Thanks Thanks:  0
Results 1 to 14 of 14

Thread: longeron replacement

  1. #1

    Join Date
    Jan 2005
    Posts
    9
    Post Thanks / Like

    longeron replacement

    I am rebuilding A PA-12 I just got the fuselage back from the sandblaster the lower longerons have been spliced a few times and they are pitted in a few places. I have decided to replace Both longerons. Is there any pitfalls to avoid when I cut the old ones out. Do i need to make some sort of jig to hold the frame so it does not move when longeron are removed. I was going to do one at a time and take lots of measurements before i cut is that the best way?. If anybody has any pointers pictures that would be greatly appreciated thanks for the help.

  2. #2
    aktango58's Avatar
    Join Date
    Aug 2004
    Location
    18AA
    Posts
    9,301
    Post Thanks / Like
    Just cause it is together now, does not mean it is correct

    I would get a set of plans and do actual distances from plans, and build a jig as needed.
    I don't know where you've been me lad, but I see you won first Prize!

  3. #3
    www.SkupTech.com mike mcs repair's Avatar
    Join Date
    Aug 2004
    Location
    chugiak AK
    Posts
    11,359
    Post Thanks / Like
    Quote Originally Posted by aktango58 View Post
    Just cause it is together now, does not mean it is correct

    I would get a set of plans and do actual distances from plans,....
    don't do that!... the plans and the plane are not the same! ain't no 2 pa-12's that are the same!! (and don't even get a Blue print near a Maule..)

    no jig needed, yes do one at a time... the only critical measurement is the stabilizer travel in relation to level flight/firewall.... and try to make bottom longerons strait. keep tail post & jack screw vertical too

    i just use a cutoff wheel and cut out tube between clusters, then cut the piece in cluster open and grind/remove it from the inside of longeron pice left till I get to the cluster...

    weld the inside corners FIRST to help keep from bending longerons as weld cools and contracts... you might also put blocks of wood to other tubes help hold longerons nice shape...

  4. #4
    behindpropellers's Avatar
    Join Date
    Feb 2003
    Location
    NE Ohio
    Posts
    6,815
    Post Thanks / Like
    Quote Originally Posted by bryan albert View Post
    I am rebuilding A PA-12 I just got the fuselage back from the sandblaster the lower longerons have been spliced a few times and they are pitted in a few places. I have decided to replace Both longerons. Is there any pitfalls to avoid when I cut the old ones out. Do i need to make some sort of jig to hold the frame so it does not move when longeron are removed. I was going to do one at a time and take lots of measurements before i cut is that the best way?. If anybody has any pointers pictures that would be greatly appreciated thanks for the help.
    Now is the time to evaluate what you have.

    A new fuselage from univair will save you tons of hours and make your plane very desirable if you decide to sell it.

    Tim

  5. #5
    nesincg's Avatar
    Join Date
    Jan 2006
    Location
    Chattanooga, TN (KAPT)
    Posts
    617
    Post Thanks / Like
    Tim the money man. Needs more time in his life. Rebuild it. Just takes time.
    The aviator formally known as 89.
    Likes Nolan liked this post

  6. #6
    behindpropellers's Avatar
    Join Date
    Feb 2003
    Location
    NE Ohio
    Posts
    6,815
    Post Thanks / Like
    Quote Originally Posted by nesincg View Post
    Tim the money man. Needs more time in his life. Rebuild it. Just takes time.
    I guess when your an airline pilot and get 2 mos vacation a year it makes sense

  7. #7

    Join Date
    Jan 2003
    Location
    nd
    Posts
    3,605
    Post Thanks / Like
    Clyde Smith at one of his seminars showed a neat tool for drilling the old tube off the cluster. Looked pretty neat. Has a bearing that fits inside the tube and chucks in a hand drill. Looked through my stuff and i cant find who made them. Anyone know? It was a counterbore something like this with a bearing pilot.http://drillsandcutters.com/counterb..._14_shank.aspxWith the outside diameter the same as the tube.http://www.supercub.org/forum/showth...light=longeronhttp://search.skygeek.com/?vwcatalog=stylespilotshop&keywords=piloted+spotfa ce+tools&x=37&y=12
    Last edited by tempdoug; 12-05-2012 at 07:51 PM.

