cappaj1

My Feedback: (1)

I have three ARFs yet to build, a 49" electric Yak, 35" Reactor Bipe, and 72" Aeroworks Yak. In my past ARFs I've not been happy with the stiffness on the control surfaces, especially the ailerons.

Any tips on getting the control surfaces to move freely and completely from one end to the other? I'm thinking specifically for examples like bending the hinges before installing them, or using pin hinges, or tricks to keep the ca off everything but the hinges, and things along those lines as tips. Thanks in advance.

j.duncker

My Feedback: (2)

Assuming you are using fuzzy mylar hinges. Get a WAX Crayola and draw a line both sides along the hinge line. This reduces the stiffening from cyano.

If you are using Robart or any other type of hinge with a mechanical hinge apply a little hot vaseline and work it into the hinge before fitting it.

Make sure all your hinges are lined up and there is no bowed ar warp that the hinges have to fight against.

Make sure you >< the joint line sufficiently to allow for the movement you want. This can be critical if you move into 3D flying where +- 80 degree deflections get used.

DRY FIT AND CHECK FOR FREE MOVEMENT. Most of my models have fuzzy mylar hinges. I drill through the surface and the hinge apply a lttle thin cyano then a cocktail stick with a little thick cyano on it AFTER I AM HAPPY with the way the surface moves.

ChuckW

With CA hinges it sometimes helps to flex the surface by hand after installation. Maybe 50-100 times?

Also make sure you have the correct gap. Too much gap is obviously bad but a surface too tight up against a TE will have difficulty moving.

da Rock

With CA hinges, it's often a good idea to flex the surface immediately after you put the last drops of CA in.

It appears to squeeze the excess out of the flex line of each hinge so the area that has to flex isn't stiffened from the glue. Since starting to do that there hasn't been a stiff hinge line yet.

da Rock

If you want the best hinging of all, with the least resistance, it's as easy to do as CA hinges.

Use the pinned hinges and install them with hinge glue.

It's almost foolproof and takes about the same amount of time as CA hinges take. The hinge glue won't foul the hinge like epoxy does, doesn't have to be mixed, gives you time to make sure all the hinges are aligned, and the applicator tip doesn't block up like CA tips do. Excess is easily wiped off. Smears or runs don't require Acetone to wipe off. Drips don't glue your pants leg to your leg. [X(]

Those hinges give absolutely the best hinging you can do and the glue makes it worth doing.

reincarnate

I've always fought with epoxy on pinned hinges.

What is this "hinge glue" you speak of, oh giver of knowledge??

mclina

http://www3.towerhobbies.com/cgi-bin...?&I=LXCX67&P=7

Uh-oh. Tower says this is discontinued. I wonder if it's just them? I have been using the same bottle for a few years on Robart hinge points. It is great stuff. I'll have to grab a new bottle next time I am at my LHS, just in case.

Gray Beard

My Feedback: (-1)

I will be going to my LHS this week and I can check on the Pacer glue. I was using all kinds of different glues then went back to Pacer again. It's just one of those things that works. Way less tyrouble then Gorilla Glue or Epoxy but if I have a slot or hole that has wobbled out too much I do use the expanding Gorilla Glue. I don't use CA hinges but I like the Crayola idea, never tried it but it sure sounds like it would work very well.

cappaj1

My Feedback: (1)

I like the idea of the WAX crayola as well and will use it if I use CA hinges in the future, along with bending them at the flex line in advance. I'm not sure how to pin the hinges though, especially using the hinge glue. Is there a thread with pics that shows how this is done properly?

da Rock

Pinned hinges are not CA hinges which are simply sheet plastic with a coating that bonds well with CA.

Pinned hinges are hard plastic hinges that look like everyday door hinges. They are two thin flat rigid pieces that have a hinge pin holding them together.


http://www3.towerhobbies.com/cgi-bin...&I=LXD941&P=ML

They've been around the hobby for many, many years. The original way to use them was to epoxy them in. It could be a nightmare of a job. The hinge glue turned the job into something any idiot could do perfectly.

BTW, hinge glue will NOT work well with CA hinges.

da Rock

Using pinned hinges with hinge glue is really simple.

It helps to slightly enlarge the hinge slots that are the feature of most ARFs. It's easy to do with a piece of sandpaper about the width of the hinge. 150 grit works well simply because it's somewhat thick. Push it in and pull it out. Turn it over and do it again.

