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Nov 22, 2024 - 7:20:47 PM
131 posts since 12/9/2018

I have recently bought, what I would consider a rare Bacon Special Grand Concert 5 string banjo built around 1915. I think it warrants a reasonable investment to rescue it from impending doom.

Right now, I am focused on replacing the fretboard which is broken, rotted and rutted. I am trying to gather enough information about the options to make a good decision on how to proceed.

Because all of the original MOP inlays appear to be present, I would think that "re-setting" the existing inlays in a new fretboard would be an option. If there is someone tuned into this topic that has experience with the pros (assuming there are some) and cons (assuming there are not too many) of this approach, I would appreciate your comments.

The other option that would seem reasonable would be to find reproductions of the inlays and have someone inlay them into a new fretboard. I have done a quick search for someone that can supply a set of reproduction inlays but because of the rarity of the banjo, I wasn't able to find anything available "over-the-counter". If anyone out there knows where I might be able to find a supplier I would appreciate your comments.

Lastly, does anyone know of a method of converting a photograph to a CNC file format (.DXF ?) that can be used to drive a CNC router to generate new inlays that closely match the Vintage shapes?

Thanks in advance for any suggestions you may have. I can't imagine that this problem has not been solved in the past.

Edited by - UTM on 11/22/2024 19:23:06

Nov 23, 2024 - 10:13:59 AM
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898 posts since 5/29/2015

If you have the old inlays they can certainly be reinstalled. Cutting original pearl is quite a job, after the inlay has been cut, installing old/new inlays is quite doable with a little practice and a dremel tool on a router base.

As a note to anyone DePaule Supply has numerous inlays for many of the old 1900ish banjos.

Nov 23, 2024 - 6:52:39 PM

131 posts since 12/9/2018

Thanks Rob for the information. I have stumbled on to a process for converting photos of the original inlays into a digital file type that can be used by some CNC routers. I have to work thru the details but I think it is doable.

Nov 24, 2024 - 4:22:38 AM

4798 posts since 9/7/2009

Here's a device that you may want to consider. It's called Shaper Trace. I have one but have as yet not actually used it to engrave or route anything.

Shaper Trace

Here's a video of how to use it.

Introduction to Shaper Trace

Nov 25, 2024 - 3:51:45 AM

131 posts since 12/9/2018

Thanks Marvin. I took a look at the Shape Tracer devise that you mentioned. It seems pretty ingenious. It does look like a perfect tool for reproducing these Vintage shapes.Their ad on Amazon stated the it would take about three weeks to get one. The price seems vary fair but I'm kind of up against a bit of a deadline and the learning curve looked substantial to me.

As I mentioned, I had already found a website that does conversions of photos into a couple of different common CNC file formats. I have a CAD system capable of importing the .dwg format, so I took one of my photos and had it run thru their system. It took only an instant to convert it to a file I could manipulate in my CAD system.

It was a really tedious process, but I was able to 'clean up' their file and got it in shape to send it along to a guy that is willing to give it a try. If it works for his equipment, he can reproduce the inlays and cut the fretboard pockets and set the new inlays. He says it will take him a few days to 'test' it to see if it will work. If it works, it looks like it will take me about 20 hours of additional preperation work to get the full set of fretboard inlays ready.

Nov 28, 2024 - 1:53:55 PM

207 posts since 3/3/2008

I've been pretty happy with lighburn's image tracing feature. I believe that Inkscape has a similar feature also.

m.youtube.com/watch?v=5RVKw608J7U

wikihow.com/Trace-an-Image-Using-Inkscape

Nov 28, 2024 - 4:30 PM

131 posts since 12/9/2018

Since my last post, I found by trial and error that photos from the newest I Phones really work well. Using the I Phone images has reduced the time required to 'clean up' the .dxf files by about half.

The .dxf files that I sent to the fellow with the CNC router to test "worked great" with only minor tuning on his part. It looks like I have a workable process but I still have a ton of hours to complete the conversion of all of the fretboard inlays.

Experience has shown that as become more familiar with the conversion process, I'll stumble onto ways to speed thing up even more.

Dec 11, 2024 - 8:12:02 PM

131 posts since 12/9/2018

I thought I would close out this topic with a final update. I have completed the "conversion" of the digital photographs of the Bacon inlays into a type of CAD file format called .dxf. This file type is compatible with my CNC programming software.

I have generated the programs required to very accurately reproduce the c.1915 Bacon banjo inlays that I need. I am now in search of someone with a CNC router to use my programs to actually cut the MOP and the fret board pockets. I think this might just work out!

Thanks again for your thoughts and suggestions.

