[Larry DeCamp]

Recently challenges with bucking bar access for skin riveting was discussed. An alternative has a lot of merit, but may have shortcomings I don’t know.

HFS has introduced me to 3M2216 and Dan's epoxy of choice as a filling bond between skins and ribs/longerons etc. Just put the goo between the parts and cleco until cured. This eliminates the potential for rivets to pull the skin into an unsightly depression.

Then, just pull rivet the skin with flush rivets of appropriate specification. Rivets can be filled and sanded to perfection for paint.

There may be some issues with this , but it is much easier and less prone to “crooked bucking bar “ disappointments than superhuman contortions through rib lightening holes.

 

[mountainride]

Bucking bar jig

For getting the bucking bar proper positioned on the shop head when blind I created a bucking bar jig. The jig helps keep the bar straight and the rivet where it should be. This will also prevent any dings in the spar/rib as it is made from a flexible material designed for impact. https://mountainrideaviation.com/products/bucking-bar-bumper

 

[wirejock]

Lanyard

I have those. Pretty cool. They go on and off easy. (Shameless plug for a friend)
I also made a wood jig to align the bar blind.
Tip...Attach a lanyard to the bar. Sooner or later you will drop it. Saves a dent.

 

[fl-mike]

Tip...Attach a lanyard to the bar. Sooner or later you will drop it. Saves a dent.

^^^^^
This!

First step is to put towels or some good cushioning at the bottom of any area you are riveting in. I forgot...once...and yup. Hello Mr. Pimple. That is not a sound you want to hear.

I would be careful of using epoxy for liquid shimming. Consider the possible impact on shear strength of the rivet joint. And, make sure anything used is not brittle or it will fracture when setting the rivet. I think the standard method is to use metal shims in the joint.

 

[sahrens]

Repairs

Once the wing skins are bonded to the ribs and spars how will you make any repairs? If the wing gets damaged, perhaps by a bird strike, you would not be able to remove rivets and skins for repair or replacement. It seems you would have to build or buy a complete wing.

Just a thought about an unintended consequence.

 

[Brantel]

When I think about the thousands of RV's flying, one would have to ask themselves why?

 

[mountainride]

Bucking Bar Keeper

Quote:
Originally Posted by wirejock View Post
Tip...Attach a lanyard to the bar. Sooner or later you will drop it. Saves a dent.
^^^^^
This!

First step is to put towels or some good cushioning at the bottom of any area you are riveting in. I forgot...once...and yup. Hello Mr. Pimple. That is not a sound you want to hear.

I came up with a solution for this issue that will save a lot of heartache from dropping the bar in the leading edge or worse on the spar. Tried a few different lanyard system but the simple yo-yo string around the finger works best. Larry, you have one coming your way!

https://mountainrideaviation.com/products/bucking-bar-keeper

 

[wirejock]

Lanyard

I came up with a solution for this issue that will save a lot of heartache from dropping the bar in the leading edge or worse on the spar. Tried a few different lanyard system but the simple yo-yo string around the finger works best. Larry, you have one coming your way!

https://mountainrideaviation.com/products/bucking-bar-keeper

That's brilliant! I think it's time to go global. You've got some cool products.

 

[rvbuilder2002]

Recently challenges with bucking bar access for skin riveting was discussed. An alternative has a lot of merit, but may have shortcomings I don’t know.

HFS has introduced me to 3M2216 and Dan's epoxy of choice as a filling bond between skins and ribs/longerons etc. Just put the goo between the parts and cleco until cured. This eliminates the potential for rivets to pull the skin into an unsightly depression.

Then, just pull rivet the skin with flush rivets of appropriate specification. Rivets can be filled and sanded to perfection for paint.

There may be some issues with this , but it is much easier and less prone to “crooked bucking bar “ disappointments than superhuman contortions through rib lightening holes.

The issue that there may be… is that unless a test is done to evaluate the different process and affirm that it has the equivalent strength to the recommended process, it is nothing more than a WAG which is not good.

 

[Larry DeCamp]

Approved rivets.

Thanks Scott. I have naively assumed there are pull rivets at parity with solid rivets since some pull rivets are called out or approve in RV plans. Just trying to offer options for folks with short arms or those with no reliable bucking assistant.

