Even fretless fingerboard levelling tips

[Wizzu]

I resurrect this thread since it's the very best on this subject coming up on Google, and I'm a believer in centralised information instead of scattered bits here and there.

I'm a "young" electric-only luthier (young in the sense that I started professionaly only 3 years ago, but I'm 56, lol...) with a very special interest in fretless bass since it's been my main instrument for the last 30 years or so.

I noticed long ago that

• Many manufacturers don't care much about fingerboard finishing before selling their fretless basses. Too many brand new instruments, including expensive ones, have uneven fingerboards with warbling spots (sometimes even dead spots... hear me, Schecter and LTD??) and need far more neck relief than it should be. So you have to add the price of re-finishing to the price of the instrument. Only true top-of-the-line "boutique" brands like Pedulla, Roscoe, Wal, Fodera, Ken Smith, ACG etc... seem to approach the fretless fingerboard with the care it deserves.
  
  
• Most luthiers and guitar techs do a so-so job at truing/finishing fretless fingerboards, i.e. my instrument still had warble spots and still necessited too much neck relief and higher action to compensate for the problems. Only ONCE with ONE luthier, did my fingerboard come up near perfect.

The points made in this thread by genuinely experienced luthiers (thanks!), finally made me understand why so many luthiers and guitar techs do such a poor job with fretless fingerboards: they simply don't understand the geometry of it! They just re-sand following the radius with a radius block, and call it a day. I suspect that many can't even do that properly (cf. "youtube luthiers" using a radius block without a guide, with twisting hand movements, oh my!!!). And don't start me on my instructors during my training. I've heard so much nonsense from them (fretless-wise, I mean).

I've been following the fantastic advice in this thread, and my very first job at truing a fingerboard the "hourglass-shaped" way, came up with ten times better playability than I what got from most luthiers and guitar techs. Cool!

Since then, I've done 5 more fingerboards (3 re-finishing jobs and 2 from scratch / blank) and got better and better at it.

Nevertheless, two things still nag me and I'd appreciate some pointers from the experts who posted here (Bruce Johnson, Musiclogic, suraj, Son of magni, Turnaround...?) or any other member with real experience in fretless fingerboard work. Here are my questions:

1. Is it normal that when making a board from scratch/blank, at the stage of pre-finishing the radius with a radius block (I use 16" long Invalid Link Removed), the larger end of the board (towards the body) always seems to end up rougher than the rest of the board and needs far more work (at all stages) to get a smooth surface after that? Or could I be doing something wrong?
   
2. When doing the "string paths" (using a straight narrow sanding tool along the string lines), what do you guys use as a guide, and how do you make it hold onto the neck and board? I've come up with different methods with an aluminium straight edge and clamps, but I feel I'm still slightly tampering with the neck straightness by doing so (because of the clamps putting pressure on the neck). I'd love some ideas.

Take care everyone,

Franck

 

[Bruce Johnson]

Welcome, Franck! I'm glad that our combined essay was of use to you! Only a few brave souls here on TB have the patience to dig this deep into the technical end of fine bass building. Most just roll their eyes and think all this is too complicated and not worth the trouble. But, as you've found out, it is worth the trouble. For a fretless bass to perform well and sound its best, the fingerboard surface needs to be correctly trued up. In this thread, we go deep into how to do that.

Answering your questions:
1.) You're not imagining things. The heel end of the fingerboard is wider than the nut end. To sand it to a basic cylindrical shape, you have to take off more wood at the heel. Plus, because it gets rounder at the heel (going a little farther around the circle), you are getting into more of an angle on the grain and growth rings. More soft areas which scratch deeper. So yes, you usually have to spend more time sanding at the heel end, moving up through the grits to get the deep scratches out.

This brings up a general problem when truing up a fretless fingerboard: You want achieve the perfect shape and, at the same time, end up with a beautiful nearly polished surface. This ends up being a back-and-forth battle. To finely trim the shape, you have to sand spots. Then those spots have scratches. If you then sand those spots more to get the scratches out, you mess up the perfect shape. Back to truing it up...It's really annoying to get it all trued and polished, only to discover that you have some deep scratches in one spot. Most often, the missed scratches will be at either end.

The best technique I've found to minimize this is to first get the surface to the basic cylindrical (or conical, if you choose) shape using a router and/or a radius block with coarse paper (like 100 grit). Then sand the entire surface to 220, then 400 grit level. It's not at the final trued shape yet, but the reason to sand it to 400 is to make sure that you have all the tooling marks and 100 grit scratches out. Inspect it carefully. A good 400 level surface all over.