  8. #8

    Join Date
    Jul 2009
    Location
    racine,wi
    Posts
    684
    Post Thanks / Like
    think there is a old thread about it

  9. #9
    Marty57's Avatar
    Join Date
    Jan 2005
    Location
    Nipomo, Ca
    Posts
    1,406
    Post Thanks / Like
    What about using an expandable reamer? Cut the tube on ether side of the cluster and use the reamer to remove the tube from the inside - out. If the tube is pitted and thin it wouldn't take that much time to remove. I haven't done it but seems like an ok way to me.
    Marty57
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
    www.marty2plus2.com

  10. #10

    Join Date
    Nov 2002
    Location
    Charlotte, NC
    Posts
    1,859
    Post Thanks / Like
    It is a "spot facer" with a pilot.

    Sorry, the pics are scans of copies...

    John Scott
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Tubing removal 1.jpg 
Views:	188 
Size:	285.9 KB 
ID:	9434   Click image for larger version. 

Name:	Tubing removal 2.jpg 
Views:	149 
Size:	287.2 KB 
ID:	9435   Click image for larger version. 

Name:	Tubing removal 3.jpg 
Views:	196 
Size:	292.8 KB 
ID:	9436   Click image for larger version. 

Name:	Tubing removal 4.jpg 
Views:	135 
Size:	210.8 KB 
ID:	9437  

  11. #11
    phdigger123's Avatar
    Join Date
    Mar 2011
    Location
    Cottage Grove, Mn
    Posts
    316
    Post Thanks / Like
    Also called a reverse counter bore. Various sizes of pilots are available to fit into the pilot hole of the counter bore. http://www1.mscdirect.com/eCommerce/...t+-+Holemaking

  12. #12
    flybynite's Avatar
    Join Date
    Oct 2004
    Location
    Eagan, Minnesota
    Posts
    380
    Post Thanks / Like
    Jay (Javron) fastened my 12 fuselage to a level table made of I beams and cut off the tail. He replaced it with a short section from Univair. Went nuts attempting to get everything square and straight.

    Click image for larger version. 

Name:	P8020109.JPG 
Views:	117 
Size:	304.8 KB 
ID:	9439

    For cutting the longerons from clusters,you can use a hole saw of the same size as the longeron and use another section of tubing that just fits inside the holesaw and longeron as a guide (5/8" for Cub longerons). They are cheaper and easier to find than spot facers. Work slow.

    Wayne

    PS Tim, I would have been lots of money ahead buying a new fuselage, not to mention time.

  13. #13
    www.SkupTech.com mike mcs repair's Avatar
    Join Date
    Aug 2004
    Location
    chugiak AK
    Posts
    11,359
    Post Thanks / Like
    you are making this way more complicated than needed....(AND doing the same grinding then TOO!!(after you wasted the time trying to cut center out))
    just cause someone can make a fancier & more expensive mouse trap, doesn't mean you need it... especially if it takes longer to do the job....

    as shown in longwinglover's pics... cut longer on so it looks like pic #2.
    then grind from inside till it looks like pic #3... DONE!!
    and it WILL take less time...

    and I can't imaginge how slow a holesaw would be and how quick they would dull or chip teeth....

    it "might" take you 5 minutes a cluster to do it my way.....

  14. #14
    C-90 Cub's Avatar
    Join Date
    Feb 2011
    Location
    Alexandria, KY
    Posts
    154
    Post Thanks / Like
    When I did mine I built a simple jig out of metal studs with the fuselage upside down. Using metal studs you can clamp the fuselage down and they are perfectly straight. Pull a string through the center of fuselage and measure off of it to see how straight your fuselage is. Another trick is to prebend the new longerons to set in place before welding them. This takes the stress off of them so that when heat is applied welding they don't bend at the stations near as bad. Looks much nicer when finished. It's not to bad job at all. I would replace one at a time also.

    Steve

Similar Threads

  1. broken longeron
    By tamarack in forum Super Cub Sick Bay
    Replies: 9
    Last Post: 10-11-2008, 02:00 AM
  2. bend in top longeron
    By wirsig in forum Experimental Cubs
    Replies: 8
    Last Post: 04-07-2008, 08:40 PM
  3. longeron replacement
    By cruiser in forum Super Cub Sick Bay
    Replies: 7
    Last Post: 10-19-2003, 09:20 AM

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •