|Jan 28, 2013, 04:58 PM|
Nice to get this thread moved to the correct location. I've responded to Concreteman's PM...hopefully he can help.
I've buttoned up most of my other planes and this one is on the bench...so my focus won't be split...too much...I still gotta fly ya know.
|Jan 28, 2013, 08:09 PM|
I have been reading as much as possiable ,I'm sure once I get things/ parts in my hands it should clear things up a bit..
Looking forward to hearing what NOT to do..
|Feb 01, 2013, 12:57 PM|
My Precision Build
Don and Ken,
I just got finished putting together my brand new Precision. I too did not have this one pre-constructed from the factory (although they do a very good job).
Just like everyone, I laid out all of the pieces and scratched my head a lot as to how to proceed to build it out. Except for the color scheme, and the use of 6125's for the flaps instead of the minis, I have the exact set...
I did take several pics of the RDS install in the Precision that I just completed this last week. I'm going to include them here for steps that I took.
One thing I thought was odd, is that they left the servo wires that are going out to the servos without a connector on them, so I had just three bare wires coming out of each servo bay.
So, the first thing I did was put a female connector onto those wires in each bay. It requires a JR wiring kit and a nice crimper, and I was able to get past that part pretty easily, as I had already done some of that before. Although it is kinda scary doing your own connector making, because any mistakes you make could be costly...
The only difference between my setup and yours is that I wanted to go with the MKS 6125 for the flaps, and not the MKS 6125mini. The frames they provided were for four minis. So I proceeded to cut off the back support of the frames for the 6125's, because the only real difference is the length (and of course the torque
I went ahead and removed the back portion of the frames for the minis too, because with this system, it is best to slide the servo into place on the spline of the coupler, and with the minis, I could still support the back of the servo with the supplied wooden mounts if needed. Ultimately (and I know this sounds crazy), I ended up putting no support on the back of the servo. With the bearing mount, the solid coupling, and the two front screws, there was no way that this servo was going to move up and down in the back, and with the bigger servos, it ended up mostly being behind the wing skin anyways...
To be continued..
|Feb 01, 2013, 01:45 PM|
Nicely done Tim....I'm going to be going through everything I've done so far and taking new pictures. The GoPro doesn't seem to handle up-close pics very well, so I'll be using my iPhone, for ease of use...and the quality isn't so bad.
Looks like you're right where I am so far. I'm heading up to Bakersfield to visit my brother so I can't really do much for this thread until I get back, but then I'll be ready to move forward.
You're only down in Carlsbad...Perhaps I can drive down and check out the install in person or we can meet up or you could drive up and assist?
Anyways, I'll be updating the photos soon.
|Feb 01, 2013, 02:14 PM|
Precision build (continued...)
Ok, so now we start to get to the part where you have to fiddle with these things for a long time before you are comfortable whipping out the glue...
First off, protection for your wing is imperative. You don't want to mess up that beautiful paint job by accidentally dropping anything on it like epoxy or anything...
I find that the blue painters tape works really great for helping keep the whole area nice and clean. I also use paper towels taped on just to add extra protection.
But the blue tape is also really great to use to pencil on all of your measurements and such. Cause you need to know where the pocket is, and the only real way to do that is to tape up both side and draw lines that show you where the pocket is at the hinge line on the servo opening side.
Just like yours, mine did not come with the openings for the RDS rod to make it to the pocket, so you have to drill and cut your own. This is a little tricky. You have to bend back the aileron or flap far enough so the you can drill through the carbon bulkhead. You don't need a whole lot of pressure, because it is really no that thick, but you want to make sure you don't hit the wiper. You are also somewhat guessing where the hole will be. Its going to end up more like a slot really anyways, because you need to be able to get the RDS rod in and out even after the frame is glued down. Since you are coming in at an angle, the true location of where the rod will be going is more towards the servo bay side of the pocket, and its back about 8mm. You want to try and approximate the wiper in the center of the pocket. Whip out your straight edge, and make all sorts of lines to help you out...
Once you have the slot (and I do recommend making a slot that will probably end up being about as wide as the pocket but moved over towards the servo bay 5mm or so), clean it up with a small file, because the carbon tends to not drill very cleanly, so you have to file it and massage it to get a nice clean slot. The slot doesn't have to go the full height of the bulkhead. You should be able to leave a couple of mm on both sides.
Ok, so I started with the ailerons, because they are easier in general, and there is actually more room to deal with things because I was using the mini.
