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Author Topic: Ball links for control line  (Read 2798 times)

Offline Harold Brewer

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Ball links for control line
« on: June 25, 2018, 11:53:31 AM »
I have decided to try ball links on my new build.  I am going to use them on the bellcrank and elevator horn (no flaps).  I went the the web site for Central Hobbies and found a rather large list of items, to the point where it is confusing.  Any recommendations as what to use? 

Best regards,

Brew


Online T.J. Vieira

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Re: Ball links for control line
« Reply #1 on: June 25, 2018, 12:19:35 PM »
head over to an R/C Heli supplier, and just grab links for a 600 sized bird (align makes pretty consistent links that require minimal resizing)....

Online Brett Buck

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Re: Ball links for control line
« Reply #2 on: June 25, 2018, 01:12:07 PM »
I have decided to try ball links on my new build.  I am going to use them on the bellcrank and elevator horn (no flaps).  I went the the web site for Central Hobbies and found a rather large list of items, to the point where it is confusing.  Any recommendations as what to use? 

   I haven't seen any significant problems with the Rocket City #87 or the central hobbies equivalent. Unfortunately, as of this weekend, I cannot recommend the DuBro products. When inspecting airplanes at the Chumley Memorial, after extensive microsurgery, we discovered that one of the ball links had tightened up severely. The link was so tight that it had backed off the screws holding it down over time, which led to it being relatively free, but with extensive free play, as the screws, held with Nylok nuts, were acting as the bearings. Of course it had pounded out the holes in the bellcrank and flap horn, creating free play. When we tightened the screws, it was OK at the flap horn, but the link at the bellcrank was severely too tight. This was all done through a pretty small hole, so we were stumped for a while, but we confirmed the theory by dripping some oil on the ball, at which point it loosened up substantially, although it was still completely unacceptable.

   The (very temporary) solution was to back the one screw off just enough to let it turn (but not tilt), and then staking the nut in place with JB Kwik. That at least made pretty sure it was going to stay together, and it will take some time to pound out an oval hole and bring the slop back. The long-term solution is to replace the links with Rocket City links which don't usually have a problem like this. The original airplane with the #87 links is still in perfect operating order, no slop, and minimal drag, even after 30 years. The airplane itself is eligible for "rolling cutoff Classic" and the Monokote has turned to the consistency of talcum powder, and can easily be lifted with masking tape leaving perfect straightly lines.

  Paul Walker has gone back to bent-wire pushrods to defeat this type of problem (which is much more important on electric), but at least for IC engines, just get the Rocket City type, select them for the loosest fit, and move on.

    Brett

p.s. OK, it looks like you can't get them from Central Hobbies any more. Tom Morris had them the last time I checked.

   

Online Alexey Gorbunov

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Re: Ball links for control line
« Reply #3 on: June 25, 2018, 04:48:34 PM »

Online Tim Wescott

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Re: Ball links for control line
« Reply #4 on: June 25, 2018, 05:03:06 PM »
I ran across this today when I was spending time on this thread instead of working: https://www.dubro.com/collections/ball-links/products/e-z-adjust-ball-links.
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Online Tim Wescott

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Re: Ball links for control line
« Reply #5 on: June 25, 2018, 05:04:50 PM »
https://www.teamassociated.com/shop/

Do you have personal experience with 'em?  There seems to be a wide selection of ball ends for cars, but I could see them not caring even less about friction than you would on an RC airplane.
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Online Jim Mynes

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Re: Ball links for control line
« Reply #6 on: June 25, 2018, 06:55:31 PM »
Do you have personal experience with 'em?  There seems to be a wide selection of ball ends for cars, but I could see them not caring even less about friction than you would on an RC airplane.
The ball and cup style used on RC cars let go pretty easy by design. They’d rather have the link pop off than break an A-frame or strip a servo. I wouldn’t trust them on a control line plane.
I have seen the light, and it’s powered by a lipo.

Offline Avaiojet

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Re: Ball links for control line
« Reply #7 on: June 25, 2018, 07:25:00 PM »
Tom Morris is my only go to guy for CL HDWE!

Almost 'everyone' uses Tom Morris CL products. Almost.

It's so easy to call Tom up and ask questions, which he's glad to answer, or simply place your order.

I've used his CF pushrods, SS 4-40 threaded ends, ball links and control horns on these following models.