 

[Carl Froehlich]

SNIP…

Then, just pull rivet the skin with flush rivets of appropriate specification. Rivets can be filled and sanded to perfection for paint.

There may be some issues with this , but it is much easier and less prone to “crooked bucking bar “ disappointments than superhuman contortions through rib lightening holes.

Larry,

Bucking bottom wing skin rivets is always challenging. I find process is the key to a good result. And no, no contortions through lighting holes…

Attached photos show the wing set up for bottom skin riveting. The table height is key as it provides the right angles to do the “reach under the skin and work down” technique as discussed in the instructions. This ~28” tall table is also perfect for fuselage assembly.

While we all have our favorite bucking bars I find this old style to be what works for me. The bucking surface is as shown. The bar is big enough so that it fits well in the palm of your hand so that you always know (without seeing) how it is aligned with the rivet you are bucking. The size also helps avoid drops.

The last point - riveting bottom skins is not a one person job. Get a helper on the rivet gun and you stay on the bucking bar.
Carl

 

[bimmer1980]

Ordered today

For getting the bucking bar proper positioned on the shop head when blind I created a bucking bar jig. The jig helps keep the bar straight and the rivet where it should be. This will also prevent any dings in the spar/rib as it is made from a flexible material designed for impact. https://mountainrideaviation.com/products/bucking-bar-bumper

I had a similar idea, but currently do not have a 3D printer. I had also thought of using some PlasticDip or RTV material, then cut rivet openings after the material sets up. Regardless, rather than reinvent the wheel, I just placed the order today.

I'm currently working on the HS of the RV-10 and the hints in this thread are helpful.

 

[wirejock]

Bar covers

I had a similar idea, but currently do not have a 3D printer. I had also thought of using some PlasticDip or RTV material, then cut rivet openings after the material sets up. Regardless, rather than reinvent the wheel, I just placed the order today.

I'm currently working on the HS of the RV-10 and the hints in this thread are helpful.

I used Gorilla tape but these are nice because you can remove them quickly with no residue.

 

[chaskuss]

Not a good idea. Also much more expensive to do this.

Thanks Scott. I have naively assumed there are pull rivets at parity with solid rivets since some pull rivets are called out or approve in RV plans. Just trying to offer options for folks with short arms or those with no reliable bucking assistant.

I'm not aware of any "Cherry Max" rivets available in 3/32" size. Does anyone know if there are? If not, that means all your holes for 3/32" rivets will need to be drilled out and dimpled for 1/8" rivets. Cherry Max rivets are expensive. The steel shank also introduces the possibility of corrosion. Plus they are cosmetically ugly!

You can back rivet the top skins on. You don't need a skilled assistant to back rivet. Just someone who can drop a rivet in a hole, then hold a large bucking bar tightly against the skin.

Join your local EAA Chapter to find an assistant.

All that said, Scott gave the most valid reason to not do this.

 

[Marc Bourget]

Wil Taylor, Aero-Engineer, moderator of Eng-Tips forum and a contributor to Homebuilt Airplanes forum has posted at length on bonded Aluminum structures.

The following is offered to provoke thought.

From memory and some years back so tech may have improved - but provoking the thought for the individual builder's analysis is my purpose here

The takeaways I recall and benefited from are: 1) the bonding area is much increased over that from an acceptable riveted structure; 2) Proper cleaning is essential; 3) the thickness of the adhesive layer is critical to achieving proper bonding performance. In some cases beads are introduced to maintain proper bonding thickness.

IIRC, if these (and there are more) criteria aren't religiously obtained, the structure is weaker. So please look into these aspects to verify their validity.

 

[hoyden]

My bucking bar rubber nubbins arrived yesterday. I am actually looking forward to riveting the lower bottom skin to see how they work. Previously I placed thick rubber tape on the bar. The tape worked but was not durable. I wish I had the nubbins when building the empennage.

For getting the bucking bar proper positioned on the shop head when blind I created a bucking bar jig. The jig helps keep the bar straight and the rivet where it should be. This will also prevent any dings in the spar/rib as it is made from a flexible material designed for impact. https://mountainrideaviation.com/products/bucking-bar-bumper