how do I buck HS center nose ribs?

[IowaRV9Dreamer]

I ran into a stumbling block tonight and I'm hoping someone can help me out... We attached the innner and outer horizontal stab. nose ribs to the HS skins just fine but I cannot see how to start the center ribs.

The instructions say to rivet from the leading edge upwards. It is very difficult down there - none of my bucking bars seem to fit, at least on the polished edges. I have the Cleaveland kit which came with 2 bars, and I have a bunch of other ones.

What have others done in this area?

 

[DGlaeser]

Bucking HS rivets

I used the side of a bucking bar (not a polished edge) to get in there. You can hit the side with your scotchbrite wheel to smooth it a bit if you like. I've used the side of bucking bars a number of times.

 

[jlfernan]

I used the smaller of the two bars, polishing the sides on the Scotch-Brite wheel, and wrapping the other edges with duct tap. It's best done with two people. One driving, one bucking. Put the HS in the support frames, cleco the whole rib to pull it tight to the skin, and have it, it's not that bad.

 

[Bret S]

Don't be afraid to polish any rough sides of your bucking bars and use that it achieves a good fit. I've done this several times using the scotchbright wheel (not the grinding wheel). I've also reshaped some necks and edges of both bucking bars and squeezer yokes using the bench grinder when things are really tight. I would caution it is probably possible to grid so much off a yoke tip it may weaken (ruin) it costing $130 replacement.

 

[N674P]

Welcome aboard, Dave!
My first shot at this was not pretty, and I got my first practice drilling out rivets. In addition to a bucking bar with mass, I also needed help keeping the rib tight to the skin. The solution (read here on the forums) was a short piece of rubber tubing over the rivet shank, which presses the rib to the skin while you buck. For the times when the fit isn't perfect, this works great!

 

[N941WR]

Don't be afraid to polish any rough sides of your bucking bars and use that it achieves a good fit. I've done this several times using the scotchbright wheel (not the grinding wheel). I've also reshaped some necks and edges of both bucking bars and squeezer yokes using the bench grinder when things are really tight. I would caution it is probably possible to grid so much off a yoke tip it may weaken (ruin) it costing $130 replacement.

FYI - once you use your scotchbright wheel on a steel or cast iron part you can't use them on aluminum again.

The reason is they will pick up the steel/iron and push it into aluminum parts, thus causing dissimilar metal corrosion down the road.

Same goes for sanding belts. Also, don use sanding belts with iron in them for the same reason.

Also, grinding wheels should not be used on aluminum EVER. Do a search on the forum, it has been discussed before.

 

[Bret S]

FYI - once you use your scotchbright wheel on a steel or cast iron part you can't use them on aluminum again.

The reason is they will pick up the steel/iron and push it into aluminum parts, thus causing dissimilar metal corrosion down the road.

Same goes for sanding belts. Also, don use sanding belts with iron in them for the same reason.

Also, grinding wheels should not be used on aluminum EVER. Do a search on the forum, it has been discussed before.

So by dressing my scotchbright wheel with what I presume is a steel file as recomended that would not be recomended?

 

[Paul Eastham]

Those are some tough rivets...

They're not the toughest rivets to buck in the whole kit, but they're right up there. It's a bad place to start learning.

I strongly recommend setting aside the HS and try the VS first. It's much easier and will give you much-needed bucking practice on an easier subject.

That said, I ended up using the nose of a squeezer yoke to buck the forwardmost rivets. Look around for something heavy and roundish in your shop... Or you can try a MK319BS pop rivet on that first rivet like I did after botching it a few times.

Also, on the scotchbrite front... has anyone actually seen, firsthand, corrosion caused in this manner? It's hard to imagine anything getting embedded by a scotchbrite wheel, especially on an indefinite basis. Yes, Avery does recommend dressing the wheel with a steel file in his catalog and on a little slip of paper that comes with the wheel.

Paul

 

[N941WR]

So by dressing my scotchbright wheel with what I presume is a steel file as recomended that would not be recomended?

Good question. I suspect that if the file is clean there shouldn't be a problem but I try my best not to mix aluminum and steel. It might be best to buy a file to use only on the scotchbright wheel.

Also, please note the comment about aluminum and a grinding wheel, the two should never meet! The reason is that the aluminum will coat the wheel and then heat up and expand much faster than the wheel, causing it to shatter. Think about all those little projectiles coming out of your bench grinder.

 

[n2prise]

Dressing the ScotchBrite wheel...

One good way to dress the ScotchBrite wheel is to use a large piece of aluminum bar stock or angle to keep the surface "flat". After doing the edges of the various skins, the grooves in the wheel got a bit deeper than I wanted. The finishing of various heavy aluminum angle brackets and doubler plates would take down the surface of the wheel across the grooves. Polishing a bucking bar or other steel part just before you take the rough edges off those heavy aluminum parts or heavy aluminum scrap is the easy way to get any ferrous remains off the wheel.

Just so you know, my 7-inch ScotchBrite wheel was under 5 inches in diameter at the end of my RV-9A project. My hangar partner had to buy a new one to start his RV-8 quickbuild project.

Jerry K. Thorne
East Ridge, TN
(Chattanooga area)
www.n2prise.org
RV-9A N2PZ 189.6 hours on the Hobbs