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Thread: Introducing a J-4 project

  1. #281

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    Quote Originally Posted by tempdoug View Post
    so for the elevator it will be a solid linkage with no cables?
    Push-pull under floor to a horizontally mounted bellcrank under baggage area. Cables run back half way under floor allowing for long baggage space, then rise as needed to get to elevator.
    The control sticks and all bellcranks mount on ball bearings and cable ends utilize aviation REP bearings so there is very little chance of friction.
    The control surfaces themselves are also hinged on ball bearings.
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  2. #282
    RVBottomly's Avatar
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    Quote Originally Posted by CharlieN View Post
    The control sticks and all bellcranks mount on ball bearings and cable ends utilize aviation REP bearings so there is very little chance of friction.
    The control surfaces themselves are also hinged on ball bearings.
    Looks good Charlie--

    I'm really interested in these various bearings. I searched REP bearings and couldn't find anything. And I'm wondering how the control surface bearings mount. Last I recall (long ago--I know) you were talking strap hinges.

    Vic

  3. #283
    Gordon Misch's Avatar
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    Gordon

    N4328M KTDO
    My SPOT: tinyurl.com/N4328M (case sensitive)
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  4. #284
    RVBottomly's Avatar
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    Quote Originally Posted by Gordon Misch View Post

    Thanks! That looks like it. I don't know why I couldn't find it before.

  5. #285

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    Yes my original intention was to utilize strap hinges. I made the spars for the elevator in stainless to reduce the chance of corrosion within the hinge area. And with the greater selection of low friction engineering plastics as well as the ability now to 3D print extremely complex shapes strap hinges are of great interest.

    But I also like ball bearings, no stiction, yup a tough word for me to spell but low static friction, the break free force in low movement pivots.
    I had already designed ball bearings in the early parts I made. I have not taken any pictures of the bearings installed, primarily since they go against the grain in some circles, I will get some shots.

    What I do have,
    Control stick pivot, there are bearings inside the relay rod as well.
    IMG_0202.JPG

    I will take pictures of the mounts for the torque tube since they have bearings inserted as well.

    Bottom of rudder, the control horn has two bearings inserted, these are 3/8 ID flanged bearings, the lower sets over a stainless pivot pin, the upper is primarily there for support but prevents the rudder from lifting off the upper or lower pivot pins.
    IMG_6370.JPG IMG_6371.JPG

    The control cables will have threaded ends swaged in place that will be fitted into FAFNIR REP3 Bearings. There are many different sizes available, I am now over $1500 of these bearings in this project alone. The elevator horns to the left have these bearings in place.
    IMG_6375.JPG
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  6. #286

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    Thank you Gordon for that link above.

    My control torque tube rides on these these thin wall bearings, they are available in assorted sizes.

    IMG_7439.JPG
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  7. #287

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    I am getting some welding done once again. I am welding inside structure in the aft section of the fuselage. This used to be pretty easy when I was young and did not need glasses to focus on the arc. Frustrating part is depending on the reader I wear I can get a near perfect view of the weld, but only within a few inch depth of view.
    Trying to get one's helmeted head partially withing the structure allowing for the proper viewing angle and distance while allowing both arms to be positioned as needed with the precision to weld at the very low power that .028 and .035 wall tube requires.

    Dang this is kind of slow going one might say.
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  8. #288
    RVBottomly's Avatar
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    Quote Originally Posted by CharlieN View Post
    I am getting some welding done once again. I am welding inside structure in the aft section of the fuselage. This used to be pretty easy when I was young and did not need glasses to focus on the arc. Frustrating part is depending on the reader I wear I can get a near perfect view of the weld, but only within a few inch depth of view.Trying to get one's helmeted head partially withing the structure allowing for the proper viewing angle and distance while allowing both arms to be positioned as needed with the precision to weld at the very low power that .028 and .035 wall tube requires.Dang this is kind of slow going one might say.
    I feel for you, Charlie! I'm using gas, but I have three different drug-store readers for whichever task is at hand. I'm using a face shield after a few times of bumping my cheek with a hot rod tip while contorting through the airframe. It also makes it a little easier to change glasses.
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  9. #289

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    Thinking about the glasses, I stack the readers Kind of sounds stupid but I tend to wear a pair of very large lens general distance glass that works well at 3 to 8 feet or so, about a 1.5 for me. These would be considered the safety glasses. Then I slip closeup glasses under these, under as in from the top between the general ones and my eyes. This combination my focal length is 8" to a foot or so.

