Polymaker

Hi @Kaiser Matt, Thanks for the info and the picture. I finished the guitar back in august. You can see the build on this thread.

Sorry for the lack of updates, the past few weeks have been busy! I used 90% of my spare time to work on the guitar and the rest of the spare time was spent planning my upcoming trip to Los Angeles (I'm leaving Saturday morning ) So I have the pleasure to announce that the guitar is finished! My dad was overjoyed and almost shed some tears when I gave it to him! The guitar sounds and plays great but there are two small issues that I'll fix after my trip. First, the bridge pickup is too far from the strings. I designed the guitar before receiving the bridge and I assumed that the surface-mounted pickups were the tallest things... Turns out the minimum height of the bridge is too high and I had to shim the neck to adjust the break angle, So I will make a plastic shim/riser for the bridge pickup. The other thing is that the tone circuit needs some adjustment because the difference between the different modes is very subtle.. I used the capacitor values from the schematic on the website I found (see older post) and since the build was a bit rushed to reach my deadline I didn't have time to play around with other values, Here are some shots of the final guitar:

I am a bit slow on the updates because I currently spend all my spare time working on the guitar. I planned to give the guitar to my father at his wedding anniversary that is tomorrow... Fortunately, we will celebrate their anniversary the next weekend so I may be able to finish it in time. Here are the outlines of my progress (picture will follow after): Last week I made a custom tailpiece for the vibrato. I'm still not sure how it will attach to the vibrato though Last Friday I stained the guitar. I had some issues with the spruce top, it does not behave like maple and I had to sand back the top and restart. The burst is still a bit "blotchy" to my taste but I did not want to sand back a second time and I think it will look good anyway, Up until last weekend I was still not sure what to do with the headstock logo. Do I put my logo or do I replicate the saturn logo? Since the model name is Saturn, I had to use that logo but I was not sure how to do it. I did not have the time to order a custom waterslide decal. The other solution was to draw it by hand with a silver paint marker, but I thought it would be too difficult. In the end that's the method I used. To help draw the logo, I taped to the headstock the printed logo, then I lightly cut a line thought the center of each letters with an scalpel. Then I had to just follow the scratches with the marker. I did some tests and my wife had a steadier hand than me so it's her that did the logo on the headstock. For the logo on the pickguard I did also try to draw it by hand with a marker (a couple of weeks ago) but I wasn't pleased with the results. I was also not sure how to do the numbers and letters on the control plate. Finally I found a small engraving company nearby and I will laser engrave the acrylic pickguard and diamond engrave the aluminum control plate. They should be ready later today. Finally I have put the clear coats on the body and neck last weekend. I also sprayed another guitar that I built last summer. * As for the pickguard logo, I changed the headstock logo a bit. My last name is Turner so I changed the number 63 for "er" so it reads "Saturn er" * The neck for the Saturn is not on those photos because my wife was drawing the logo while I put a first coat.

I made some progress last weekend I installed the frets and shaped the back of the neck. It still needs some more sanding. I also finished carving the inside of the top. You may able to see in the picture that I left untouched the area were the vibrato unit will rest on the top. What you might not see is that I also left a 'lump' under the bridge. I originally planned that both the bridge and vibrato areas would rest on the 'center block' since I did not want to use bracing as in a traditional archtop. The main reason is that the acoustic properties are not a priority for this build and I wanted to keep the build as simple as possible. But even though the acoustics are not a priority, I still would like that it had at least some acoustic volume if possible. So that's why I changed my plan and removed some material under the bridge. I don't know if it will change much in the end but at least there is some room for the top to vibrate and it should still be sturdy enough. Some variations of the Saturn 63 had a kind of chrome ridged molding on the side of the guitar. I found an aluminum molding that looks very similar at Home Depot. Sadly it was only available in gold but someone in a review on the product page said that he used muriatic acid to de-anodize it because he needed to have it in silver. I will give this method a shot. Does anyone knows if it needs to rest for a long period of time in the acid or can I apply-it with a brush? I also thought that it could be easier to apply the acid if the molding is pre-shaped instead of a long flat bar. I feared that it could crack when bending around 'sharp' corners so I used a blowtorch to heat-it up a little and it went well.

