ARF or RTF Discuss ARF (Almost Ready to Fly) radio control airplanes here.

RC Guys 33% Pitts S1 ARF

Reply

Old 12-11-2013, 04:16 PM
  #51  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Ace (Robert),
Agreed. More of an irritation than a problem. In fact, I dropped into my local special-hardware store today and picked up four new 5mm X 45mm bolts. They're grade 12.5 - that's higher than the originals, which I believe the guy said were grade 8.8. I should be all set with those, with no cutting required. 50mm is about two inches, so 45mm should be short enough to miss the forward sensor array. (I know, it's just the ignition pickup, but I had to slip some Star Trek lingo in there, like, "We need to reconfigure the bolts just ahead of the forward sensor array!"

~ Jim ~
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-11-2013, 04:28 PM
  #52  
acerc
 
acerc's Avatar
 
Join Date: Sep 2006
Location: The Sunshine state, when it's not raining!
Posts: 8,131
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

A trekkie huh!!
acerc is offline  
Reply With Quote
Old 12-11-2013, 04:30 PM
  #53  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Wow, Ron, so you dug right in and didn't let it get you down! You're a better man than me, tackling it so quickly. Here's how it would go with me; I'd plan it for about two weeks, and then stew on that plan for another week or two, and then change it some. Then, maybe a week or two later, I'd finally say the hell with the whole plan, go buy a bunch of covering, cut it open, and see what I find. By my way of thinking, you just saved yourself five or six weeks of Jim-style agonizing.

Well, when you go to Fastenal, just get the 5mm X 45mm bolts in the same thread, and you should be good (I'll verify that later this evening).


I've built one of these from a kit, and let me tell you, this is like heaven to me. I STILL remember how tough that build was,and that was thirty years ago! It was a Pilot kit with the same wingspan as this one.

Though, I reckon these lite-ply setups are considerably easier than the old Pilot massive box-O-sticks-N-balsa version. I doubt anything you find is going to create too much extra work.

Did you add extra thickness to the firewall to reinforce it?

Do you have a color scheme in mind?

~ Jim ~

Last edited by PacificNWSkyPilot; 12-11-2013 at 04:36 PM.
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-11-2013, 04:37 PM
  #54  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by acerc View Post
A trekkie huh!!
Lol - Yeah, when you're a writer, imaginative stuff like that just captures you. It doesn't get much better than Star Trek, although the Matrix was right up there with it.

~ Jim ~
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-11-2013, 05:19 PM
  #55  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Okay, here are a few photos. Look at how nice the cooling holes fit this engine! Sweet. That's the only word for it. I had this lovely 3.5" Tru-Turn red anodized P-51 style spinner just looking for a home, and as you can see, it's smokin' hot on the nose of this Pitts! I haven't totally completed the cowl/spinner washer fit at the front, but it looks pretty nice even as it is. The lines on the cowl line up pretty well with the lines on the fuse. It's important to remember that the cowl flares up and swells away from the fuse as it goes up, so the lines don't visually match anyway.

~ Jim ~
Attached Thumbnails Click image for larger version

Name:	Pitts Build Cooling hole 1.jpg
Views:	584
Size:	119.1 KB
ID:	1946868   Click image for larger version

Name:	Pitts Build Cooling hole 2.jpg
Views:	572
Size:	111.0 KB
ID:	1946869   Click image for larger version

Name:	Pitts Build Cowl & Spinner 1.jpg
Views:	605
Size:	155.5 KB
ID:	1946870   Click image for larger version

Name:	Pitts Build Cowl & Spinner 2.jpg
Views:	619
Size:	159.6 KB
ID:	1946871  
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-11-2013, 05:21 PM
  #56  
acerc
 
acerc's Avatar
 
Join Date: Sep 2006
Location: The Sunshine state, when it's not raining!
Posts: 8,131
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

WOW! That look's a whole lot better than I thought. Have you considered giving it a clear coat for a little gloss and to protect the vinyl?
acerc is offline  
Reply With Quote
Old 12-11-2013, 05:50 PM
  #57  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Sorry, to protect what vinyl? The cowl is fiberglass.
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-11-2013, 05:56 PM
  #58  
acerc
 
acerc's Avatar
 
Join Date: Sep 2006
Location: The Sunshine state, when it's not raining!
Posts: 8,131
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

