judsterky

My Feedback: (4)

After I drill holes for my control horns I always have problems lining up the holes on both sides of the control surfaces and often unable to mount the plastic backplate. I often have to enlarge the holes too big to get the backplate to line up with the top piece. This problem sounds elementary but it kills me every time.
If anyone has a technique for this it would be well appreciated.

Thanks!

RCKen

My Feedback: (9)

What do you mean by not being able to line up the plastic backplate? If you are drilling straight through the control surface you should be able to attach the backplate with no problems. Is it possible for you to post a picture of your situation?

judsterky

My Feedback: (4)

Basically what I mean is one screw hole lines up but the other one is slightly off maybe a 1/32 off which is enough that the screw will not go into the second screw hole. And I have to drill the hole larger.

lex2bits

My Feedback: (12)

Yeah Jud, I have the same problem. I've made up jigs and alignment tools to try to make the holes parallel with minimal success. There has to be a way that we are overlooking to keep the drilled holes parallel.

Hope someone can enlighten us.

Ray

Flyboy Dave

My Feedback: (21)

We all have the same problem, it just takes practice to get the holes
drilled straight. Sometimes it's a tight squeeze in by the tail surfaces
and makes it harder to drill straight.

One little tip I learned to make it easier to get the second screw in, I
take the screw to the small belt sander and put a nice 45 degree taper
on the end of the threads. This makes it much easier for the screw to
find the hole in the plastic backplate.

FBD.

RCKen

My Feedback: (9)

ok, now I understand. It's like lex2bits said, you aren't drilling your holes straight through the control surface. The best answer is to tell you to use a drill press when you drill your holes in the control surface. If you don't have a drill press you need to make sure you are drilling a perpendicular hole when you drill it. My best advice is to ask around at your flying field/club and see if you can find someone with a drill press. They can make you a guide fairly quickly so you can drill straight.

hookedonrc

One trick that I use and has helped a little is to take a T pin and run it through the balsa so that it goes into the hole on the plate. By doing this, it makes a path for the drill bit to follow. Other than this idea and the drill press, I agree with the others that say "practice." Of course, you can always convert to a single post control horn...but where would the fun be in that?

campbec

Hi,

I can't claim any originality for the following system it was passed on to me by a great scale builder who regretfully is no longer with us, but I still use many of his tips and suggestions.

What works for me is to use a guide. I have some old broken timber engine bearer that I first used the drill press to accurately drill holes through that are the same pattern/dimensions as the control horn and base plate. I do taper the start of the screws to a fine point on the bench grinder first.

I then place the guide over the control surface and use my cordless drill with a bit smaller than the diameter of the screws and the horn and backing plate holes align. Then put a couple of drops of thin CA in the holes and when dry screw on the horns. This method is much quicker than using the drill press for every surface and just as accurate with the guide.

Cheers,

Colin

MinnFlyer

My Feedback: (4)

If I miss, it's not usually by much. I just ise the drill bit like a file and enlarge the hole. The holes themselves do very little in the way of keeping the horn from moving. It's the clamping action of the two plastic plates that does 95% of the holding, so you could make the holes HUGE and the horn would still work.

Bumstead

My Feedback: (2)

Here's a trick that I read somewhere. If you stick to a standard type of control horn, you can
use one as a guide. That is, snip off the threads on two screws so that just a small amount
of thread is protruding from
a spare horn. Position and mark the first hole for the new control horn.
Then use your spare with the two shortened screws to mark the second hole.
Place the screw in the marked hole and press down which will position/mark the second hole.
Then drill accordingly

PlaneFlyer

Hi, I HAD the same problem with drilling the holes. What I do now to much success, is to first line up the control horn, and use a sharp pencil and poke a hole, then use the correct drill bit size and carefully drill STRAIGHT. A right angle cordless drill makes this easier. You can also make a little jig by getting a piece of aluminum or hardwood, aluminum is better, about 1" thick or more. Drill the hole (using a drill press to insure a straight hole). The guide doesn't need to be big, 2" diameter. Then use that as a guide. WHEN YOU DRILL THE HOLE, do it at low speed, NOT IN A HURRY, concentrate on looking at the angle your drilling. With the jig I mentioned above, poke the bit through it and rest it on the hole the pencil made and keep it flat to "plane" you want. Ailerons are usually tapered, so make sure it is flat to the plane you want and NOT flat on the aileron.

Hope I helped,
Joe

Starfighter

My Feedback: (78)

Hi, name's Ken (Starfighter), been building/flying for 43yrs.
Answered this in another post a few weeks ago, but nobody commented on my suggestion (pro/con).
This is VERY EASY to do. HOW? Well, all you have to do is use the base plate of the horn as the screw guide.
Yes, use the base plate of the horn as the guide for the screws.
You do this by placing the horn on the surface at the correct location, and then take a pin and puncture the surface at the screw locations in the base of the horn. THEN, use the 9/16"socket head servo screws available from several sources (as they are self tapping, and #2[same as the control horn screws]) as your drill bit. Use these screws to finish drilling the hole through the surface, while the base of the horn serves as the drill(screw) guide. The horn base plate will keep the screws vertical and the correct angular relationship to the control surface, and the exit holes on the other side will line up correctly for the back plate of the control horn. After I've finished drilling(screwing?) the holes, I apply thin CA to harden everything up.
Try this out, it really works!

AlphaOrion

Hey guys, I was looking at this forum for some help because today I spent about 30 minutes trying to line up holes for the three screw plastic control horn.

So far, these are the techniques I have read about here.

1. Mark hole drill locations
2. Use a pin to push through and create line-up holes for the screws to travel through (I tried this one today, with limited success)
2a. Alternatively, use a drill press
3. Bevel the tip of the screws to a 45 degree point, so that it is easier to line up and enter the plate on the other side.

I was thinking about using the drill press to create the aligned holes on a piece of 1 inch thick x 5 inches long x 2 inches wide wood, then bevel it lengthwise to achieve a desired angle (so that the holes are drilled as perpendicular as possible to the chord line) . Once done, secure the guide with tape to the control surface, and use a regular drill so the holes come out aligned on the other side. The only hard part in this is to properly bevel the wood guide so the set of three holes come out straight through on the other side.

Another alternative would be to make a guide with enough beveling so it supports the control surface on the drill press mount, and use the drill press itself to make the three holes. Again, the hard part is sanding the correct angle onto the support guide...

Any commercial guides available?

Will try it out sometime today, and see how that goes.

UPDATE.
While looking for some more tools, I found these tap and drill guides at Harry Higley's website.
[link=http://www.harryhigley.com/75TapNDrillGuide.htm]http://www.harryhigley.com/75TapNDrillGuide.htm[/link]
On that page, scroll down past the 5 step wing bolt drill process, on the new section without numbered steps, the third image shows an aileron being drilled for a wire insertion. He has installed a piece of scrap wood to align the aileron chord with the surface, and although he is drilling parallel to the surface with his tap guide, you can do the same process for a perpendicular drill using a drill press!

wjcalhoun

For a control surface with parallel sides, straight and 90* is fine; mark and drill, etc.
It does get a little more complex with a control surface that has taper, because then the hole should not be 90* to the surface, but 90* to the centerplane of the moving part.

DustBen

My Feedback: (3)

Exactly correct. "straight" is straight but relative to what? You said it perfectly.

Another tip is that if the control surface is to be tapered by hand, predrill the horn mount holes, then shape the taper in.