I'm not disputing what you said. I think 6 string guitars, with the smaller strings and higher pitches, are more prone to buzzing at the nut. there's probably more room for error with a bass.
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Converting an Acoustic Guitar to a Bass, and String Selection
- Thread starter CTGull
- Start date
Gotcha. I think I misunderstood what you said before. Yes, even with the makeshift files it seemed like I needed to be more precise with guitars. Fortunately, I found a deal on a relatively complete set of used files so it’s not an issue now.
Wrong—
I build lots of stuff— have a complete workshop— metal, wood, and electronics.
I build multimillion dollar process lines for a living.
There’s a lot of craftsmanship and science to make an acoustic instrument that will play and sound good. And not self destruct.
COOL!! I'm a Tool Designer by trade. Mostly fixtures and gages, but I've worked on a few 6 figure robotic assembly machines. I probably have a lame incomplete version of your workshop, but I also have a Toolroom at work that occasionally makes me stuff. I'm just experimenting and having some fun. It'll probably end up as an interesting wall hanger. But as long as I learn something it'll be worth it. I've learned a lot in the last 2 days and I'm sure I'll learn much more. I'm working on designing an adjustable bridge (that fits in the outline of the existing bridge) with a brass tailpiece. I'll post a picture later tonight.
This might be a stupid question. Is there any reason I can't open the upper & lower tuner holes and plug the middle ones?? I might need a string tree to keep the back strings off the front strings and give the strings some break angle. I'm just trying to not have to plug all 6 holes and add a new head plate to cover the damage. At that point, I might as well strip the whole neck. I may do that anyway. There are some large shallow dents in the back of the neck, about 1/16" at its worst. The neck is 50 year old mahogany. And there's some lacquer chipped off on the side of the fretboard. I was thinking of stripping the whole thing and refinish with teak oil, as I did on the Yamagull. It's more of a sealer than a hard finish, there's no build up, you apply/wait/apply/wait/wipe/let dry for a day. It's nice an smooth and looks great, it's just not the shiny lacquer or poly finish everyone is used to.
Here's the existing bridge. It'll be removed and new one made to fit the existing footprint.
Here is the horrible rendering of my first version of the adjustable bridge. No screws to adjust the saddles, just put them where they intonate. I wonder when you tension the string the saddles will move forward. Carl Thompson seems to build them loose like that. Invalid Link Removed
Yea I know the curved brass tailpiece is going to a pain to make, assuming I can get the Toolroom to do it. I could make a straight one and mount it behind the bridge. I did some checking for a trapeze tailpiece and I'm only finding 1-3/4" string spacing max. Based on the width of the fretboard, the string spacing at the saddles will be 2". I'd kind of like it to look like the old guitar, without a bunch of stuff added, like a brass tailpiece. Do I go with bridge pins?? Or thru holes??
I did some research on scale length compensation. This site has plenty of "over your head" stuff. Including this page. Liutaio Mottola Lutherie Information Website It allows you to select nylon and steel strings, scale length, and action. It puts numbers in for the core diameters, which we don't know, so you have to assume the resulting values will be close but not exact. BUT, it does give you an idea of the compensation change from nylon to steel string. AND, if you change the action numbers it makes a HUGE difference in the required compensation for steel strings. I used 0.08" & 0.11" for the action. If you go with the values they drop in (0.141" & 0.172") the steel string compensation is about a half inch more than required for the nylon strings. But with the action numbers I put in, the compensation is somewhere in the middle.
So based on the numbers I put in, I think the picture above is a semi-accurate representation of where the saddles will be for steel strings on this guitar, based on the action mentioned above. I think the saddles are far enough from the holes in the tailpiece to not have too severe a break angle.
Here's the existing bridge. It'll be removed and new one made to fit the existing footprint.
Here is the horrible rendering of my first version of the adjustable bridge. No screws to adjust the saddles, just put them where they intonate. I wonder when you tension the string the saddles will move forward. Carl Thompson seems to build them loose like that. Invalid Link Removed
Yea I know the curved brass tailpiece is going to a pain to make, assuming I can get the Toolroom to do it. I could make a straight one and mount it behind the bridge. I did some checking for a trapeze tailpiece and I'm only finding 1-3/4" string spacing max. Based on the width of the fretboard, the string spacing at the saddles will be 2". I'd kind of like it to look like the old guitar, without a bunch of stuff added, like a brass tailpiece. Do I go with bridge pins?? Or thru holes??
I did some research on scale length compensation. This site has plenty of "over your head" stuff. Including this page. Liutaio Mottola Lutherie Information Website It allows you to select nylon and steel strings, scale length, and action. It puts numbers in for the core diameters, which we don't know, so you have to assume the resulting values will be close but not exact. BUT, it does give you an idea of the compensation change from nylon to steel string. AND, if you change the action numbers it makes a HUGE difference in the required compensation for steel strings. I used 0.08" & 0.11" for the action. If you go with the values they drop in (0.141" & 0.172") the steel string compensation is about a half inch more than required for the nylon strings. But with the action numbers I put in, the compensation is somewhere in the middle.
