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Inst. Of Control Horns

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Inst. Of Control Horns

Old 01-24-2007, 05:57 PM
  #1  
Camcanfly
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Default Inst. Of Control Horns

Hey there I was wondering how you install your Control Horns on your Surface's. Can’t seem to ever get them right, there has to be a solution. Is there a Control Horn hole drill thingy? What Techniques do you know?
Old 01-24-2007, 06:00 PM
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mmattockx
 
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Default RE: Inst. Of Control Horns

Use a drill press. It will increase the quality and precision of your work so much you will wonder how you ever got by without it.


Mark
Old 01-24-2007, 06:09 PM
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Nitrodan73
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Default RE: Inst. Of Control Horns

I was just searching the web looking for a solution for this problem as well. I do have a drill press but I was thinking it would be easier to use a machine screw and washers and drill one hole per side instead of 3 holes per side to make it easier. Maybe reinforce the balsa underneath with some CA in the drilled hole. As long as you have a washer with a good surface area, I can't see why it won't work. I saw that sullivan sells something like this idea and it looks like I can get the same thing from Home depot. Any other thoughts?
Old 01-24-2007, 06:23 PM
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Camcanfly
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Default RE: Inst. Of Control Horns

What Im thinking is if you were to use a drill press how to you secure what you are working on if GIANT or an ARF, etc, and how would you get it straight shot I guess you would say so that it comes out other end at same place with a beveled** area.
Old 01-24-2007, 08:34 PM
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dbacque
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Default RE: Inst. Of Control Horns

I block up the trailing edge of the control surface on the drill press table so that the centerline of the surface is horizontal. Holes are then nicely square to the center line, not the surface.

Dave
Old 01-24-2007, 09:40 PM
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Charlie P.
 
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Default RE: Inst. Of Control Horns

Yep. Costs $2.99 at Tower. http://www2.towerhobbies.com/cgi-bin...?&I=LXL468&P=7



Set the horn where you want it (holes lined up on the hinge line). Stick a "T" pin through any hole. Place the reenforcement pad where the pin comes out in the mating hole on the pad. Drill the other hole(s) out using the finger drill by drilling halfway through from each side. Remove the pin and drill the final hole. All done.

This little drill is handy for all kinds of small holes.

I've really come to like the control horns that use #6 or #8 bolts with one hole. Strong and simple.
Old 01-24-2007, 11:23 PM
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Nitrodan73
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Default RE: Inst. Of Control Horns

I know what you mean now Dbaque. I used my drill press to drill the holes for the aileron control horn but didn't block up the trailing edge. Now I have 3 holes on the opposite side that are grouped closer together so the backplate won't fit. I had to drill extra sized holes to get it to work. I reinforced the balsa with CA so the balsa won't get weak. I knew I was doing something wrong![:@] I'll try blocking up the trailing edge on the other side.
Old 01-24-2007, 11:32 PM
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Camcanfly
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Default RE: Inst. Of Control Horns

Awsome thanks so much. Any more tips for others and myself are welcome aswell. Thanks Much Guys and Gals!
Old 01-25-2007, 07:23 AM
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Default RE: Inst. Of Control Horns

If I had a drill press I'd use it. However, they are fairly expensive and take up room I don't have. I'm a tool and die maker, so I know all about how good a tool a drill press is. However, I use my Black & Decker rechargible drill motor. Align the horn where it needs to be, drill one hole making sure you are holding the drill motor perpendicular to the surface being drilled (as best as you can) and install a screw to hold the horn in position. Drill the second hole through the horn and install a second screw. Finish drilling all the holes needed and remove the screws and horn. Using one size larger then the drill bit just used, ream the holes out, again attempting to be perpendicular to the surface as possible. Remove the covering from under where the horn and backing plate are located. Using a common pin (T-pin) make many piercings in the balsa wood in the area where the covering was removed on both sides. With thin CA, soak these areas (this hardens the wood). Allow to completely dry. Insall the horn and then screws one at a time. If alignment is off on a screw or screws, us a small file to move the screw hole in the direction it needs to go to allow the screw to enter the backing plate.

This is a process, I know! You need patience (gaining this what building models is for). A drill press would make things easier! However, until you have one, the above works just fine. I may get stuck on one horn which just doesn't seem to want to line up. However, within a half hour, I generally get through this process for the pesky ones. Normally, in less then 2 hours all the horns are mounted on my planes.
Old 01-25-2007, 10:41 AM
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da Rock
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Default RE: Inst. Of Control Horns

Drill presses are nice for surfaces with parallel sides, but are a mess when the surface tapers.

