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| Harmony arch top restoration http://www-.luthiersforum.com/forum/viewtopic.php?f=10137&t=41433 |
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| Author: | ernie [ Wed Sep 18, 2013 11:49 am ] |
| Post subject: | Harmony arch top restoration |
I have an older harmony , that needed restoration work.Since I find these older guitars funky an cool I slimmed down the clunky hog neck , and replaced the bowed walnut FB, tailpiece was rusted , tuners kaput, My question the dovetail mortice was also loose.The body is abt 15in wide at lower bout.It is made from hog plywood. Does anyone know what angle the neck should be in relation to the body?? Benedetto/s book says 4.5 deg? Anyone out there worked on one of these?? . How does one calculate the neck to body angle?? .It also had a ebony adj archtop bridge which is new Thank you.. Sorrydon/tknow how to take pics an post them. |
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| Author: | cphanna [ Thu Sep 19, 2013 3:51 pm ] |
| Post subject: | Re: Harmony arch top restoration |
Hi, Ernie, Your question is about one of those things that is not too hard to do but a little difficult to describe. You really want to find the string path, but that can be estimated by shooting a line from your fret tops to the bridge location. Put your neck back in its socket temporarily and see if you can clamp it or snug it with shims so that the heel of the neck is tight to the body, and fully seated in its mortise. Then lay a straight edge along the center line of your frets (I used a long metal ruler on its edge the last time I did this). Make sure the ruler is touching as many of the frets as possible, and that it extends out over the top to a point above where the bridge will rest. Measure the distance from the bottom edge of your straight edge to the top at that point. It should measure somewhere around 7/8" or 1". (Benedetto specifies one inch, but a slight variance is probably okay). If you have an adjustable bridge, that height should get you in the neighborhood. What you just measured was the height of your bridge IF the strings were touching the very tops of the frets. Obviously, you'll want your bridge to be a little higher than that when it is on the guitar and fully strung up. If you arrive at such a measurement, you can probably clean the old glue off your dovetail mortise and tenon surfaces, shim the joint for tightness and re-glue. If your measurement is much smaller or larger, you will need to alter the neck angle accordingly. The specific angle you need is one that will give you a good, playable string path, and that angle can vary with the shape of the top, height of its arch, etc. Benedetto's angle is a good working angle and it works for him because he can consistently carve his tops to the same arch. Couple of other suggestions: If your neck didn't have an adjustable truss rod, you could probably add one now--or even make a replacement neck. You said you shaved off a lot of its thickness, and I suspect that was there for strength, and that your original neck doesn't have a rod. While re-fitting your neck, also be very careful to keep it aligned with the center line of your top. This is especially true if you need to change the angle of the heel joint. It's pretty easy to keep them straight, but also easy to accidentally get them cranked to one side or the other, so keep an eye on that critical alignment. I like these old guitars, too. Many years ago, I was given a plywood Regal, literally in pieces. I made a new neck for it in the manner I've just described, and re-assembled the body. I still have it and it's a good playing old axe. Not a fine guitar, you understand, but a cool old axe that's easy to play. I know this is a wordy response, but I hope it helps you. Good luck! Patrick |
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| Author: | ernie [ Fri Sep 20, 2013 7:42 am ] |
| Post subject: | Re: Harmony arch top restoration |
Thank you vy much for the detailed explanation. I was planning to use this one with nylon strings , so did not rout truss rod, but added an O. orange FB which stiffened everything up considerably .Will replace the rusty tailpiece with a benedetto style O O . one. I will go back and make a dummy bridge from scrap to simulate the string heights I am looking for abt 3mm on treble an 3.5mm on bass. Will type out your detailed e- mail and use it to calculate the heights , guess I should add abt .020 .030 for string pull as well. |
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| Author: | cphanna [ Fri Sep 20, 2013 9:19 am ] |
| Post subject: | Re: Harmony arch top restoration |
Ernie, glad I could help you a bit. I am not able to lend any further advice about nylon strings, but I know Benedetto, John D'Angelico and Bill Moll have built nylon stringed instruments with arched tops. It should be an interesting experiment, and be fun to do. It might have a rather quiet voice, depending on a lot of factors, but that's okay, too, as long as you enjoy it. Good luck with the whole thing. Post some pictures when you're finished and let us see it! Patrick |
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| Author: | ernie [ Fri Sep 20, 2013 9:36 am ] |
| Post subject: | Re: Harmony arch top restoration |
Thanks , I was going to use this harmony as a model for future builds So want to get the numbers right. And occassionaly try to play a few funky jazz chords. When I did it originally I screwed up the angle, and it/s off center by 1 or 2 degrees, so I bought one of those center finders to realign the center . I measured it at the bridge it/s only 1/2in high. So will steam the neck off and take off material from the bottom of the heel until I get the magic 7/8in .Will use the ebony adj. bridge and will follow your instructions regarding shimming the joint . If it touches the frets and lands on the bridge at 7/8, that when strung up , it should be vy close to that 1 in marker you suggested . Once again thanks for all your help , it is much appreciated. Will get my wife to post the photos I will do it here when it gets done . Have to make a new tailpiece too. |
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| Author: | cphanna [ Fri Sep 20, 2013 6:28 pm ] |
| Post subject: | Re: Harmony arch top restoration |
Hey, Ernie, Just to clarify, Benedetto specifies 1" measured from the straight edge to the guitar top. This is not his string path. His string path is higher. However, I still think a little variance is okay, because your Harmony's top probably won't have the same contours as a Benedetto top. One other thing (and I'll admit this is a pure hunch): With nylon strings, you might need a little more down force over the bridge to power the top. Ergo, you might want a bridge saddle that is a little higher to create a slightly sharper break angle for the strings over the saddle. A higher bridge would require a slightly greater neck joint angle to keep the strings playable over the frets. Again, it's just a hunch, but it might help you calculate where your neck angle needs to be. I'm sure some of you other guys have experimented with this. I wish you would chime in and give Ernie the benefit of your experiences--whether or not your experiments were successful. Now that I've chimed in to this extent, I'm pretty curious about the use of nylon, too. I've seen those guitars and ukes, but I've never seen their specs posted anywhere. Patrick |
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| Author: | ernie [ Sun Sep 22, 2013 11:50 am ] |
| Post subject: | Re: Harmony arch top restoration |
The reason we haven/t seen those specs, is that a lot of loofiers are vy secretive abt their trade secrets..Especially in the vln world. Thanks for the tip pat . I/m halfway through the neck removal. This one is only going to be a model for future builds. I won/t actually set it up for playing I just want to get the numbers and angles correctly. |
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