Lets talk about the RDS rods. They fit extremely nicely into the couplers, with NO wiggle room. If you'll notice, even the air is a little difficult to push out when you insert the end into the coupler. I'm not sire why they did this, because what I found was that there was not an easy way to glue them in. After taking my measurements, I determined that if the rods were pushed all the way into the coupler that there should be enough length for the ailerons. This is good, because I would not have wanted to find out how to glue them in for a particular length.
So, to take care of the air tight problem, I used my dremmel to grind a bevel on the rod. You don't need to worry about the orientation of it, just that it extends all the way up to past the edge of the coupler. This will allow the air (and some of the glue) to escape when you push the rod down into it so that you get it pressed all the way down.
I used JB Weld for this. Clean your rod surface, give it a little bit of sandpaper to roughen up the surface just a bit and make sure your bevel will allow the air and glue to escape. I used a toothpick to mix up some JB Weld, and put some inside the coupler, and then gave a light coat of it on the rod too. I then pushed it on and wiped it clean from the extra that came out and left it overnight to cure.
Now, the next part is that you need to get your electronics working to help test it out. My wiring harness actually came uninstalled in the fuse, so I could hook it up to the wing that I was working on, attache the leads to a receiver, plug the battery in, bind it to the transmitter and plug the servo into the bay that I was working on. If you can't use the wiring harness, going straight to the servo is ok too. Key here is to start off with a fresh plane program in your transmitter and zero EVERYTHING. All the servo sub trims, the trim tabs, the camber settings, etc...all to zero. Get it working so that your servo goes back and forth.
Before you take the next step, you should push the coupler onto the servo and remove it a few times. It has a steel spring that keeps it snug on the coupler, and its a little too snug to easily take it on and off. You want to put it on and wiggle it a little bit to loosen it up, or you'll find it extremely difficult to get it on once in the pocket.
Now, take your servo frame and make sure you already have the bearing mount pressed into it. Be careful when you do this because the top of the bearing mount is thin and can get crushed easily. You should be able to press it in place so that its flush with the bottom of the frame. You don't need to glue it there, as its press fit pretty well, and you will be gluing it down with the frame soon enough. Take the frame and put it in the servo bay. Get comfortable on which orientation you should use to get it in and out, cause when you go to glue it down, you want to slide it in nice and easy without dragging it all over the place. Put it in place roughly at the angle that you think will extend the rod to the pocket. Take your freshly cured from last night RDS coupler + rod and insert it through the bearing mount and push it out through the hole in the bulkhead and into the pocket. Make sure you are using the one for the aileron, because they are bent at different angles. Now make sure the bearing is pressed into the bearing mount and then push it forward into the pocket. Put your servo in the frame and push it forward to couple.
Now you've basically got everything in place, but its not glued. So, using your fingers as pressure, simply hold down the servo and frame, and then use your transmitter to go back and forth. You will definitely feel the servo and frame wanting to move. Let it move and keep going back and forth until you've got it in a place where it seems to move the aileron effortlessly, and doesn't want to push itself around. I found that the angle of the aileron servo is not going to be nearly as important as that of the flap, so find the angle and go with it. I get WAY more travel than I need, so the angle doesn't really matter. Just as long as it is moving smoothly and the rod end is somewhere close to the middle of the pocket.
Now, use a pencil and mark where the frame is. Outline it, make marks on the tape where it overlaps the skin. Do whatever you want to help you know where that position is, and how to get back to it.
Edited : Tom suggested this idea that originally comes from Target about clear overlays...very nice :
to be continued...
|Feb 01, 2013, 02:25 PM|
I did a Baudis RDS build of a Cyril last year and here is what I did. I pretty much did everything outlined in this and other threads. I did do one additional thing that I have not seen mentioned. When the frame was just glued in with the servo in place and wiper shaft on and in the pocket, I would gently move the control surface through its range of motion. In doing so, I could feel the servo slide around a bit as it found it's position of least resistance. I would keep an eye on where it ended up relative to my original marks and they would never move much, but I could clearly feel when it reached the place it needed to be.
Oops, Tim just said this.
|Feb 01, 2013, 02:40 PM|
More build continuation...
Ok, so you've got things all marked up, and gave it your test, and you've found the sweet spot.
Now lets make sure that you can mount the servo onto the frame. Put the servo in place, and drill small holes for the retaining screws. Also take this opportunity to drill a few more holes in the wooden frame around the frame. This will allow some of the glue or epoxy to come up through the frame and have something to grab on to. I think I use a 1/16th bit to do these.
Test out the mounting of the servos by going ahead and screwing them down. And now take them out. Get some saran wrap, and wrap up your servo with a couple of layers. Now screw the servo back on the frame, so its in place. You want to definitely glue the frames in with the servo in them.
Now on to the scary part.