All that black and white trim, is it vinyl or covering? But irregardless a clear coat will protect the edges.
acerc is offline  
Reply With Quote
Old 12-11-2013, 06:09 PM
  #59  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Goodness knows what the trim on the fuse is made of. My guess is that it's Chinakote. No, I'm not going to spray anything over it. I want to see how the regular covering and trim hold up to my everyday use. I honestly don't know how it will do. It seems tough enough, but on the tabs in front of the fuse, the edges lift a bit easily for my liking. On the obvious spots, I'll probably use a little Black Baron film adhesive, just like I would on any ARF. The cowl appears to be all painted.

Yes, she's one pretty bird. Now you can see why I'm keeping the paint just the way it is, at least for now. One item I found somewhat lacking was the wheel pants. They're yellow and white, with no black trim at all, and without any trim, the white is almost invisible. I'll probably bash a little on that, at least enough to add some 3M trim tape to give it some contrast. I think the white was a poor choice there. Black stripes would have done nicely, and in fact would have matched the rest of the paint job.

The good thing about a gas engine is that very little oil gets on the covering.

Unless you run smoke. And granted, this is the type of plane that could handle a smoke system.

~ Jim ~

Last edited by PacificNWSkyPilot; 12-11-2013 at 06:17 PM.
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-11-2013, 06:20 PM
  #60  
acerc
 
acerc's Avatar
 
Join Date: Sep 2006
Location: The Sunshine state, when it's not raining!
Posts: 8,131
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Thanks Jim, I was just curious. Believe it or not I seriously considered the RCGUYS Pitts for quite some time. Even a few months into the scratch build of mine I was still thinking of it. And apparently I still think of it, I'm here watching others assemble it. Mine is the same physical size, but, it weigh's 22lbs and is powered by a CRRC 55cc twin. Mine will float in a landing or given some power scream like a rocket, so yours should be even more of a hoot. How about some video when you get her up?
acerc is offline  
Reply With Quote
Old 12-11-2013, 06:21 PM
  #61  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Ron,

You mentioned one or two bad spots when you were going over the fuselage, looking for inadequate gluing. Any specific places you can point out?

~ Jim ~
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-11-2013, 07:30 PM
  #62  
RonMcCormick
My Feedback: (4)
 
RonMcCormick's Avatar
 
Join Date: Feb 2008
Location: Joliet, IL
Posts: 329
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by TexasSkyPilot View Post
Ron,

You mentioned one or two bad spots when you were going over the fuselage, looking for inadequate gluing. Any specific places you can point out?

~ Jim ~
Yes every single glue joint, took a few bottles of CA the high stress areas around the engine box will get high strength epoxy. Oh the corner stock that pop out has something on it like one part of two part epoxy. These are pictures of not aligned joints of engine box, hope you can see them with flash. I will finish reinforcing the box tomorrow.
Attached Thumbnails Click image for larger version

Name:	IMAG0318.jpg
Views:	208
Size:	155.8 KB
ID:	1946906   Click image for larger version

Name:	IMAG0320.jpg
Views:	264
Size:	179.4 KB
ID:	1946907  
RonMcCormick is offline  
Reply With Quote
Old 12-11-2013, 07:32 PM
  #63  
Jim Branaum
My Feedback: (3)
 
Join Date: Oct 2002
Location: Fair Oaks Ranch, TX
Posts: 2,615
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I am a big fan of engine cooling.

While your engine jugs do line up well, there are still several easier places for the air to go than through the fins. *I* would go to Michaels and buy a sheet of black 1/4 foam board, and cut it to fit the cowl just in front of your engine, and make slots right where the jugs are and a hole for the crankshaft assembly. That forces ALL the incoming air past the fins and assures you have lots more exit that entry and a cool engine. But I am known for doing things differently. It is too cold this month to find out if that is needed or not, but just wait until July or August!


A cheap way to subscribe to the thread....
Jim Branaum is offline  
Reply With Quote
Old 12-11-2013, 08:33 PM
  #64  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Ron, those look like some pretty standard glue gaps I often find on ARFs. Nothing serious, and they don't look too hard to get to. I'll let you know if I find anything that's serious or important, but you know me, I mostly just like to whine about small, unimportant stuff.


