another conversion

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tippie53
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Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
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another conversion

Post by tippie53 »

this conversion is different in that its the first one I am doing that I don't have to replace the top. Instead I am converting the rosette from 28 to 45. This procedure was difficult but not impossible. The hardest part was creating the process.
The first think I had to do was glue in 3 tabs. Then create the hole plate with the center hole. I can use my old rosette cutter. I had to determine what I had to remove and what I had to replace. I did this by, first laying out the fretboard extension and know where the 45 extension was going to fall out in relationship to the hole and rosette location. The 45 had a wider rosette and the hole is placed for all the pearl to fall in the rosette.
So the normal spacing is a.095 rosette ring inner and outer. Here I use .075. The spacing of the rings on the rosette is .115 and .125. So on the conversion I had to change this so the fretboard would not be trimmed too close to the 20th fret. So in the pictures you can see where I removed wood around the rosette and inlaid a ring of Sitka spruce. Then I could route for the 45 style rosette. This is a nut shell may be over simplifying it , but you can see how I did things and why.
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John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
tippie53
Posts: 7011
Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
Contact:

Re: another conversion

Post by tippie53 »

More getting done on this. Many of the repair techniques used on these conversions can be used in other repairs.

With this guitar one issue was some older repairs that were not very well executed. Also there was a cracked bridge plate. So here I can show how I pull these cold. I use a wet sponge and soak the plate. The key here is to make a sponge that is cut to the shape of the plate you want to pull.
Also how wet you make it. They key is wet but not saturated. I want the plate wet not the entire top . So here you can see the plate out of the guitar but how the sponge fits on the plate. I had soaked this for about 6 hr and the back part behind the crack came out. The rest came out this morning after about 18 hrs
I use a small artists pallet knife to get under the top and plate.
DO NOT FORCE
take your time. You will know when its ready , the knife will separate the joint just by slipping the knife back and forth and letting it "cut" the joint. As the plate pulls off the top you will feel it releasing and you can just pull it off the top.
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John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
tippie53
Posts: 7011
Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
Contact:

Re: another conversion

Post by tippie53 »

To replace the back purfling strip is more involved. I use a straight edge and a new bit 3/32. I also use my inlay tool with a die grinder that spins at 56000 rpm. I set the depth to about .080. I measure and set the straight edge and work using a rout cut so the tool is tight to the fence I am using.
I do make some test cuts first so I know I am where I need to be. Once I am happy I rout cut the channel , sand the new purfling to thickness and set it in. Be aware of center lines and TAKE YOUR TIME.
So you can see the old 28 style is removed and the multi color 45 strip replaced it
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John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
TEETERFAN
Posts: 342
Joined: Fri Sep 07, 2018 12:43 pm
Location: Kansas City, MO

Re: another conversion

Post by TEETERFAN »

That is pretty slick! I imagine the maple doesn’t really absorb or wick the moisture really fast, but given enough time the job will be done. Very useful. Thanks!
Kevin Doty
Kansas City
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