Bearing Edges

Manufacturers, brands, skins, maintenance, stands, sticks, michrophones and other accessories for congueros can be discussed into this forum ...... leave your experience or express your doubts!

Re: Bearing Edges

Postby Chupacabra » Thu Jun 23, 2011 11:36 pm

In my past experience in reshaping the bearing edges of both a djembe and a conga (both solid wood shell, just to add) I have learned that the contact area that a skin has with the edge has a significant influence in the sound of the drums. With the sharper edge you have less contact area, therefore more resonance of the membrane (skin). A larger radius of the bearing edge, therefore more contact area will generate less resonance of the membrane. This is pure fact. When there is more resonance there will be more sustained bass and midrange sounds and less high range sounds. They are there but have a muffled sound.

A master percussionist, or even a pretty decent one will be able to get great sounds from either type. He or she will make a choice whether it's the right sound for them or the style of music they want to play with the instrument.

In my opinion, the only thing that is of utmost importance with a bearing edge is that the whole contact surface, no matter what shape, must be true and flat. No high spots or low spots and perpendicular to the vertical centreline of the drum.

I use a roundover bit on the router and it has to be done on a router table, not by hand. The radius of the round over bit depends on the wall thickness of the shell. If the shell is thinner you will have a smaller radius, and a larger radius for a thicker shell. If you aren't savvy with the power tools then you can get reasonably inexpensive hand tools such as a beading tool, or other specialty carving tools to do it by hand. I have made many a woodworking project on the balcony of my old apartment just using hand tools!

The top perpendicular surface can be trued by resting a pane of glass across the top and a level as long as the bottom edge of the drum is reasonably perpendicular to the vertical centreline of the drum. Use a marker to mark the high spots and a block plane to remove the high spots and then plane the whole top surface the same shape before running it over the router.

It's not rocket scientist folks! Just a whole lotta fun!
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Re: Bearing Edges

Postby BMac » Fri Jun 24, 2011 2:58 am

That all makes sense to me. I too have used a block plane to level out the edge of a drum. I agree, a perfect plane for the edge is critical. So I've started by planing, and then moved on to choosing and forming the best bearing edge shape only after a plane is formed. For the pros who have big lathes and jigs for turning a drum, this is all trivial. But to us little guys, hand planes and routers are the tools of choice.

About hand planes: A guy at Highland Hardware in Atlanta really broke things down for me one day, saved me a lot of money, and I am forever grateful. I told him I was ready to buy a plane, and was ready to spend the money ... looking at hand planes that cost between $100 and $300. He asked me if I just felt I needed to buy one of the fancy inlay decorated models. Top of the line hand planes are works of art themselves. They have beautifully hand-carved handles and forward knobs and such. I said "no" ... my interest was purely functional. He steered me toward a little Stanley that only cost about $30. He also told me that the handcrafted and gorgeous but expensive hand planes were set up and ready to use with expertly sharpened blades. But, he said, if I would be willing to get some high grit sandpaper, apply some oil, and lay that sand paper on a glass plane, that I could hone the Stanley blades and polish its glide surface to match the more expensive models. So he showed me all the gear I needed ... an angled blade holder to hone the blade was a key thing that I needed. He convinced me that ultimately, no matter which plane I bought, I would need these other honing items to keep the plane maintained. So unless I just was enamored with the higher end planes, I could keep my $300 and just spend $60 or so and with some patient care, I could get my little Stanley plane to work quite well. What a salesman. He actually talked me down from spending hundreds of dollars. He was right. My inexpensive little Stanley plane still holds honor in my shop. Anybody here who works with wood, if you haven't worked magic with a hand plane yet ... what are you waiting for? I've tried building a sandpaper board to plane off drum heads ... and I gotta tell you ... a sharp and well-maintained hand plane works better and faster. Nothing but a fine lathe will give you a flatter bearing edge than a hand plane.

That is my word.

BMac
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Re: Bearing Edges

Postby Greensail » Sun Dec 13, 2015 11:33 pm

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I know it's been years since this discussion but I've been reading my way through over the last 3 years and just recently read this good discourse. I happened to have my head very loose om my moperc tumba so decided to take it off for a look. As you can see, rounded over on the outside and drops off more rapidly on the inside -similar to the description of matt smith's. See photos.

My LP's are thinner and the profile is fairly symmetrical, rounded ovet egaully inside and out.

The Moperc edge was actually quite smooth but I did use a scuff pad to lightly clean the edge, a touch of lanolin on the inside of the skin, a little rubbed on top of the skin and a few hours in the sun. We'll see how she sings tomorrow. Of course, she was a virtuoso to begin with. I've said it before, I haven't played every drum but it's hard to imagine anything much better than Mopercs. The shell looks perfect and the hardware is phenomenal.

Finally I do some woodworking and echo BMac's comments on the wood plane. A good one is a joy to use. The key is balance of the tool AND especially a VERY SHARP BLADE.
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