@curtisaThanks for the thorough break down of the circuit! I thrust your explanations but to my (basic electronic) knowledge, low-pass and high-pass filters uses a combination of a resistor and a capacitor, but in this circuit there is no resistor except for the "rhythm" circuit that can be bypassed. Since pickups have high resistance, do they act as the resistors?

Yes it is! Also you can't really see it from theses pictures but I used flamed maple for the back to match the original. And thanks to you I also have the closest thing to the actual bridge that was used I used a slab of basswood between the spruce top and maple back to get the proper body thickness. Hollowing-out a ~2" slab of maple seemed a bit ridiculous and expensive Since the burst get solid black on the edges it won't show that there is three layers of wood.

I finally started to work on the replica I want to build for my Dad. It was about time because I plan to give it to him on his wedding anniversary that coming early August Here is my CAD model and bellow are some progress pictures: * I changed the logo on the pickguard to spell my father's name instead of "Hopf". I kept the same style of calligraphy. I recently found a schematic for the mysterious 4 positions rotary tone switch but I can't figure out how it works. I'm trying to reproduce it in CircuitLab and it don't seems to work like intended. Maybe someone could help me break it down? I can't figure out how there is only one resistor for a band pass and also I don't understand where ther "R. M." switch comes from.

@Bizman62 You made me realize that the dial is a separate part under the volume knob. I had the impression it was some kind of skirt like this.

@Drak I'm so in shock I have difficulty typing this message Simply WOW! I cannot believe it. A million thanks for your generosity! I have no words.

@Drak Thanks for the info! And you are right I totally missed that the short scale-length was because it is an arch-top, I knew that but I didn't connect the dots for this guitar I completely agree with your point and like I said before, I'm not looking to make an exact replica. I was ready to try my hands at making an arch-top but I wanted to know for sure how it was built before going that route. Now that I know that it is some kind of weird hybrid, I'm definitively taking the simpler approach. My CAD drawing was already made with a center block design in mind. To not pollute this thread with images of other guitars, here is a link to an imgur gallery with the 3 guitars that I have built so far. Also, I presume you don't have the third ovation bridge on hand... It would be great to find one like this. The bridge I got for this build is the one on the recent reissue by Eastwood. I bought it when I first started looking to build this guitar a few years ago and I did not quite figure out at the time they were so different. Anyway if someone knows where I could get a bridge similar to yours I would be very happy to know. @Bizman62 I now regret buying the stainless tubes... I knew something like this existed but I did not know what it was called. I got this for the larger outer binding and that for the f-holes bindings. Should be a piece of cake to install While at it... if you guys know where I could find similar knobs it would be very much appreciated. I might go for modern chicken knobs but I can't find something close for the volume knob.

This is what I believe also. And that would make the building process a whole lot easier. Thanks for your opinion on the matter!

Thank you both for helping me in my hunt for information! Also I should have mentioned that I'm not looking to make an exact replica, but rather a close look-alike. Like for example, in my design I have changed the body shape to have better access to the upper frets. Also the original has a short scale-length (can't remember or find where I got this info) so I'm making it with the standard 25.5in. I'm also thinking of skipping the arched back for simplicity. But for the most part I try to keep it as close as possible to the original. Now about the construction, some website says that it is a semi-hollow. That would mean that it is not braced but rather it has a center block right? Otherwise should it be braced something like this: (I'm not so sure how the brace should end up around the controls) I don't have much knowledge about arch-tops and semi-hollows and I was wondering how well the tremolo would be supported. Also the bridge looks like it is mounted with tune-o-matic style posts instead of a surface mounted bridge common for arch-top. Would-it need some kind of reinforcement? I know it is common to have a reinforcement plate under the bridge but with inserts for tune-o-matic like posts it would have to be much thicker.

