New Products Flash Sale
Thread Tools
Old Jun 19, 2015, 03:35 AM
mapes12 is offline
Find More Posts by mapes12
Mark
mapes12's Avatar
United Kingdom, England, Gnosall
Joined Oct 2012
171 Posts
Question
No Slop Control Linkage Advice?

I've been looking everywhere for pics or a HowTo to connect up my control surfaces with zero slop. The plane I'm working on comes with plastic horns and clevis but there is a tiny amount of play in these which I need to eliminate. I recall reading somewhere that a ball linkage would be a better solution but I can't find anything despite searching for ages. Any hardware recommendations would be helpful with UK or EU stockists. Thanks in advance.
mapes12 is offline Find More Posts by mapes12
Reply With Quote
Sign up now
to remove ads between posts
Old Jun 19, 2015, 04:43 AM
Daniel003 is offline
Find More Posts by Daniel003
Registered User
Australia, VIC, Bendigo
Joined Apr 2014
202 Posts
Hi mapes12, just search 2mm ball links or m2 ball links on ebay and heaps should pop up. They are a good size for a range of model sizes. Use carbon fiber rod and cut to suit and epoxy them into the ball links. Easily done
Daniel003 is offline Find More Posts by Daniel003
Reply With Quote
Old Jun 19, 2015, 06:07 AM
GordonTarling is offline
Find More Posts by GordonTarling
Supersonic Engineering
GordonTarling's Avatar
UK, Greater London, Uxbridge
Joined Mar 2001
3,282 Posts
Lots of choice here High quality stuff at fair prices.
GordonTarling is offline Find More Posts by GordonTarling
Reply With Quote
Old Jun 19, 2015, 11:47 AM
BMatthews is online now
Find More Posts by BMatthews
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
12,674 Posts
There's slop and there's flex. The following is rather general because you don't provide any description of the setup you've got now other than to say that it has some slop. It's very likely that you simply need to do a little more detail work than to install something else. In any event you'll need to totally re-do the pushrod ends to install any ball links. So perhaps something simpler that is as effective or more effective will work. So here goes.

First off any of the tube in tube or cable in tube pushrods will have some lost motion. It's impossible to make them with no play between the two parts. You can limit this by keeping them in as straight a line as possible. But it's always there waiting to strike. So for truly accurate linkages you don't want to use any of these flexible options. Instead solid pushrods with minimal bends in the wire ends is a better way to go.

You want a GOOD fit of the wire ends or connectors in the holes of the servo arms and the control horns. As in this should be a light push fit. Then trust on the self lubricating nature of the nylon or whatever plastic is used. Getting the most out of this means dressing the ends of the wire that you use for making your pushrod ends so it doesn't cut or force the plastic when inserted. And with all the different size holes in the hardware these days it's tough to pick the other pushrod components that fit correctly. When I started in this the standard for all the servo outputs and control horns was 1/16". Now it's all over the map thanks to the variety of sizes in servos. But it's still just as important to fit the pushrod hardware so it fits slightly snug in the holes.

Ball ends are not any more precise than a good fitting plain wire end. I've used them and found that they too have a slight amount of play. It needs that or the ball would bind in the socket. In the end I found that a proper size wire end has less play than even a ball end.

But being a ball end it has free motion in two axes. And sometimes that's needed. You can avoid the need for that in short setups by positioning the servo so the output rotation axis is parallel to the hinge line axis. That way the rotation and motion of the pushrod is all in one plane. Mind you in some cases that's not practical.

Another issue with some of these things like screw lock fittings and ball ends is that there will end up being some offset where a clevis fits in line. So swapping a clevis for a ball end may require more distortion in the pushrod. And depending on the setup that might be bad too. Remember that a key factor for any pushrod is keeping it as straight as possible/practical. You can't fix a bad pushrod with just a couple of ball ends.

