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Rotary Couplers

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G-JIMG14/06/2018 23:30:24
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73 forum posts
9 photos

I'm designing and building a 1/10th scale King Air 350CER and want to keep all the linkages hidden.

For the ailerons I'd like to use RDS. There's no problem making the pockets or bending the metal rod but I've hit a wall when it comes to connecting the rod to the (Futaba) servo. There's plenty of cheap solution available in the US (see image of Kimbrough Coupler set) but I can't find anything in the UK.

Does anybody know a UK supplier or have an alternative solution?

couplers.jpg

Jim G

Denis Watkins15/06/2018 06:24:45
3388 forum posts
151 photos

Do you mean pushrod keepers Jim, from SLEC UK

5509640_1024x1024.jpg

shopping.jpeg

Edited By Denis Watkins on 15/06/2018 06:26:48

Edited By Denis Watkins on 15/06/2018 06:27:40

cymaz15/06/2018 06:34:21
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8202 forum posts
1135 photos

Here is a thread at for some reading. Top hat couplers is what I think you were asking for. Someone with a lathe might turn a few up for you.

Dave Hopkin15/06/2018 07:51:23
3672 forum posts
294 photos

Do you mean these RDS Adaptors?

**LINK**

G-JIMG15/06/2018 12:39:42
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73 forum posts
9 photos

Thanks for the help guys.

Dave, that's exactly what I was looking for, but for Futaba S3150 servos. However, your link led me to rewording the Google search, which in turn led me to a robotics company in Somerset that had exactly what I needed, and at a very reasonable price. Result!

Thanks again,

Jim G

AVC15/06/2018 12:53:20
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539 forum posts
147 photos

Hi G-JIMG, do you mind sharing the link to the company, please? I'm about to start building an Arado AR-96 and I'd like to use RDS controls.

Thanks!

G-JIMG15/06/2018 12:58:42
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73 forum posts
9 photos

Hi AVC,

Here's the link **LINK**

Plummet15/06/2018 13:12:34
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1372 forum posts
41 photos

It occurs to me that by the application of Murphy's law, the splines on the bought products will always be different to any servos available.

How about a two tine fork made of piano wire. The tines should be spaced so as to go through the holes in opposite arms of a standard servo arm. The tips of the tines should be bent at a right angle to lock them into the holes when the shaft of the fork is inline with the servo axis. The rotation of the servo will then rotate the shaft of the fork.

Does this make sense?

Plummet

G-JIMG15/06/2018 15:29:51
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73 forum posts
9 photos

Hi Plummet,

That makes perfect sense, but ............................ I'd considered a number of ways to make a coupler, including soldering a wheel collet onto a washer and then drilling a couple of holes in the washer so I could fasten it to a Servo Ring. However, the model's wing is very narrow and there wasn't enough room for anything involving Servo Rings or Arms to rotate.

The beauty of this product is that it comes with 5 adaptors, each with a different spline count, so it works with a number of Servo types.

Jim G

kc15/06/2018 15:49:34
5801 forum posts
167 photos

You could always file a flat onto the servo splines so that a collet with set screw will hold. Or use a brass tube with a D shaped insert soldered inside to fit on the flat filed on the servo splines. Some servos used square instead of splines.

Percy Verance15/06/2018 18:18:02
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7385 forum posts
143 photos

a bit of a silly question maybe Jim, but why the need to keep the linkages hidden? You wouldn't see them when the model is in the air.

G-JIMG15/06/2018 19:30:43
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73 forum posts
9 photos

Hi Percy,

It's because I'm trying to make it as scale as possible, even to the point of adding panel lines, rivet heads, etc.

Danny Fenton18/06/2018 10:28:42
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8909 forum posts
3774 photos

Jim, there is another way to do the links and that is to use an adaptor to go from the servo disk to the coupler. I made my own but they are easier to make than something with a spline!!

Cheers

Danny

Danny Fenton18/06/2018 10:36:15
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8909 forum posts
3774 photos

dsc_4636.jpg

rds adaptor.jpg

Cheers

Danny

Danny Fenton18/06/2018 10:37:28
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8909 forum posts
3774 photos

You could make somethig similar by soldering a large collet to a brass washer

PatMc18/06/2018 11:31:17
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4003 forum posts
501 photos

,,,or a strip of brass/mild steel soldered to a collet.

Danny Fenton18/06/2018 11:45:13
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8909 forum posts
3774 photos

I saw Ian Redshaw use a variation of RDS using a pushrod to do the coupling from a regular servo arm. This picture is not of Ian's installation, but does show the idea.

2006-09-07_143945_wing_2.jpg

Cheers

Danny

G-JIMG18/06/2018 11:49:54
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73 forum posts
9 photos

Thanks for all the suggestions, especially the homemade solutions. That's normally the way I would go, but in this case the wing is just too thin to accept anything much wider than the servo spline.

I'm using S3150 (10mm) Servos and there's not much room for much else. So unfortunately, on this occasion, I've had to open the wallet and buy a couple of rotary drivers.

rotary driver.jpg

Thanks again,

Jim G

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