    But yes, when you blast a hole through a tube or burn back an edge, it does not matter what torch was in your hand, ya still got to fix it.

    I think back, I have not done much torch work in recent years but I have some to do, my go to torch is a set of Purox 200 "aircraft" torches my dad brought home from work when I turned 14. They still run well now fifty years after I got them used.

    There are times the softer flame is easier to work than the higher energy of the TIG rig.
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  10. #290
    Larry G's Avatar
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    I get the lenses for my welding helmet then I don't have to where glasses
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  11. #291

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    Quote Originally Posted by Larry G View Post
    I get the lenses for my welding helmet then I don't have to where glasses
    I have not had luck fitting corrective lenses with the newest auto dimming helmets. I should probably revisit them.

  12. #292

  13. #293

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  14. #294

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    Interesting, a friend of mine lives 6 miles from his listed location. There is another rafter rat hanging on Bob's Island near here as well.
    In many ways, for the money it would not be worth my time to finish the rebuild of my original one.

    But scrolling down that FB listing the Swift at $26K caught my eye.

  15. #295

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    As I am picking away at the small hard to get to welds, when I step back I keep getting an illusion something just Ain't right.

    IMG_7513.JPG

    My mind playing tricks on me since the fuse is hanging upside down from the ceiling, but the curve of the longerons looks like it is upright, but missing the vertical spar.
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  16. #296
    skywagon8a's Avatar
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    Charlie, Looking forward there is a horizontal tube which ends. It looks like a mid partial longeron and is the same on both sides. Above that end cutoff there is a vertical which goes to the bottom longeron, top of picture. Why is one of these verticals bent in the middle and the opposite one not bent?
    N1PA

  17. #297

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    Good eye Pete,
    Not sure I really like this mid longeron but I wanted substantial shoulder height structure to mount the shoulder belts too. The structure adds allot of torsional strength which just may not be needed. I am used to the cars I have built where each one is stiffer than 10,000 Ft-Lbs in torsion. The plane has no need to be but it is hard for me to back down.
    I have yet to measure this frame in torsion or bending since there are a number of critical diagonals in the last bay near the tail that are not installed yet.

    This mid structure also imitates the original J-4 shelf behind the seats.

    The asymmetry you see is where on one side is a lower baggage door with upper on the other side.
    The bent tubes are where a mid stringer will terminate while eliminating the need for additional tin work around the door openings.
    Intention is the fabric will directly wrap the tubes around openings with either V or D seal gaskets on the door edges. Simple with fewer parts and especially greatly reduced cavities for rust to start.
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  18. #298
    Southern Aero's Avatar
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    Charlie

    Dunno if you have ever seen these or not but great for gas welding, you put whatever "cheater" lens in that you need and don't have to stack your glasses.

    Wouldn't help RV from poking himself with a hot filler rod tho!


    Spits.jpg

    https://www.ebay.com/itm/MAGWELD-IR5....c100010.m2109


    A friend turned me on to them years ago................ work great. I still have to use 2.5 cheaters for tig work. The glasses seem to work better for me than the inserts for the helmet
    ......... It doesn't cost any more to go first class! You just can't stay as long.

  19. #299
    RVBottomly's Avatar
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    Quote Originally Posted by Southern Aero View Post

    Wouldn't help RV from poking himself with a hot filler rod tho!
    There is no help for me. If I weld long enough my hand goes numb and I can't feel what direction the rod is heading after I stop. People at work have started looking for the latest interesting brand marks on me. The face shield helps a lot!