I used a product called Hysol, which is a rubbery epoxy that comes in one of the easy mix-it dual chamber squeezy things (such a technical term). Its a slow curing epoxy that allows you time to move it around, and clean up any big splurges. You can use any kind of epoxy you want to glue these things to the skin. Maybe some West Systems with some micro balloons mixed in so you don't use too much. Whatever you use, you don't need a whole lot of it. Sand down both the bottom of the wing skin, and the bottom of the frames to give them a nice clean rough surface.
I left the RDS coupler and rod out at this point, because you can't put the whole assembly in at once. Plus I don't want to accidentally get glue all over the coupler and such. If you needed to dremmel away any part of the top skin that may overlap the screws on your servo, then do it before you glue it in.
Now mix up your favorite glue, put a little bit on the surface of the bottom wing, and make sure that all of the bottom surface of the wood frame has a coat on it. You don't need massive amounts to make a giant splooge. Make sure there is enough to go up through your little holes that you drilled.
Now orient yourself, and put the servo and frame in the bay, and find your spot that was marked all in pencil. Give it some pressure to seat the epoxy. Now you'll want to put some weight on it to make sure that it stays in that place, and that any curing or expanding of the epoxy doesn't move it from your nice location. I used the ballast from the kit. I taped up three pieces of it and put it on top of the servo. I guess you need to try and make sure that the top of the servo with the saran wrap is flat enough to sit it there...I even put some tape over the top of it to keep it in place...
Now, let it dry, and pray...
|Feb 01, 2013, 03:35 PM|
|Feb 01, 2013, 03:44 PM|
More and More build continuation
Ok, so you come back the next day, and hopefully everything went to plan. I actually did one wing at a time (both aileron and flap), but here's special info about the flaps.
Doing the flap is not really any different. Go through the same process as outlined. Make sure that the range of motion that you have set up in your radio will allow you to get the flaps to come down as far as you want. This might require some things on your radio depending on which one you have. But you need to get your radio to show you the WHOLE range of motion. Often times they have settings for like 100%, but if you find the right place, you can actually set it to 150% each way, with an offset, etc...In any case, master your radio to give you the most travel. These servos have a very small resolution, so they are not known for giving you a LOT of travel. So this is an important step in figuring out your flap travel. The angle is way more important than that in the aileron to get your travel right, and to get it in the right position.
I found that I could get the servo in a position in the bay with a little overlap of the skins that I didn't need to change the length of the rods for the flaps. I glued them in all the way to the bottom of the coupler, just like I did the ailerons, and that appears to be plenty long. They are a little longer anyways, and have a more angled bend so that you can get the travel you need. You'll need to dremmel away a little bit of the top skin to make way for the screws on this one for sure, but I'd rather do that then have to figure out how to glue in the RDS rods to a particular length. When all was said and done, I was able to get probably 75 degrees of flap travel down and maybe 10 up, which is pretty good for this setup, but if you're used to 80 or 90 on standard linkages, you're just not going to get it...
Ok, so now pull out the screws, and take out the wrapped servo. It may be a little stuck, but with a little pressure, it should come out. Take the saran wrap off, clean up the servo if any epoxy got on it.
Now, another tricky part. Since we didn't glue the frames in with the RDS rod and coupler in place, you now have to insert the coupler into the frame and push it into the pocket like you did before. However, the frame is now rigid, so getting the rod through it with the interference from the top skin is difficult, and may require adjusting the size of the slot that you made through the bulkhead. On one of them, I had to make the slot bigger so that I could get the bent rod through the bearing facing the right direction to head down towards the pocket. A little tweaking, and its in...
Now, you'll need to dremmel away some of the wiper for interference with the RDS rod. Not too much, but for the upward movement of the surface, it needs it.
Now lets talk about the importance of the second wing.
Now that you've got your first wing done, doing the second wing is exactly the same, except you now want to pay close attention to the angles that you used on the first wing. For instance, I said the angle of the aileron doesn't matter too much, but you want to keep the angle on the second aileron as close to the one on the first as you can. This will allow them to move more closely in unison, and make all of your setup issues much easier.
This is especially important for the flaps! Make measurements from the hinge line, the angles, etc to try and get these real close. Its hard to do, and you don't need to get it dead on, but the closer you get, the better.
Now, once they are all done, connect the servo leads (I suggest taping them together, or tying them with dental floss or however you want to make sure that connection doesn't slip), and push them into the bay. Cover with the clear servo covers that were provided and you're good to go. I use clear tape for the servo covers, but I've seen some better ways maybe using a little rubber cement.
On to the fuse install!
|Feb 01, 2013, 04:08 PM|
|Feb 01, 2013, 04:38 PM|
Precision build (continued...) fuse tray
Ok, next step is the rest of the plane. The hard stuff should be over, but you're not out of the woods just yet...