Put the spout of the glue bottle to the hinge slot and squeeze a touch into the slot. Put the spout to one hinge half and just "paint" that half, making sure to get glue in the holes. The glue in the holes is the trick. It is carried into the slot and winds up creating glue bridges that lock the hinge into the slot. They're like cross bolts, so to speak. Push one side of the hinge into the slot and wipe away any glue that's squeezed out.

Set all the hinges needed for that one surface into one side, like the stab when you're attaching an elevator half to the horizontal stab. You'll have a row of hinges hanging out of that stab waiting for the elevator half to be matched to them.
Then squeeze glue into all the slots in that elevator half. OK, get glue onto the hinge halves that're hanging out of that stab. Slide the elevator half onto all those hinges. Press the elevator onto the hinges until you have almost no gap between the elevator and stab.
If needed, wipe any excess glue that's been squeezed out with a wet paper towel. Work the elevator to see if all the hinges are aligned and see that it'll deflect the amount recommended by the build instructions.
Set that aside and do something like hinge an aileron to a wing. etc etc Or if you've ever installed hinges with epoxy, you could do something like trying to wipe the HUGE SILLY GRIN off of your face.

da Rock

If you do decide to crayon your hinges, keep in mind that it's good to seal the hinge slots as close to the hingeline as possible and excess crayon will mess that up. Try this: Bend the hinge and run the bend along the crayon. That way only a very thin line of hinge will be protected which means the CA will have a chance to seal the hinge slot right up to the hinge line.

You want the hinge slots glued closed for a couple of reasons. If you simply work the surface immediately after the CA has been applied the hinging will actually be as free as it can be. The working will also insure the slot is CA'd right to the hinge line. Both requirements met. Crayoning or not, flex the surface.

cappaj1

My Feedback: (1)

Isn't there also a pinned hinge method whereby a ca hinge is drilled from the side after it's inserted and tootpicks or small dowels are glued in the holes for strength? If so, how does this method compare for ease of movement? It would seem it's main advantage would be strength.

cappaj1

My Feedback: (1)

Thanks.
Learned something here. I'm now thinking there are three hinge methods I'm aware of; simple ca hinges with a score and crayon over the score to prevent ca from stiffening them; robart hinges, which seem like if they're done right would be the best method for fluidity and ease of motion; and pin hinges, which if done as described seemed to be a less expensive way than Robart hinges but with great results. I'm thinking anyway. Other opinions would be helpful. Thanks.

da Rock

Yeah, pinning hinges is something people do, but CA hinges today shouldn't need it. Matter of fact, any hinge that's put in properly won't pull out. Do the job right and the additional pinning is a waste of time.

Nope, pinning doesn't do a thing for ease of movement.

It actually doesn't have a main advantage. Anyone who can't install hinges securely probably won't do the pinning very well. Truth is, if the hinge isn't securely installed, the pin will rip a nice chunk of trailing edge out when the job fails. Trying to hold a wide hinge in a balsa trailing edge with something as little as a toothpick is a monumental waste of time. Look at any crash and you'll see how those pins work. If you need them, you really ought to try another method of hinging, because they can't make up for bad technique, and you only need them when your technique is bad..............

da Rock

OK, then there is a 4th method.

Stick the hinges in, apply drops of CA, after the last drop flex the surface some.

Thousands of us do that every day.... uhh... ok...... Thousands of us do that every evening after work....... And they're nice and flexible and strong as a bull. (The flexing is the key to not stiffening.)

Robarts ARE awesome. The hinge glue makes them even easier. But the CA hinges that've come in the last 10-20 ARFs I've done have been good quality and there was no good reason for spending more money than already spent.

da Rock

BTW, pinning hinges to "make them hold better" pretty much showed up around the time we got the first pinned hinges.

The first ones didn't have holes in the flats. Some had ripples and such, like texture that was supposed to grip the balsa better or maybe just advertise the maker's name, who knows. And those "unholie" flats often were wiped clean of epoxy as they were inserted into the slit. Not good. So many of us came up with ways to get epoxy into the slit before we slid in the hinge. Not good because it took time and didn't insure anything. Also you often ran out of time while you tried to "wipe" epoxy into a tiny slit with your pin/knife blade/whatever.

And along came pinned hinges with little holes all over the flats. Taa Daaaaa....... You know what those holes did.... If you wiped epoxy on the flat, some got into the holes. When the flat was inserted, the slit didn't wipe away the epoxy in the holes. And the epoxy in the holes would grab the balsa on both sides of the flat and basically rivet the flat in the slit. Magic things those holes. Of course, you couldn't sit back and sigh, knowing the epoxy would rivet the hinges in, because you needed to try and wipe the epoxy that'd been squeezed out by the slits and was all over the hinge's hinge part. You had to try and wipe that stuff AWAY and not into the hinge's hinge. Talk about a pita.

