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z-Bends and Control Rods!

Discussion in '* Scratch Built Section *' started by sdparkflyers, Mar 27, 2010.

  1. sdparkflyers

    sdparkflyers New Member

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    Ok I have been building and flying as most of you know for a while! And I dont mind asking for help when I hit the Wall!

    z-bends and sloppy control surfaces seeem to go hand in hand with me!

    And I have a $20.00 Z-Bender Tool

    How can I stop the slop! in my services?
    I level every thing I tape the control service straight before doing the rods heatshirnk like all the videos have shown me to do and then I still get slop!

    I understand that a little play at the horn can translate to more play on the surface!

    Whats asure fire way to get 100% no play and a perfect fit!

    I have tried z-bends,quick connects,heatshrink rods, wooden horns,plastic horns just looking for what I call is the perfect combo of parts to make my planes even that much cleaner!
     
  2. 7up

    7up Moderator Staff Member

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    Although I use zbends most of the time, I don't think you'll ever get a 100% slop free connectiom. About the best connection would be to use the Du-bro ez-connectors with the set screw on top, on both the servo horn and the control horn and a 2mm cf rod.

    I have several z-benders and I use them to weigh parts down while the glue dries. I use a pair of lineman pliers and needle nose to get the best z-bend.
     
  3. Anonymous

    Anonymous New Member

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    One trick I have used, with great success, is to install the z-bent wire into the control horn, but don't bother to wipe the rod clean (a TINY amount of oil helps here).
    Carefully center the z-bend in the hole.
    Then, apply a small drop of CA glue to the affair, right where the rod goes through the hole. Medium weight works well - then hit it with a shot of accelerator so it sets up.
    Now, rotate the rod in its normal rotational plane (to actuate the control surface) and the glue will let go of the rod but stay firmly attached to your control horn.
    Voila! An almost-zero-slop control connection that will last a long time!

    I learned this from the discus-launch-glider guys. They're also interested in no-slop connections, and their planes are pretty high-performance (and expensive) models.
    http://www.youtube.com/watch?v=LP44_8sR ... re=related
     
  4. rjarois

    rjarois Moderator Staff Member

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    i make my own control horns out of 1/16 ply. i use .047in. dia music wire on my smaller models. i always rough out the hole with a #57 drill ".425 dia." then i use ca glue to harden the wood. then i finish drill the hole with a #56 drill ".046 dia." when i bend the .047 dia. wire, i just do a 90 deg angle. then i will make a small keeper outta real thin .015 plywood fixed with a very small drop of ca with a needle. my control linkages come out as good as the slop in the servo gear-trains. on bigger models, i use the same technique, just with carbon rod and bigger hardware with the dental floss and ca method. randy.
     
  5. rcav8r

    rcav8r Moderator Staff Member

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    I use U bends. IMO, WAY better than Z-Bends. A lot of the slop in a Z bend is from the up and down movement. With U-Bends there is no up down or side to side movement...none. As an added bonus they are super simple to make.

    I actually had a rudder on a Kougar flutter off a long time ago due to a Z bend. The up down movement caused the hole in the servo wheel to enlarge, which caused more slop which made the hole even larger which.... well you get the idea.

    With the U-bend, I have some planes that have hundreds of flights with zero slop...well at the U-bend anyway.

    I can post a pic if you want. I just need to dig one up.
     
  6. sdparkflyers

    sdparkflyers New Member

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    Thanks everyone for the input!
    The Best part about a Forum like this is that everyone wants to help offer what works!
    keep the post coming!
     
  7. Chuck

    Chuck New Member

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    I guess I am out of tune here. I have been building and flying RC planes since early 1970. I was told then, and believe now, that "Z" bends are the best way to hook up control surfaces. I know multiple prize-winning pattern pilots who have won tough competition with planes using "Z" bends and I have never heard them complain about slop in these connections. Now I don't fly exceptionally well, or even well at all, but I guarantee you my skill level would never suffer from a tiny bit of movement in a "Z" bend connection. I have had more problems with flexing in the control rod than in the connection or with the control horn getting slight movement glued into foam. I select a wire size that is a tight fit for the whole in the control horn and literally force the wire into the hole. No slop here. In order to put EZ connectors on tight enough to not wobble a bit, they are almost too tight to rotate.
    Very interesting stuff here guys, makes me wonder what I should be paying more attention to.

    Chuck
    ...somewhere in Indiana...
     
  8. rcav8r

    rcav8r Moderator Staff Member

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    Z-bends are so 1970s :D
    I too would never notice the tiny bit of slop, nor do I notice the improved latency in a 2.4G system ;), but here is why I think the U-Bend is better.
    WAY easier to make. To make a Z-bend with as little slop as possible the height of the vertical part has to be just right. Too short and you get binding, too tall and here is where the slop comes in to play. May not seem a lot to start off with, but over time with with use, it can get rather sloppy as I found out first hand. I think this is the most often over looked part of making a Z-bend; the height of the vertical part.

