Rib Joggles

[Bucky]

Ok. I am having a little difficulty with getting my joggles right. After reading some of the posts about joggling, I get the impressions that they are not a big deal and we can skip this step without any problems. I have asked my sheet metal guys on base and they said they would leave them off and just be careful on rivet spacing. What says the forum?

[Chris In Milwaukee]

I think your sheet metal guys are right. I'm going to give it a try with mine when I get ready to assemble things. If the first one or two don't work out, I'll continue without them.

[Gavin Chester]

If you put the joggle on your rib forming pattern you can do the joggles When you form the flanges IMG_2146.JPG IMG_2163.JPG

[Gavin Chester]

You really do not need them anyway. The skin pulls down a little and the rib flange pulls up a little. It was just easy at the time to add the relief when I was making the forming template. For my four place I did them with a home made joggle block and I had to do one at a time.

[sjt]

What is the black material that you used for a form? I have noticed that my MDF would change my a small amount. I do not know if it was temperature or humidity.

[Gavin Chester]

Black UHMW

[mswain]

You might get away without joggles, but you will get a much nicer fit with them. I just used a piece of .040 Aluminum and a vice.

[Bucky]

You might get away without joggles, but you will get a much nicer fit with them. I just used a piece of .040 Aluminum and a vice.

I tried using one of those jigs, it didn't do that we'll for me. Maybe I was doing it wrong. I just tried to make a form to put the juggles in, and now I have to remake a spar rib. Not sure what to do from here

Sent from my SM-T350 using Tapatalk

[Gavin Chester]

Here are the instructions for your joggle tool.

[SpruceForest]

The directions from NAVAIR specify cold joggling only with -0 or -W temper, and penetrant testing if cold joggling -T3/-T42 tempered sheet. Option is implied in the tech order to hot joggle and artificial age tempered material after cold working, but I suspect that is beyond most small shops. Given that we've already aggressively worked the material in bending the flanges, it seems a better bet to either build the joggle into the form block to avoid reworking the piece or forego/work cosmetics with rib spacing adjustment.

So...are the folks that elected to post-form the joggle doing the penetrant testing? If so, any magic for avoiding failed parts if post-forming?

Also... on cold joggling per the TO/NAVAIR manual, the clip looks like it has to be a bit thicker (one gauge) and harder than the base material being formed, so that likely means a steel clip for 2024-T3 aluminum. Any comments on how thick/material used for those that had some success cold joggling?

The most current version of the technical order - USAF and USN/USMC General Manual for Structural Repair - is attached for those that want the entire reference. Apparently, this manual dates back to at least the Army Air Forces, so a long history of updates to address changing practices. The tables that appear at the end of the excerpt posted earlier in this thread are located a couple pages prior to the actual joggling instructions in the full doc.

[Frank]

Great, another reason to worry about my workmanship...
My project is EAB with emphasis on Amateur!
Regarding rib joggles, for me the die is cast.
I beat them mercilessly on joggle blocks!

[SpruceForest]

I never worry about my workmanship... just the end result ;-). I think the point is that with post-forming joggles with a mallet, we're beating on tempered material with a pretty shallow critical crack depth that's already been heavily worked once. Given the difficulty of inspection once the spars and ribs get wrapped in aluminum or fabric, taking a good gander at the beaten-on and beaten-on-again rib end seems like a reasonable use of time. Is dye penetrant a good idea? Certainly for anything that looks a little sketch, it's cheap insurance and pretty easy to do.

For stuff formed with a joggle clip and vise, I have to wonder if the process is not inherently a bit easier on the aluminum than playing whack-a-mole with the dead-blow.

[Chewie]

See pg 247

https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/amt_airframe_hb_vol_1.pdf

[SpruceForest]

Not sure if that was intended for me, but if so, 1) thanks for the link... I think I had the older version, and 2) I'm apparently reading right past the section that answers either of the questions posed above:

" So...are the folks that elected to post-form the joggle doing the penetrant testing? If so, any magic for avoiding failed parts if post-forming?"

"Also... on cold joggling per the TO/NAVAIR manual, the clip looks like it has to be a bit thicker (one gauge) and harder than the base material being formed, so that likely means a steel clip for 2024-T3 aluminum. Any comments on how thick/material used for those that had some success cold joggling?"

Please steer me towards the specific text or graphic in the linked material.

Thanks!

[nborer]

Watching this thread… like SpruceForest, I was concerned that the instructions indicated that joggling heat-treated aluminum needed to be followed up with an inspection. I also know many Bearhawkers have joggled their T3 ribs with no issues. Others have seemingly done fine without joggling at all. I didn’t have the foresight to build a joggle into my formblocks and have formed most of my ribs, so I am electing to forgo the joggle and plan to just build slightly taller spar webs. That said, I’m not yet past the point of no return. I’ve searched the joggling debate on this forum and see a mixed set of opinions, but it’s the T3 inspection statement in the instructions that pushed me over to the no-joggle camp. I suspect my fear is overblown but I’m curious about what others have done.

[Chewie]

morning SpruceForest ,
Yes the link was intended for you. Sorry I didn't put it into better context. My point was that the section on page 247 illustrates what I did. It's fairly straightforward. I appreciate the value in NAVAIR manuals and other specifications, but I think they go above and beyond what's necessary for what we're doing. If I'm seeking an AW certificate from the FAA and their best practices are good enough for A&Ps, they're good enough for me.
I used a 1/16 piece of steel for my joggle on .032 ribs. Also for the false spar.

[SpruceForest]

I kind of like the additional detail in 1-1A-1… the recommendation to use a harder material shows up in the TO, but I cannot seem to locate it in the four words expended in the FAA guidance on joggling clips ;-)

But seriously…good to know a steel clip of about 2x material thickness worked for you!

[nborer]

If you're an EAA member, they have a short video segment on joggling (link). I noted that the guy in the video used T3 and didn't say anything about penetrant inspection, etc. That doesn't make it definitive, but I thought I'd post it if others weren't aware of it.

[SpruceForest]

I think it's a personal choice as to how far down the rabbit hole we go. Just trying to chose wisely ;-)

[Bcone1381]

As I read this thread the idea of "Minimum Bend Radius" comes to my mind. I suppose a tight slot in the joggle jig could push the bend radius and put a kink in the material. Super tight slot might act a bit like scissors I suppose.

It seems prudent Honor the minimum bend radius for the material you are joggling. If the joggle jig has generous slot the joggle's bend radius will be generous. Radius the edge of your joggle jig to prevent those tooling marks on your material. I could not measure the radius of a joggle, but "TLAR" common sense would prevail in my shop.

[Frank]

That looks about right. I say that after I've cut or drilled. Try not to say it before cutting or drilling. My pile of rejects is growing!

[Bcone1381]

My fist step would be to joggle the oversize piece first.

I Worte down a formula in my shop I read on this forum. 1) Cut piece oversize, 2) Bend it. 3) Drill it. 4) trim to final size. Bending is most difficult, its easier locate holes after its bent. Its almost impossible for me to locate a bend in an exact location.