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Posts: 2303
Location: Lake Forest, CA | Thanks, Jonmark and you're welcome.
Getting closer, Patch. After this molding stuff, building a guitar almost seems easy.
Michel,
Thanks. I'd planned to pretty much do it like the factory does with a large mahogany wood block. When I lay up the bowl, I'll add an extra layer of cloth at the neck block area to add strength.
Stewmac sells wood neck blocks, but I'm not sure it has enough height. I'll order one in the future to check it out. Failing that, I'll give JB a shout and see if I can get an OEM bolt on block like they use.
While the bare bowls are pretty flexible on their own, once you glue it to a top it forms a cantilever beam of sorts and gets really rigid. |
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Posts: 2303
Location: Lake Forest, CA | Moving right along.
I'm jointing the top. Once that's done, I'll route the groove for the rosette, then take it over to my sanding buddy for thicknessing. 
I also rough cut the braces. This guitar will be getting an A-brace pattern using torrefied Adirondack spruce. 
One change of plans is that I was going to make this a bolt-on neck. Because the dovetail is so thin, I'm afraid that it would split the heel when I drill it or try to screw in the threaded insert. So, this is going to be a glue-on neck, with the neck glued to an SMC bowl, just like the 1624 the neck came from. |
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Location: Muenster/Germany | DetlefMichel - 2017-12-15 7:43 PM
the structural reinforcements
I ment the arched structures inside on the neck heel, you can see them if you look in an Ovation. Aren´t they necessary to prevent torsion from the neck joint?
And if you want to built a bolt-on neck: My luthier used an incredibly thin CLV board for the inside reinforcement of my 12 string guitar with bolt-on neck (and for my other guitars). This may be better than a solid mahogany block.
(I hate guitars with set necks).
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Posts: 2303
Location: Lake Forest, CA | Ah, now I understand what you meant.
When comparing SMC bowl to a hand-laid bowl, the neck mount on the SMC bowl is quite a bit smaller. The trusses are necessary in the SMC bowl to spread the load of the string tension from the top of the bowl across the back of the bowl.
On the hand-laid bowl, the large wood block does the same thing. Another way to add strength to this area is to add another layer of cloth during the molding process.
Here's a pic of the inside of my 50th. This is a hybrid of the mahogany block and a bolt-on neck.
If you look at the bass bout where the strap mount is located you can see the extra layer of cloth. It wraps around the neck area down into the inner part of the cut-away.
Like I say, the bare hand-laid bowl is pretty flexible until the top gets glued to it. Once the top is joined, the bowl becomes a monocoque structure. I wrote cantilever before, but it's actually a monocoque structure.
Monocoque structures, also known as stressed skin structures, get their strength from the outer shell without any internal supports because they spread the load across the entire skin. (Think of an egg shell)
Edited by DanSavage 2017-12-19 10:14 AM
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Posts: 1249
Location: Texas | I wrote cantilever before, but it's actually a monocoque structure. Just checked with Vegas...the over/under for the # of folks this provided clarity for is at 1...with some heavy hitters betting the under. I thought a monocoque structure was the class of spaceship the Millennium Falcon belonged to.
Edited by jay 2017-12-19 6:35 PM
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Location: Lake Forest, CA | LOL!
Did you google the word, monocoque? |
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Posts: 1249
Location: Texas | No. No need to look up words I can't pronounce |
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Posts: 2303
Location: Lake Forest, CA | Its pronunciation almost sounds dirty. LOL!
Mono-****.
LOL! The dirty word filter won't let me post how it sounds.
Edited by DanSavage 2017-12-19 8:32 PM
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Posts: 3599
Location: Pacific Northwest Inland Empire | A single rooster.
Sift that, Filter Censor!
BTW, nice work, Dan. I understand the principle & physics- just didn't know that is what it's called. |
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Location: Muenster/Germany | Now I see. I did several neck-resets on my old Ovations and I always wondered how the tiny neck mounts should hold up all the tension. It´s not only the strings, but whan I grab my guitar I always have it on the neck, never on the body, and thus there are enormous leverage forces on that point if you simply put the guitar out of the case...Since I have seen (and touched) this small construction inside I handle my Ovations with much more care. Especially when I have my heavyweight 1688 in hands I always remember that 2 screws in a 1,5 cm piece of plastic compound on a 55cm torsion arm...brrrrr...for me that is a nightmare.
Your woodblock joint looks more trustable to me. |
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Location: Lake Forest, CA | I had to acquire a couple of tools to route the rosette channel and cut and round the sound hole.
First step is to measure and drill the indexing hole. Even though it looks off center in the photo below, it's actually on-center for the glue joint. The glue line was caused by the masking tape I used when jointing the top.
The Dremel circle cutter is pretty crude. So I decided to splurge and buy the Stewmac circle cutter. It's pretty nice, but it only cuts to 6" and the rosette for this guitar is ~6-3/8". So, I had to use the old Dremel to route the outside of the groove, then use the Stewmac to route the inside of the groove, the sound hole and round the sound hole.
The sound board is clamped into the routing fixture. 
The outside of the groove has been routed.