My kit didn't come with a servo tray, so I had to make one. If you've already got one, then this is way easier...I measured up the fuse and cut out a piece that would extend back towards the wing a ways, have enough room for both tail servos, but leave plenty of room in the front for your other stuff. Once you can slide that in and get it in the right position, then pencil it up for the holes you are about to put in it for the servos...
Its kind of unfortunate that the servo lead wires are coming out of the servo 1/3 of the way up, because it makes it a PITA to make the holes for them snug, and still be able to squeeze them in at an angle. Make the holes too big, and there's not enough on the edge for the screws. I'm sure there's a way to put some kind of cross piece, but I like the simplicity and cleanliness of one layer. Just be careful to not overdo it and you can squeeze them in...
Before you go further, you'll want to cut the sheaths for the ruddervator rods back to just inside the opening. They give them to you long, and you'll need some room for the rods to come forward and have enough length to add the coupler as well as your clevis. Just the sheaths, not the actual rods. Just extend them out the back a ways to get them out of the way.
So, now you've got your servos in the tray. Take them out and prep them for more gluing! same as before, rough up the surface on the wood, and the carbon/kevlar areas they are going to be against. This one is a little tricky to not get epoxy everywhere, but you can do it... Put a clamp on the outside of the fuse making sure the servo tray was pressed against the inner fuse and let it dry overnight...
Now that the tray is in, you'll want to install the wiring harness. You may have to use something akin to a fish tape system to feed the wiring harness wires through the right holes, under the servo tray, and out towards the open compartment. Its not too hard. Once I did that, I used some regular thick CA to glue in the connectors to the fuse. The press fit is perfect, so you don't need a whole lot...
Now install the fuse servos. You may have to try and hold the wiring harnesses to one side or the other while doing it, but you should be able to install them, and get them all screwed down.
You'll need to make your servo horns now. These servos are really great, so you should only need to use the inner most hole on the plastic servo horns. Use your dremmel to get rid of everything else, and you may need to drill out the hole for a clevis pin to actually get through.
Now you'll need to put on the tails, and pop on the rods to the rear ball joints. Get the position of tail surface at about neutral. Take the brass coupler they gave you and screw a clevis on it most of the way down. Connect your radio so that you can put the servos at the neutral position, and put the horns on at 90 degrees from lengthwise. Take the coupler/clevis and put it next to the rod and horns so you can mark where you need to cut the rod. Cut the rod at that point.
The rod material is interesting in that the outer portion is some kind of hard plastic, and it is a press fit to the coupler. But the coupler is threaded, so you actually have to thread it on the rod. I used an extra clevis as my leverage while threading it on so I didn't have to grab it with pliers. Once you have it on, but a nice fresh clevis on, and connect it all up and check it. The lengths are relatively important on these. You would like the angles to be the same on both servos for neutral position so that they travel the same amount in both directions. Once you have those set in place, a drop of CA on the threads of the clevis, and at the back of the coupler should get rid of any movement (although I had virtually none).
Now that you've got all of that in place, you need to put the rest of the stuff in the fuse so you can put the plane together and measure for the CG to determine what kind of weight you need to add to the nose. I assembled the whole plane, and then put it on my CG - o - meter, and while it was sitting on it, I hung weight from the nose area until I got it to around 101mm, and weighed that amount. (2.25 oz with the stuff I had).
So now for the final assembly. I put 2.25oz of weight in the nose, and then I pushed my battery pack as far forward as I could. I use a 4 Cell Eneloop XX cell pack in a == configuration. The XX's are 2500mah so they give a little more than the regular 2000mah eneloops. So far, they have done me well. I'm not going to bother with the arguments about what battery packs to use...LIFE is cool, but I wouldn't do it unregulated with the MKS servos. Lipos are ok, but same issue. Good news is that there is plenty of room in the front of this fuse for whatever battery you want. I used the mag switch for this build, and it appears to work really nice. For the radio, I use Spektrum with the DX18 and the 9020 for the receiver. Its got two "remotes" to deal with. One I put in the nose next to the battery (a good thing about the eneloops is that they are skinny). and the other one I put so that the antennas are going cross ways. I took them out of their little black cases, wrapped them in saran wrap and a layer of electrical tape to protect them. It makes them much easier to place being that small.
My wing connections are pretty tight, so hopefully those will loosen up after a while, cause getting them on and off is tough. The colder weather is probably not helping...
And Wala! your plane is now ready for setup!!!
If everything goes well with programming, I'll maiden this plane tomorrow out at Perris!
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