Charlie P.'s post #6 describes about the best method if you plan to use the plate. It's simple and quick and almost foolproof. And it requires no special, expensive tools. So it's not just easy and foolproof, but cheap. What more could you ask.

There is another way to consider. But it's a way to use just the horn without anything on the other side of the wing. Some people call it "potting". It's very useful when you have fairly wide surfaces. It's also useful when the surfaces have a large taper. (When they taper a lot, getting the horn and backing plate alingned is always a mess.)

Trim the covering where the horn is going to go.
If there is sufficient depth, cut out some of the underlying wood.
A small chisel works good for this. And you can angle the cut to better align the horn with the hingeline.
Place the horn and mark the holes.
If the surface is balsa, then use a small drill in your fingers to create some holes in the balsa.
(a couple of holes running out from the sides are worthwhile in balsa)
Use epoxy. Make sure it gets into those holes.
Press the horn down into the epoxy. Make sure some squishes up out of the holes in the horn.
If the surface is hardwood, you can use woodscrews through the horn's holes.
Wipe the excess off.

When the epoxy sets, the epoxy that went down into the holes in the balsa have turned that balsa into "hardwood". It's also been absorbed a bit to strengthen the area around. The epoxy that has extruded from the horn's holes now has created a continuous hard connection from above the horn's foot down into the balsa. Try and pull that horn off. Don't try too hard, because you'll destroy a fairly large section of the elevator/rudder/whatever.

I also use toothpicks when doing this. When I've placed the horn into the epoxy, I push toothpicks into the horn's bolt holes and down into the balsa. After the epoxy has cured, I trim the toothpicks flush with the horn.

You wind up with a horn that is basically an extension of the surface. And it's as strong as that area of the surface is. It's actually stronger by far, but any horn attachment is only as strong as the balsa around it. And this has widened that area but it's still an area surrounded by balsa.
Old 01-25-2007, 10:48 AM
  #11  
da Rock
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Default RE: Inst. Of Control Horns

But you don't have anything showing on the other side of the surface from the horn.

And btw, the normal attachment of horns using the bolts and plate very often actually weakens the balsa surface. When you tighten the bolts, the foot of the horn and the boltplate tend to crush the balsa between them. And the crushing is exactly where the balsa is stressed when the horn tries to push the surface. It's obviously not a bad problem, because we've been using that same horn design since forever. But the potting actually sidesteps the problem. Actually, it improves on the strength of the connection, not just sidesteps weakening.
Old 01-25-2007, 11:09 AM
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2slow2matter
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Default RE: Inst. Of Control Horns

The absolute worst part of building, IMO. I hate it. I always have to go to confession after installing these things. Did i mention that I hate it?
A drill press seems a bit over the edge IMO when we are talking about (usually) 1/2 or so stock BALSA. I use a finger drill. I just use a 1/16 inch bit that has the quick grip end on it. Works OK. Best to get one in (not too tight, though) and then drill about 1/2 way through from the top, and then go to the bottom and drill 1/2 way up. Usually the bit will find the other hole and follow it right up through the top plate. Once you get two in, you are set usually. Good luck!!!
Old 01-25-2007, 05:58 PM
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Default RE: Inst. Of Control Horns

The clamping and crushing of the balsa by the horn and back plate is the reason I punch pin holes in the area where the horn & back plate mount, and saturate with thin CA. The method I described is how I do airplanes of normal size: up to .60 2 stroke, 1.20 4 stroke. There are many way's to skin a cat! I am always willing to try new approaches and have come up with stronger methods on bigger planes, where the stresses are greater
Old 01-26-2007, 07:51 AM
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woodbutcher
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Default RE: Inst. Of Control Horns

Put a crease in a small piece of paper . Slip this between the elevator and stab, with the crease at the hinge line. Put the horn on top of the paper. Mark the holes for the horn. This can be with a pencil or pin through the paper and into the balsa. I like to use a drill bit the size of the hole to get it centered. Remove paper and fold at the crease. Push a pin through the marked side and both layers of paper.

Reinstall the paper and mark the holes on the other side. I like to then use a pin first, working from both sides until I get them coming out in the right location. Then using a small hand bit enlargeing the holes until they're right.

Yeah, this is the operation I hate also.
Old 01-26-2007, 09:17 AM
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MinnFlyer
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Default RE: Inst. Of Control Horns

I just grind the end of a pushrod scrap to a "Pyramid" shape and drill through the balsa with it.

And the extra length also helps you to keep the holes at the same angle
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