Acoustic Guitar Construction

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Construction Log for KMG J45-Style Dreadnought

https://acousticguitarconstructionforum.com/viewtopic.php?t=983

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Construction Log for KMG J45-Style Dreadnought

Posted: Sat Mar 02, 2013 9:27 pm
by dave d
Introduced by Gibson in 1942 as one of the dreadnought acoustics to compete with Martin's 'D' line, and often referred to as "The Workhorse."

Peruvian Walnut back and sides, Sitka spruce top, abalone rosette, cherry/walnut laminated neck.
Setting up the mold with the template.
Setting up the mold with the template.
DBD_7370.JPG (114.92 KiB) Viewed 7519 times
Make sure the template is centered.
Make sure the template is centered.
DBD_7372.JPG (70.39 KiB) Viewed 7519 times
Post is placed near the innermost waist curve.
Post is placed near the innermost waist curve.
DBD_7375.JPG (81.8 KiB) Viewed 7519 times
Sides are placed in the mold and marked at the centre line for cutting.
Sides are placed in the mold and marked at the centre line for cutting.
DBD_7381.JPG (80.21 KiB) Viewed 7519 times
I use my bench-hook and a japanese pull-saw to cut the side at the marked location.
I use my bench-hook and a japanese pull-saw to cut the side at the marked location.
DBD_7384.JPG (76.97 KiB) Viewed 7519 times
Sides placed back in the mold to check for fit.
Sides placed back in the mold to check for fit.
DBD_7386.JPG (63.39 KiB) Viewed 7519 times
Drill a couple of holes for the nails to hold the sides in place when you are gluing.
Drill a couple of holes for the nails to hold the sides in place when you are gluing.
DBD_7393.JPG (71.78 KiB) Viewed 7519 times
Neck block being clamped to the sides.
Neck block being clamped to the sides.
DBD_7397.JPG (76.79 KiB) Viewed 7519 times
A little bit of glue squeeze-out is a good sign.
A little bit of glue squeeze-out is a good sign.
DBD_7399.JPG (77.48 KiB) Viewed 7519 times
Neck and tail blocks glued to the sides.
Neck and tail blocks glued to the sides.
DBD_7404.JPG (57.63 KiB) Viewed 7519 times

Re: Construction Log for KMG J45-Style Dreadnought

Posted: Sat Mar 02, 2013 10:11 pm
by dave d
On to the next steps: kerfing and profiling.
After wetting and pre-bending the kerfing, it is glued to the top side of the rim.
After wetting and pre-bending the kerfing, it is glued to the top side of the rim.
DBD_7410.JPG (86.38 KiB) Viewed 7512 times
The top edge is lightly sanded with a sandpaper-covered piece of stock so the edge has a flat plane.
The top edge is lightly sanded with a sandpaper-covered piece of stock so the edge has a flat plane.
DBD_7411.JPG (85.98 KiB) Viewed 7512 times
The rim and neck/tail block are all in a flat plane.
The rim and neck/tail block are all in a flat plane.
DBD_7419.JPG (32.42 KiB) Viewed 7512 times
The sides are flipped over so the top is facing down, and the kerfing is glued to the back side.
The sides are flipped over so the top is facing down, and the kerfing is glued to the back side.
DBD_7427.JPG (71.97 KiB) Viewed 7512 times
Kerfing shown on both the top and back sides.
Kerfing shown on both the top and back sides.
DBD_7430.JPG (90.66 KiB) Viewed 7512 times
Cedar reinforcing pieces are glued to the sides.
Cedar reinforcing pieces are glued to the sides.
DBD_7435.JPG (74.89 KiB) Viewed 7512 times
Profiling the top: Take a measurement using feeler gauges at the front part of the neck block.
Profiling the top: Take a measurement using feeler gauges at the front part of the neck block.
DBD_7443.JPG (73.62 KiB) Viewed 7512 times
Transfer the measurement to the collar on the spindle. This is the distance the sanding bar will drop to when the neck angle is properly profiled.
Transfer the measurement to the collar on the spindle. This is the distance the sanding bar will drop to when the neck angle is properly profiled.
DBD_7444.JPG (59.78 KiB) Viewed 7512 times
Photo showing neck block mid-way through sanding. Pencil marks gauge your progress.
Photo showing neck block mid-way through sanding. Pencil marks gauge your progress.
DBD_7446.JPG (56.11 KiB) Viewed 7512 times
Side view of the mold, showing the angle that the neck block is sanded to.
Side view of the mold, showing the angle that the neck block is sanded to.
DBD_7454.JPG (58.98 KiB) Viewed 7512 times

Re: Construction Log for KMG J45-Style Dreadnought

Posted: Sat Mar 02, 2013 10:32 pm
by dave d
Profiling the back, and getting the abalone strips into the rosette channel.
now to put the 15' radius on the back edge.
now to put the 15' radius on the back edge.
DBD_7460.JPG (62.24 KiB) Viewed 7510 times
I like to check the fit of the back on the rim, just to get an early look even though the bracing isn't on yet.
I like to check the fit of the back on the rim, just to get an early look even though the bracing isn't on yet.
DBD_7463.JPG (54.3 KiB) Viewed 7510 times
The sitka spruce top.
The sitka spruce top.
DBD_7468.JPG (48.73 KiB) Viewed 7510 times
Trial fit of the abalone strips and purfling.
Trial fit of the abalone strips and purfling.
DBD_7476.JPG (55.65 KiB) Viewed 7510 times
Sealing the rosette channel with lacquer to prevent the CA glue from seeping into the spruce and turning it a weird color.
Sealing the rosette channel with lacquer to prevent the CA glue from seeping into the spruce and turning it a weird color.
DBD_7477.JPG (62.7 KiB) Viewed 7510 times
Everything back in place and CA wicked in.
Everything back in place and CA wicked in.
DBD_7480.JPG (54.03 KiB) Viewed 7510 times
Scraping to level it out with the top.
Scraping to level it out with the top.
DBD_7484.JPG (83.28 KiB) Viewed 7510 times
Scrape scrape scrape. Be careful to not tear the spruce when going across the grain.
Scrape scrape scrape. Be careful to not tear the spruce when going across the grain.
DBD_7486.JPG (75.41 KiB) Viewed 7510 times
Rosette done for now.
Rosette done for now.
DBD_7500.JPG (110.57 KiB) Viewed 7510 times

Re: Construction Log for KMG J45-Style Dreadnought

Posted: Sun Mar 03, 2013 12:14 am
by Dave Bagwill
Thanks for posting Dave, I never get tired of watching a building log. The macro tips were good also.

Re: Construction Log for KMG J45-Style Dreadnought

Posted: Tue Mar 05, 2013 2:40 pm
by ken cierp
Awesome!!! As usual. Very enjoyable to follow -- Thank you

Re: Construction Log for KMG J45-Style Dreadnought

Posted: Tue Mar 05, 2013 11:48 pm
by Jackspt28
Beautiful work!! Like the bench hook for trimming the sides, will have to use that idea! Thanks for posting. Jack.

Re: Construction Log for KMG J45-Style Dreadnought

Posted: Wed Mar 06, 2013 2:08 pm
by Kevin in California
Coming along very well in deed. You have to love abalone rosettes!

Kevin
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