  20. #300

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    Those glasses look allot better than the glasses/goggles of the past. I have had clear wrap arounds that technically had correction but either I did not know how much correction I needed at the time since I grew up as a hawkeye, the transition to lenses took me some time.
    And I have burnt my cheek more than once.
    Heck a few decades ago I was doing some torchwork, hot summer day wearing shorts. I was one of those muscle bound weight lifter types that wore short shorts.
    I fumbled and dropped the torch, tip went down right into my inner leg, that mark is still there.
    Vic, I now have a new to me pinched nerve in my neck, makes my left arm and hand go numb. I have motor control but the full arm tingles. Not every weld but is a half dozen times a day. I am going to have to give in and go for PT.

  21. #301

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    Almost a step forward, I first attempted to tack the mounts of the control sticks onto the fuse, but could not get them to stabilize at all. With everything mounted on ball bearings it just could not be made to sit in place.
    So I used a piece of 1 X 4, mounted on the milling machine and made a jig for locating the control stick mounts. Last night I set the mounts in place then walked away happy.
    So this morning I went down, fired up the Tig and did the initial welds for the mounts, now I am happy again.

    IMG_7520.JPG IMG_7521.JPG IMG_7522.JPG

    Cool, now I can mount the sticks for the first time, granted the fuselage is upside down and hanging from the rafters I can not sit and fiddle,

    IMG_7527.JPG IMG_7528.JPG

    But now, and only now I find I made the mounts such the the torque tube is a half inch or so too low. The top of the tube was to be just a touch below the floor level which allows proper geometry of the aileron cables and clearance to other systems. Oh well, cut it apart and make things right.
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  22. #302

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    I decided the mounts for the control stick will be fine as they are, not sure I intended the torque tube to be where it is but there is technically nothing wrong with it.

    I got back to making parts. This entailed doing some detail drawings, machining a few bits and the welding.
    What I am concentrating on now is making the mounting points for the pedal assembly. Since the seats are fixed I have chosen to make the pedals adjustable. It comes down to adjustable pedals are less of a weight gain or safety hazard than a movable seat that does not have proper crush structure under it.

    These few parts have quite a few hours in them but they are a start.
    IMG_7536.JPG IMG_7538.JPG

    Now I have the fuselage sitting upside down on the shop floor. The lift eyes on top of the front spar are nice since they are threaded into the structure and allow for leveling.
    Basically the parts made today are the rectangular tube along the centerline, the two dowels seen up front are for the center mount for the brake torque tube. Aft of that the pin hanging down is the center pivot where the pedal structure will be mounted. Next will be to make some tooling to align the outer pedal mounts, then to fabricate that structure.
    The pedal assembly will be a L&R cradle mounted on Delrin bushings. These will locate the pedals which will utilize ball bearings for all pivots.
    I have yet to decide if the pedals will be fabricated in stainless or if I will spring for all Titanium tubing. That might be decided if I am buying a new camera for Oshkosh this year or not.
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  23. #303

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    Here is a screenshot of the pedal assembly as being built. Lots and lots of little parts to be made.

    June2019 FrontLow1.jpg

    I got a few hours in on this making parts and doing minor but needed revisions, basically updating where I left off on these parts drawings a few years back.

  24. #304

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    Another screenshot,

    June2019A.jpg

    Looks like the image gets scaled in reverse with the rudder being proportionally big with the engine being way too small. Damn software.

  25. #305

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    Today's task was more detail design work followed by making the outer brake torsion shaft mounts that mount onto the frame. I did take pictures but then got busy preparing for our first planning meeting for the B-17 tour we have coming in September. If it's not raining that weekend I may bring this frame over for people to look at.

  26. #306

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    A little more being done,
    I need to mount a mixer connecting the left and right pedals. This system will allow the unused pedals to be stowed forward reducing the chance of un-trained toes getting to them or the brakes.

    Earlier I welded in a cross box tube that has two thin wall dowels which an AN-3 bolt can pass though to hold some brackets in place.
    This morning I placed a chunk of 1X4 in the mill and drilled holes so I have an accurate jig.