According to your website, this description is for the knob beside the volume. So it is the one labeled: O, I, I+II, II (or 0, 1, 1+2, 2 in decimal) My personal guess (before this information) was 0 = kill switch, 1 = neck, 1+2 = neck + bridge and 2 = bridge. For the other knob with (B- T+B-, etc..) the site describe: "The next rotary seems to be for tone caps but only one position seems to alter the sound." So no luck for this one About the tremolo, I simply think it is a variation. If you look at the pictures of the two sites you linked, they both have different trem and tailpieces. As I stated in my first post, the trem/tailpiece is different in almost each picture I find. As for the binding, I also thought it could be plastic but I don't know what it could be named and where to search. If you have an idea let me know!

Hi guys, I need your help reverse-engineering a vintage guitar. Since I started building electric guitars my dad wanted that I make one of his favorite guitars. It is the "Saturn 63" made by Hopf. It was used by the guitarist of the band "The Cure" (if I'm not mistaken) I always put off making it because it seemed too daunting but now I thing I'm up to the challenge. Since that guitar is pretty uncommon, the info I can find is pretty limited. There is a couple of things that I'm not sure on about how it is constructed. Also the model had a lot of variation, almost each picture I find on Google has different controls and trem system. *To clear things up, there was a recent re-issue by Eastwood (around 2012) but that version is lacking a lot of details. Here is what it looks like: Here is what I need help for: 1# The guitar has an arch top (and back) but I'm not sure if it is fully hollow or semi-hollow. I don't see any braces (from reference pictures) through the large "f holes" and I don't know how they would fit. So maybe the top and back are not carved-out. I lean toward semi-hollow because I'm certain it is not built with bent sides, but don't know if it has a center block or if it is braced. 2# I'm trying to find a tremelo/tailpiece that would look as close as possible. I first thought to use a bigsby but it doesn't quite match the looks. I managed to find a Teisco tremelo that is similar but it does not have a tailpiece. What is bothering me is that the space at the back of the Teisco tremolo is not that high so if I wedge a tailpiece on top of the trem's baseplate I fear it will prevent bending backward. Looking at pictures of the Saturn 63, the top of the trem is resting (relatively) high above the body. here is the tremolo I found 3# The tone control on this guitar looks "interesting". On the plate it is engraved: "B-, T+B+, T+B-, T-" With the addition of a "chicken head" knob, I suspect it is not a simple potentiometer with a capacitor. Could it be a 4-way rotary switch? Also the guitar is certainly passive so I'm not sure how the bass and treble boost works (T+B+, T+) 4# I'm not sue how I'm gonna make those chrome tube bindings. I found stainless tubes with 0.5mm wall thickness that should be bendable. But I'm not too confident on how to bend them and mount/glue them. That sums up pretty much what I am missing. Any additional detail that you could find is appreciated. To the moderators: Now that I think of if, the post might be more appropriate in the "Solidbody Guitar and Bass Chat" sub-forum. If it does please move it there. Thanks.

I found the issue and I just released a new version. This version also includes some improvements and new export options.

I've just tested it and having equal spacing at the bridge has less effect than at the nut. Since the spacing is larger at the bridge, the offset is proportionally smaller (moving a string by 1mm at the bridge is less apparent than moving by 1mm at the nut). I didn't mean to imply this, I was just saying that even if the error caused by equal-spacing is not considerable, it is still added on top of the variation produced by playing. One way of fixing the deflection when fretting a note on multiscale layouts would be to use "à la" true temperament frets:

@Prostheta I'm not entirely sure I understand what you ask but I also had the impression that the errors induced by equal spacing could be compared to the variation induced by fretting, but my current view is that equal-spacing won't make you fret more precisely... So in theory you are inducing more error when using equal-spacing. It may be possible in some case that they cancel-out but I'm not sure. Using (slightly) curved fret on mild multiscale layout would greatly help intonation. But I think that even normal multiscale and up (e.g. 25"-27") are greatly affected by the variation induced by deflection from fretting whether using equal-spacing or not. Back to the difference between equal and center spacing, here is an example of a mild-extreme bass layout: The top layout uses equal-spacing at the nut, the bottom one use equal center-to-center. As you can see, the last three frets in the top layout are curved because the points are not straight enough for the tolerance used in the software. You can also see the red lines I was talking about (the lines are made up from the points generated by the 12th root of 2) In the bottom layout (equal-center) they all are centered with the frets, but in the equal-spacing you can see that there is a considerable offset.