Hi Jim! Sorry I haven't attended any meetings for a long time, I've just been crazy with the two book releases this year.

There are still several holes that need to be cut out in this cowl. With the extra-large exit hole at the bottom, combined with the sizable gaps at the top on both sides where the cowl flares away from the fuse, there's wonderful airflow on this cowl. I figure at least three to one, exit versus entry. The best I've had in any models I've seen for quite a while. I was just commenting on how fortunate I am that the air holes are where they are. Usually I do have to make some mods to insure good air flow, just like you do. We're alike in that way. I'd rather be sure a plane is perfect (or as close as I can get it) than rush it to the field. Of course, it makes sense that the air holes would be there, since the stock engine has horizontal cylinders in the full-scale. Custom deluxe, for my application!

Give me a call if you want to come over and check this one out. I'm hoping to make some headway on it by next week.

~ Jim ~
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-12-2013, 06:55 AM
  #65  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Here are more photos.


The first two photos show the engine mounted to the nose. You can see the down-thrust in this photo. If you go to the fourth photo, you can see the way I used the washers to build the down-thrust into the installation. Now, if I need to reduce or increase the down-thrust after testing the bird, I can simply remove or add washers as needed, or shift them around. On the first photo, you can see where the firewall and engine box meet, and I think I'll epoxy some more hardwood tri-stock there for good measure. In photos 3 and 4, you can see how I used some marine-grade ply to reinforce the firewall, before I added the interior tri-stock. You can see the five layers of the higher-quality ply. This isn't the final installation, so I haven't cut the bolts flush with the nuts yet. You can also see how I used some of my old Saito prop washers from my odds-and-ends drawer to back up the bolt on the inside of the firewall. Top quality washers, they won't bend or give out, and the price was right!

The firewall bracing was done by using 30-minute epoxy, and clamping the reinforcement ply piece the firewall, to properly laminate the two pieces together.

~ Jim ~
Attached Thumbnails Click image for larger version

Name:	Pitts Build Engine mounted view.jpg
Views:	638
Size:	177.8 KB
ID:	1947020   Click image for larger version

Name:	Pitts Build Engine mounted view 2.jpg
Views:	638
Size:	192.3 KB
ID:	1947021   Click image for larger version

Name:	Pitts Build Firewall reinforcement.jpg
Views:	648
Size:	198.6 KB
ID:	1947022   Click image for larger version

Name:	Pitts Build simple downthrust.jpg
Views:	649
Size:	180.9 KB
ID:	1947023  

Last edited by PacificNWSkyPilot; 12-12-2013 at 06:57 AM.
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-16-2013, 06:02 AM
  #66  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Okay, I managed to get a little work done over the weekend, and I've got a handful of photos to share with you.


The first photo is the top view of the joined lower wing. You can see in the closer look in photo 2 that I have some X's on tape. This is a little trick I taught myself years back. How many times have we gotten a wing brace all sanded so that it fits perfectly, only to have it give you trouble on final assembly because we put the wrong end into the wrong side? So, on top of my braces, I use a sharpie to mark an X on one side, and I put tape with X's on that side. I used to put O's on the other side, but I'm fond of overkill. Match the X's and life gets easier when you're juggling wing halves and braces and epoxy. You can also see that I pulled strings through each wing half and taped the knotted ends out of the way. Those strings will help get your servo wires through the wing. Once I got both halves pressed tightly together, I grabbed an old sock or small piece of clean rag, and soaked it in Denatured Alcohol. After wiping the excess epoxy off, I used the alcohol to clean the area, and then I wiped it dry, and used tape to secure it for a nice, pretty joint. Ironically, this is mostly for my OCD on this wing, as there is a belly pan going over the bottom joint, and the top joint ends up inside the plane.