Edited by - UTM on 12/11/2024 20:13:13

Dec 11, 2024 - 10:15:58 PM

121 posts since 8/23/2022

UTM. I have worked with customer supplied scans and I have not found them very accurate for precision machining. I do a lot of CNC machining (I have 11 CNC's). I have found the scans are best for reference and then adjusted with secondary precision measurements.

I would try just a piece or two to make sure that the fit is good.

Dec 12, 2024 - 6:03:27 AM

131 posts since 12/9/2018

Hello Scott. Thanks for the reply. Being semi-retired from CNC machining trade for about ten years now, I 'm am sure that the explosion in manufacturing technology has probably been harnessed to this wagon in ways that I can't imagine.

You mentioned that you have CNC machines. Are they high speed routers that could machine MOP? If you were interested I could send you a file (.dxf format) to mess with to see if it would be useful to you.

The geometry is generated by what was called 'curve fitting', 'best fit' or 'curve rendering' back in "...the day..." (1980 to 2100 ish). It was a tedious time consuming manual process that required hours of staring at a computer screen picking a little bit of pepper out of a lot of salt; so to speak. It was the only alternative in some projects. To me it was an interesting part of my job. Kind of like sorting out the pieces of three puzzles that were all mixed together.

Thanks for your reply. Contact me if you might be interested in doing the machining.

Edited by - UTM on 12/12/2024 06:06:24

Dec 15, 2024 - 4:21:38 AM

15149 posts since 2/7/2003

In a perfect world reusing the inlays sounds great, in reality you could be in for amazingly bad surprises, there is no way knowing how thin those inlays are, they could very well be paper thin after a century

Dec 16, 2024 - 4:14:42 AM

131 posts since 12/9/2018

Scott, thanks for your comments. I did consider the 're-use' option for a few minutes in the beginning of this project. I tried 'steaming' the fretboard to see if it would loosen the glue. It seemed to be working but I could see almost immediately that I lacked the experience to deal with all of the uncertainties, so I started looking for other options. At this point it seems to have been a wise choice to replicate the inlays and install them in a new fretboard.

I'm still 'grinding' on the possibilty of attaching a high speed router spindle to on my CNC milling machine so that I can do the machining myself. That option has several large 'warts' too!

Dec 28, 2024 - 5:16:27 AM
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131 posts since 12/9/2018

I would like to offer 'another' final update to my project. I have committed to giving the DIY option a try.

I ordered and received a 25,000 RPM air cooled spindle motor and the "inverter" required to control it from Amazon. I have completed the process of attaching it to my industrial CNC milling machine that will actually provide the motion required to cut the abalone inlay material and the new fret board pockets and fret slots. The wiring was pretty straight forward and the spindle runs like a top.

I have ordered and received the .022" and .031" diameter carbide end milling cutters and the 'collets' required to mount them in the high speed spindle.

I have completed a specialized 'outdoor' dust collection system with an auxiliary HEPA grade filter to grab the dust (I estimate that there will be about 1/4 of a teaspoon for the whole project). Between the dust collector and a good dust mask, I think I'll be plenty safe from the nasty dust particles.

I have completed the 18 CNC programs required to replicate the original Bacon inlays and the new fret board pockets so I have officially run out of excuses not to get started.

As a 'final' comment on this 'final' update; IF I AM SUCCESSFUL, not counting the 60 hours (so far, with at least 60 hrs to go !) of labor, I will have slightly more than an ABSOLUTELY RIDICULOUS amount of money invested. BUT, I will have the satisfaction of having explored the long and winding road that is the "...longest route from A to B...". Who could resist that temptation. The "EXPERIENCE" alone will easily be worth spending 10 times more than it would have cost to have a professional do it; .....RIGHT?

Edited by - UTM on 12/28/2024 05:28:08

Jan 6, 2025 - 10:58:09 AM

136 posts since 5/4/2010

That's my motto : never the easy way. Good luck. I'd love to see the results.

Jan 6, 2025 - 7:13:15 PM

131 posts since 12/9/2018

Thanks for the encouragement Brad. I started messing with this project in mid November and today I finally got some results. I machined the first fret inlays (3 pieces) and they turned out really nice. I have all of the fixturing figured out and I should be able to finish the inlay machining and hand finish work in a couple of days.

I got the Ebony fretboard blank ordered today from Allied Lutherie Supply, so it will be here about the time the inlays are completed. Everything is ready for the machining of the inlay pockets so a couple of additional days should put me in good shape to start fitting the inlays.

Jan 7, 2025 - 4:40:49 AM

pfolmar

USA

82 posts since 4/13/2004

UTM, I took an inkscape image and sent it to custominlay.com. Bryan England did an incredible job of getting things cut out for my custom inlay. He should be able to do the same for you if he’s still around. His email is bryan@custominlay.com. 270-879-0779

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