New Design Proto Build - Lyra

preeb

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Neck shape is roughed on a pin router using this jig

IMG_20190531_091334.jpg~original



Like that

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The innitial cutting is very close to the final

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but some more shaping and finalizing is required which is mostly done on this combination face/slack belt sander

IMG_20190531_092443.jpg~original
 
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preeb

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The face block sander is used to create the headstock and heel transitions

IMG_20190531_092501.jpg~original


IMG_20190531_092745.jpg~original


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and the headstock back (as well as thicknessing).
The thicknessing initial size is 0.6" and I will finalize later..

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Note the different color of the Cuban Mahogany being densier and darker, here against a Khaya Bone neck

IMG_20190531_101532.jpg~original




The profile (or neck shape) is done on the slack belt area.
This area is very flexible and "giving" but I still do it very carefully and try not to sand the skin off my arms.
I learned this from Marvin Lamb who showed me how he did the 50's Gibson LP's necks back in the day when I met him at the Kalamazoo factory a few years ago.
A lot of the "right" 50's shape and feel comes from this irregular method and it is not as straight and perfect as the modern rolling method which is... well... too straight (-;
A big part of the old necks feel comes from them not being "perfect".

IMG_20190531_101616_1.jpg~original




Only issue is that the sanding is done across the grain leaving horizontal marks

IMG_20190531_125209.jpg~original


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and I need to manually sand it with the grain to remove the cross grain scratches that may become an issue when finishing the guitar later on..

IMG_20190531_125650.jpg~original




Once the neck is shaped I tune the headstock tap tone. The way to do this is by holding (pinching) the neck at the nut location and tapping the headstock.

IMG_20190531_130636.jpg~original



A big part of the tone is coming from the headstock which is basically a plate at the end of the neck.. I slowly remove material from the back until I get the desired tone and level.
For the Lyra I'm going for a lower and deeper note to match with the semi hollow body to emphasize the warmth and depth of the rich lows.
I ended up at about 0.5" which is 0.1" thinner than the Bone line spec (0.6") and you can see the difference here

IMG_20190531_130502.jpg~original



Looking nice...

IMG_20190531_130528.jpg~original


IMG_20190531_130532.jpg~original
 
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preeb

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Next step is exposing the trussrod adjustment access hole.
I manually cut the step in the tenon. From the board end down first

IMG_20190531_134137.jpg~original



and then bellow the hole level

IMG_20190531_134218.jpg~original



Like that.. the cavity will accept the brass ring that will hold the spoke wheel rod adjuster

IMG_20190531_134257yb.jpg~original



At this point I check the neck again for any warping or irregularities after the shaping and all... and both necks are straight as an arrow.
Time to glue them to the bodies and I will be using hide glue for that jointing.
Kaking sure there are no gaps and that all the glue has squeezed out without excessive tightening of the clamp

PANO_20190531_134733.vr.jpg~original


IMG_20190531_134743.jpg~original



I let it sit horizontally for a few minutes to avoid the glue from dripping from the end of the moprtise gap..

IMG_20190531_134750.jpg~original



and then hang them for at least 48 hours to fully cure and to allow all the moisture to evaporate (no need for more than 48 hours in Arizona (-; )

IMG_20190531_135646.jpg~original


IMG_20190531_135650.jpg~original




Next week I will continue with the PU cavities and the heel area shaping... Shabat Shalom!
 
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scmavl

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Those look amazing, Gil. If you're pleased with the final outcome and one is not spoken for, please let me know. We tried to meet up when I was in Phoenix a couple of months ago, but our schedules didn't quite line up (so you'll remember who I am.;-) ).
 

Jay Jernigan

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Absolutely awe inspiring. This coming from someone whose skill set is "partscaster" at best, but still, uncanny work on any level.
 

preeb

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Time to rout the PU cavities. The Lyra will come with a few PU options: PAF, AirGap3, P90, AirGapP90 and the newly designed Lyra PU if it will turn out well ( I will get to that later in this thread).
Both protos will share the same PU type so it will be easy comparing the two different tops with the same PU's.


True center line extended from the neck with this jig. PU cavities should be completely aligned with the strings but I'm less concearned with the STP alignment because the margins are very small (+-1mm) so I drill the STP before the neck is glued along with the rest of the top drills.