Use the same principle on the top wing, though, and you'll have a nice assembly when you finish. On my top wing (both wings, actually), before doing anything else, I went ahead and fit the Interplaner strut mount brackets into the wings first. Looks easy. It's not. The holes were too tight and had bits of glue, so I had a considerable amount of carving with my X-Acto knife and sanding with little home-made tools I made using popsicle sticks (epoxy stir-sticks) and sandpaper. I'm pleased to say, though, that the end result is a rock-solid mount bracket. When you assemble the top wing, remember to put the Cabane Strut mount bracket piece in between the wing halves, and to carve away the extra covering so there's plenty of surface to glue together. I also used some rough sandpaper to scuff up the mating surfaces, as I found them to be almost shiny, and I want my epoxy to have something rough to soak into and grab onto. This looks like a nice, easy assembly, and from a mechanical perspective, it really is simple. Once you factor in two wing halves, holes for the braces, the braces, and both sides of the Cabane bracket that sandwiches in between, you realize that when you begin assembly on this wing, you're going to be busier than a one-armed paper-hanger. I recommend taking two or three dry-runs, pretending that you have (a ton of) epoxy mixed, and running through the routine of spreading it onto all those surfaces, and getting some into the holes, and then assembling it, pressing it together, cleaning off the epoxy that squeezes out, cleaning off the area, and taping it securely. You'll be amazed at how much you have to do in the short time you have with the curing epoxy. I recommend AT LEAST 30-minute epoxy be used, because when you mix this big of a pot of epoxy up, the curing time shortens as the pot grows warmer. 45 minute epoxy would be ideal. I kept three extra sheets of wax paper off to the side, just in case, and 20 half-sheets of paper towels for wiping goo. I used ALL the wax-paper sheets, and only had three half-sheets of paper towels left! But as you can see, the end result was a nice, clean, pretty assembly.
I normally do all my pin-hinges before assembling joined surfaces, but this time I decided to wait on that until the wings are joined. I hope these photos are helpful.

~ Jim ~
Attached Thumbnails Click image for larger version

Name:	Low wing top side strings.jpg
Views:	570
Size:	172.4 KB
ID:	1947932   Click image for larger version

Name:	Pitts Build low wing upper joint view.jpg
Views:	545
Size:	125.6 KB
ID:	1947933   Click image for larger version

Name:	Pitts Build low wing joint.jpg
Views:	531
Size:	149.9 KB
ID:	1947934   Click image for larger version

Name:	Pitts Build I-Strut mount.jpg
Views:	564
Size:	100.0 KB
ID:	1947935   Click image for larger version

Name:	Pitts Build top wing.jpg
Views:	534
Size:	144.5 KB
ID:	1947936   Click image for larger version

Name:	Pitts Build top wing brackets.jpg
Views:	533
Size:	142.8 KB
ID:	1947937   Click image for larger version

Name:	Pitts Build top wing Cabane bracket.jpg
Views:	526
Size:	90.7 KB
ID:	1947938   Click image for larger version

Name:	Pitts Build top wing joint.jpg
Views:	532
Size:	166.7 KB
ID:	1947939  


Last edited by PacificNWSkyPilot; 12-16-2013 at 06:06 AM.
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-16-2013, 07:01 AM
  #67  
Jim Branaum
My Feedback: (3)
 
Join Date: Oct 2002
Location: Fair Oaks Ranch, TX
Posts: 2,615
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Hmm...

I have a way to solve the correct strut problem but your X's and O's are much simpler than my method, so I will steal yours.

These days I use Robart hinges and Gorilla Glue for my control surfaces. After normal putting the hinges in and making sure the travel is correct and free, I install them on one side at a time. A drop of oil on the hinge, a spritz of water in the hole, a shot of glue, set the hinge and tape it in place and repeat the process the second day after cleaning any excess that has grown out of the holes. A long time ago I lost a 30% bird to a hinge that was epoxied in and the glue joint failed under load.

Part of the problem is as you have noticed, much of the wood surface is too slick for the epoxy to get a good grab on and the other part of the potential problem is that (discovered by autopsy) many ARF's don't give much wood for the glue to grab on. Gorilla Glue grows into a ball that keeps the hinge inside even if it becomes adrift.
Jim Branaum is offline  
Reply With Quote
Old 12-16-2013, 07:27 AM
  #68  
acerc
 
acerc's Avatar
 
Join Date: Sep 2006
Location: The Sunshine state, when it's not raining!
Posts: 8,131
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I once had the same issue as Jim but went a different route. Now when making the hole I drill it two sizes smaller and thread it with a tap bit, and the hinge block is always hardwood. Many ways to skin a cat, just have to find what works for you.
acerc is offline  
Reply With Quote
Old 12-16-2013, 09:25 AM
  #69  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Robert Pin hinges, absolutely. I found these stock pin hinges hinges to be pretty solid, and I tested them. I honestly think they'd hold together just fine. And then I tossed them and used Robarts anyway. That's just me. I find what works, and stay with it. I took a photo of what I found in an aileron pocket, and I'll post it later. Two sets of holes drilled next to each other. NOT cool.

