Vintage Gon Bops - a new project!

[Thomas Altmann]

I play Schalloch prototype congas generally, but own exactly such a Gon Bops quinto for rumba and comparsa situations. The open tones really whistle up there. For the slaps I have to cramp up my hands, because the surface is so small. Many people have since asked me whether I wanted to sell it, but as a quinto, this model is hard to beat, so I declined the inquiries.

I was stupid enough to round off the bearing edge. That's irreversible. All you could do is cut down the edge, which is uncomfortable, if you wanted to play the drum in a complete set.

As a rule, a sharp bearing edge makes for clean skin vibrations with a lot of overtones. The more surface the head touches, the more actual drum sound is incorporated, and you get more punch. I know this from the drums of the drum kit, and I checked it myself, too. I once bought an old Slingerland Radio King snare drum, and the guy who restored it had filed the edge as sharp as a knife. It sounded like a timbal, but the sound chamber did not play any role anymore. I flattened the edge a bit, and it regained that deep Radio King sound again. So you have to decide which sound components you want to hear from your instrument, and how you want to balance them.

Thomas

[bongosnotbombs]

Thanks for the advice on the bearing edge, I'm still making my mind up on that.

Blango who I got this drum through, gave me a cool little sketch of bearing edges taken from drums he restores, I was gonna start from there.

Attachment: http://mycongaplace.com/forum/eng/uploa ... _edges.jpg

[blango]

Bombs!

I cant draw to save my life, but these were out of my 'minds eye' and not taken from the drums themselves, as it were.

I wanted to patten tony's edge too... oh well

I also have to add, there are a couple of other bearing edges ive seen on Gon Bops from the 80's. - more flat at the top with a larger contact of skin to drum at the top.

My take on the sound - as long as the skin makes a clean 'exit' from the wood rim, and the edge is nice and level, its all good.

I agree with Thomas about how much skin is in contact with the shell effects how much of the shell you hear - ie fatter sound with more solid punch.

But ive reworked bearing edges many a time with very little change in the sound of the drum. (am almost always changing the skin at that point, however)

In my experience, an edge like the one marked 'tony's edge' gives a more fat tone with less ring, as well as being very easy on the hands.

The sharper edges give more of a bell like tone, but ring too easily for me.

I think too much thought goes into the edge, thats why there are so many uncomfortable playing drums out there - over thinking this one.

Tony

[blango]

A tip for reworking a bearing edge thats not even, but mostly level.

turn the drum, skin off, upside down on a very flat and level surface. take a carpenters pencil and hold it flat to the floor, drawing a line all around the edge of the drum.

Rasp the edge flat to the pencil line, and then work the shape from there, with a final light sand with a 2ft 2x4 with sand paper glued to it.

In the end, you should take off only what you have to to make it even and level, so if you have to find a thinner pencil or pen to use, so be it.

Hope that helps,

Tony

[bongosnotbombs]

Ha ha, sorry Tony, it seemed like a good enough drawing to me, and I'm an architect.

I've never had a Gon Bops before so I was curious what the bearing edge looked like.

Anyways, the bearing edge on this drum surely needs some work so it's as good a time as any to have a discussion on bearing edges.

[Thomas Altmann]

Some sketches do not look very different from others, Tony; but I can imagine that your edge produces a funky sound.

Another thing that I think is important is, how much the heads really "float", i.e. how wide (or tight, otherwise) the flesh hoop and crown are in relation to the circumference of the body of the drum. If they are lying too tightly around the body, when you tune it up you stretch the collar of the skin much more than the actual playing surface. This results in what I find a special sound, and an awkward vibration that used to do harm to my hands.

But usually you won't change THAT when you restore a drum. I think most of us would use the hardware that came with the drum, anyway.

TA

[Joseph]

turn the drum, skin off, upside down on a very flat and level surface. take a carpenters pencil and hold it flat to the floor, drawing a line all around the edge of the drum.

Rasp the edge flat to the pencil line, and then work the shape from there, with a final light sand with a 2ft 2x4 with sand paper glued to it.

In the end, you should take off only what you have to to make it even and level, so if you have to find a thinner pencil or pen to use, so be it.

I've reworked the bearing edge on a few djembes, and the trick for making a nice level (even) bearing surface to be shaped, is:
find a nice level flat concrete surface
turn shell upside down (skin off )
Use the concrete surface as your rasp by rotating shell as you apply light pressure downward.
No pencil marks required, and it will be very obvious when entire rim edge has a milled surface
You now have an even surface to shape as desired.