So based on the numbers I put in, I think the picture above is a semi-accurate representation of where the saddles will be for steel strings on this guitar, based on the action mentioned above. I think the saddles are far enough from the holes in the tailpiece to not have too severe a break angle.
If you plugged and enlarged 6 to 4, you wouldn't be the first. Don't know why that would be any problem.
Now, regarding your bridge design - brilliant. Every acoustic bass bridge design in production should be like yours. [except your end tail design can/should be wood, too.] Fantastic. Submit that for a patent.
Thanks. I'm not sure it's patent worthy. I like your wood tailpiece idea. I used brass because it is stronger and Carl Thompson used it. But it would be very difficult to make in a home shop. I copied the whole concept from him but adapted it to the old bridge footprint. I'll have to research a suitable hardwood that would look good and match the bridge. The fretboard is very beautiful 50 year old rosewood. I definitely want that to be visible. I think ebony is harder. Maple certainly is. But maybe I'll make the tailpiece out of rosewood and add 2 laminations of brass, as Carl did here. That will prevent the strings from splitting the tailpiece. I'll just have to wrap the brass around the wood. I should cut strips and laminate the rosewood too, I'll be a lot stronger. If this ends up sounding like crap at least it'll look good hanging on the wall!
A quick laminated tailpiece. Not sure how to put countersunk holes in the assembly. Maybe tomorrow.
My gut would lean to "trapezing" your tailpiece rather than screwing it to the top - add some other holes and cable it back there like an upright tailpiece so it's (mechanically) talking to the tailblock, not just the top. Just my gut, not an actual "voice of experience" on this point.
That's certainly a consideration and would be the way to go if I didn't want it to look like the original guitar. There are 2 braces very close to the location of the 2 screws that will hold the tailpiece to the top. I'll also add a "bridge plate" to reinforce the area. Another option is a JLP Bridge Doctor type device, which is a small block of wood that mounts under the bridge and has a small dowel that presses on the internal tailblock. I bought one a few years ago and make my own smaller hardwood copies. I've put them in a couple of 12 strings. The bridge will never tip!
Here's a new version. SolidWorks can't add holes to an assembly (WHY???!!!) and doesn't like adding holes to a multi-body part.
I sure wish Every builder would use your sliding saddle concept. Fanfriggintastic. What a joy it would be to fine tune intonation on acoustics.
That is an interesting concept for a bridge. The only thing I can see is that it might be somewhat tall? I'm guessing you may end up resetting the neck, possibly a decent amount?
OH YES! It needs a serious neck reset. Right now the neck projects 3/16" below the top of the bridge. I like to see 1/16" above, this guitar will probably need to be 1/8" above. This is typical of 50 year old guitars. So far I've done 10 neck resets on these old Yamaha's.
The biggest pain of this bridge will be needing to make saddles of various heights for the final setup. And put some string grooves in them. I'll probably make them out of rosewood, maybe maple, but it would be real cool to make them out of bone! Wood first, make sure the whole thing works before getting fancy with bone.
Especially when you change to different strings! You've done lots of experimentation with strings. Steel flat wounds must get sharp quickly of a fretted 25" micro bass since they were designed for nylon core only.
My thought, FWIW, would be to make a tallish set of saddles out of maple or some relatively inexpensive hardwood and file or sand to height as needed then, when you have decided on strings and setup, make the final saddles out of bone. Which is probably what you were planning.
My thought, FWIW, would be to make a tallish set of saddles out of maple or some relatively inexpensive hardwood and file or sand to height as needed then, when you have decided on strings and setup, make the final saddles out of bone. Which is probably what you were planning.
We're all maniacs. I was just thinking through something like that and then I came here and saw more dialog.
My idea is the saddle is a wood post with graphite roof screwed in. Height gets adjusted by turns of the roof into the post.
How about an adjustable height and adjustable angle STRAIGHT saddle? Similar to an archtop, but with 2 runners in grooves in the bridge. It would allow adjusting the height at both ends of the saddle, and a small adjustment on the angle. I'll try to model something up tomorrow. I don't think I have enough height in this guitar for that kind of setup.
I've made some progress on the YamaBass. I have a thread in my vintage Yamaha forum that's the most up to date. I'll add a thread here sooner or later. YamaBass!!! | Yamaha Vintage FG Acoustic Guitars
It took a couple of days to sand all the finish off the neck. I plugged the middle tuner holes and opened the 4 outer holes. The heel ended up a lot worse than I thought, 1/4" short!! So I cut it shorter to remove most of the distorted part, and added about 5/8". Check out the details on the thread above for now.