IMG_20190603_075858.jpg~original



Here you can see how the STP drills are also accurately aligned

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Lyra receives longer than usual STP stud inserts to firmly hold the extra leverage of the studs resulting from the floating top design

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Ground wire inserted

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Note how the enlarged top hole is clearing the stud to allow for the top to vibrate freely

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Inserts are pressed all the way into the mahogany core section of the body

IMG_20190603_080820.jpg~original


IMG_20190603_081112.jpg~original




Testing the fit and clearance of the STP

IMG_20190603_081041.jpg~original




PU's are routed at the same angle as the neck with the same triangular jigs used to rout the mortise

IMG_20190603_082300.jpg~original





I zero the CNC to the actual center line

IMG_20190603_082459.jpg~original




and cut the PU cavities to PAF HB size

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preeb

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The heel section and the cutaway transition roundovers are next.
I start by sanding down the body oversize areas down to the fingerboard line

IMG_20190603_110828.jpg~original



like this

IMG_20190603_110835.jpg~original




the back will transition by curving down to the neck heel.

I sand it down with the oscilating sander

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leaving just a thin ledge

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and continue manually (and carefully...) with a block sander

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like that

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Next I file the cutaway roundover transitions with a Japanese curved file cutter

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IMG_20190603_114555.jpg~original
 
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telepraise

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Amazing work preeb! Your artful design and flawless execution are world class. Your superb craftsmanship combined with gorgeous woods has me dying to see them with finish on them.

I'm curious how you came up with the concept of taptuning the top and back to eachother. I'm a crossover from the acoustic world and have built several archtop mandolins. In fully hollow archtops, the top and back are never tuned to the same note to avoid sympathetic wolftones. Some even go so far as to tune the treble and bass side of the sound board 50 cents apart.

Thanks for posting such a detailed and well-illustrated thread, those of us who build are fascinated and impressed. Can't wait to see and hear these proto's!
 

GunsOfBrixton

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When you cut the mortise and pickup cavities using the triangular wedge, do you account for the fractional movement forward of the routes (due to the angle) in your tool paths or by actually sliding the whole body just a bit forward? Or do you not worry about it?
 

preeb

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Amazing work preeb! Your artful design and flawless execution are world class. Your superb craftsmanship combined with gorgeous woods has me dying to see them with finish on them.

I'm curious how you came up with the concept of taptuning the top and back to eachother. I'm a crossover from the acoustic world and have built several archtop mandolins. In fully hollow archtops, the top and back are never tuned to the same note to avoid sympathetic wolftones. Some even go so far as to tune the treble and bass side of the sound board 50 cents apart.

Thanks for posting such a detailed and well-illustrated thread, those of us who build are fascinated and impressed. Can't wait to see and hear these proto's!

Thanks.
I never tune them to the same note but rather match them. It is all a trial and error journey for me... Like dog breeding, I keep the measurements that end up with a better instrument and keep trying to get better and better. I set a starting point and document every build with all the tunings and measurements so I can compare over time and once I hit a sweet spot the model is finalized. I wish there was a mathematical method to design the perfect guitar.. LOL.. it will never happen TMHO.
As to this Lyra project, the tuning is mostly based on my arch top model the Bone Voyage and I feel very confident with the initial Lyra design. At this point the guitar is complete with pretty satisfactory tap tones to say the least... So like yourself, I can't wait to string it and strum it for the first time. It's like a new born child to me (-:
 

preeb

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When you cut the mortise and pickup cavities using the triangular wedge, do you account for the fractional movement forward of the routes (due to the angle) in your tool paths or by actually sliding the whole body just a bit forward? Or do you not worry about it?

I worry about everything... Too much and all the time unfortunately (-;
CAD models are done with every possible consideration I can think of. I do it all in Rhino and test every CAM output a few times until the cutting is perfect.
For the mortise or any other angled jig holder I design the CAD normally and then tilt the entire model in Rhino before exporting and working the CAM and eventually running the code on my CNC.
Hope that helps...
 

GunsOfBrixton

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I worry about everything... Too much and all the time unfortunately (-;
CAD models are done with every possible consideration I can think of. I do it all in Rhino and test every CAM output a few times until the cutting is perfect.
For the mortise or any other angled jig holder I design the CAD normally and then tilt the entire model in Rhino before exporting and working the CAM and eventually running the code on my CNC.
Hope that helps...

I figured you had it covered someway. Just was wondering what method you were using.
 




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