Bearing Edge Sound Impact/Right Track?

[Dub Town]

Im working a bearing edge from scratch on a new shell which I haven't done before.

I know theirs been loads of discussion surrounding bearing edges on the forum (which I have searched and read), so far I have gathered that what I need to do is turn it upside down on concrete and rotate it to level the edge first.

Then file away the edge with rasps/files (I dont have a planer or belt sander).

then round out the edge with sand paper.

Their was a post on bearing edges a while back that showed different bearing edge profiles from different countries, am I correct in saying that it should have the least degree of angle so long as it stays round with a slight bevel on the inside?

So far Ive taken off the edge and started to round it off but realized I need to file away more of an angle because the top is still flat (which I know should NOT stay that way)

am I on the right track? What are some things that i need to make sure i do NOT do as I am filing away on it?

Ive seen/read that the bearing edge does impact the sound, can anyone describe how? Ive read that flat tops and no bevel on the inside can create more buzzing or ringing, how does the bearing edge effect tone/slaps?

Any info would be great...I don't mean to beat a dead horse with the topic since it's been discussed but It's my first Guinea Lenge shell and basically I don't want my inexperience with making the bearing edge from scratch to send it south.

[Paul]

I need to do is turn it upside down on concrete and rotate it to level the edge first.

I would get a flat board and glue rough grade sandpaper on it instead unless its really level concrete

[michi]

Here is a nice profile. Basically, you want to make a quarter-circle arc that takes in the entire width of the shell and put a small bevel on the inside, so you get a clean take-off for the skin onto the playing surface.

Bearing edge profile

Bearing edge.jpg (19.68 KiB) Viewed 258 times

When you shape the edge, run your fingers over it all the way around and feel for flat/raised spots that you need to correct. (Your sense of touch will be far more accurate than your eyes.)

You can remove the outermost part of the wood with a rasp. Then switch to coarse (80-grit) sandpaper with a sanding block to shape it a bit more. (Don't use the rasp to do all of the shape because a rasp has very coarse teeth and you can end up with little gouges in the edge where some of the teeth have dug in below what you want as the eventual surface.)

Use a half-round bastard file or a (very sharp) spoke shave to create the bevel. If you use a file, don't move it straight up and down. Instead, move down and right-to-left simultaneously, holding the file at an angle. That avoids having the file "dig" into the edge at a particular spot and making a dimple. (You want a nice circular edge, without any undulations.)

Progressively use smaller-grit sandpaper (120, 240, 400, 800) to smooth the surface. Once you've done the 800-grit pass, the wood will be super-smooth and shiny, making it more slippery.

Apply a small amount of shea butter to the finished edge, rubbing the butter into the edge with your palms. Rub hard enough so you can feel the heat from the friction. This seals the end grain against moisture, so the wood fibres don't swell up as much as you fit the skin. The shea butter will not damage the skin. However, be sure to thoroughly wipe the edge with a cloth to make sure that there is no excess shea butter. (You want the shea butter in the pores of the wood, not on top of the surface.)

Cheers,

Michi.

[teb]

Thanks Michi for the diagram of the bearing edge. It is helpful seeing what it should look like. I also appreciate all the additional information.