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| Questions for First Time Cutaway Build https://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=53901 |
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| Author: | Mark Mc [ Thu Feb 25, 2021 4:33 pm ] |
| Post subject: | Re: Questions for First Time Cutaway Build |
Nice job Patrick. That is quite a tight bend at the horn but it looks like you pulled it off very well. |
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| Author: | PatrickW [ Tue Mar 02, 2021 3:38 pm ] |
| Post subject: | Re: Questions for First Time Cutaway Build |
So I am confused at thee moment with my cutaway design and I am full of Novocain after a dentist visit. I mocked up a fingerboard, 1 3/4” nut, 2 1/4” at the body, and the fingerboard hangs over my cut out a 1/4”. My neck block is a 1/4” shorter on the treble. Did I need to offset my fingerboard? Or is it a larger problem? |
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| Author: | J De Rocher [ Tue Mar 02, 2021 3:52 pm ] |
| Post subject: | Re: Questions for First Time Cutaway Build |
PatrickW wrote: So I am confused at thee moment with my cutaway design and I am full of Novocain after a dentist visit. I mocked up a fingerboard, 1 3/4” nut, 2 1/4” at the body, and the fingerboard hangs over my cut out a 1/4”. My neck block is a 1/4” shorter on the treble. Did I need to offset my fingerboard? Or is it a larger problem? The width of treble side of the neck block from the body center line should be 1/2 the fretboard width at the 14th fret minus the thickness of the side. So, 2 1/4" / 2 = 1 1/8" and then subtract the thickness of your cutaway side from that so that the edge of the side falls just under the fretboard. Sounds like maybe the neck block is cut too narrow or maybe the neck block isn't located correctly on the center line of the body? Looking back at your photo of the sides at the bottom of the previous page, is the line on the top of the neck block the center line of the guitar? |
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| Author: | PatrickW [ Tue Mar 02, 2021 5:18 pm ] |
| Post subject: | Re: Questions for First Time Cutaway Build |
I realized that I made my fretboard template 5/16” too wide. Adjusted that and I need to add 2mm to the treble side of the neck block and that will make the cutout proud of the fretboard. Wow! Edit: Jay the line on the neck block is the centerline. |
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| Author: | J De Rocher [ Tue Mar 02, 2021 7:17 pm ] |
| Post subject: | Re: Questions for First Time Cutaway Build |
Phew! I hope you didn't suffer a panic attack. |
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| Author: | PatrickW [ Sat May 22, 2021 9:19 pm ] |
| Post subject: | Re: Questions for First Time Cutaway Build |
So I just closed the body up and will be trimming the back and top overhang. Do I follow the cutting pattern in the picture or do I trim the cutaway different? [img] Attachment: 1ACB9517-0920-4BA9-9B80-3476121A17AA.jpeg [/img]
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| Author: | Woodie G [ Sun May 23, 2021 6:49 am ] |
| Post subject: | Re: Questions for First Time Cutaway Build |
Response to earlier question: A notch in the mold about 1/4" wide and 1/2" in depth allows adjustment of the outer surface of the cutaway side for varying fretboard widths at the body...shim the side in or out with veneer, then use the mold as the caul against which to glue up the neck block. This avoids the geometry or measurement issues (e.g., induced twists; incorrect allowance for side thickness) seen with glue-ups done outside the mold, and is easily accomplished with the right selection of clamps. Leaving a sanding/fitting allowance of 0.005"-0.010" allows some fine tuning of the closed body to get that flush-trimmed neck exactly right. Response to later question: We are still dealing with paper or perhaps electrons, correct? A bit of time with a french curve or whatever curve-generating algorithm your CAD software has available might fair the previous line into the new calculated fret board edge. That said, it is not a bad idea to get the fretboard done in the real and take measurements directly off that object before fixing the neck-side location. A bent cutaway side has enough flex to adjust for minor variation in actual fretboard width and distance to the centerline from the fretboard edge. Further - considering the manufacturing technology available in most small shops, it may be advantageous to get the sides in the mold and clamped as needed, verify the fretboard centerline with the actual fretboard, then fine-tune the cutaway location as needed (one approach to this discussed above). With that complete, mill an oversized-in-width neck block sans any precut neck joint, then fit to the sides. Just before I wrapped up with Greenridge, we had a very pretty instrument in from a very competent builder with the neck off centerline by a bit over 2mm...this pushed the bridge over a bit as well. The only way that this would ever be noticeable to someone not charged with something line a bridge reglue or neck reset would be detailed measurement. I would have thought an off-center soundhole would be necessary for that sort of error, but it seems to be something that very few people would ever notice, despite being glaringly evident when highlighted. My point is that even if you build with the cut in the wrong location, small errors may be addressed by offsetting the neck joint and some adjustment of the bridge in terms of centering. That said, I would not do what one very well known builder did on a guitar we saw in the past year or so: cantilever the fretboard out from the heel end of the neck and over the cutaway (I suspect done after the customer changed their desired fretboard configuration after the body was completed). |
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| Author: | PatrickW [ Sun May 23, 2021 1:20 pm ] |
| Post subject: | Re: Questions for First Time Cutaway Build |
Thanks Woodie for the reply but my question was in reference to trimming the back and top overhang. Do I trim the overhang the same as a non-cutaway or is there a different way to address the cutaway area of the body. [img] Attachment: 7F330AE3-7D54-40D2-91FC-C17C6A84AA31.jpeg [/img]Patrick |
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| Author: | J De Rocher [ Sun May 23, 2021 1:54 pm ] |
| Post subject: | Re: Questions for First Time Cutaway Build |
I've routed off the top and back overhangs on my guitars by routing from the tip of the horn to the neck end of the cutaway. The same path as routing off the overhangs on the upper bout of a non-cutaway guitar. My cutaways are not as deep as yours though so if you want to play it safe, you could rout out from the lowest point of the cutaway so that you are routing "downhill" with respect to the top and back endgrain in both directions. Like this: Attachment: Routing top overhang in cutaway.jpg
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| Author: | PatrickW [ Sun May 23, 2021 4:11 pm ] |
| Post subject: | Re: Questions for First Time Cutaway Build |
Jay thanks, I followed your diagram, no blowout! [img] Attachment: B02DF907-6CCA-4079-8152-E80C03A0BF4D.jpeg [/img][img] Attachment: E89B0438-32F0-4238-871B-4E5B4EEB5259.jpeg [/img]
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