Some of the HDWE, flap horns, he custom made exactly to my drawings. Perfect!

Call Tom Morris.

P-40
ARGO
ARGO 2
Stuka Tank Buster
Gee Bee R 3
Mig-3
Pushy Galore
Gee Bee Z

All Tom Morris HDWE and ball links can be seen installed in these models at my Build Threads.

Charles



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Offline Dan McEntee

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Re: Ball links for control line
« Reply #8 on: June 25, 2018, 08:01:40 PM »
Tom Morris is my only go to guy for CL HDWE!

Almost 'everyone' uses Tom Morris CL products. Almost.

It's so easy to call Tom up and ask questions, which he's glad to answer, or simply place your order.

I've used his CF pushrods, SS 4-40 threaded ends, ball links and control horns on these following models.

Some of the HDWE, flap horns, he custom made exactly to my drawings. Perfect!

Call Tom Morris.

P-40
ARGO
ARGO 2
Stuka Tank Buster
Gee Bee R 3
Mig-3
Pushy Galore
Gee Bee Z

All Tom Morris HDWE and ball links can be seen installed in these models at my Build Threads.

Charles

  And how much air time has any of these models seen? Kind of hard to make any claims about a products performance if it is never really tested. You could be using paper clips and it wouldn't make any difference.. A shameful hijack of a thread to call attention to your hanger queens
  Type at you later,
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Online Tim Wescott

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Re: Ball links for control line
« Reply #9 on: June 25, 2018, 10:21:06 PM »
The ball and cup style used on RC cars let go pretty easy by design. They’d rather have the link pop off than break an A-frame or strip a servo. I wouldn’t trust them on a control line plane.

I took a look at the site Alexey referenced -- the only ball and cup links were for throttles; the rest were normal-looking ball links.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Online Brett Buck

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Re: Ball links for control line
« Reply #10 on: June 26, 2018, 01:09:59 AM »
Do you have personal experience with 'em?  There seems to be a wide selection of ball ends for cars, but I could see them not caring even less about friction than you would on an RC airplane.

   After the example above, I am looking at the metal type, not because they are stronger, but because I can do something about how they fit, like lap them to get the desired fit. And you can lube them (which may have been an issue in the case I mentioned).

    Brett

Online Alexey Gorbunov

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Re: Ball links for control line
« Reply #11 on: June 26, 2018, 03:40:09 AM »
I took a look at the site Alexey referenced -- the only ball and cup links were for throttles; the rest were normal-looking ball links.

https://www.teamassociated.com/parts/details/31305-ASC31305-turnbuckle_eyelets/
These ball ends for suspension links. For them the thread of M3 or 4-40 is used. Plastic here very good. These parts have to maintain serious shock loads.

Online T.J. Vieira

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Re: Ball links for control line
« Reply #12 on: June 26, 2018, 05:46:51 AM »
an 800 class helicopter, the way these 3d guys fly, will likely see WAY more force than we could ever throw at it, and they glide around like greased snot on a frictionless bearing....

https://www.amainhobbies.com/align-dfc-ball-link-set-agnh70z002xx/p252722

Offline TDM

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Re: Ball links for control line
« Reply #13 on: June 26, 2018, 07:17:01 AM »
Plastic ball links are not ever completely free. You have to apply some force to have them deflect. A buddy of mine had issues with that exact thing, and the model was hunting because of that. With IC is not much of a problem because the vibration from the power plant breaks the bind loose. With electric where the vibration is kind of nonexistent you have to be aware of this potential problem.

This is my go to option #1. https://www.ebay.com/itm/20pcs-Aluminum-M3-Link-Rod-End-Ball-Joint-CW-CCW-for-1-10-RC-Car-Crawler-Buggy/262241396196?epid=1254466092&hash=item3d0ece25e4:g:IfwAAOSwoydWmJ1o They should last the lifetime of the model. They are a steel ball in an aluminium anodized sleeve they are 100% loose. They have a smallest slop in them (perhaps .0002in), and that can be used to grease the link.  And yes with RH and LH screws you have a built in infinite adjustment.
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Offline Avaiojet

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Re: Ball links for control line
« Reply #14 on: June 26, 2018, 08:33:37 AM »
  And how much air time has any of these models seen? Kind of hard to make any claims about a products performance if it is never really tested. You could be using paper clips and it wouldn't make any difference.. A shameful hijack of a thread to call attention to your hanger queens
  Type at you later,
  Dan McEntee
 

Dan,

 LL~ LL~ LL~

You're only bringing attention to yourself as Avaiojet's Forum #1 "troll queen."