    Not only that, but the angle has to be just right with a Z-bend. With a U-bend you can have an angle far greater than you would ever use, and it will still be free with no binding, or slop. This angle comes in handy a lot of times.

    Yes you still need to get the hole size in the arm or horn just right with either. I have a set of numbered drill bits that I use for this. A cheap set is more than ample for our use.

    I'll snap some pics tonight to hopefully explain better. I know the guys at the field who try them love them. My one flying buddy has special Z-bend pliers that lets you control the height of the vertical part, (it's not the die type that you simply squeeze to make the Z) and he still uses U-bends.
     
  9. kyyu

    kyyu Active Member

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    I'm confused about this U-bend, so will be interested in the the explanation later. I know what a U shape is, but don't really see the difference between a Z.

    Here's my opinion of links. I a really stickler for finish details, like the play. I seriously don't understand why one would use a Z-bend at all. You drill the hole in the control horn perfectly and there is not way to put the z-bend through that hole without seriously deforming the hole. Like trying to turn a big sofa, that has no way of fitting, through you front door. In, my gas days I've always used cleaves. Even the cheap plastic ones that come with lots of balsa kits, worked great. Now these are bigger planes, like 3-4 lbs. I've not really done a full setup of foamy, yet. But I assume it about the same. The one and only foamy, I have flown was bought used, with the links already done. It just used a 90 deg L-bend with something CA on the other side to lock it in place. I used EZ connectors at the servo end, like I have always done. Except the micro ones, this time. L-bends seems the better way, to me. And I seen it secured with a second wire acting as a spring to keep the connector on. Here is an diagram of wire keeper version for the L-bend: http://www.rcgroups.com/forums/showpost ... ostcount=7 Same idea as these, dubro plastic keepers. I already bought a set of these to try on the next foamy: http://www.hobbypeople.net/gallery/871049.asp
    Here is a picture of one in use: http://www.airfieldmodels.com/informati ... -bends.htm

    -Kwok
     
  10. Crash

    Crash Moderator Staff Member

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    I am one of those guys that generally uses whatever is available to him. That means sometimes using 1/16" ply for my control horns on one plane, then I may scrounge up some Dubro Micro Control Horns for the next. Sometimes, I even use those sample credit cards that seem to find their way to my mailbox each week. :D

    As for pushrods - I like to use 0.047" music wire (like Randy uses) in general applications, but in my really lightweight projects I'll use 1mm CF.

    Now, for hooking those pushrods up...

    Almost all of my electric planes utilize the Micro Dubro EZ Connects on the servo horn. These tiny little connectors are a PITA for folks with declining vision and big hands (LOL), but make adjustments really easy. The cool things about these little gadgets is that they will easily accept both the 0.047 wire AND the 1mm CF (just don't crank down on the set screw too tightly on the CF, lest the CF will snap!).

    When hooking up the pushrod to the control surface's horn, for me it's always a Z-Bend. I don't fool around with those Z-Bend pliers. They don't give you any control over the dimensions of the bend, and some of them don't really work at all! Making them MY way will allow for you to make that middle length whatever size you need it to be to eliminate slop in your linkage. I made a vid of a really simple technique that has served me well over the years: http://www.youtube.com/watch?v=TBJHmDuphJc

    When I am using one of the Dubro control horns, I usually find that the hole is too small for my pushrod to pass through and my technique for opening the hole is to take the point of my Xacto and carefully ream the hole (a little on each side) until the wire will pass through it. You want it to go in snugly (no slop) but not so tight that the linkage binds or strains your servo. I use the same technique for when I am using horns that I have made (plastic or ply) and never bother with a drill bit to start the hole - I just use the Xacto. Remember, (like suggested earlier) always use a little Thin CA on the hole of ply horns to strengthen the hole!

    When I am using CF pushrods, I create a Z-bend from 0.047" wire and then cut the piece down so that the whole thing is only an inch to inch-and-a-half in total length. I will then lash that short piece of wire to the end of my CF pushrod with some regular old sewing thread snagged from the wife's sewing drawer. Hit that with some thin CA to wick into the thread and you've got a Z-bend that will stay on that CF FOREVER! LOL

    Anyway, those are my tricks. If the distance on the Z-bends are only as wide as what you need and the holes are only as large as you need to pass the wire through, a slop-free linkage will be the end result.

    Now, of course, I am a total perfectionist. LOL You really need not concern yourself with this kind of slop-free linkage if you are building a 3D/High Alpha/Slow-Flyer type of plane. You'll never really notice the affects that a little "play" will have in flight. However, if you are building something with an airfoil (KF, or "real") that will be flying with some speed, slop-free linkages are a must to keep flutter down. I've seen that phenom blow some really nice planes to pieces! LOL
     
  11. sdparkflyers

    sdparkflyers New Member

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    Crash your the man!