I've used Gorilla glue a number of times for other things, but I haven't used it for pin hinge installation yet. I know a number of the guys are giving it high marks for this.

Robert, I used to drill out the area, install a dowel rod into the hole, and then drill that for the pin hinge. The only thing is, I've never lost a Robart pin hinge, period, so I just make sure I rough up the plastic on the hinge (after giving the hinges a bath in Denatured alcohol and a brisk rub dry with an absorbent cloth, to remove the mold release agent), and make sure the epoxy is well-mixed ( And NEVER 5-minute epoxy) and well-inside the hole and on the pin.

Jim, I also use a drop of oil in the hinge section, carefully dried by paper towel bits before going ahead with glue and install.

One wing has all its hinges installed, and she's taped and waiting. I have to go out for some errands, and I hope to finish the second wing before today is through. One nice thing about this kit is that the Robart regular pins and the pins in this kit are nearly identical in size. I just had to carve out near the surface a bit for the bigger hinge section on the Robart, and they fit like a glove.

~ Jim ~
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-17-2013, 08:38 AM
  #70  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I had a few PMs from some intermediate-level builders, asking me where my videos went on installing the Robart Pin Hinges. Because of the branding going on with my book publishing, and some other stuff that has very little to do with RC, I had to pull my RC videos down. So, I've put together a thread within my thread to provide much of the same information. I'll start out with the basics. The first two photos show what I found when I went to hinge my ailerons. Definitely Monday morning work, when the worker was still hung over from the weekend.
Nothing I can't work with, but it's a little disappointing.

Next, We open our Robart Pin Hinges, and pour the bunch of them into a clean jar, like a Peanut Butter (shown) or Jelly jar. Pin hinges are built using molds, and where there are molds, there is mold release agent used. Mold release agent keeps things from sticking to the parts, the initial thing, of course, being the mold itself. However, if we follow the pin hinge through its life, we find it NEEDS to stick to something. It'll need to stick to the glue/epoxy/etc. and the holes in the surfaces and wings, and so forth. So we want that mold release GONE. We do this by washing the hinges in Denatured Alcohol, a cleaning agent/solvent which we modelers typically keep around to help us soak off errant epoxy spots, daubs, and fingerprints. Pour some into the jar with the hinges, and cover the jar, and shake it vigorously for a few seconds. That should wash off any mold release from the hinges. The reason I use a Peanut Butter jar is because I can fit my hand into it afterward, and scoop out the hinges, which I then deposit onto a couple of folded paper towels, and pat them and rub them until they are dry. LEAVE THEM OUT on the towels for an hour or two, so the alcohol in the hinge sections can finish drying. I leave a small fan running over them. Your hinges are now crystal-clean, and you should store them in something that lets you know they're ready for use. I use a baggie, as shown here. Close up your Peanut Butter jar, and place it on the shelf. You can't pour the alcohol back into its can, but you can use it for other things, like washing the gooey epoxy from your hands after gluing something.

Attached Thumbnails Click image for larger version

Name:	Shoddy work 1.jpg
Views:	508
Size:	96.6 KB
ID:	1948289   Click image for larger version

Name:	Shoddy work 2.jpg
Views:	548
Size:	110.3 KB
ID:	1948290   Click image for larger version

Name:	Washing Pin Hinges.jpg
Views:	496
Size:	215.4 KB
ID:	1948292   Click image for larger version

Name:	Drying washed pin hinges.jpg
Views:	500
Size:	227.7 KB
ID:	1948293   Click image for larger version

Name:	Washed Pin Hinges.jpg
Views:	500
Size:	227.9 KB
ID:	1948294  
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-17-2013, 09:01 AM
  #71  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Okay, you now have some nice, clean hinges, and you're ready to install some hinges! The first thing you want to do is increase the surface area by roughing up the brabed area of the pins. I use rough sandpaper. The digs and scuffs you create actually increase the surface area for gluing, and THAT increases the holding power of your glue or epoxy. I install mine with epoxy.