'You' just hijacked the thread, I only replied with honestly. Besides, we all know how popular Tom Morris's HDWE is.

And what's so wrong with bringing attention to my efforts in the hobby.

I am quite the designer and builder, you know.  LL~

Why don't you Post at the "Future of CL" Thread?

You can explain how you've done so much to promote the CL hobby, while you've trolled every one of my Posts, each and every day, for over 6 years.

And don't think everyone doesn't realize it.

BTW. It's so funny.

All I have to do is Post, and you show up trolling.  LL~ LL~ LL~ LL~

It's so constructive and adds so much to Forum participation and growth to the CL Hobby.

Keep up the good work Dan, where would SH Forum and the CL hobby be without you?



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"No one has ever made a difference by being like everyone else."

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I look at the Forum as a place to contribute and make friends, some view it as a Realm where they could be King.

"Ya gotta love it when a plane comes together."

Proverb 11.9  "With his mouth the Godless destroys his neighbor..."

"Perhaps the greatest challenge in modeling is to build a competitive control line stunter that looks like a real airplane." David McCellan, 1980.

Offline Harold Brewer

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Re: Ball links for control line
« Reply #15 on: June 26, 2018, 09:49:24 AM »
Thanks for the information.  I have searched and can not find any contact information for Tom Morris.  Can anyone help me?  It looks like he may be the best source (although his information on Stunthanger has not been updated in some time).

Best regards,

Brew

Offline George Truett

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Re: Ball links for control line
« Reply #16 on: June 26, 2018, 10:23:31 AM »
Brew,

Just scroll up to the top of the page and click on Stunt Hangar Hobby, the SHH home page has a contact button if you don't see what you need.

Online Brett Buck

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Re: Ball links for control line
« Reply #17 on: June 26, 2018, 01:08:51 PM »
The ball and cup style used on RC cars let go pretty easy by design. They’d rather have the link pop off than break an A-frame or strip a servo. I wouldn’t trust them on a control line plane.

   These can be retained by putting a wire loop (either a small Cotter pin or something bent like it) over the "root" of the link and lashing it to the barrel of the link, a la the Imitation article. It doesn't interfere with the motion and it doesn't take too much to keep them attached, so it doesn't have to be terribly tough.

   As always, the Imitation article is required reading for any budding stunt flier. A few things in there may have been overcome by events, but it is absolutely chock full of nuggets and almost anyone will benefit from reading it.

   Brett

Online Brett Buck

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Re: Ball links for control line
« Reply #18 on: June 26, 2018, 01:10:58 PM »

This is my go to option #1. https://www.ebay.com/itm/20pcs-Aluminum-M3-Link-Rod-End-Ball-Joint-CW-CCW-for-1-10-RC-Car-Crawler-Buggy/262241396196?epid=1254466092&hash=item3d0ece25e4:g:IfwAAOSwoydWmJ1o They should last the lifetime of the model. They are a steel ball in an aluminium anodized sleeve they are 100% loose. They have a smallest slop in them (perhaps .0002in), and that can be used to grease the link.  And yes with RH and LH screws you have a built in infinite adjustment.

  Excellent, I will probably try those. The only downside is mixing in metric parts but I suppose its fine as long as you keep the control hardware segregated from the conventional types. I take it that the hole in the ball is also for M3?

   Brett
   

Offline Fredvon4

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Re: Ball links for control line
« Reply #19 on: June 26, 2018, 01:27:33 PM »
 I have many hours with my son On RC 10 electric race cars and not as much time flying CL models...in that time I have observed that the Quality and durability of the RC Helicopter and RC car links are much better than any of the products offed for the RC and CL airplane use

I have a 1987 RC 10 race car here with all metal Ball links...the car has hundreds of long races by my son all over the country...dust,dirt, sand

I can hold it and articulate the steering with no perceptible slop....unlike my Ford F250 with front end slop in 60,000 miles

alloy helicopter or RC car ball links --all alloy metal-- are NOT dramatically heavier than the plastic counterparts.... for PA 75 piped model use

BUT what do I know....I tend to believe the loads on a flap elevator are probably more for a 4~5 pound  65~73 Oz+ stunt ship than the 3 pound RC car steering links

My thinking is the miniaturize High End RC helicopter and RC car items...appropriately priced.... are a superior product...in a very wide variety of sizes
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Offline Motorman

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Re: Ball links for control line
« Reply #20 on: July 05, 2018, 12:41:52 PM »
Just ordered aluminum ball links and 3mm x 60mm shcs. I did a test tapping out a 3mm thread to 4-40 and it was unacceptable. The main difference I can see is the need for a jam nut since the metal ball links won't cold flow like the plastics.