    Just when I thought I knew it all I learned a new Trick thanks partner your the man!
     
  12. Crash

    Crash Moderator Staff Member

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    You're quite welcome! I was fortunate to have great folks share info with me when I needed it, so it's only right to pay it back. :D
     
  13. rcav8r

    rcav8r Moderator Staff Member

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    Hay Crash...Nice video, and great presentation. I tried that method too, but still prefer U-Bends ;)
    OK, here are some pics to hopefully clear up the U-bend mystery...
    Close up pics show a 2-56 rod as it is larger, and easier to see in the pics, but the principles are the same for the smaller wire; only the smaller wire is so easy to bend, a vice is not need. Attached files [​IMG] [​IMG] [​IMG] [​IMG] [​IMG] [​IMG] [​IMG] [​IMG]
     
  14. theothers

    theothers Administrator Staff Member

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    Nice info guyz.
     
  15. Crash

    Crash Moderator Staff Member

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  16. Martin

    Martin New Member

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    I have had the same problems with Z bends. I now use Dubro mini quick links. I attach them with CA onto the CF rod and use music wire with ez connectors at the servo end of the rod which allows for easy adjustment. The hole in the control horn for the quick link can be made the perfect size so there is no slop. Works for me.
     
  17. Tweakie

    Tweakie Member

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    Just for anyone who has not seen this method of making Z bends before :-

    You get an old pair of pliers and drill a hole, the diameter of the wire you use close to the end of one jaw. (I had to anneal this jaw – heating to yellow red then allowing to cool down slowly before I could drill the hole and afterwards heating to cherry red and quenching in oil to harden it up again). Then grind away the end of the jaw to leave the correct dimension of the Z required. (If drilling more than one diameter hole, for different wire sizes, the end grinding of the jaw could be stepped for the different Z dimensions).

    Use is simple – put a 90 degree bend in the wire then insert the short end through the hole, grip, then straighten the wire – perfect Z bend in seconds.

    Tweakie. Attached files [​IMG]
     
  18. 7up

    7up Moderator Staff Member

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    Nice one Tweakie.
     
  19. Crash

    Crash Moderator Staff Member

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    Awesome, Tweakie! There's one I've not seen before. I have an old set of pliers like that I'm gonna drill out so I can give this method a try.
     
  20. Tweakie

    Tweakie Member

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    Take it slow and put plenty of lube on the drill Crash - Pliers are pretty hard material for drilling small holes. Good luck. ;)

    Tweakie.
     
  21. rcav8r

    rcav8r Moderator Staff Member

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    Hay Crash...Did ya try the U-bends yet? You already have the tools ;)

    Here's a link to Harry's site. http://www.harryhigley.com/Tools2.htm
     
  22. jkarnacki

    jkarnacki Member

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    I just use two pairs of needle nose pliers to make the z-bends for the control horn linkage and Dubro EZconnectors at the servo end. To get a perfect size hole on the control horn, heat the end of the wire with a lighter for just a couple seconds, then push the heated end through a plastic control horn and pull out quickly. Like sliding a keycard through a hotel room door - gotta be quick or you get the red light and have to swipe it again. ;)

    - Jeff
     
  23. dz1sfb

    dz1sfb Member

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    Crash,

    Just wanted to second you on the method you use. I use this method exclusively. Never met a Z bender I liked yet. Just not enough control over the width of the Z.

    I would say that 95% of my builds utilize .032" music wire. This has been more than adequate for park flyers in the 40" range. If I have a long stretch of solid wire pushrod I'll up that to .039". Z bend at the servo and an L bend at the control horn with a Dubro #849 (connector). If I am using the credit card stock for control horns, then you can get away with a Z bend at both ends.
     
  24. kram242

    kram242 Administrator Staff Member

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    Heres the one I have from dubro, got it at the Toledo show a few years.
    I really like the way it works. The best part is that you can mark the stopping points you like and get exact bends every time.

    Mark and Trish
     
  25. dz1sfb

    dz1sfb Member

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    Mark and Trish,

    I purchased one of those recently and ended up returning it without even using it. The distance between the bends was just too great. It becomes more critical as your wire size gets smaller. I really thought this was going to be the cats pajamas. The repeatability factor is there, it just does not produce to my specifications. I want to be able to get from 1-2mm between the bends. Just enough room for the horn and no more is optimum.

    As far as being useful for making single bends it falls short there as well. Many times you want a to bend against a radius rather than a sharp corner that is on the die. This is just metalworking common sense. I suppose this is more for pushrods than anything else, but they are stating using it for landing gear as well.

    Dubro makes outstanding products and if possible I buy there hardware exclusively.
     

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