Under Ribs

[bigirons]

I was looking at under ribs on TOW for a potential TC Seneca barrel replacement. Need advice on the type to get or if it even matters. They have a smooth flat one and one with an edge/rail on ea. side. Also best way to install it. I've never soldered before but read a good post on here about soldering ribs and it sounds doable for me.

 

[Bill Hall]

Flat on bottom to match the bottom flat on your rifle. Order by barrel measurement, i.e. 13/16", 7/8", 15/16". You can solder, screw, or stake it in place. Might not line up perfectly with the existing ramrod hole, so you may need to get a little creative.

The round bottom ribs are for round barrels. I have no idea what those ribs with the rails are for. Maybe to custom match a given web thickness :idunno: . Bill

 

[Herb]

They are called a lipped underrib. You buy them for your barrel size (7/8") and I like them. The lips hang over the flat and hide the joint, which sometimes is a little uneven. I am fitting one now to a .50 7/8" Rice barrel for a Hawken caplock I am custom building. My rib wasn't flat so I had to heat and straighten it. Soldering them on takes a lot of heat and I don't want to put that much heat on a barrel. Screwing them on takes very careful attention to hole depth, then you have to tap the holes. My plan is to rivet this one on. I will align the rib on the barrel, with the rivet holes already drilled through the rib, and drill through the rib holes. They have to align exactly. To control hole depth, I level the barrel under the drill and bring the quill down to the stop, with the drill just touching the barrel. Then I add a .100 shim under the barrel to raise it. Then when I bring the drill down to cut the hole, it cannot go deeper. Repeat for each hole. Then I will carefully fit a rivet shank into each hole, a piece of nail will work. Solder them in and clean up the surface around them. Set the rib on with the rivets just protruding enough to gently peen them into the countersink, a test of the fit. But before I put the rib on, I'll coat the rib and barrel mating surfaces with superglue. Then quickly set the rib on and clamp it in several places to make sure it is in contact and level. Then peen the rivets and with a 3/8" round chainsaw file, smooth them to contour if needed. The pipes have been previously inlet into the rib and soldered on. The joint is smoothed with the round file if need be.

I used superglue on the last rib I put on. My plan was to glue the rib on and drill the holes through the rib and into the barrel, thus assuring perfect hole alignment. Then take my propane torch and heat the rib enough to take it off, and tap the holes for screws. Well, I couldn't heat that rib enough to get it off. Turns out that the melting point for superglue is about 450 degrees. It is on there for keeps. So I then soldered the rivet stubs in the holes and peened them over. I think this is about the easiest way you could fit a rib, that is the method above.

 

[crockett]

Lead melts around 700 "ish" and there is another tin based solder that melts at 430 degrees. The idea is to solder on the pipes- to the rib with the lead and then the rib to the barrel with the tin. The lower heat for the tin doesn't impact the lead soldered on pipes. I don't think the 430 on the barrel for a few minutes will hurt any heat treatment.
BUT, I usually solder the pipes but screw the rib to the barrel. On soldering- I use a section of 3/8 mild steel rod. It keeps the pipes lined up. I "tin" plate everything first and then re-heat and you'll see the pipes slightly move and settle in place once the solder re-melts.

 

[Bill Hall]

Ok, the lipped ribs make sense now. I also rivet the ribs onto the barrel, much like you described, but flat bottom ribs can be problematic. If you countersink the rivit holes too much, you need to really peen that metal in there, and this causes stretching of the rib. The problem is, the bottom side (radiused side) stretches more than the flat side, causing slight curves in the ribs between rivits. You think you did a good job, but if you shine light through the joint, you can see where the rib is bowing up slightly in between the rivits. Pre-bending the rib helps, and the bows are barely visible, but still, just knowing they are there can get under your skin.

I can see where the lipped ribs can solve this problem, like molding covering up the rough spots on walls and corners in a house. Something to think about in the future. Thanks Herb.

Now I'm thinking that lipped ribs may be something to consider by the original poster. They sound like a good solution for a retro-fit. Bill