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Online Brett Buck

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Re: Ball links for control line
« Reply #21 on: July 05, 2018, 04:30:47 PM »
Just ordered aluminum ball links and 3mm x 60mm shcs. I did a test tapping out a 3mm thread to 4-40 and it was unacceptable. The main difference I can see is the need for a jam nut since the metal ball links won't cold flow like the plastics.

    I think the right answer is to just use 3mm hardware and be careful about segregating it from the conventional stuff. Last thing anyone needs is to accidentally stick a 3mm screw into a 4-40 or 3-48 hole. I also have 5-40 which is even more dangerous to have.

     Brett


Online Tim Wescott

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Re: Ball links for control line
« Reply #22 on: July 05, 2018, 04:55:13 PM »
  Excellent, I will probably try those. The only downside is mixing in metric parts but I suppose its fine as long as you keep the control hardware segregated from the conventional types. I take it that the hole in the ball is also for M3?

It's advertised as having a 3mm hole, which is 0.118".  If my memory serves me correctly, that's a tiny bit loose for #4 hardware but not really bad.  Stick a screw in the hole when you get 'em, rattle it around, and report back.  The only way to get a perfect fit is with a shoulder screw anyway.
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Offline George Truett

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Re: Ball links for control line
« Reply #23 on: July 05, 2018, 05:28:05 PM »
On my new SV-11 build I used aluminum ball links from Integy, one of the car suppliers.  This one has about a 15 degree offset in it which was perfect for the bellcrank.  I bought a several years supply of 3mm threaded rod from McMaster-Carr for about $20.  I have not flown it yet but it is my smoothest control linkage yet, at least on the ground.

Offline Mark Mc

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Re: Ball links for control line
« Reply #24 on: July 05, 2018, 06:03:40 PM »
George, is there a reason you went with the long alloy links over the short alloy links?

And a general question: Alloy vs. Plastic? Any negatives or bad experiences on the plastic type ball links?

Mark

Offline George Truett

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Re: Ball links for control line
« Reply #25 on: July 05, 2018, 06:21:33 PM »
Mark,  I went with the long links just for more thread engagement.  I have never had a plastic link fail, I'm just always looking for better/smoother linkages and those looked interesting.  I fly mostly for my own enjoyment now, I doubt I fly as much in a year as Brett does in a month, these may never fail on me.

Online Tim Wescott

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Re: Ball links for control line
« Reply #26 on: July 05, 2018, 11:02:04 PM »
And a general question: Alloy vs. Plastic? Any negatives or bad experiences on the plastic type ball links?

The plastic ones bind up, either out of the package or over time.  Or not.  It's a crap shoot, which is pretty frustrating when you just want to fly.
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Online Brett Buck

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Re: Ball links for control line
« Reply #27 on: July 06, 2018, 12:12:40 AM »
And a general question: Alloy vs. Plastic? Any negatives or bad experiences on the plastic type ball links?

   As noted above. I have never had the Rocket City type bind up, but the DuBros sure were stuck. The vast, vast majority of the airplanes using ball links over the years (dating back to about 1978) have used plastic or nylon. I have never seen a metal type in a stunt plane, but now I am going to try them.
 
    BTW, the Rocket City #87 wasn't chosen by careful testing or detailed analysis. I went to San Antonio hobbies one day, found the sturdiest-looking 4-40 links they had, Rocket City #87, stuck them in the airplane. I later suggested them to Ted, he put them on the plans for the Trivial Pursuit, and we told people about it one Compuserve, AOL, RCO, SSW, and now Stunthangar, and that's what most people used.

     Brett

Offline FLOYD CARTER

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Re: Ball links for control line
« Reply #28 on: July 06, 2018, 11:30:58 AM »
I have heard that San Antonio Hobby shop went out of business.  Is that so?

I lived in Los Altos, just a short drive to SA Hobby.  Definitely one of the biggest and most complete shops I have ever seen.

