two small motors from action in my HDML 1/48th which was virtually the same size  18inches by 4 and although it was a bit more costly than two servo's it was worth it.   

Offline kit

  • Warrant Officer
  • *
  • Posts: 36
  • Gender: Male
Re: Stipping a servo
« Reply #8 on: 15 January 2015, 19:48:00 »
And another ancient thread reopened...

I also built a Tamiya KGV and found space to power all four shafts using Grauper 195s and a 10 amp mtronics viper esc - plenty of space and weight no problem, still had to add lead to bring her down to the correct waterline trim