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Z Bend vs. FT Linkage Stopper

jross

Well-known member
#1
I love the idea of linkage stoppers as opposed to Z bends. That ability to adjust is appealing to me.

My issue comes when using the linkage stoppers. Half the time, they bind and don't rotate with the control arm causing deflection in the control rod and incorrect throws.

I've watched the videos about Z bending. I've not seen much on how to properly use linkage stoppers.

Anyone have a trick for linkage stoppers or accurate Z bends?
 

makattack

Winter is coming
Moderator
Mentor
#2
If I were to use linkage stoppers and wanted them to rotate freely in the control horn (or servo arm/horn) I would make sure the hole it's going into is slightly bigger than the stopper threads but smaller than the nut that goes on the threaded screw part. Then, I would install the nut so that neither the nut or stopper is tight against the horn. I would use CA / epoxy / thread locker (your choice on how strong to make it) on the nut to lock it down.

For that reason I tend to use z-bends, and I don't really worry about the accuracy of them because I make sure I have enough wire to put in one "V" bend along it for adjusting / fine-tuning / trimming the control surface.
 

Merv

Well-known member
#3
I use Z bend on one end and linkage stoper on the other. I prefer the Great Planes linkage stopper. They have a press on washer that stays on. The problem with thread on, you have to tighten it, now it will not swivel. If you don’t tighten it, they will vibrate off. Dubro link also has a good stopper but theirs is round. Great Planes is square, much easier to grab with pliers and really tighten the wire.

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Headbang

Well-known member
#4
I get a lot of comfort in dual z bends. Knowing they can not fail is piece of mind. I have had linkage stoppers fail, I just don't trust them. One would be better off using nylon clevises and threaded rod for 1/2A planes. You still have adjustability, but as long as you put on a piece of fuel tubing to keep them closed, they will not fail. Another option is my old school solution on all of my 20yr old plus planes. Z bend or L bend with a keeper on the servo, nylon clevis on the control surface.
All my planes over 25 sized used threaded rod, braze a threaded couple on one end for long rods, use dual ball links. Best of all worlds. But a bit heavy and overkill for 25 size and under.
 

jaredstrees

Well-known member
#6
I have had linkage stoppers fail a couple times, but I think they are worth it. Really the only time I have had them fail, it was my fault for not checking them out before a flight. I use a Z bend on one end and the stopper on the other. Like Mak said, little CA, glue or something else and the nuts will stay put. Only when you haven't added that (like my last fail where I finished the model but forgot the thread lock) do they tend to come apart. Being able to adjust my control surfaces is worth the risk to me.
 

Merv

Well-known member
#7
That’s why I only use the square ones. You can grab hold of then and really tighten them down. The set screw will make a small mark on the wire. I’ve never had one fail.
 
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jaredstrees

Well-known member
#8
That’s why I only use the square ones. You cue grab hold of then and really tighten them down. The set screw will make a small mark on the wire. I’ve never had one fail.
Well, I only have a couple of the round ones left and need to order some more. looks like I need to try a different style.
 

Merv

Well-known member
#11
Got a source for those stoppers Merv? everywhere seems to be out of them.
I have not gotten any for some time now, I usually get them from eBay.

For me a good stopper needs three things, a push on washer, a square body & an Allen wrench tightener. A Philipps head tightener is the worst.
 

jross

Well-known member
#12
I would make sure the hole it's going into is slightly bigger than the stopper threads but smaller than the nut that goes on the threaded screw part.
My issue isn't the hole, it's the thickness of the servo arm or control horn. When tight, many of the linkage stopper nuts are too snug if you tighten them to the end of the threaded portion. On some, it works fine. but not all.
 

jross

Well-known member
#13
I get a lot of comfort in dual z bends. Knowing they can not fail is piece of mind. I have had linkage stoppers fail, I just don't trust them.
Guess I need to revisit my Z bending skills. Seems like it's a thing that takes a bit to get the hang of.
 

Headbang

Well-known member
#14
It is pretty easy to do, just need to take it slow and make sure everything is where you want it before you mark and bend the final linkage. If it is a little off, not to worry. Most modern radios have sub trim. Other then wanting to be old school and proper, there is little reason to be to worried about having things mechanically dead on as long as it is close.
 

jross

Well-known member
#15
Other then wanting to be old school and proper, there is little reason to be to worried about having things mechanically dead on as long as it is close.
Okay. Your advice hasn't failed me so far. The Mini Arrow is getting dual Z bends. Can't wait to crash that baby!
 

Jaxx

Posted a thousand or more times
#17
I love my linkage stoppers. I guess I've been lucky, as I have not had any fail. I usually put a z-bend on one end and a linkage stopper on the other, but depending on the situation I may use two linkage stoppers (cheap ones from HK).

I find the key to be blue thread locker. I use a toothpick to apply a small amount to the threaded areas, and I have never had a problem. Once the thread locker has cured, I spin linkage stopper in the mounting hole until it moves freely (it acts as a file). You have to be sure not to over-tighten when applying the nut/fastener.
 

jross

Well-known member
#18
All I can do is share my experiences, for what ever they are worth.
If I didn't live two day's drive away from your flatlands, I'd gladly drive out to fly together. I've not been much east of Calgary unless I was on a plane. I watched out the window over the Rockies but fell asleep after that...

You've taught me some cool ****. The rig pig suit? Brilliant. Taking off from the snow with an Explorer? A eureka moment for me as a Canadian. Looks really cool when fresh snow is blasting past your prop. A cloud of powder. I'm all about sea planes now. Have yet to build one but it's next on the bench. Frickin snow. Just won't go away. How long till spring?
 
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Headbang

Well-known member
#19
If I didn't live two day's drive away from your flatlands, I'd gladly drive out to fly together. I've not been much east of Calgary unless I was on a plane. I watched out the window over the Rockies but fell asleep after that...

You've taught me some cool ****. The rig pig suit? Brilliant. Taking off from the snow with an Explorer? A eureka moment for me as a Canadian. Looks really cool when fresh snow is blasting past your prop. A cloud of powder. I'm all about sea planes now. Have yet to build one but it's next on the bench. Frickin snow. Just won't go away. How long till spring?
Got 2" today, another ft expected over the next few days. Spring happens in April if we are lucky lol. I might go flying tomorrow anyways, be damd the snow! And my jeep always needs a good excuse to break track so those 4x4 trucks don't get stuck!
 

jross

Well-known member
#20
I might go flying tomorrow anyways, be damd the snow!
I got nothing on schedule tomorrow except some book keeping/invoicing. Always looking for an excuse to get some fresh air when doing that.

Figure I'll try to fly the Explorer with some 3500 3S a buddy left me. Only used 2200 previously and I only have one of those. Gonna take the Tiny Trainer with 900s instead of the 500s I've been flying on. Chance of flurries here and near zero tomorrow. Should be good flying.