Ukulele nut intonation fixer

thingiverse

Bought a cheap ukulele that doesn't sound in tune after tuning it? Don't worry, there are lots of reasons that could happen, but this replacement nut will fix one of the reasons. Intonation is the accuracy of the pitch of the instrument, and I'm here to guide you through fixing it. First, let's check if this will help. Tune your ukulele while pressing a fret, instead of on an open string. If most of the fretted notes are in tune within a couple of cents, but the open string is out of tune, this replacement nut will fix that problem. My first experience with fixing intonation was through a blog post suggesting jamming a toothpick next to the nut. That did a surprisingly good job, but this is a step better because by the time you're done, each string can be customized to perfect tuning. Tools -------- This replacement nut was designed using OpenSCAD and will give you the best results if you just install it, rather than trying to use the Thingiverse customizer. Open the file, edit the parameters as directed below, and then press F6 to render, and F7 to export to STL. Then slice away! Customizing the Nut ------------------ The odds of this fitting your ukulele and fixing everything are slim. The concert uke I have is the Cordoba Protege U100CM, and the soprano is the super popular Mahalo Rainbow Series, so if you have one of those models, it might just work for you. However, I'm guessing this is a per-ukulele problem (maybe even per-string manufacturer?) otherwise it wouldn't be necessary and they would ship with good intonation. You'll need to remove the old nut (obviously?), and in the case of the Cordoba Uke that involved prying it off with a utility knife because they glued it on. When prying, try to prefer damaging the nut over the wood, since you will be replacing the nut. Please be careful, and don't do any damage you'll regret. String tension is enough to hold the replacement in place, and the Mahalo came unglued. It will really help to have a 3D printer with a high layer resolution, like an FDM printer with a layer thickness of 0.1mm or lower, to get accurate string grooves. Variables ---------- The string height is determined by str_z. The default value of 1.27 mm is good for both my ukes and comes from a quick search for ukulele setup. The cut_slope is the angle the strings go down, so that the string is held taut at the edge of the nut. Finally string_ff is some fudge added to the string diameter to make sure the cutout is large enough to actually hold the strings. Printing -------- This is a really short print. It is oriented so that the greatest accuracy (x/y) is in applied to the string grooves. This means the overlap section of the nut is only as accurate as the layer size. A finer layer size will give more accuracy and also make a smoother curve, which is why I printed at 0.1mm for the final version. Note: This text has been modified to fit within the character limit while maintaining its original meaning and structure.