    This mounted in place over the existing dowels allowing me to drill through thin wall ¾ tube.
    These holes will get thin wall stainless sleeves as I utilize in all through tube holes.

    IMG_7545.JPG IMG_7546.JPG IMG_7547.JPG

  27. #307
    RVBottomly's Avatar
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    Quote Originally Posted by CharlieN View Post

    This mounted in place over the existing dowels allowing me to drill through thin wall ¾ tube.
    These holes will get thin wall stainless sleeves as I utilize in all through tube holes.
    That's an idea I hadn't run across. Is there an issue with dissimilar metals?

    Vic

  28. #308

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    Quote Originally Posted by RVBottomly View Post
    That's an idea I hadn't run across. Is there an issue with dissimilar metals?

    Vic
    Yes and no,
    The Stl tubes weld into the 4130 frame using ER312 rod. The stainless to the steel is no concern with that alloy. Where it may get moody is if the dowel locates aluminum as I will have in some areas, a good anti seize should be used since Stl & aluminum do not play well together. Best if the aluminum is anodized or acid-zinc plated.
    Some of what the dowels will locate are made in engineering plastics, no issues here. I will also be mounting all the control system bellcranks and pulleys over stainless. These are generally not an issue since many bearing are plated, but should use an antisieze as well in not to insure conductivity between parts.
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  29. #309

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    The dowels are inserted here.
    IMG_7549.JPG

    And in front of those is the aft brace of the inner pivot for the pedal assemblies.
    What might look out of alignment in the upper pic, that ½" tube is actually on the centerline, it is just the ¾ cross tubes are asymmetrical due to the differences at the firewall with the fittings for the swing out mount.

    Up front in this shot is the inner pivot for the pedals to hinge on.
    IMG_7550.JPG
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  30. #310

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    A few more bits, I now have the mounts for the relay tubes. I have machined the arms for said parts as well and next will machine the ends of the tubes where they will fit in the ball bearings.
    Not sure how far I will get today since I ave to finish some documents to hand out to my workers for the upcoming B-17 tour we are hosting.

    IMG_7551.JPG IMG_7552.JPG

    I might change the material of these blocks before the plane flies since the UHMWPE was selected when the tubes were going to ride directly in the block, but I decided to go with ball bearings so the super slippery plastic is not needed as much.

  31. #311

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    My next little tool, I need to locate the outer pivots for the brake shaft. The two master cylinders are on the outermost section of the firewall structure. One left and one right.
    I had shown the inner mount located on the centerline. Now how to accurately mark where the center of each outer mount needs to be.
    Well a few minutes in the lathe to turn up a holder for a .223 bore sight laser. This mounts up sweet.

    IMG_7554.JPG IMG_7556.JPG IMG_7555.JPG
    Last edited by CharlieN; 06-22-2019 at 03:50 AM.
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  32. #312

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    My next task has been to get the brake actuator parts underway. I did not take pictures of using the laser setup to layout the end brackets but the system worked well. Those parts will show in this next set of images.

    The brake pedals will drive torsion tubes to apply force to the masters, I chose to stay with stainless rather than go with Ti. Just not enough weight saving on these small parts.

    I will start here with the short arms that link to the masters, these got drilled, reamed and rough milled to shape.
    IMG_7559.JPG IMG_7566.JPG

    Then dressed on my 18" disk sander,
    IMG_7573.JPG IMG_7574.JPG

    These bits then get slid over the ⅝ x.020 tube that has machined ends pressed in place that fit in the end bearings.
    IMG_7576.JPG IMG_7578.JPG

    IMG_7579.JPG

    The aluminum angle end brackets will later get dressed down to shape but for now I want to see if they need to be larger than expected should they hang something else. The brackets are drilled and tapped and when actually mounted will get double nutted with MS 21042 nuts.
    Last edited by CharlieN; Today at 07:09 AM.
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  33. #313

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    I decided to spend a few hours and make the upper rear shock mount and get it tacked in.
    IMG_7589.JPG IMG_7592.JPG
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