When are my ribs "Good Enough" ?

[fairchild]

I now have a 30 Ton jack on my rubber pad press. That extra push got my lightening hole close enough to 30 degrees that Im
happy now on that.

When i am doing the fluting and straightening operation--- I finish the outer flanged lip from about 75 degrees to 90 degrees using the
RV overbending tool. then I alternate between that tool and fluting until the edge of the flange perfectly touches the table all way round
and the flange is 90 degrees with no bumps sticking up high. When I get to that stage-- i still have some front-to-back potato chip
bend. I flip it over on its back onto a rubber pad and hit the flat areas with my small dead blow to bend the bowed area back the other way.
The rubber pad underneath is intended to give the work a little room to move..... and to facilitate the un-bending.

After I do this several times--- and then continue to adjust fluting and so forth---- I end up with the end-to-end bend better but not
completely gone. When I am all done- the cut edge of the flange touches the table all way round-- flange is 90 degrees with no
bumps....... and when I flip it over down flat---- if I put my finger in the flat area between the two lightening holes- I still have a gap
of between 3/32 and 1/8 between the metal and the table. I have not added any of the stiffener angles yet (but I expect they will have no
effect because that bend is 90 degrees to them)

My question is ---- when those ribs are mounted into the wing---- will that slight curve have any effect as long as the outer flange
is square and flat (in a single plane in space) ? Do I need to work harder and get rid of ALL that bowing ? Or-- is a little OK if
the flange is 90 degrees and flat on the table ?

I have done the first 15 nose ribs for one side. Hope I havnt wasted a bunch of expensive material. !

( I have noticed when I have tried more agressively to un-bend that bow - it can induce a wrinkle in the edge of the lightening hole.
I have to go back and try to un-do it with the bob-tool. even being as careful as I can be- after working it out- it is never quite as
smooth and even as before------- hence I want to know If what I have done so far is good enough.)

Thanks ahead of time -
Tim

[Chris In Milwaukee]

If it takes just a wee bit of pressure to flatten them out, then when you rivet the stiffening angles to them, they’ll be perfect. Mine were similar.

[N3UW]

I agree with Chris. you can upload a photo but they sound pretty good to me.

[fairchild]

Here are 3 views--- one face up - one face down and a 3-rd with a maple strip across it as a visual straightedge.
This is some of the new sheet that didnt have film and I added my own film. The gap under the straightedge appears
to be about 3/32........ It appears on this one that most of the bend is in the front half. Thinking maybe I could take a 1 inch wood dowel
and glue a rubber disk on the end and use it to hit with around the front hole (afraid I might miss with my little rubber hammer.)

[Chris In Milwaukee]

Looks perfect to me. Again, the rib stiffener angle will take that out.

[JimParker256]

Your rib looks amazingly good. Remember that "perfect" is the enemy of "completion." You want it good enough, but you're already there! As Chris said, take one rib and add the stiffener angle to it, and see how good it looks!

[fairchild]

THANKS CHRIS an JIM !!!!!!!!
Some of my nose ribs have that little curve and some came out much flatter. I might try some more tweaking but If the ones with a slight curve
resist my straightening attempts- i will just pretend they are perfect. :-)
If its just a little - AND the cut edge lays flat on the table (so the rivet line is straight on the centerline of the flange) I didnt see how it
could hurt much- other than just cosmetic.

I have 2 plastic tubs now-- I think I will get ready to clean and prep them for acid wash and the chromic acid (alodyne) treatment and
then eco-poxy prime. After that I can move on to making the stiffener angles (a whole BUNCH of them-) - and the 15 for the other side
Kind of neat how quickly I can make them considering that they are a fairly complicated shape. (thanks Bob and N3N JS there-)

Thanks for the look-see----- I feel much better now ------ just wanted to make sure I wasnt making a mistake and ruining lots of expensive
sheet metal. (im NOT beyond that... ) BTW---- the carpet protective film I applied to the sheet did a good job of keeping the surface nice during forming.

Thanks again !
Tim in Orlando