Jeff-RCU

My Feedback: (4)

I'm getting tired of putting in a dowel for a hard point, trying to sand it smooth, and then drilling a hole at the right angle to have the connector over the hing line. Does anybody make a control horn for larger planes where you could just make a saw cut perpendicular to the hing line and glue them in (kind of like you see on some foamies)?

Troy Newman

I use a ply plate mounted flush with the surface. I then attach the MK offset control horns. They attach with 3 tiny #2 size wood screws. The screws come with the horns. They work great and are adjustable for height. Also these horns put the pivot point over the hinge line.

I use the MKD0815 these are the medium aluminum horns. They also make a small horn too. In other situations I have used the MK large aluminum horns and converted the Offset horns to make them the large size.

Works well.

I use these for ailerons, elevator and rudder.

A dremel router bit set to the depth of the plywood plate, I choose about 1/8th inch plates, will remove the balsa tot he proper depth. I then use Pro-Bond polyurethane glue and clamp the surface to a flat table. This keeps the plate flush with the balsa skin. Sand it and fill with model magic around the edges of the ply plate and once covered you can't see the the plates. To install the horns I drill the hole equivalent to a #2-56 drill for tapping. I then run the wood screws in, remove them and use foam safe CA on the holes to stiffen the wood.

Once its covered and ready to install the horn I use some thick CA in the hole and run the screw in. Have not had one vibrate out, no plates come loose, and the setup is clean and simple. Also it saves me lots of time in setting up the bolt thru control horns. Another advantage is the horn load is now spread over a wide area. Another great thing is the tops of the control surfaces are clean and have nothing sticking out.

Not the cheapest solution but I think the time saved and the finished result is worth the extra $25 you spend on the model. Others will disagree but to me its worth ever dime I spend on it.

8178

My Feedback: (17)

This works well for me and it’s easy and quick to do. There is a hardwood dowel in the control surface with a hardened socket head bolt with the head cut off. Quick and clean! I usually put the dowel in before finishing but in this example the dowel was put in after the finish work. The eye of the connecter lines up with the center line of hinge almost by default.

Jeff-RCU

My Feedback: (4)

8178 - yeah, that's the way I usually do it. it's not hard, but I always have a hard time sanding smoooth because of the difference in hardness between the dowel and the balsa wood. Plus, it's just about the cheapest way to do it.

Troy - Your way does look slightly quicker and easier, a little more money.

I'm still thinking that a a thin sheet of fiberglass or carbon fiber could be cut into shape and then a single saw cut is all you need.

Thanks to both of you guys for replying.

grotto2

My Feedback: (2)

Jeff-
Sam Turner showed me how to do this a long time ago. First, use furniture dowels. They have a knurl that is easier to adhere to than the pushrod type dowel material you find at the hobby shop. You can chuck the dowel up in your drill and put in a really straight, centered hole with a little effort. Use a piece of brass tubing modified with some teeth to cut the hole for the dowel. I find that they’re a little softer for that touch-up sanding, too

Troy-
Boy, do I like ball-bearing horn pivots!
Unfortunately, I’ve been disappointed in the horn stanchions being produced and marketed as high-quality, high-ticket items. They leave a lot to be desired. You state that the MKs you’re using put the pivot point over the hinge line. They do not. You, the builder put the pivot point over what you *think* is the hinge line and *then* hope that you drill the holes in the right place. So there’s at least two places where accuracy can be compromised.
Even as an experienced builder, I feel Jeff’s frustration. I went through this when setting up the pull-pull on my Smaragd and trying to get good equal tensioning with slightly misaligned holes. Perhaps you read my article at http://www.mindspring.com/%7Erellis2/rcpattrn/ppull.htm .
What’s sorely needed from the manufacturers is a nice horn stanchion that is adjustable in two axes, height for throw magnitude and fore/aft for equilibrium.
Maybe if you don’t use P-P, it doesn’t matter as much ‘cause you can ATV it out, but such a horn would make a lot of people like Jeff and me very happy and more willing to cough up the six to nine bucks for it. Maybe you can stick a bug in Central’s ear for us.
-Ron Ellis

Troy Newman

Ron,

agreed the horns don't place themselves properly to get the pivot over the hinge line. I place them in the right location to get the pivot over the hinge line.

Yes it is possible to be off small amounts and I can say that I'm usually off a little here or a little there. After all we are talking about wood, foam, plastic and aluminum. The builder must put the connection point in the right spot.

These horns allow you to put the pivot in the right spot as they offset the connection point forward of where they attach to the surface. Just like anything some people can break an anvil with a rubber hammer. I know a couple of them. And I think I've done it once or twice myself. I never meant to say the horns were self aligning. They are not! But neither is any other horn on the market. Perhaps an adjustable one would be cool. I'll see what I can come up with. I know a good machinist guy and we can design something and see if it works. Who knows it may make life easier yet again. There is always a better mouse trap out there.

There are other ways to do it too. The bolt can got in at an angle, or there are lots an lots of other options. This is the one I choose. Never failed, never broken, survived mid-airs and crashes. They are light and strong, the plastic base is easy to install. Since I have never had a problem with one I chalk it up to the fact that I save time installing them. The other thing is if you need to move them they are easy to move even after the surface is covered. Just fill the old #2 holes and drill new ones the plywood plate is bigger than the base of the horn.

Eric.Henderson

Hi Troy,
Here's a couple of pic's of some hybrid horns that I made from Chip's bb horns and the MK versions. I have not found a better clevices part yet. this one does not either have slop in the bearing inner ring fit or bind on the bearing.

Eric.

flyintexan

My Feedback: (1)

What if the normal MK horn was replaced with straight all-thread that had a (near) 90° bend facing forward (over the hinge line). The all-thread could go through a threaded base with a jam nut. Any excess thread would be down inside the flying surface. The hieght of the horn could be changed one full rotation at a time, and the distance to the hinge line could changed with one rotation of the MK plastic piece. Of course the all-thread would have to be bent carefully with heat to retain strength...

here is a quick image of the idea...no threads shown on the all-thread to speed up the modeling...

Any comments???

Eric.Henderson

Great image - how did you do that?

MHester

My Feedback: (1)

Great idea, but I see one flaw. Fix it and it's perfect. See how the adjustable horn piece points down? Make it straight on, like a clevis itself, THEN you can turn it and adjust it and it won't bind under deflection! But I would consider making it aluminum like the H9 stuff so it wouldn't flex with the clevis point.

-Mike

ElectRick

My Feedback: (2)

That looks interesting. I think that it might possibly have issues with hitting or binding on the clevis at the forward end of the stroke, however. A fitting that has the part of the horn with the clevis hole coming straight off the end of the bent segment would solve that, but I can't think of an existing nylon fitting that would screw on, in that configuration.

Such a simple problem, so elusive a solution. Where are the R/C hardware designers when you need them?

Rick

flyintexan

My Feedback: (1)

This is not to scale, but what if the plastic end (heavy duty) was setup like this??... or as Mike H. said (see second image), which is much better, thanks Mike.

patternrules

My Feedback: (6)

The big problem with benting all-threat is fatiquing at the back side and the end result is breakage. Have seen this in my business.
Steve Maxwell

grotto2

My Feedback: (2)

You guys are great! Such fertile open minds!!!
I was imagining a flat base with a rack-and-pinion slider. The slider would have a vertical threaded post that you could screw on an MK control fitting.
At any rate, the finer the thread, the better.
-Ron

flyintexan

My Feedback: (1)

in reply to Patternrules:

DOH!

your right, it would not be a feasible bend.

MTK

Jeff, you might consider doing what I have done. Go to the local ACE hardware and buy 1/4" OD aluminum threaded bushings. These come in a various lengths, so buy a slightly oversized length. Look for 6-32 threaded stock items. Epoxy these into the control surface and voila, instant hard point that has a built in thread. There's no need to cut these flush to the surface. You can make a very neat installation into the surface with care.

As Steve stated, don't use all-thread material for horns. But screws will work great. Following Ron's note, to bend them easily such that the horn is right over the hinge line, use another bushing on the screw, and you get a nice handle to work with. It's very simple and effective.

MattK

Bob Pastorello

My Feedback: (198)

I am ALWAYS in awe of the creativity of us......think we could solve the National Debt??

Anyway - for fear of offending the pattern gods, and the exclusive, nearly-unobtanium parts that components must be made of....several of you are following my Excelleron thread, and I had assymmetric offsets on the pull-pull horns. Threaded rod sunken into triangle pads screwed onto the control surface a la MK (sort of).
Solution to get to the hinge line (barring the use of either Sullivan # 566, or Dubro 867, which both have long plastic parts for the clevis), I came up with these. Yes, those are Dubro regular old steering arms with the collars discarded, then they are drilled and threaded onto the 3mm rod. Little 3mm nut, drop of Loctite. Hold control at neutral, drill hole where desired.

It is definitely Un-trick, and Un-pattern-ish, but golly .... it sure solved the problem and actually increased the load bearing area of the threaded control horn part....

Enjoy, and think about it after the laughter subsides.

MHester

My Feedback: (1)

That's it!!!

Now to get a set made up and do some testing Any takers?

-Mike

Jeff-RCU

My Feedback: (4)

Matt,
Do you mount them directly into the foam/balsa, or do you insert hardwood first?
Jeff

flyintexan

My Feedback: (1)

I think I'll go with bob's idea....although, you still have to drill a hole at some point...after that hole is drilled, no more adjustment toward or away from the hinge line.

MTK

Jeff, directly into the foam/balsa. It develops into an extremely strong arrangement. A 1/4" brass tube makes a great drill.

MattK