Nifty project ya got there

[taikonoatama]

I've seen a wide range of bearing edges on Gon Bops. The bearing edge on yours reminds me of one I used to have (see pic below), though yours look to be even sharper (and the roughness sure makes it look like GB probably did not do that). I cannot say whether the bearing edge on mine was stock or not, but I can say that it was one of the sweetest sounding rumba quintos you'd ever want to hear - super dry sound. I put a medium-thick Stern Tanning steer hide on it, which may have been enough to calm the ringing you might expect - it had no ring, just a wonderful sound all around. I'm still kicking myself that I sold it cheap to a friend who fell for it big time - I miss that drum. On mine, that sharpness was done in a way that did not overly impact the outer bearing edge - it was still rounded enough there and easy on the hands. Yours, on the other hand ... yeah, you've got some work to do there.

James



Edited By taikonoatama on 1202434588

Attachment: http://mycongaplace.com/forum/eng/uploa ... quinto.jpg

[blango]

Hey James,

Cool, that's the 80's, more flat edge to which i was referring. Ive only seen these three edges on a gonbops, myself. unless it was reworked by a previous owner - as is the case here with this drum.

Has anyone seen any other edges they think came from the GB shop?

Thomas,

Yes, the drawings are similar, but so are the edges. There are differences for sure. Valje has a more sharp, yet rounded edge than the rounded gon bops. My edge feels more comfortable than a gonbops for sure, but the lack of clarity is most likely due to my lack of drawing skill.

Joseph,

The using the cement as a rasp idea is a bit schetchy for me, but if it works for you, cool. I like the control of a hand held rasp.

Tony



Edited By blango on 1202438674

[taikonoatama]

I've reworked the bearing edge on a few djembes, and the trick for making a nice level (even) bearing surface to be shaped, is:
find a nice level flat concrete surface
turn shell upside down (skin off )
Use the concrete surface as your rasp by rotating shell as you apply light pressure downward.
No pencil marks required, and it will be very obvious when entire rim edge has a milled surface
You now have an even surface to shape as desired.

I've done the same sort of thing, but the flatness of the concrete in my laundry room was a bit debatable, so instead I used a big flat piece of granite tile that I have (which is quite smooth, and perfectly flat) and I put a full sheet of very rough US 60 grit sandpaper on that, put the drum upside down on that and, while holding the sandpaper in place with one hand (or a friend's hands) slid and rotated the drum across the sandpaper. Takes a little experimentation to get the technique right, but it's effective for getting that top edge on a even plane, and then you can do further work with a rasp and more sandpaper.

James

PS. I was just over at BNB's for a sesssion tonight and saw his drum. The shell is in good shape, without any major cracks, but that bearing edge is a disaster. Obviously not the work of Gon Bops. It's in major need of a re-planing - it'll probably need to be taken down 1/4" (6 mm) or more to get rid of the all the undulations the happy rasper put in.



Edited By taikonoatama on 1202493167

[blango]

here is the big sister, even more ugly...

Attachment: http://mycongaplace.com/forum/eng/uploa ... y2_001.JPG

[blango]

dont get too close, she may kiss you



Edited By blango on 1202490725

Attachment: http://mycongaplace.com/forum/eng/uploa ... y2_002.JPG

[blango]

and after the repairs and the reworked edge... ready to finish

Attachment: http://mycongaplace.com/forum/eng/uploa ... d_008t.jpg

[bongosnotbombs]

I like the sand paper on a tile idea, I bet I could tape the sandpaper to something flat and then just rotate the conga till the bearing edge is nice and flat.

After that I guess I'll just reconstruct a new bearing edge.

I'll probably lose between 1/8' - 1/2" in overall height, but I don't think that's significant.



Yeah, thats the other half of this pair of drums.

What glue did you use Tony?

Are you going to keep those brass bands?

I'm gonna ditch them except for the bottom one which I'm going to try and improve.



Edited By bongosnotbombs on 1202493255

[taikonoatama]

Double-sided tape would make a lot of sense here.

Also, I've found that, depending on the size and weight of the drum, it's sometimes easier to have the drum upright and the flat granite tile with the sandpaper on it lying across the top, and then moving the granite tile/sandpaper across the drum rim instead of the other way around. With the drum securely held, you can really go at the sanding and level it off in no time, and the weight of the granite helps to keep the whole plane of the head level.



Edited By taikonoatama on 1202494487