You know, I forgot to mention that I almost always use the CA hinges that come in ARFs BUT that I very often do retrofit here and there, depending. If an aileron horn for example is at one end of the ailreon, the closest hinge slot will get a pinned hinge instead of a CA. You see, the force from the horn will be into an area of the aileron that's not well supported on both sides by hinges. I just trust a pinned hinge to deal with extra load better than a CA.

We often do things like that because we THINK it's worth the effort.

anuthabubba

My Feedback: (102)

The CA type hinges probably help reduce flutter by being a bit stiffer than pivot-pin type hinges as well as being easier to install maintaining a smaller gap. Except maybe for larger (over 10 lbs) models.

Terry in LP

Gray Beard

My Feedback: (-1)

Photos showing the flat Durbro hinge and another brand, a plastic solid hinge used instead of a standard CA type and the hinge pin. Also shown ar the drill guide for the pins and the slot guide for the flat type. Nothing hard, you just hold the guides and drill or cut. I'm showing the hinge slot macine and one of the old hand cutters, an exacto knife works too but it is a longer process. On pins you just drill to size then either bevel or slot for hinge movement. Squish in some glue and push in the pin and wipe off the pacer hinge glue that will flow out. The flat hinge you just cut then drill a small hole for glue flow, squish in the glue and wipe. To pin a hinge you just drill from the bottom of the control surfaces and go just through the hinge, you can feel when you are through. Use thick CA and glue in the tooth pick after you have cut off the tapered point. On planes with large control surfaces pinning is just a bit of added strength. When you lamanate in the hard wood to the balsa it turns into a very strong section. After a crash you will find the balsa wood stull clinging to the tooth pick. When you lamanate hard wood to soft wood you do not come up with a weak spot. If you use the pacer glue and have a nice tight fit I haven't found pinning necessary but you will be hard pressed to find a 40% IMAC plane builder that doesn't pin any flat hinges. It's just added safety and strength. Not a must do but it is done.

cappaj1

My Feedback: (1)

Wow, you guys went above and beyond! Thanks so much. I wish I knew where to get those tools, the centering jigs and the slotter. Can you provide any links? Thanks again.

ro347

My Feedback: (13)

Great presentation of examples.


I have a question...I have an Arf im thinking of completely stripping and reworking this winter. At the moment it has CA hinges. I know that I can cut the hinges and install new ones right next to the old if I decide on CA again..... but I have one side of the elevator which I had to cut in install new ones already. Now If I cut again, im not going to have the area to install new ones. How would I work with this?

cappaj1

My Feedback: (1)

Two silly questions on your great pics, Gray Beard! That's not blood on the board is it? AND, who's Nancy?

cappaj1

My Feedback: (1)

Note to self ( and others ) I found these from researching the photos:

hinge slotter http://www3.towerhobbies.com/cgi-bin...&I=LXK263&P=ML
centering guide http://www3.towerhobbies.com/cgi-bin...?&I=LXDMR8&P=7
robart centering guide http://www3.towerhobbies.com/cgi-bin...&I=LXET65&P=ML
various hinges http://www3.towerhobbies.com/cgi-bin...inge&search=Go

Gray Beard

My Feedback: (-1)

Hinge pins come in several sizes, some very small ones for even the little electric planes. When you buy the drill guide it comes with two bit guides in different sizes. You just buy the one in the size that will work best for you. RO, you may be able to drill right into an old CA hinge, I have gotten away with drilling through the flat Dubro hinges and the glue stick just fine. It drills out the CA soaked wood. Sometimes it works and sometimes it doesn't? You just have to give it a try.
Nancy is a cute little lady from Japan that asked me to make a NO POOP dog for her front yard like I have in mine. Now you are going to want to see a shot of the dog!! When I take photos out in my shop people notice a lot of things like phone numbers writen on my building board, works for me until I sane it down. I have had people spot numbers on my floor by my chargers, I just write the numbers on the floor when I'm doing a cycle. Comes off with Acetone!
Blood?? Nope, I use sheets of card board to get my air brush set the way I want the spray to fan. I was doing the finish work on a scratch built Daddy Rabbit pattern plane from the 60s. I tried to find something in my shop with a dark enough back ground so you guys could see the hinges and that's what I found. Just noticed, you can see the hinge pins I installed in this plane.

cappaj1

My Feedback: (1)

What type hinges do they use on giant scales?