I do something similar to you. When extruding thin line to the actual fret thickness, the sides of the frets don't match the taper of the fretboard. So I used to extend all the line manually, extrude them, then trim them to the fingerboard. This is the main reason why I made the option when exporting, but while at it I made it so you can trim them shorter for those who want to do "blind" frets with a CNC. This is a thing I discovered while developing my software. In theory, straight frets are not accurate, not because of the true temperament stuff but just due to the fact that since the fretboard has a taper the strings are not perpendicular to the frets. Now in practice this is not very noticeable and can be adjusted at the bridge, but when combined with equal spacing and large gauges it displace the strings enough to make a good difference in length and it is more an issue with multiscale layouts. This made me realize that the direction you bend a string on a multiscale fretboard will drastically change the sound. Since the fret is at an angle with the string, the fretted length will change considerably when bending up or down the string. For multiscale layouts, my software tries to adjust the bridge position of each strings so all their centers are aligned at the 12th fret. This does help but do not solve all the issues. I made an option to see the accurate fret positions. It is not available by the UI but you can set it in the config file. Open the file located at "%AppData%\SiGen\AppConfig.json", find the entry named "DisplayAccuratePositions" and set it to true. It will show a red line over the frets where their correct position should be. Also in extreme cases the frets will be splines (curves) instead of straight. This is an artefact of the support for true temperament fret.

Yes it is calculated. You may have missed my previous post where I explained it. Changing the tuning and physical properties in the SIL file will have effect on the generated layout. Here are the values that are used to calculate the fret compensation: The unit weights (named UW in lbs./ inch). The default values are from d'Addario data. The modulus of elasticity (named MOE in GPa). The default values are based on what I found on the internet. The core wire diameter (named CoreWireDiameter). The values are the same as the gauge for unwound strings but for wound strings I estimated the values. The action at the first and twelfth fret (both values are in a tag named Action). The tuning (tag named Tuning).

You're in luck! Like I mentioned, the calculation requires a lot of variables and I haven't found yet a proper way to input them. To achieve such result at the moment you need to manually edit a saved ".sil" file (with notepad). Here is a quick how-to: Create a new blank file and save-it. The default file template has actually most of the values needed for TT. Open the created file in notepad. You will see a tag named "Temperament", set "ThidellFormula" as the value Now set the "FretCompensation" tag value to "true" The next step is required for accuracy but opening the file now will produce good enough result. For the string index "0" in the Tuning tag. add CentsOffset="-1" For the string index "1" in the Tuning tag. add CentsOffset="-1" For the string index "2" in the Tuning tag. add CentsOffset="4" For the string index "3" in the Tuning tag. add CentsOffset="2" For the string index "5" in the Tuning tag. add CentsOffset="-2" Now if you want to play around you can change the values contained inside the "Properties" tags under each strings. If you have no idea of what I'm talking about I've attached a demo file True Temperament Example.zip

It is designed for Windows. On the release page you can find 32-bit (x86) and 64-bit (x64) installers (.MSI). Just download the setup and install like any other windows program. The only issue is that Windows 10 security will popup when installing, warning you that it came from internet. Just click advanced and check install anyway (or something like that I don't remember exactly). In the beginning I wanted to make this software cross-platform (for Linux and OSX) but I had trouble finding a cross-platform UI library that could do what I wanted. Documentation is also on my to-do list. There is a bunch of features and functions that are not obvious (like the preview can be zoomed and dragged with the scroll-wheel and double-clicking the scroll-wheel resets the view). I plan to make a basic wiki on the project page in the near future, but I'm currently planning my wedding so I'm a bit busy to say the least This is also parts of why I rushed to complete this project because I did not want for it to get in the pile of unfinished side projects that I have