Now, switch to the fancy-schmancy Stewmac circle cutter. (All kidding aside, it is really nice)
Inside of the groove has been routed.
Routing off everything in-between.
Test-fit of the rosette --success! 
Route open the sound hole. 
Route a round corner into the sound hole. This will get fine-sanding after the sound board has been thicknessed.
Test-fit the rosette into groove. 
Wet down with naptha to get an idea of how it will look. It's pwetty...
Put the top into the go-bar deck to glue the rosette.
Squirted a bunch of binding cement into the groove, then pushed the rosette in all around. Laid down a disc of visqueen, then a clamping disc made from a scrap test piece.
I'll let this dry for 24 hours, then it'll be ready for the thickness sander. Once that's done, things will start happening pretty quickly.
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Location: Indiana | Pretty rosette. |
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Location: Indiana | Nice job Dan.
Edited by Jonmark Stone 2017-12-30 9:45 AM
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January 2009
Posts: 1249
Location: Texas | Dan, these builds never get old. It becomes clearly evident why they started slapping the rosette on top of the guitars back in the late 60s and continued the practice. Tremendous effort! It is bound to be a stunning guitar. Congrats. |
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Location: Lake Forest, CA | Thanks, Jonmark. Thanks, Jay.
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Location: Lake Forest, CA | I pulled the top out of the gobar deck. I'm happy with how it turned out. It was easy to get very clean edges when routing the redwood. The spruce tends to fray a little bit which requires sanding to clean up the edges. The depth of the groove leaves the rosette just a little proud of the surface. 
Here's a shot of the top and rosette wet with naptha.
I'll take the top to the sanders next week to surface sand the top, then thickness sand it. Then, it's time to rough cut the top and glue the braces.
Once the top is made, I'll glue the kerfed linings to the bowl. Things should start moving pretty quickly now.
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Location: Steeler Nation, Hudson Valley Contingent | Looking over the last posts in detail lifted my spirits a bit after a very tough December. Can't wait to see more! |
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Posts: 128
| Helping Dan with routing the groove for Patch's Parlor was a great experience. We did 4 tests, plus a couple of go-no-furthers. Mostly, I ran the vacuum except on the final cut when I was a human clamp, holding the top down to ensure an even cut. We cut a variety of woods during our tests, and the final cut in Patch's redwood was the cleanest. Whew!
Edited by DarenSavage 2018-01-05 5:47 PM
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Location: SoCal | You mean Dan doesn't get it right, the first time, every time? I'm bummed.....
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Posts: 128
| moody, p.i. - 2018-01-06 4:45 PM
You mean Dan doesn't get it right, the first time, every time? I'm bummed.....
Ha ha! For the tests, no. For Patch's top, yes. I did come away with a pretty cool drink coaster, though.  |
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Posts: 2303
Location: Lake Forest, CA | I got the top thickness sanded yesterday. 
Bowl outline is traced onto the top.
Top is rough but to shape.
Time to start mating the top, bowl and neck. First job is to mock-up the bowl to the neck to fit the top.
Top is fitted to the bowl/neck. Bridge is in its approximate location.
This guitar will be getting the same under-saddle pick-up I used on my Frankenvation.
Bridge location has been measured and hole for pick-up lead drilled.
Matching hole in bridge.
Bridge and pick-up mocked-up.
Brace locations are marked onto the underside of the top.
Braces being glued. I'll let the OBG dry for 24 hours, then glue the aluminum reinforcements.
While that's drying, time to start prepping the bowl to get the top and neck glued to it. First step is to sand the periphery so the kerfed lining can be glued to it.
Soaking the mahogany reverse-kerfed lining in water to help minimize fractures.
After soaking for an hour or so, it's time to start clamping the lining to the bowl to help mold it to shape. Piece #1 is clamped and working my way around the bowl.
Filler piece made from scrap mahogany. I'll let the lining dry for 24 hours. Once it's dry, I'll remove each strip one at a time and glue it to the bowl. 
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Location: Steeler Nation, Hudson Valley Contingent | I've been crazy-sick all weekend. Seeing this update made me feel a little better. Thanks Dan. (And Daren too apparently.) |
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Posts: 2303
Location: Lake Forest, CA | Sorry to hear you've been under he weather, Patch.
Here's a little more of the same good medicine.
I glued the aluminum reinforcements this afternoon. 
Once the aluminum reinforcements are cured, the top is pretty much done and can be set aside until it's time for final fitting.
Time to give the bowl some attention. The kerfed lining is dry. I added a strip of masking tape to the inside of the bowl underneath the lining.
This will do two things for me. First, it'll show me where to stop gluing and second, once I get the lining clamped, I can peel the tape away leaving a clean glue line. 
The linings come off one at a time. I ran a bead of Hysol 0151 on the inside of the bowl, then painted it smooth with an acid brush. Once the glue was spread out, I clamped the lining back into place.
All the linings are glued and clamped. The filler piece is also glued into place.
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Posts: 268
| You can never have too many clamps! |
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Posts: 2303
Location: Lake Forest, CA | Ha ha! Yeah, I actually need to order 10-20 more.  |
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Patch's Parlor Build...
