If the wrap is thick enough to keep its "own round" it will leave an air pocket at the deformation. With nothing to support it there, the wrap may crack when the tension casing is installed and tightened.

If the wrap is thin enough to conform to the shell and adhere to the wood at the deformation this wouldn't be an issue.

I'd install the casings and try out your head/hoop/rod and claw combination before wrapping - as a test to make sure the casings aren't angled down at the front too much.

Hope that helps!

Mitch

If you are re-wrapping, why wouldn't you use a bit of wood filler to level of fthe areas in question, sanding it level to the surrounding portions of the shell and then apply the wrap?

Dan is thinking logically and logic would tell you that sanding will solve the problem when in fact the opposite is true. The last thing you want to do to a high stress area like where the lugs mount on the shell is to make it thinner/weaker by sanding away material.

If you sand the surface level two things are going to happen: 1. You're going to blow right through the upper ply and 2. you're going to further weaken an already compromised area of the shell. The solution would be to first, reinforce the back (inside the shell,) of where the lugs mount with a (thin) 1/4" thick wood block shims (preferably maple,) and -then- you can sand the surface level. Drill the shims using the lug holes as a guide. Use large washers on the back to help distribute the pull-stress at the mounting points. That's what blew out the shell at the lugs in the first place. The last owner must have over-tightened the heads and there was so much pull on the lugs (plus maybe a humid environment) that eventually after some years, the wood shell bulged out/distorted behind the lugs as you see it now.

Add wood shims and larger washers behind the lugs and you can sand your heart out on the surface to level it for wrap. To get the backs of the shims to match the inside curvature of the shell, just adhere a piece of one-side-sticky sandpaper inside the shell and sand the back of the shims until the shims take on the same curvature as the shell. When you glue on the shims they'll fit tight and make good contact with the shell.

Pain in the butt, but it can be done.

John

Purdie,

You misinterpreted my inquiry. I was suggesting to fill the depression created in the outer ply by the level of force applied to anchoring the the tension casings - too much at some time in my view. Doesn't take a lot of force to properly hold the casings in place. Nicely snugged screws will do it.

Mahogany does not respond well to compression and the unit load on it from the thin edges of the tension casing is like unto walking across a soft pine floor with high heels - maybe worse. Thus, for example, Rogers used shells with an outer ply of maple and as a result, you don't see as much tendency toward this outcome on their drums.

Again, I'm asking why one wouldn't simply fill the depressions and sand them to a level even with the remainder of the outer ply? No suggestion of sanding he outer ply itself per se.

Exactly. This would fill the air pocket [that I mentioned] otherwise left from a thick wrap. Even if the wrap is thin enough to follow the deformation and adhere to the wood, why not eliminate the deformation altogether by filling it?

Good call.

The deformation is a bump, you'd have to add a lot of filler on both sides of it to create a level surface. You'd end up with a larger, longer bulge in the shell where all the filler was added.

An alternative to slathering filler onto the shell is to level the bump by sanding it flush with the rest of the shell and reinforcing with wood shims from behind.

Filler is something I use for small holes and very small problem areas. Back-filling/adding filler around bump that pronounced is only going to make the shell look more lop-sided than it does now. You need to 'take away' material to level it to the rest of the shell, not 'add more mass' in an -already raised- above the surface area. That's how I'd tackle it, shims in back, then sand the surface bump level with rest of shell. I'm sure there's other ways, but adding more goop around the bump isn't going to fix anything.

I wish that Jeff would chime in on this one, he's a pro carpenter and will know which way is best to remedy the situation. Jeff????? Where are you at?

John

I am a little surprised that there are not more definitive answers this far. The "Ludwig hump" is a really common occurrence. I am no expert, but I think most guys simply wrap the shell as is. I would avoid really thick wraps like glass glitter. I'll be interested to see what the experts say.

I thought the bump was over a lug area! If it's 'the seam bump', then no problem. Wrap away. I thought we were talking apples, not oranges.

John

That looks like a joint. Like two tubes were joined together. Purdie is correct on this, if you turn that down, you`ll go through a ply. Maybe into a second. (too thin) Downtown brings up a very good point too. It looks like you are gonna have splay issues if you do nothing. Probably why the drum got sold. I think you can wrap it as is but like DTF says, the bottom screw hole is higher than the top on the drum and when you turn the t-rods into it, they`ll catch on the edges on the threads. The drum needs to be turned plumb and another ply added to cover the results of tooling it down if you want it trued up.

I say like DTF, assemble it to see if you have splay issues first, if it goes well then wrap it.