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Jan 20, 2025 - 1:50:40 PM
105 posts since 3/24/2004

I have a 2009 Gibson RB-75 JD Crowe model that I just noticed doesn’t have a Gibson stamped flange. Did Gibson always use Gibson-stamped flanges around this time? Wondering if a previous owner might have lifted the original.

Any help is appreciated.

Thanks!

— Jeff


 

Edited by - BanjoDaddy2000 on 01/20/2025 13:53:47

Jan 20, 2025 - 4:24:39 PM

GStump

USA

624 posts since 9/12/2006

Hey Jeff - I am not 100% sure on this, BUT I have in fact heard that every once in a while for whatever reason, (most of the time I suppose Doehler, or the company that was supplying the flanges in the late 90's thru the 2000's) Gibson did in fact obtain some flanges from other sources. NOW - It is also my understanding that at that point or by that time, Gibson actually owned (I am not positive on this) the tooling / die to make the "Gibson USA" stamped flanges, but I suppose at times the die had to be taken out of service for cleaning or refurbishing. There were times over the last 20 years or so that Gibson was producing banjos that that 1 (one) die simply could not keep up with demand.

Jan 20, 2025 - 4:36:18 PM
like this

3385 posts since 1/16/2013

They should, but they don't.

Jan 20, 2025 - 6:36:27 PM

105 posts since 3/24/2004

Thanks Gregg and Jim, appreciate it!

— Jeff

Edited by - BanjoDaddy2000 on 01/20/2025 18:36:48

Jan 20, 2025 - 8:46:16 PM

RB3

USA

2264 posts since 4/12/2004

The flange shown in the photo of the original post is not made in a "stamping" process, it's made in a process called "die-casting".  Typically, die-cast components are made from alloys of aluminum or zinc.  In the process, molten metal alloy is injected under high pressure into a steel mold. Below is a YouTube video that shows a part being made on a die-casting machine.

Die-casting
 

Edited by - RB3 on 01/20/2025 20:51:05

Jan 21, 2025 - 11:47:37 AM

JackGrave

Czech Republic

35 posts since 11/22/2022

I have heard rumors that some fairly recent Gibson banjos have their hardware supplied via Jaroslav Prucha from Czech republic. On his web pages is article mentioning how they made direct copy of pre-war Gibson one piece flange.
Jack

Edited by - JackGrave on 01/21/2025 11:48:02

Jan 21, 2025 - 2:30:40 PM

RB3

USA

2264 posts since 4/12/2004

JackGrave,

Thanks for the heads-up on the Prucha website. I found the narrative about tooling up to make the reproduction flange to be interesting. I was surprised that they used a "reverse engineering" method with an original pre-war flange to determine the dimensional information for their new flange. There are Gibson Pre-war banjo enthusiasts who have copies of the original, Gibson, engineering drawing of the one-piece flange, so Prucha's job would have been much easier if he could have obtained drawing copies from those who possess them. Reverse engineering can be a perilous process, because the dimensions you measure on a sample part may not be the dimensions intended by the original part designer.  Below is a link to a BHO discussion that includes an image of that drawing.

Gibson One Piece Flange Drawing

Jan 22, 2025 - 11:24:46 AM

JackGrave

Czech Republic

35 posts since 11/22/2022

@RB3 any time. And I have question: Does exist something like online (preferably) archive for expired patent drawings (blueprints)? I would love to obtain one for Grover Pick holder, because I have sadly mised one which was on sale here on BHO.
Jack

Jan 24, 2025 - 12:30:16 AM

15151 posts since 2/7/2003

This topic has been covered here on the hangout in detail in the past, so to restate the facts.

The original doehler tooling needed rewworking about half a dozen times during its life, an expensive undertaking, the last time it needed reworking in the 1990s, the casting tooling was removed, packed up and trucked to California, when Gibson got the estimate for the work they said NO. From that date all one piece flanges were sourced elsewhere and have no doehler casting marks. The original casting tooling sits to this day in a back lot in California. source Greg Rich

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