Your hinges are now nicely roughed up, and you want to start gluing! BUT WAIT! Pin hinges have exposed hinge surfaces, and glue can (and often does) work its way into the hinge, locking it. Well, we HAD to remove the mold release, so there's nothing to stop the glue from getting into the hinges!
Never fear. A simple drop of oil will soak into the hinge section, and that will usually keep the glue or epoxy from getting in there and locking it up. But we want to keep the barbed section CLEAN, or all that work could be for nothing. Here's how I do it:
I use a super-fine oiler, which you'll recognize as a hypodermic syringe. Pretty much anything that will give you a very-small droplet of oil will do the job.

I grab the ends of the pin hinge, and work it back and forth, until I'm sure the oil has spread throughout the hinge plates. Now, we have the excess oil to deal with.
I cut a paper towel into small squares, and then fold them up and wrap them around the hinge in a single wrap with my fingers. DO NOT MOVE IT AROUND. Simply close it, and then remove it, and throw the bit of towel away. Grab another few towel squares, and repeat this until the towel comes away without oil. Grab a few more squares.
Pinching it at the hinges, flex the hinge back and forth, and repeat until the oil isn't staining the paper towel bits any more. Using this process, we've kept the oil from getting onto the rest of the hinge, but we've insured that there's enough oil inside the hinge to prevent the epoxy from taking over the inside of the hinge. Even if a little seeps into the hinge, it can't hold onto it because of the oil, and will pop loose upon flexing the hinge. This hinge is now completely ready for use.
Attached Thumbnails Click image for larger version

Name:	Scuff up hinges.jpg
Views:	515
Size:	237.2 KB
ID:	1948299   Click image for larger version

Name:	Oiling pin hinge.jpg
Views:	486
Size:	165.4 KB
ID:	1948300   Click image for larger version

Name:	working oil into hinge.jpg
Views:	514
Size:	124.3 KB
ID:	1948301   Click image for larger version

Name:	remove excess oil from hinge.jpg
Views:	475
Size:	166.2 KB
ID:	1948302   Click image for larger version

Name:	Pinch oil from hinge.jpg
Views:	474
Size:	150.4 KB
ID:	1948303  
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-17-2013, 10:39 AM
  #72  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Mixing epoxy is an art. So many modelers lose models to poorly mixed epoxy, and it doesn't need to happen.

Your hobby store has little plastic medicine cups they sell in stacks for mixing epoxy, and they also sell mixing sticks in packs (popsicle sticks). For hinge work, I use 30-minute epoxy, or 45-minute if the job promises to be difficult. Try to squeeze out portions as close to the same as you can. Sometime you can use the marking on the cups to help with that. Start mixing it, and pay close attention to getting into the center, and scraping the sides to make sure unmixed epoxy doesn't remain in deposits. Remember to scrape off your stick on the edge, and then mix that stuff back into the rest. Get into the corners/bottom/middle of the cup. You'll get a feel for doing it right. Well-mixed epoxy has amazing holding power. Poorly mixed epoxy is inviting disaster.
Here, you can see I've built a small, special application stick for doing pin-hinge holes and pin hinges. I tear up two or three paper towels into smaller pieces, and I keep a waste can right at my feet. You're going to be getting epoxy on things, and some of it you'll want to wipe off again. Now, on this Pitts, I have FOUR ailerons to deal with, so I decided to take some of the load off myself by installing the hinges into the aileron surfaces first. Sorry to make you jump ahead to the next photo, but it shows best just how I apply my masking tape to this. You can see the seam running right down the center of the aileron pocket. NOTICE how the tape butts up against the other piece, but never overlaps. In this fashion, I protect the work area from the epoxy, and I also insure that I can remove the tape afterward from the respective side I'm working from. On the aileron itself, the hinge-edge is in the shape of a "V", so the edge of the tape is run along the point, from each side. It provides the same protection, and the same ease of removal. Apply the tape, make sure it's tight against the opposing piece, and THEN cut out around the hinge hole with your X-Acto knife.
I take my special small applicator, and use it to tuck some epoxy into the holes where the hinges will live. I also use it to apply some epoxy onto one side of the pin hinge, to make sure there are no missed sections. I always place the "head" of the hinge pin facing the outboard ( my OCD at play), and the neatest thing about ailerons is that the aforementioned "V" is the perfect place to position the center of the hinge pin head. That will assure it pivots properly once dry.
Look at the photo above, and you'll see the hinges flexed upward. From this view, with the edge going left and right from you, the hinges should be flexed upward, and they SHOULD NOT LEAN LEFT OR RIGHT. They should be pointing straight upward from this perspective. Make sure of that, and make sure the pin head centers on the "V", and they should work perfectly once you install the surface. Of course, this is the final position you want to place them in. Make sure all the excess epoxy is carefully wiped away from the hinge point and off the tape before positioning them. Once they're properly positioned, I usually stand the piece up against something so the epoxy stays in the hinge hole.
Once the ailerons are dry, then you want to prepare the wing for installation of the aileron. Using the small applicator, make sure epoxy is thoroughly worked into the hole. Wipe the surrounding area clean. Apply epoxy to the protruding hinges on the aileron, making sure you don't miss any spots (Make sure you miss the hinge areas, of course!). I usually grab an empty epoxy cup and run the inside of it in a circle, around each hinge, to remove excess globs of glue. The globs stick to the empty cup, and leave only a light layer on the hinge.

