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.