Today I realized I won't get very far on the neck reset until I know about what the saddle height will be. So I went back to working on the bridge design. While the individual wood saddles are cool, there's no adjustability. I'd have to finish the neck reset, make some saddles, and hope I'm close and alter or make new saddles until I get the action right.
So I came up with 2 new bridge designs. In both versions I changed the tailblock to solid maple, for simplicity. I also looked to see if I could buy a bridge and steal parts from it. Not really. Standard bridges have a 2-1/4" total string spacing, or about 19mm between strings. Mine has to be 2", or about 17mm, due to the width of the neck. I still need to do a layout. All I need is to add a few more hours to the day.
The first design is similar to a conventional bass saddle design, with adjustable height round saddles. I have to make all this stuff, it's a little complex, and I'd like to see more wood and less metal. The large area that is 1/16" thick would have to be a separate piece of wood or metal, that probably wouldn't look good.
The second bridge is the 1 piece wood saddle I mentioned earlier. I made a replacement adjustable bridge assembly for 1954 Harmony Monterey archtop a couple of years ago. I found the replacement thumbwheels that I can also use here. This version is much simpler than the individual saddles. I'll add some grooves to locate the strings.
ONE VERY IMPORTANT THOUGHT. BOTH OF THESE DESIGNS PUT THE TOPS OF THE SADDLES AT ABOUT 5/8" FROM THE TOP OF THE GUITAR. That is about 1/8" higher than a guitar saddle. I could tip the neck back further during the neck reset, or I could add a 1/8" shim under the fretboard extension and lift the whole neck up 1/8".
I also have another idea to eliminate the maple tailblock and make the bridge similar to an Ovation where the strings anchor to the bridge as they pass thru the back thru holes. I think that would big and ugly, but it's an option and would probably be simpler. I'd have to keep the break angle down to keep the strings from popping the top of the bridge off. That'll be the next version.
THOUGHTS?????? SUGGESTIONS?????
I really need a solid bridge design before I can go too much further.
It took a couple of days to sand all the finish off the neck. I plugged the middle tuner holes and opened the 4 outer holes. The heel ended up a lot worse than I thought, 1/4" short!! So I cut it shorter to remove most of the distorted part, and added about 5/8". Check out the details on the thread above for now.
Today I realized I won't get very far on the neck reset until I know about what the saddle height will be. So I went back to working on the bridge design. While the individual wood saddles are cool, there's no adjustability. I'd have to finish the neck reset, make some saddles, and hope I'm close and alter or make new saddles until I get the action right.
So I came up with 2 new bridge designs. In both versions I changed the tailblock to solid maple, for simplicity. I also looked to see if I could buy a bridge and steal parts from it. Not really. Standard bridges have a 2-1/4" total string spacing, or about 19mm between strings. Mine has to be 2", or about 17mm, due to the width of the neck. I still need to do a layout. All I need is to add a few more hours to the day.
The first design is similar to a conventional bass saddle design, with adjustable height round saddles. I have to make all this stuff, it's a little complex, and I'd like to see more wood and less metal. The large area that is 1/16" thick would have to be a separate piece of wood or metal, that probably wouldn't look good.
The second bridge is the 1 piece wood saddle I mentioned earlier. I made a replacement adjustable bridge assembly for 1954 Harmony Monterey archtop a couple of years ago. I found the replacement thumbwheels that I can also use here. This version is much simpler than the individual saddles. I'll add some grooves to locate the strings.
ONE VERY IMPORTANT THOUGHT. BOTH OF THESE DESIGNS PUT THE TOPS OF THE SADDLES AT ABOUT 5/8" FROM THE TOP OF THE GUITAR. That is about 1/8" higher than a guitar saddle. I could tip the neck back further during the neck reset, or I could add a 1/8" shim under the fretboard extension and lift the whole neck up 1/8".
I also have another idea to eliminate the maple tailblock and make the bridge similar to an Ovation where the strings anchor to the bridge as they pass thru the back thru holes. I think that would big and ugly, but it's an option and would probably be simpler. I'd have to keep the break angle down to keep the strings from popping the top of the bridge off. That'll be the next version.
THOUGHTS?????? SUGGESTIONS?????
I really need a solid bridge design before I can go too much further.
Here's the next bridge design. Eliminated the tailblock. No color. I quickly banged it out at work.
The angle of the holes should take the strings right to the top of the saddle. Same 5/8" top of the saddle height, 1/8" higher than a 6 string guitar.
COMMENTS???? SUGGESTIONS?????
The angle of the holes should take the strings right to the top of the saddle. Same 5/8" top of the saddle height, 1/8" higher than a 6 string guitar.
COMMENTS???? SUGGESTIONS?????