Normally, this is where you simply press the parts together. However, we need to remember that we're working on a Pitts here. The top wing sweeps back, and the aileron pockets are built such that the aileron will not slide straight into the pocket. Easily solved. Refer to the photo above, showing the hinges flexed. Position your hinges just like that, and with the surface flexed downward or upward, as the position of the hinges require, you should be able to slide the surface into the pocket without too much resistance. Once they're in, grab some bits of paper towel, and clean thoroughly around the edges of each hinge, and you'll have to go back and forth a few times. Once you have the area clean enough to suit you, use some long strips of masking tape to tape the aileron tightly to the wing. I use one in the center, followed by one at each end.

This may not be how others install their Robart pin hinges. It's how I install mine,and I've never lost a surface using the Robarts, not ever. Once it's dry, remove the tape and flex it back and forth. If it's only been an hour, you may need to come back and flex it again a few times. Sometimes, it'll "Bust" loose as you flex it, and it'll work freely.

If you feel the epoxy got into your hinge and your flexing is not having the desired effect, take a drop of Denatured Alcohol (just one drop), and drip it into the hinge section of each hinge on that surface. Start to work it back and forth immediately, and continue for about thirty seconds. That should free it up, and it'll get better from there. Also, at this point, another tiny drop of oil will not affect the fastened-in pins of the hinge, so you can add that after the alcohol begins to dissipate.

If you're REALLY still bound up after the alcohol, then you can go one step further ( and this is extreme, so don't do it unless it's really not moving well.). You can place one drop of Acetone onto the hinge(s), and flex it the same way, followed up by a drop of oil.

I hope this is of some help to you guys.
Attached Thumbnails Click image for larger version

Name:	epoxy into hinge holes.jpg
Views:	487
Size:	141.5 KB
ID:	1948339   Click image for larger version

Name:	Install hinges in ailerons.jpg
Views:	482
Size:	221.2 KB
ID:	1948355   Click image for larger version

Name:	Tape aileron down tightly.jpg
Views:	495
Size:	166.4 KB
ID:	1950569  

Last edited by PacificNWSkyPilot; 12-23-2013 at 10:39 AM.
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-17-2013, 03:56 PM
  #73  
Jim Branaum
My Feedback: (3)
 
Join Date: Oct 2002
Location: Fair Oaks Ranch, TX
Posts: 2,615
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Jim,

Two comments, questions, or observations - whatever you want to call them.

Where are you finding 45 minute epoxy these days? I thought that stuff was pulled from the market because of inability to meet some esoteric EPA regulations. Or at least that is what I was TOLD at some LHS a few years ago...