From there, start the string path "hourglassing" sanding with 220 grit paper on the beam. The 220 paper will cut reasonably quickly, plus you'll be able to watch your progress because the 220 scratches will be visible on the 400 level surface. When the string paths are good, draw lines with a white pencil right down the string paths. Then, work with the beam blending the areas between the string paths, but not touching the white lines. Next, gently go over the whole surface with 220 on a soft pad. Get everything to 220 level, including the ends, which you barely touched with the beam.

Now, the whole surface is the trued shape and all at 220 level. From there, use soft pads to bring the whole surface to 400, then 800, then use grey and white Scotchbrite to bring it up to a full gloss. Sand evenly all over, not rubbing too much in any area. If you've done it carefully, the surface will stay true as you bring it up to a gloss, and you won't discover any hidden 100 grit scratches.

2.) I don't use a mechanical guide when sanding the string paths. I draw white pencil lines down the string paths using a straight edge spanning from the nut to the bridge. I work my sanding block/beam by hand, guiding it right down the line. It erases the line and leaves a narrow flat facet of 220 grit level. Watch the progress as little facet starts at the middle and extends to either end. Redraw the white line if you think you've gotten off course. When the facet is nearly full length, start checking it with the straightedge.

 

[Wizzu]

Wow!

First thanks for the welcome, Bruce.

I don't know how you find the patience to re-explain all this on a forum to people you don't even know! That's gold. A lot of what you just posted was already in this thread, but you add more invaluable hints.

So OK, it's to be expected to have more work at the wider end of the fingerboard. Your explanations makes perfect sense. Good to know, since I was really wondering if I was doing something wrong.

I start the strings paths @320 grit for now, because I prefer to loose some time than to make mistakes, but I'll try @220 grit for my next project.

This brings up a general problem when truing up a fretless fingerboard: You want achieve the perfect shape and, at the same time, end up with a beautiful nearly polished surface. This ends up being a back-and-forth battle. To finely trim the shape, you have to sand spots. Then those spots have scratches. If you then sand those spots more to get the scratches out, you mess up the perfect shape.

I think I've been avoiding this issue until now, since I've done all 6 fingerboards with a Super Glue finish. It kinda takes care of this since it fills the remaining scratches nicely and hides them under the glare. *I* know they are still there of course, and I can find them if I look for them, but nobody else seems them... I for one put the "perfect shape" (and by extension playability) before the looks... for now at least. Things will probably change with experience (and, I hope so, more picky customers!)


No mechanical guide when sanding the string paths?! Ooooh I'm chicken . Not confident enough to do that. My hand is not that precise. Need more practise. On an expendable block of wood. On the actual fingerboard, I prefer to use a guide. For now. (that's a lot of "for now's" )

Thanks again for sharing. I wish there was a teacher with your knowledge of the fretless bass in my area... but since you explain things so well, it's just as good to me.

 

[Five String]

Many thanks to the skilled craftsperspons/writers for this terrific thread. I have read and re-read it many times, sometimes just for pleasure, because it is such a fantastic resource.

I am posting today to add, in some small, inept, pathetic way, some insight for the other ham-fisted weekend loothiers who indulge their tragic fantasies that they can enhance their fretless necks: don't start sanding until you've tried all the other standard things, like adjusting the truss rod, the bridge adjusting barrels, the nut, etc.

I bought a kit or otherwise unbranded bass with a neck the seller had defretted himself. He showed me some other instruments he had built and they looked very good, as did the bass he was selling, so I bought it. Unfortunately, he was comfortable with pretty high action, and I am not.

When I got it home I found there was no tension at all on the truss rod. I think the seller knew what he was doing, he just didn't have an issue with the string height. It took a few days of gradual tightening to get the action more to my liking, as well as adjustment of the bridge barrels.

In this first phase, however, between the 14th and 19th frets on the d string there was no distinction between the notes, just the uniform buzz of the string on the fretboard. The 20th and 21st frets were fine. I thought I would have to sand the neck. Despite the wonderful instruction on this thread, I was not comfortable with that at all, but if I had to do it I would.

Instead, I gave it a few more days, periodically adjusting the truss rod and barrels, and the buzz on the upper frets is pretty much gone.

No, it's not perfect, but I paid $100 for this instrument, I am an amateur, I use this instrument as a learning tool and for my own amusement. I acknowledge I am never going to spend the $1500-$3000 necessary to get a really good fretless bass partially because that kind of quality would be wasted on me.