So maybe look to see what the problem really is and figure out the easiest way to fix it.
BMatthews is online now Find More Posts by BMatthews
Reply With Quote
Old Jun 19, 2015, 01:04 PM
Bare is offline
Find More Posts by Bare
Registered User
Canada
Joined Nov 2000
7,958 Posts
Assuming your hinges are capable and slop free?
Then a Pull Pull setup is the best choice.
Any mechanical push pull setup will have slop, in the connections at least.
Unless they are so precision as to be either Cost prohibitive and/or Massive.
Bare is offline Find More Posts by Bare
Reply With Quote
Old Jun 19, 2015, 01:44 PM
mapes12 is offline
Find More Posts by mapes12
Mark
mapes12's Avatar
United Kingdom, England, Gnosall
Joined Oct 2012
171 Posts
Quote:
Originally Posted by Daniel003 View Post
Hi mapes12, just search 2mm ball links or m2 ball links on ebay and heaps should pop up. They are a good size for a range of model sizes. Use carbon fiber rod and cut to suit and epoxy them into the ball links. Easily done
Thanks. Once I've epoxied the carbon fiber rod into the ball (how long does it need to be?) how do you fix it to the horn and servo? Epoxy again?

EDIT: I forgot to mention that the control surfaces I'm trying to eliminate the slop on are the ailerons. The supplied plastic clevis and horn appear to be the best fit that can be provided by these type of components but the tiny amount of slop in them is resulting in about 2mm of play at the trailing edge of the ailerons. Just to add to this, each aileron has it's own servo in the wing.
mapes12 is offline Find More Posts by mapes12
Last edited by mapes12; Jun 19, 2015 at 02:01 PM.
Reply With Quote
Old Jun 19, 2015, 04:11 PM
BMatthews is online now
Find More Posts by BMatthews
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
12,674 Posts
Quote:
Originally Posted by mapes12 View Post
....Once I've epoxied the carbon fiber rod into the ball (how long does it need to be?) how do you fix it to the horn and servo? Epoxy again?......
GOOD GRIEF NO! ! ! !

Epoxy isn't an option for any of this. The body of ball links are supposed to screw onto a threaded stud glued into the end of a pushrod. That threaded stud can be set in place with epoxy.

The ball itself is typically secured to the control horn or the servo arm or wheel with a small screw and nuts. No glue should be used at any of these points.

Epoxy won't stick at all well to the nylon plastic used for the ball joint body piece or to the plastics used for control horns or the servo output arms. It likely would not survive for more than 1/3 to 1/2 of the first flight. And you know what I mean about 1/3 to 1/2 a flight and how it's going to end, right?

If you want to use carbon for the pushrod I'd suggest you get some carbon tube which has a center hole that is a close fit for the size of threaded stud you need to use. Typically for the smaller sizes this was 2-56. These days I'd be surprised if it's not 2mm metric in many cases. Otherwise you can get metal rods that are threaded on one end to screw into the ball joint bodies. The other end will need to be cut and joined to a threaded end. They make solder on threaded adapters for doing this. Here again I would not use epoxy. They should be soldered for the best safety.
BMatthews is online now Find More Posts by BMatthews
Reply With Quote
Old Jun 19, 2015, 05:52 PM
Daniel003 is offline
Find More Posts by Daniel003
Registered User
Australia, VIC, Bendigo
Joined Apr 2014
202 Posts
Ive used carbon fiber puchrods epoxied into ball links on all my 50" and smaller planes and they have had hundreds of flights, and no you do not glue the horn to the servo, the only thing that will have glue is rither end of the carbon rod into the ball links on eash end. The ball links then get screwed to your control horn and your servo arm. Every precision aerobatics model you see are set up this way
Daniel003 is offline Find More Posts by Daniel003
Reply With Quote
Old Jun 19, 2015, 06:01 PM
Daniel003 is offline
Find More Posts by Daniel003
Registered User
Australia, VIC, Bendigo
Joined Apr 2014
202 Posts
The only problem with this setup is that it is non adjustable so you have to get it right the first time
Daniel003 is offline Find More Posts by Daniel003
Reply With Quote
Old Jun 19, 2015, 06:02 PM
Daniel003 is offline
Find More Posts by Daniel003
Registered User
Australia, VIC, Bendigo
Joined Apr 2014
202 Posts
Setup like these but use carbon fiber OR threaded rod between the ball links
Daniel003 is offline Find More Posts by Daniel003
Reply With Quote
Old Jun 20, 2015, 02:24 AM
BMatthews is online now
Find More Posts by BMatthews
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
12,674 Posts
Ah, I see.... I was thinking bigger rods. I didn't think of rods that would fit into the threads and be epoxied into the threads. Yep, that's a great way to go.