Second, I either missed it or noticed that you did not identify your "special small applicator". When using epoxy (and actually some Titebond but that is a very special case and only works for a while - more later) I have used a Monojet 412 to put it deep in the hinge hole. http://www.pethealthmarket.com/Produ...FcVQ7AoddhwABQ

The last comment has to do with cleaning the hinge pin after all the glue is in place. That step is the same for epoxy or Gorilla glue except for the time line. Messing around with Gorilla Glue after it has started the curing process is generally not a superb idea. Oh, there is the newer stuff that cures in an hour but I am not sure what the expansion ratio is.

Monojet 412 trick with Titebond.

The only thing I don't like about Titebond is there is no convenient way to use a little bit. Every time I get some out, I wind up wiping a large portion off on a paper towel which gets expensive in paper and glue. However, I have found that you can bend some 1/16 " music wire into a 'plug' that can be used to close off the glue supply of Titebond transferred to a Monojet 412. That allows you to put just the amount of glue exactly where you want it and very significantly reduces waste. The warnings are, don't count on that for a long term place to keep the glue but more in the order of a couple of weeks or so. When the music wire begins to rust, hurry and put the remainder of the glue back in it original bottle. If you weren't paying attention and the rust got bad, dispose of that load of glue and count of possibly having to replace that 'injector'.

Oh, I KNEW I was forgetting something. Rather than mix up a big batch of epoxy, I try to estimate the total I will be using and put it on a small sheet of aluminum foil on top of this:

http://www.ebay.com/itm/5kg-5000g-1g...item2ebfb70de3

and mix by weight. The foil is to keep the scale clean, but since it has an auto tare function, you could put you cup on it and still mix by weight. Less guess work.

Last edited by Jim Branaum; 12-17-2013 at 03:59 PM.
Jim Branaum is offline  
Reply With Quote
Old 12-18-2013, 04:28 AM
  #74  
PacificNWSkyPilot
Thread Starter
My Feedback: (19)
 
PacificNWSkyPilot's Avatar
 
Join Date: Feb 2004
Location: Tacoma, WA
Posts: 3,984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Hi Jim,
My Special Small Applicator isn't patented, so anybody with a popsicle stick, an X-Acto knife, and a little sandpaper can have their very own, without threat of patent infringement on mine. Take a close look at what I'm using in the photos. It's a whittled-down popsicle stick.

I just checked my 45-minute epoxy bottles, and they say Great Planes on them. I must have bought some from Tower a few months back when I bought parts for rebuilding my crunched Giant Super Sportster. Some years back, I owned a glue company, but I haven't had my ear to the ground lately. I haven't heard anything about problems getting the 45-minute epoxy. In fact, I'm pretty sure the reason I ordered it from Tower was because the stuff in the LHS was clearly not fresh, and I'm a stickler for using fresh adhesives.

Because I have such great results using epoxy, I don't use Titebond for Pin hinges, but I have no reason to think it wouldn't do a great job. Monoject 412 - yep, I've got a whole box of them (I work on medical stuff), and they're a great tool for glue delivery.

Nice scale! I have one, but I don't use it for mixing epoxy. I try to mix the epoxy in equal parts, but even with my OCD, I don't get compulsive about exactly equal amounts. As long as the hardener and epoxy are fairly equal and mixed well, it'll catalyze properly.

~ Jim ~
PacificNWSkyPilot is offline  
Reply With Quote
Old 12-18-2013, 07:31 AM
  #75  
Jim Branaum
My Feedback: (3)
 
Join Date: Oct 2002
Location: Fair Oaks Ranch, TX
Posts: 2,615
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I apologize for not being clear about the Titebond. I do not use it on hinges, but for building. I strongly recommend AGAINST its use for pin hinges!

Your way of measuring epoxy is what I used for years until someone else taught me about measuring exactly and demonstrated the benefits in the final product, so I am sold. Try it, you might like it. Use the gram function...

Since I no longer use CA very much, I keep it in the freezer. I always use a felt tip to put the month and year on the bottle when I get it. CA seems to keep for several years in the freezer if you thaw it before opening, but after 5 years you will probably not like to use it. I was told by a kit manufacturer that Titebond shelf life is less than a year as there is some kind of mold that grows in the bottle. I have found that epoxies tend to do nasty things in their second or third year in my shop.

In short, you are absolutely right, fresh adhesives ALWAYS work better.
Jim Branaum is offline  
Reply With Quote

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service