Further, the neck on this bass is much better than the two commercially produced fretless basses I've owned. I agree with other posters on this thread, commercially produced fretless basses are a mixed bag at best. I think I did well buying from a guy who did a good job defretting it himself.

Once again, thanks so much to the talented folks who posted on this thread.

 

[omri643]

Hello dear people! first of all, this thread is super useful and helped me learn so much about instrument geometry, so thanks alot for all the great info and advices!

im only resurructing this thread because i have some points misunderstood, that prevent me from finalizing the work on my bass and keep playing it and maybe be ready for another defret experience..

would love to hear some advice..

1. Whats the most common\your personal order\routine to do this "conical" sanding tingie...? if i understand correctly, its best first working with a radius block and then "finalizing" the proccess with the Leveling Beam?

2. Regarding CA finish - (i guess epoxy\poly would be pretty much the same but my road is CA) -
Considering i want to coat my fingerboard with CA, and Level it like said in this thread.
in what order would you do this?
there's not enough info on the net for it to be clear, so..
My Logic says something like this -
a. first perfectly level the fingerboard till it reached the desired playability "By its own", with no coating.
b. apply a layer of CA (Or other materials but its especially relevant for CA as you have to use at least 10 coats) and let dry before sandind
c. Level the CA Between layers. (not sure with which tool\technique)
d. Level the the final layer, and then go up in sandpaper grit until getting the surface to the desired smoothness.


Now here comes the tricky part. in stage c - usually when using either of these materials, after each layer there's minor "hills " on the surface of the coating. its not perfectly flat. now, the more layers you add without sanding, the bigger these imperfections are gonna get.
so, to solve that.. how should i level it between every coat?
with a radius block? some people say to do so, but it doesnt make sense to me to go radius again after giving the neck a conical shape. its just gonna bring it back to "cylindrical" again...
Level with a long straight leveling between coats? sounds perfect and most logical to me, but i have a feeling that somehow its always gonna remove too much of the material in some spots and bring you back to the fingerboard wood.. also, its gonna be hard to make sure the thickness of the coating is the same all around the radius, to prevent difference in sound and attack..
in most instructionals on this coating proccess it seems that people just "sand by hand" between layers, and for me it caused some buzzings around the neck because of this hills. and doesnt really go well with this whole
"Make your fretless fingerboard perfectly straight and flat or go to hell" Principle. (Just joking, im doing this only cuz i love my action SUPER low...)

or just apply enough layers with only basic sanding between them, just to have "SOME MEAT" of hard coating material to work with, and then give it a final sanding with a leveling beam? or maybe first with a radius block and then again with the flat beam? seems like this route would cause much more sanding and expense on coating material, as most of it will eventually be sanded

so many options.. so many details.. cannot.. decide.. so CONFUSED!
PLEASE HELP ME GET MY MWAH BACK!

 

[Bruce Johnson]

Hello Omri643;

Some quick answers to your questions:

1.) When I cut a conical (compound radius) fingerboard, I first cut it to a straight cylindrical radius using my routing fixture. If I'm doing a 12"-16" radius, for example, I'll first cut it to a straight 16" radius with the router. Then I'll hand shape it using straight blocks to bring it to the conical shape. It's possible to make a routing fixture or a sanding rig to cut a conical surface, but it's a lot of work. I rarely do conical fingerboards, so I haven't bothered making up a fancy rig. Shaping the conical surface by hand isn't hard, once you have the base cylindrical surface.

2.) Yes, that's the problem with putting a coating (CA glue, epoxy, polyester) on the fingerboard surface. The surface of the coating has to be trimmed to the perfect shape, and polished. To do that, you first have to get the fingerboard surface to the perfect shape, sanded to maybe 400 grit, but not polished. Then, put on the coating as thin and even as you can. Then sand the surface of the coating to the perfect shape, and polish it. Without sanding through anywhere. It's tricky and can be frustrating. The thinner you make the coating, the more precise you have to make the whole process.

I personally don't like coated fingerboards. I did a few epoxy coatings for customers years back, and they were a real hassle. They came out looking nice, but I didn't like the feel or sound of them. I like the mwah sound from an uncoated polished ebony fingerboard much better.

 

[Rôckhewer]

a. first perfectly level the fingerboard till it reached the desired playability "By its own", with no coating.
b. apply a layer of CA (Or other materials but its especially relevant for CA as you have to use at least 10 coats) and let dry before sandind
c. Level the CA Between layers. (not sure with which tool\technique)
d. Level the the final layer, and then go up in sandpaper grit until getting the surface to the desired smoothness.