@curtisa Sorry if it was not clear, but it is based on the actual calculation. What I meant is since there is many variables (string action, modulus of elasticity, core wire diameter, desired frequency, etc) the results I get at the moment is not quite like the pictures I see (I supperpose my result over a picture of TT). I found an interesting paper that explain how to calculate the fret compensation. * I can no longer find it on the website but I managed to find it again with internetarchive and if you want to look I've put it on my google drive. I'm mostly sure that the differences I get are caused by the values I'm using because for most I've used what I could find on the internet but the paper suggest calculating them with actual strings. But since I cannot validate my result I am not able to determine if the differences comes from the inputs of if my calculation is flawed. About TT (the brand), it is actually a combination of fret compensation and compensated temperament. The fretted notes are based on the "equal" temperament but some notes are offsetted by a few cents according to the Thidell formula. The fret compensation in itself is only to compensate the string displacement when fretting a note. Like you said, it is used to get closer to equal temperament because it is what TT uses but it can be applied to any temperament. I had this in the back of my mind for a long time and made me doubt if it would be useful at all to be able to generate compensated layouts . But one way I see is to CNC a mold and cast the frets yourself. It is not easy work but should be doable and it is probably what TT does.

Hi folk! I just wanted to let people know that I released a software to generate stringed instrument layouts (aka fingerboard). It is called SiGen and stands for Stringed Instrument layout Generator. I started this project a long time ago and I finally have something that is complete enough to be used by everyone. The software allows a lot of customization through simple inputs/parameters and can export layouts in DXF or SVG. I started this project originally only to have a tool that could handle both metric and imperial values at the same time, a frustration I had with a free tool on the web. But after building the base engine to generate a fretboard layout, I realized that I had an open playground to experiment and that there was a lot that could be added. Then I used this project to try to understand something that was fascinating me since I first saw it: fret compensation (aka true temperament). After many research and experiments, I managed to develop something that could produce close enough results to the pictures I found on the web. Sadly, since calculating frets compensation requires a lot of values and physical properties, the app does not allow yet a way to input all those values but the core functionality is implemented. For the moment it is required to manually edit a layout file to be able to generate a layout with fret compensation. Fully integrating this functionality is in my to-do list. You can get the latest release on GitHub here SiGen latest release If you encounter any issue with the software or have any suggestion you can open an issue on my GitHub project page (if you have an account) or PM me on project guitar. Here is a couple images showing what it can do: 5 string banjo layout Dual scale layout (aka multiscale) Fret compensation On-screen measuring

This is exactly how I figured it out the pickups were inverted. That's reassuring to hear. My friend gave me the pickups after fixing a phase issue on his guitar. He upgraded his pickups a long time ago with Seymour Duncans HB and a DiMarzio SC and position 2 & 4 were not sounding good. When I did the fix I did not understand at all how it was wired. Having fixed a phase issue on my own-made T type guitar (1SC 1HB), I assumed that I needed to invert the wiring on the middle pickup, but from reading recently about coil splitting and complex wiring I had second thoughts if it was the right problem/solution. Also thank you for all the information, it is very useful and much appreciated.

Hi guys, I've been given an HSH pickups set not too long ago and while I already finished designing the guitar I'll used them on, I still haven't decided on how I'm going to wire-up the pups. For this build I want to understand what I'm doing instead of blindly following a wiring diagram. Electronics has been my nemesis for a very long time and now I decided to take the time to try and understand how it works. I already learnt quite a bit while finishing my pickup winder last month (I'll make a topic on that as soon as I get my new motor, I fried-it like a rookie when trying to measure the current ). Just today I finally solved the mystery of coil-splitting. I couldn't understand how the coil that stays on was different on the neck and bridge while the wiring is the same for each. Many diagrams do not show properly that the neck humbucker is flipped (or the bridge idk) so the coils are opposed to each other. Now to get back on topic, I have two questions regarding coil split: First, how do I figure out with which coil (adjustable or slug) the middle pickup will hum-cancel. I've read that it has to do with how the pickups is wired/wound and so it can vary from one band to another, Second, this one is a thought I had that I think may be crazy or may not work at all because I couldn't find anything on the internet. Normally, from what I understand, when combining the middle pickup with a coil-split humbucker, they are wired in parallel right? Is it possible to wire them in series to make a virtual humbucker? How would it sounds like? Is this crazy? For information the pickups are from an early 2000 Ibanez S model.