In fact if the threads in the ball links were greased up a bit with a mold release I wonder if the threads could be encouraged to break off the plastic easily and form adjustable threaded ends. Or is this what you're already doing?
BMatthews is online now Find More Posts by BMatthews
Reply With Quote
Old Jun 20, 2015, 02:25 AM
mapes12 is offline
Find More Posts by mapes12
Mark
mapes12's Avatar
United Kingdom, England, Gnosall
Joined Oct 2012
171 Posts
Quote:
Originally Posted by Daniel003 View Post
Setup like these but use carbon fiber OR threaded rod between the ball links
Thanks for the pic. Do you have a pic of the component that then connects the ball to the horn / servo?
mapes12 is offline Find More Posts by mapes12
Reply With Quote
Old Jun 20, 2015, 04:22 AM
GordonTarling is offline
Find More Posts by GordonTarling
Supersonic Engineering
GordonTarling's Avatar
UK, Greater London, Uxbridge
Joined Mar 2001
3,282 Posts
Quote:
Originally Posted by mapes12 View Post
Do you have a pic of the component that then connects the ball to the horn / servo?
It's a simple screw of appropriate size (usually 2mm) that goes through the ball, the horn and then has a locknut fitted to secure it.
GordonTarling is offline Find More Posts by GordonTarling
Reply With Quote
Old Jun 20, 2015, 10:49 AM
mapes12 is offline
Find More Posts by mapes12
Mark
mapes12's Avatar
United Kingdom, England, Gnosall
Joined Oct 2012
171 Posts
Quote:
Originally Posted by GordonTarling View Post
It's a simple screw of appropriate size (usually 2mm) that goes through the ball, the horn and then has a locknut fitted to secure it.
Thanks for your help. HK do these: http://www.hobbyking.com/hobbyking/s...ch=ball%20link

The ball size is shown at 4.8mm and I've read in other postings that the plastic bit needs to be shaved a little bit sometimes to obtain free movement. My understanding is that you use a ball end resizing tool / reamer to do this. However, the only size tool I can find close to this ball size is 4.7mm. Would this be suitable or are the HK balls a none standard size?
mapes12 is offline Find More Posts by mapes12
Reply With Quote
Old Jun 20, 2015, 02:37 PM
Rodney is offline
Find More Posts by Rodney
Registered User
Florida
Joined Aug 2004
4,321 Posts
I think Bare in his post above gave some very good advice. For the easiest, at least for me, way to get good slop free controls is pull-pull. You just have to make sure you get a wee bit of positive Ackerman in the installation and DO NOT over tighten the lines. You want them just taunt enough so that there is no slack when the surfaces are at neutral.
Rodney is offline Find More Posts by Rodney
Reply With Quote


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion No Slop Linkage 3D-Seth Indoor Pattern/F3P 4 Aug 15, 2007 01:26 PM
Best flap linkage with minimal slop? ferradas Electric Plane Talk 9 Nov 12, 2002 11:46 PM
Mini-max linkage slop, how to solve? T-Bo Foamies (Kits) 13 Aug 14, 2002 02:57 PM
Question Control Linkage Slop Question Yakrobat Fuel Plane Talk 2 Jun 06, 2002 06:06 AM
Alert Control Linkage Slop Question Yakrobat Fuel Plane Talk 0 May 27, 2002 05:51 PM