I am a fan of a coated board. I will share my process.
(a...? Yes, flat... but not as highly polished as you would a finished non coated board. Like Bruce said, it needs some 'tooth' for the coating to stick. 320 - 400g max.
(b...
I apply CA with folded squares of paper towel. About 2 inch pads.
As lint free as possible. Blue shop towel rolls work well.
(Not cheap kitchen paper)
Must use THIN viscosity CA.
Using fairly small pipette tip... run a quick bead down the center of the board with one hand, immediately followed by the towel pad in the other.
Wipe only ONCE.... let that dry. It will flash off quickly.
Then repeat (with fresh towel) on either side of center.
That's 3 thin beads spread out... = 1 "coat"
I do about 30 of these coats.
This sounds like a lot ... but you lose more in the towel than you put on the board.
If you are careful and patient...it goes on fairly flat this way.
After the first 10 coats, mist lightly with AEROSOL activator/accelerator (Not pump spray or brush)
Then I will do a quick level check with 320g sandpaper on a leveling beam. The high spots will stand out. Just looking for high spots, read the landscape...don't try to level anything. Maybe adjust the bead/wipe ammount/ pattern accordingly.
After 20 coats.. a little more earnest leveling... but don't go nuts... this is where I used to always break through to bare wood... patience.
And...resist the urge to drop below 320 grit !
Blow out sandpaper with compressed air to keep from loading....change paper often... whatever, just don't take the short cut of low grit material removal
Now ...there will be stubborn low areas.
Don't sand down... spot fill up... once you get a feel for the squirt/wipe process... spot filling becomes intuitive. It just takes forever.
Once flat is achieved... still use a leveling beam until about 800 grit. I occasionally hit it with a radius block... but more to gently blend & rock & roll out any minor facets.
After that (1000-3000g) you can wet polish (carefully) with a flexible but stiff rubber backer...by hand.
Then buff.
I use Maguires & a foam pad on a pneumatic polisher.
I go through about 3 oz of CA ... I recommend "Fastcap" 2P-10

 

[omri643]

Thanks alot Bruce & Rockhewer.
Both of you gave me very useful advice and combining your replys i pretty much got all the "hills and holes" in my head\theory "sanded level"

im glad i asked this as i was pretty much digging all over TB and other forums for this information and nobody got it covered! i mean, there's plenty of info on how to "Conical" Level a fingerboard, and also on how to CA finish a fretless board. but there's pretty much no info about how to combine together two of this techniques. i think if someone who's gifted enough would write an updated "all around" instructable of how to do this together it would be a VERY useful sticky and will save lots of people some time. as for now, to do either of these in a more-then-amateur level you have to like, spend a whole week on the net just to "gather" all the correct info together.

so.. who's got some free time to spend? maybe some covid-19 lockdown victim wants to get his karma fixed?

 

[ardgedee]

im glad i asked this as i was pretty much digging all over TB and other forums for this information and nobody got it covered! i mean, there's plenty of info on how to "Conical" Level a fingerboard, and also on how to CA finish a fretless board. but there's pretty much no info about how to combine together two of this techniques. i think if someone who's gifted enough would write an updated "all around" instructable of how to do this together it would be a VERY useful sticky and will save lots of people some time. as for now, to do either of these in a more-then-amateur level you have to like, spend a whole week on the net just to "gather" all the correct info together.

This isn't the all-in-one guide you need, but earlier this year @vid1900 posted detailed step-by-step instructions with diagrammed photos on how to properly defret and resurface a fingerboard. The problem is the posts are spread out across a sprawling thread about $35 basses (most of which ended up being a scam), so here are links to each of those posts in that thread. I would love to see these collected and made into a sticky, it's the best tutorial I've seen on the whole of the web (so far).

Preamble/bonus content: Turning cheap tuners into good tuners: 1, 2, 3, 4, 5.

Pulling frets: 1, 2, 3, 4.
Cleaning out fret slots: 1.
Maple veneer for markers: 1, 2, 3. (link to Ebay listing for veneer is dead.)
Filling slots: 1, 2, 3, 4, 5.
An economical sanding beam: 1, 2, 3.
Sanding the string paths (for both single and compound radii boards): 1.
Leveling the fingerboard surface with fallaway near the heel: 1, 2, 3, 4, 5, 6.

(edits: Added note. Fixed broken link in "Filling slots".)