Floyd

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Online Brett Buck

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Re: Ball links for control line
« Reply #29 on: July 06, 2018, 12:10:14 PM »
I have heard that San Antonio Hobby shop went out of business.  Is that so?

  Yes, for at least 10 years.  It was repurposed for a whiile, but it may have been torn down by now.

   You are right, in terms of scope, I have never seen anything like it. They had an entire aisle - an aisle, mind you, maybe 100 feet long, both sides - just to show *plastic vacu-form models*, which many people have never heard of and were a "thing" for about 1 year in 1955. They are flat in plastic bags about the size of a sheet of paper and maybe an inch thick. You know how many of those you can get in a entire very large store aisle?

      The sheer volume was remarkable, none of this "hole in the wall"/"back of a bike shop" stuff. If you wanted something obscure in the larger hobby world, this was the place to go. Not super-great for CL model airplane competitors - go to J&M Hobby House for that - but general hobby and model construction supplies.

     Brett

   

Online Brett Buck

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Re: Ball links for control line
« Reply #30 on: July 07, 2018, 08:16:55 PM »
This is my go to option #1. https://www.ebay.com/itm/20pcs-Aluminum-M3-Link-Rod-End-Ball-Joint-CW-CCW-for-1-10-RC-Car-Crawler-Buggy/262241396196?epid=1254466092&hash=item3d0ece25e4:g:IfwAAOSwoydWmJ1o They should last the lifetime of the model. They are a steel ball in an aluminium anodized sleeve they are 100% loose. They have a smallest slop in them (perhaps .0002in), and that can be used to grease the link.  And yes with RH and LH screws you have a built in infinite adjustment.

    I got my order of these, and they are indeed very loose, completely free in fact. I think the slop it a lot more than .0002, but seems acceptable (considering that we all used wire pushrods through brass bushings for 50-ish years). I am going to try to test a few of them to destruction to see if I can get the pressed-in fitting to come loose, but otherwise, seems fine.

    I also want to drill them out for a heli-coil so I can use it with 4-40 pushrods. I am not comfortable with the length of thread engagement or the slop in the threads as it comes - it would be OK, probably, with a jam nut, but I would sure like a bit more threads on it, and not in aluminum. I also had trouble finding 3mm left-handed threaded rod. I can find short bits of it, but not enough to make up the pushrod end fitting the way I normally do it.

     Looks like a good find!

    Brett

Offline Trostle

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Re: Ball links for control line
« Reply #31 on: July 07, 2018, 08:57:38 PM »
. I also had trouble finding 3mm left-handed threaded rod. I can find short bits of it, but not enough to make up the pushrod end fitting the way I normally do it.

       Brett

Hi Brett,

You can get titanium 3 mm tie rods from the race car counter.  Of course, they have left and right threads on the same piece.  They provide plenty of material to fit in the ends of the carbon pushrods.  I also like the titanium ball links from the same race car counter as well as the cups for them.  These cups also provide plenty of length to thread them over titanium threaded rods.  I have never had them bind up on any of my ships like we have seen with the smaller Dubro cups/ball links.  I have been using them for 20 years on lots of airplanes and lots of flights (though I do not fly much here with this 6,000 ft sometimes 7,000+ ft pressure density when the temperature goes over 90o.

Keith

Offline Target

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Re: Ball links for control line
« Reply #32 on: July 08, 2018, 10:37:56 AM »
On my new SV-11 build I used aluminum ball links from Integy, one of the car suppliers.  This one has about a 15 degree offset in it which was perfect for the bellcrank.  I bought a several years supply of 3mm threaded rod from McMaster-Carr for about $20.  I have not flown it yet but it is my smoothest control linkage yet, at least on the ground.


Edit-
I found them....Thanks!
http://www.integy.com/st_prod.html?p_prodid=24410&p_catid=107&ratesortby=New#.W0I_UfZFyM8

These look awesome, any chance you can share the part number?
I looked on Integy's  website but could not find them after a decent search.

Thank you!!
Regards,
Chris
AMA 5956

Online Brett Buck

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Re: Ball links for control line
« Reply #33 on: July 09, 2018, 02:00:43 PM »
OK. In my brief moments of lucidity between doses of pain medication for kidney stones, I tried testing some of the links noted above to destruction. Using appropriately-sized sockets as anvils, the insert side of the link drove out easily, leaving the ball loose on the link. They are pressed together. The fit is very good and it's plenty tight enough to stay together under normal loads, but I am not at all comfortable with them staying together under 2000 flights worth of vibration. I think we need to find some way of staking them in place, either by making crimps across the interface or relieving the edge and using JB-Weld or something.

