Author Topic: 45/90 degree servos  (Read 2603 times)

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speedweeder1

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45/90 degree servos
« on: February 16, 2016, 13:24:55 »
Looking at the advert in a popular modelling magazine in an advert selling Schottel drives it states :  the swivel range is 2x90 (180) if a 45 servo is used ?????
 I have purchased 2 as I am building a harbour tug and I intend to use tank steering moving each Schottel drive through 180 degrees with astern for for the other 180 if that makes sense.
 So what do they mean in the advert ?

Steve. ???

sea monkey

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Re: 45/90 degree servos
« Reply #1 on: February 16, 2016, 15:23:30 »
The servo arm swings through a 90 arc, the gearing in the drive unit brings this up to 180 at the drive.
If you have one of the smaller Graupner units, the a point at the steering end where is attaches to the hull is very flimsy. You may need to re-inforce it.
Steve

speedweeder1

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Re: 45/90 degree servos
« Reply #2 on: February 17, 2016, 02:15:01 »
Thanks Seamonkey, 
 The tug I am building is the W.H. PARR at Port Nelson,you might know of it.
Are you thinking about the schottel drives that have a servo attached ? As mine will be on linkages to the servos.
 By the way , the Speedweeder is the English version of your Wonder Weeder.

Steve.

sea monkey

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Re: 45/90 degree servos
« Reply #3 on: February 17, 2016, 12:36:27 »
I've used the Graupner 1761 units. They are not too robust, I've marked the weak points on the image. The bit marked with the arrow is particularly prone to bending and breaking. The little clips that hold on the nozzles are also very easy to snap off.
I know the WH Parr it's on my wish list some day, maybe?  I'm in Nelson next week, do you need any photos?

speedweeder1

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Re: 45/90 degree servos
« Reply #4 on: February 17, 2016, 14:04:21 »
I see what you mean now,thanks for the warning,I think that by putting a screw right through into the spacer I have made to lift the drive to the right height will or should reinforce the joint, I will have to have a think about the nozzle clips.
  Thanks for the offer of photos,the only ones I haven't got are looking down onto the tug and underneath but that will only be possible if it's out of the water.
  A close up of the towing hook would be handy and bollards as well. I would also like to know if the bow wheel is freewheeling all the time and is it possible to lock it .
 It would be great if you could get these details,as Bill Parr was my mothers cousin.

Thanks
Steve.

mike_victoriabc

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Re: 45/90 degree servos
« Reply #5 on: February 17, 2016, 14:17:20 »
I had one of those arms break at the Arrow - couldn't find a replacement so cut out a brass 'patch' in the shape of the arm and glued it on with CA glue. Works fine now. Thinking of doing the same to the other drive unit before it goes as well.

PHILNZ

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Re: 45/90 degree servos
« Reply #6 on: February 17, 2016, 20:55:22 »
Hi speedweeder and seamonkey.

I live here in Nelson and have a couple of friends that work at the port. If you have any issues getting up close to the Parr, PM me and will see if i can get in close for pics . Also sometimes it gets slipped here for minor work  and might be able to find out when for hull pics.

Regards
Phil

speedweeder1

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Re: 45/90 degree servos
« Reply #7 on: February 18, 2016, 11:08:33 »
Hi Mike,and Phil and Steve,,
 Thanks for your input  I should have looked closer at the drawings.It might be worth me having a look around for a gear wheel instead of a quadrant and then put a decent arm on the gear wheel. What sort of loading do the drives impose on the servos ?there must be all sorts of forces there. Thanks for the offer of photos all will be appreciated.

Steve.

tugnut

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Re: 45/90 degree servos
« Reply #8 on: February 18, 2016, 11:12:34 »
Hi Steve, have you finished the hull yet would be good to get some more pictures.
« Last Edit: February 18, 2016, 11:16:25 by tugnut »
john b

speedweeder1

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Re: 45/90 degree servos
« Reply #9 on: February 18, 2016, 11:41:13 »
Hi John, I keep finding gaps in the wood all the time, I've,hold it up to the light another gap in sight oh !!!!! Whilst waiting for glue to set I am dodging all over the place. Just padded out the keel waiting for glue to set before putting a bit of shape into it. I am using aliphatic glue which is recommended but what a pain.
 What did you use before fibreglass ? Made some portholes for the cabin area ,cut 3/8" copper tube and glued them into the walls.
I am getting of the thread so will give you a call.

Steve.