 

[Deleted member 365158]

This isn't the all-in-one guide you need, but earlier this year @vid1900 posted detailed step-by-step instructions with diagrammed photos on how to properly defret and resurface a fingerboard. The problem is the posts are spread out across a sprawling thread about $35 basses (most of which ended up being a scam), so here are links to each of those posts in that thread. I would love to see these collected and made into a sticky, it's the best tutorial I've seen on the whole of the web (so far).

Preamble/bonus content: Turning cheap tuners into good tuners: 1, 2, 3, 4, 5.

Pulling frets: 1, 2, 3, 4.
Cleaning out fret slots: 1.
Maple veneer for markers: 1, 2, 3. (link to Ebay listing for veneer is dead.)
Filling slots: 1, 2, 3, 4, 5.
An economical sanding beam: 1, 2, 3.
Sanding the string paths (for both single and compound radii boards): 1.
Leveling the fingerboard surface with fallaway near the heel: 1, 2, 3, 4, 5, 6.

(edits: Added note. Fixed broken link in "Filling slots".)

Super cool! Im actually in the middle of de fretting (a cheap bass). This info definitely helps!

 

[subtlestew]

Super cool! Im actually in the middle of de fretting (a cheap bass). This info definitely helps!

I followed these posts, hunting around for them in that Glarry bass thread (which I found because I was one of the ones who ordered one) and ended up defretting a cheap bass as well. Thanks for consolidating all of these links to make it easier for future de-fretters to follow this excellent tutorial!

 

[YellowJacket]

Hah. I realize I haven't been posting here in AGES now but I'm still playing bass in addition to all the other instruments I play. I thought carefully about posting in this threat and bumping it, but it seems to me like a better option than making yet ANOTHER thread on this same topic.

I recently acquired a SDGR 505F off of the buy and sell. The fingerboard is ok overall, but it's a bit flat on the bass side compared to the treble side. This is from about 0 to about 'fret' 8 or so? It's the most flat for the first five 'frets'. I'm basically getting a bit of a rattle on the low C mostly and I find it distasteful.

I am wondering if this is something to tough out and get a fingerboard level down the line, or if spot adjustments would be a good option here. We're talking for SURE less than 0.5mm difference between the bass and the treble side (7th 'fret' when holding the string down on 'frets' 1 and 12') and I think the B and somewhat the E string are affected. Keep in mind that it seems like a pretty minor tweak, not a huge deal.

My monkey brain was thinking that I would be able to just sand very slowly and carefully to introduce a bit of a curve on that side of the fingerboard. Slowly, painfully, bit by bit. Is this even doable or is it a fools errand?

I've been really enjoying playing fretless. I am a cellist so I already understand how intonation works. It's such a comfortable, laid back, and fun way to play bass!!!

 

[Bruce Johnson]

Welcome back, YellowJacket;

Well, it's possible to correct one area of a fretless fingerboard, but it's tricky. Can you sand a specific spot lower by an exact amount, without creating new lumps and dips at either end? And then get the surface finish all evened up? Maybe, with a lot of patience.

It's usually less trouble to just redo the whole surface, all at one time. Do the whole process, all the steps. If only one spot needs correction, then it won't really take very long. And the whole fingerboard will be true, and an even level of polish.

The same is true with leveling frets. You can spend two hours chasing a small fret buzz, filing individual frets. Or spend a half hour leveling them all at one time.

 

[Matthew_84]

Hey @Bruce Johnson, I read through this thread and have just a quick question (or two, haha). I was going to post it on my other thread (Re-Levelling Panga Panga Fingerboard (Ibanez Portamento Fretless)) but this one is such a good resource, I thought it’d be better here…

when you’re using the soft sanding blocks (after sanding along the string path), what are you using exactly? Is it like a rubber sanding block, or a sanding sponge or something?

also, during this step, you’re not following the string path, correct? My understanding is that you’re going down the centre line and covering the whole board, as if you were using a radius block (just with lighter pressure and after you sanded the string paths and blended them).

thanks again! I really appreciate your help!

 

[Bruce Johnson]

Hello Matthew_84;

I guess I haven't shown the sanding blocks that I use. Okay, here they are; pictures taken just moments ago....

Here's the set of sanding tools that I use most often for truing up and polishing the surfaces of fingerboards. Fretless and fretted, mostly Macassar ebony, sometimes African ebony, rosewood or walnut.

From left to right: Two hard maple short blocks, an auto body shop Short Board, two Norton Drywall Sanders, and a small rubber sanding block.