    Fortunately you can't easily drive the pressed-in part too far and bind it up. You can make the fit tighter by bending the knife-edge portion, but I don't expect that to last due to wear. The balls are not particularly smooth, they have ridges around the direction they were turned, but you could probably smooth that out.

    After all this, I am not too enthusiastic about closing them up inside an airplane with no easy way to lube or service/replace them. I think if I had the means to easily do it, I would smooth out the balls (relatively easy), make one side of the link float, then use a Bellville washer or similar to apply a preload. And have an easy way of lubricating them in place.

    Brett

Online Tim Wescott

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Re: Ball links for control line
« Reply #34 on: July 09, 2018, 02:28:50 PM »
OK. In my brief moments of lucidity between doses of pain medication for kidney stones,

Ouch.  You have my sympathy.  I've never had 'em, but I understand they're the worst.

Using appropriately-sized sockets as anvils, the insert side of the link drove out easily, leaving the ball loose on the link. They are pressed together.

Huh?  Could you post pictures?  Are you saying that these are 3-piece assemblies, with a ball, a thingie that goes around the ball, and a thingie that has the 3mm thread on it?  Clearly I'm confused here -- I'd like to fix that.
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Online Brett Buck

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Re: Ball links for control line
« Reply #35 on: July 09, 2018, 02:42:04 PM »
Huh?  Could you post pictures?  Are you saying that these are 3-piece assemblies, with a ball, a thingie that goes around the ball, and a thingie that has the 3mm thread on it?  Clearly I'm confused here -- I'd like to fix that.

  I am talking about staking 3 into 1.

    Brett

Online Tim Wescott

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Re: Ball links for control line
« Reply #36 on: July 09, 2018, 03:56:47 PM »
Thank you for the picture -- that makes all clear.
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Offline Harold Brewer

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Re: Ball links for control line
« Reply #37 on: July 11, 2018, 12:40:31 PM »
Thanks for the information.  I have looked at several sites that carry ball links, but do not see the way that they are attached to the bellcrank or control horn.  Can someone help me?

Best regards,

Brew H^^

Online Brett Buck

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Re: Ball links for control line
« Reply #38 on: July 11, 2018, 01:43:30 PM »
Thanks for the information.  I have looked at several sites that carry ball links, but do not see the way that they are attached to the bellcrank or control horn.  Can someone help me?

  Screws with nylok nuts and then staked with JB WELD.

    Brett

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Re: Ball links for control line
« Reply #39 on: July 11, 2018, 03:17:42 PM »
For a connection between bellcrank and flaps I prefer Dubro Monsters, because they are the only ball links I trust for this application. Yes, they all are tight right from a package and are not suitable for use. But I have found a solution - there is a thin layer of nickel (or whatever it is) to be removed from a ball. I put a ball on a screw between two small spacers made out of brass tube and mount that assembly into a hobby drill. I start sanding with P800-P1000 paper grit and finish with P2000-P2500. Usually that's enough for friction free operation of a ball link. Just keep in mind that bare brass surface is much more britle, therefore you need to treat brass ball with care.

Vitalis

Offline Harold Brewer

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Re: Ball links for control line
« Reply #40 on: July 11, 2018, 06:29:12 PM »
So the bearing surface for the bellcrank or the control horn is the crest of the screw threads?  Couldn't this present a wear issue over time?

Best regards,

Brew

Online Brett Buck

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Re: Ball links for control line
« Reply #41 on: July 11, 2018, 09:54:56 PM »
So the bearing surface for the bellcrank or the control horn is the crest of the screw threads?  Couldn't this present a wear issue over time?

    ???  I am not sure how you are getting that. You hard-mount the ball to the horn upright, screwed down tight. The ball then moves with the horn, inside the outer plastic part of the link, rotating and tilting as necessary.

    In the very temporary example of an emergency fix, the link shrunk over the ball and was too tight, so in that case, the bearing was the screw through the threads. But that was a temporary "field" fix (actually the conference room of a Best Western), and has already been fully replaced with acceptable links.

