sparow89

On the LE of an rudder for example it has to be like an acute angle (<) where it meets the fin to be able to move. How do you create this edge well.

blvdbuzzard

I have made a few jigs to hole the piece while I use a Stanley #5 to plan the angle. I have used a 6"X48" belt sander for a quick way of putting an angle on it. You can always use a sanding block while holding the pice on the edge of your bench.


Dru.

Flypaper 2

My Little David razor plane does it for me. Draw a line down the centre and do it freehand.

moneymaker

I don't know if you have the equipment, but I use a reinforced rottary tool which has a 45 degrees angle. I reinforce the aileron and move it along the drill bit.

britbrat

I usually clamp mine in my B&D Workmate & use a razor plane & finish by hand-filing. Sometimes I hand-file the whole thing.

Tall Paul

I mark a line along the center of the piece, where the point is to be.
Then with a long (18") sanding block, holding the piece flat at the edge of the work bench, sand one 1/2 of the angle.
Flip the piece over, and sand the other half.

delman

I have used triangle stock to form the leading edge of the rudder and elevator

lownslo

Triangle stock is a great idea!! I would suggest that you don't use CA to glue it to the control surface IF you are going to use CA hinges. Use yellow glue for example. The CA will wick into the future hinging area. When applying the CA for the hinges later...... it will not wick in as good because the grain is partially sealed from the first application.
... lownslo

Rcpilot

My Feedback: (78)

I use the triangle stock method all the time.

Let's say your LE of the elevator is 3/8" thick. So- you need to buy 3/8" tri-stock and glue it on.

The problem is that 3/8" tri-stock is actually 3/8" on the 2 sides that will serve as your bevel on the hinge-line. The part your going to glue to the LE of the elevator is more like 1/2" wide---so, it'll hang over a bit.

Just center it up--with an even amount of overlap on the top and bottom of the LE of the elevator. Look down the hinge line to make sure it's straight. You can use T-pins to hold it in place on a nice straight line while the glue dries. Make sure it's straight as it goes down the hinge-line or you'll have all kinds of problems later.

I rarely use CA hinges--so I glue my Tri-stock with CA. I just eyeball it and tack it in place about every 2 or 3 inches. Constantly looking down the hinge-line to assure that I'm glueing it on straight.

Once it's all tacked in place--go back and run a quick bead of thin CA down both sides.

Allow to dry for about a minute and then get out the sanding block or the electric palm sander with 60 grit paper on it. About 30 seconods on a side will knock off the overhang and leave you with a perfectly beveled hingline on the LE of any control surface.

If you don't want the really sharp point of the tri-stock--just take a VERY long sanding block and use BIG and LONG strokes to avoid warping it and making it all lumpy.

You can knock the sharp point off a bit and flatten it out to about 1/16" or 1/8" wide.

I do this with Robart hingepoints or the Great plains hinges that look like the robarts--only white.

When you knock the sharp point off the tri-stock it's easier to get the CL established and then use your 1/8" drill bit to drill the holes.

It's REALLY hard to dril an 1/8" hole in a piece of sharply angled tri-stock---if you want to get it straight.

Another trick is to leave the sharp edge on the tri-stock and then just cut little flat "knotches" in the tri-stock where your hingepoints will be. Then you got a flat spot to get the drill bit started, but it maintains the sharp point of the tri-stock everywhere else.

This allows you to sort of "countersink" the center--bulky part of the hingpoint and still get the hingeline gaps closed up real nice--to avoid any flutter problems later.

lownslo

I really like Robart hinge points. Below is an attached photo of what RCPilet was explaining about a notch. You can get the gap very tight......IF you are careful and have nice straight and level sanding lines as he explained. Before you glue it .... move the surface BOTH directions to make SURE there is no binding. If there is an "un-even" area it may open your hinge line a little bit. By careful examination you can usually find the "high spot". In final gluing just make sure of desired deflection by moving surface slowly to full deflection. It may?? open the gap a VERY small amount if you have not found the high spot. .....lownslo

Rcpilot

My Feedback: (78)

A picture is worth a thousand words--isn't it?

Thats exactly how I install my Robarts or GP Hingepoints.


As lownslo explained:

You need to flex the control surface to check for binding before you start glueing. Sometimes you have to tweak one of the holes a bit and open it up a little more to allow the hingepoint to move and works its' way into a better position to prevent binding.

Once your satisfied with the hinge movement and the gaps at the hingeline--then apply your glue.

Don't use CA on Robarts or any similar hingepoints. It won't hold--and you'll have problems.

I use rubbing alcohol and a few Q-tips to clean the glueing surfaces of all the hinges first. They are made in a mold at the factory and sometimes--not all the "release agent" gets washed off the hinges. They can sometimes arrive a bit oily. Glue won't stick to oil or mold release agents.

After cleaning the hingepoints, I take some 60grit or 80grit sand paper and scuff the surfaces to be glued. It helps to have a little bit rough surface for the glue to stick onto.

You'll need to put something oily or greasy on the hingepoints at the knuckle--where it flexes. If you don't--you run the risk of getting glue into the flexible joint--and then you've got a worthless hinge--and fouled up the WHOLE job. Because if one hinge gets glued and stuck--then NONE of them are going to flex.

You can fix it by digging at the knuckle with a hobby knife--but it's a real pain in the rear-end. Easier to just put something on the knuckles first.

I use KY Jelly--and apply it with a Q-tip into the hinge knuckle. It doesn't take much--just enough to keep any epoxy from sticking to the "fingers" and the pin inside the joint.

I use 30-minute epoxy and mix microballoons into it untill the mixture is about as thick as toothpaste.

Of course, you need a good solid amount of wood to glue your hingepoints into. The TE stock of the wing--typically isn't enough. It's rarely over 3/8" thick. And the hingepoints have long barbed ends on them. You really need at least 1/2" of balsa to get a good hold on them. Those barbs are there for a reason.

So--when I'm building a kit. I install little blocks of balsa behind my TE--and build it up a little bit. Usually another piece of 3/8" stock is good enough--but you can use 1/2" stock too. The little blocks needn't be huge or be as wide as the entire rib spacing. That would add a lot of unnecessary weight.

I try and stratigically place the CL of my hinges about 1/4" away from a rib. Then you can take a little 1" or 3/4" long piece of 1/2" stock and glue it right to the rib and the TE stock. That will give you some extra bond strength--by glueing it to the rib. You don't have to put a huge hunk of wood in there to accomplish the goal. You just want something in there, to grab onto as many of those little barbs on the hingepoint as possible.

lownslo

RCPilet.........YOU DA MAN!!! Your's is a great detailed explanation of what to do besides the notch. (all the details are right on!!!
.... lownslo
PS. Once on an ARF.... I replaced the CA hinges with the Robart points. I cut covering from the bottom in the proposed hinge point areas and added the small balsa block you described. This was on a GP Spacewalker and the TE wood was only 1/4 to 3/8" thick!!