The maple short blocks are home made. Simple to make from hard maple, 1" wide x 1 1/2" tall. The center area is surfaced flat, with slight ramps at the ends. The ends are made to clamp onto the ends of the sandpaper; a screw on top tightens them. No tape or adhesive is needed, and the paper can be changed very quickly. Although I don't have to change it often. I'm using cloth-backed stearated sandpaper, bought in rolls, 1" wide.

I've made a whole set of these short blocks, but these are the two I use most often. They are fitted with 80 grit and 120 grit paper. This is for the rough work, taking down lumps and high spots.

This is a Short Board, a common auto body work tool. They are available in auto parts stores and online. A flat aluminum plate with clips and a wood handle. They normally have a thin hard rubber pad, but I stripped it off of this one. Flat hard aluminum, fitted with 120 grit paper.

This is the tool I use most often for sanding the string paths, putting the Hourglassing into a fretless fingerboard. You really don't need a long beam to get the string path flat, once you have some practice and work with a straightedge. The short board is comfortable to use.

These Norton Drywall Sanders are right from the hardware store, and they work well as they are. They have a 1/4" thick firm rubber pad on a rigid plastic back. I have one fitted with 220 paper and the other with 400 paper. I use them for the blending and surfacing of the fingerboard, after the string paths are done.

For the final sanding steps, I use a small rectangular block of firm rubber. This is available from Stew-Mac and other places. Some people use a rubber Pink Pearl eraser, which is almost the same thing. I use this small block for 800 grit paper (which I only use sometimes) and the Light Grey and White Scotchbrite.

Other longer sanding boards that I use sometimes: On the left, two auto body shop Long Boards. On the right, 24" versions of my maple blocks.

The Long Boards still have the thin hard rubber pad on them. I have them fitted with 120 paper.

Here's the end detail of the long maple blocks. A hole and a bandsawn slot creates an upper jaw that flexes. The screw clamps it tightly on the end of the sandpaper. Very easy to make.

I made this set of 4 24" maple blocks more than 20 years ago, thinking they would be the perfect tools for surfacing fretless fingerboards. Four sandpaper grits: 180, 220, 320 and 400. They work well. But over the years, I've found that I like using the shorter blocks and boards better.

I may go back and work on the design of these long maple blocks; improve them. Maybe add better handles on top, sort of like the Long Boards? Or a guide system that they slide in, to stay right on the string paths?

 

[Matthew_84]

That’s amazing detail Bruce! It’s great to see your tools, and it definitely helps!

I was surprised the tool you use for the string paths is pretty wide (I was expecting a beam like 3/4” to an 1” wide), but I realized as you get experienced and comfortable, it would be fine as long as you follow the string path accurately and don’t take off more than you need… I’m neither experienced or comfortable so I’ll probably go with something narrower, haha. But that really helps to fill out my shopping list.

Thanks again!

edit to add: thinking about it some more, I suppose the sander you use would be easier to control due to how you’d hold it and push it forward. I feel like using a straight beam would be more difficult to keep straight while pushing it forward.

 

[ardgedee]

It's probably also easier to ensure the whole length is evenly sanded with a shorter sanding block. With a long block, the area in the middle of the neck will have the most contact unless you take care to take full strokes end to end.

 

[1n3]

Interesting topic, and I've been wondering...

Several describe making a facet that's normal to the string, and that makes sense. Exaggerated illustration of faceted cone:

Then the next step is typically to smooth those facets to more of a curved conical surface. But what if you were to stop at the facets? Has anyone tried doing a fingerboard that way?

 

[Bruce Johnson]

Interesting topic, and I've been wondering...

Several describe making a facet that's normal to the string, and that makes sense. Exaggerated illustration of faceted cone:
View attachment 4707425

Then the next step is typically to smooth those facets to more of a curved conical surface. But what if you were to stop at the facets? Has anyone tried doing a fingerboard that way?

You certainly could leave the fingerboard faceted like that, if you like. It would function just fine as a fretless fingerboard, as long as the strips down the string paths are true. The wood between the the string paths is just there for decoration. As long as the radius isn't too small, the ridges between the paths would be much lower in height than the strings. You probably wouldn't even touch them or feel them.

You could also rout grooves down between the string paths, if you wanted to. I don't know if there would be any benefit or change in the feel, but it could look cool.

 

[ardgedee]

Am I guessing correctly that on a five string, the fingerboard under the middle string (A if it's tuned BEADG) shouldn't need string path surfacing beyond what the default radius provides?