      Brett
« Last Edit: July 12, 2018, 09:13:48 AM by Brett Buck »

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Re: Ball links for control line
« Reply #42 on: July 12, 2018, 04:50:47 AM »
i have been using du-bro large ball links for ages ( on R/C big jets, 33% scale gas extra´s and alike and on control line models for years) never had a failure and they are pretty light for our planes. i was using the 4.40 bolt but recently changed to Swivel Ball Link - 2-56 Swivel Ball Link for 4-40 Rods  as i belive they are as strong as our wire links used to attach them to the arrow shafts.
after years of use, no signal of slope or bendind even on 18KG big r/c planes.



Offline Harold Brewer

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Re: Ball links for control line
« Reply #43 on: July 12, 2018, 01:21:38 PM »
I am trying to start using new technology in my builds.  My problem is that I have not seen any photos or other information concerning usage.  My apologies for asking a dumb question; I guess that it should have been obvious to me.

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Re: Ball links for control line
« Reply #44 on: July 12, 2018, 02:07:11 PM »
I am trying to start using new technology in my builds.  My problem is that I have not seen any photos or other information concerning usage.  My apologies for asking a dumb question; I guess that it should have been obvious to me.
the only "dumb" question is the one never asked, we are here to learn and to improve...
one positive thing of this hobby and foruns is that we cross information of other fields and other categories of modelling and all benefits.

Online Brett Buck

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Re: Ball links for control line
« Reply #45 on: July 12, 2018, 04:02:02 PM »
I am trying to start using new technology in my builds.  My problem is that I have not seen any photos or other information concerning usage.  My apologies for asking a dumb question; I guess that it should have been obvious to me.

   It wasn't a dumb question at all, but I though the baseline usage would be clear.

     Brett

Offline George Truett

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Re: Ball links for control line
« Reply #46 on: July 12, 2018, 04:07:32 PM »
Brew,  Sorry,  I didn't have a chance to get some pictures until this evening.  These are just mockups, anything closed up in an airplane needs a permanent attachment like mentioned earlier.  Photo 1 shows a ball end attached to a flap horn with a 3mm bolt and locknut.  Photo 2 shows a linkage like I would use for a bellcrank to flap horn using the angled ball end.  This is just to show what it looks like, the carbon tube still needs to go over the threaded rod.  Photo 3 shows what it would look like bolted to a bellcrank (again 3mm bolt and locknut with JB Weld insurance).  George T

Online Tim Wescott

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Re: Ball links for control line
« Reply #47 on: July 12, 2018, 04:17:38 PM »
I am trying to start using new technology in my builds.  My problem is that I have not seen any photos or other information concerning usage.  My apologies for asking a dumb question; I guess that it should have been obvious to me.

It's not a dumb question, and if a picture is worth 1000 words, actually doing it once has to be worth about 100 pictures.  What Brett said -- the ball portion should not move with respect to the thing it's mounted on (bellcrank or horn).  It is a section of a sphere, and it, and the outer part of the link, forms a bearing that can twist every which way.

The reason they're good is that in a typical control linkage, the rods don't all move in one plane -- the bellcrank is twisting one way while the horn is twisting another.  You can solve this by using the old-style bent music wire in a loose bushing, but then your control system has slop.  You can solve it by using an RC ball link, but they're made with a brass ball and a plastic outer link -- the plastic outer link shrinks with age (or just gets made different sizes due to manufacturing variations) and that means that links bind up over time.  That's the problem that we're trying to overcome, and these all-metal links certainly give me hope that it's overcomable.
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Re: Ball links for control line
« Reply #48 on: July 12, 2018, 04:27:22 PM »
I thought i had heard there is a way to "size" the plastic yokes so that the fit wasn't too tight. I know the heli guys use small and fast servos (fast has less torque for the same motor in the servos), and a draggy ball link that might "double center" would certainly cause issues i would think.
Regards,
Chris
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Offline George Truett

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Re: Ball links for control line
« Reply #49 on: July 12, 2018, 04:59:16 PM »
You can resize them, here's the tool for links on a 450 size heli.  If you look close you can see the ridge on the ball, you insert it into the plastic link and twist a few times, the ridge removes plastic uniformly.  Problem is once you size a link, it's on the way to being worn out.  Not a big deal for a serious flier who always checks his linkages.  Not a great option for something sealed inside a plane I'm afraid.


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