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Even fretless fingerboard levelling tips

jesterbass

jesterbass

Apr 20, 2007
366
131
#1
Hello everybody,

I have this nice medium scale (32") Warwick neck which I thought would be very cool as a fretless so I did the big leap and removed the frets. Removing the frets was a tough job as the wenge board is extremely hard. After removing the frets I placed some medium viscosity ca glue around the fret slots to keep chips in place and as a guide as to when I should stop sanding afterwards. The plan was to remove as little wood as possible afterwards and count on the factory levelling for a nice fretless board. After initial hand sanding with something like 400-grit sandpaper if I remember well, I put the bass back together. It's pretty good overall, BUT it has this effect as if there are still frets on the bass, that is, slight intermittent buzzing as you slide up a string. What has happened is that the glue has left small bumps that just could not be properly removed by hand sanding. So, according to plan, I bought a 20" radius sanding block and I am planning on continuing sanding using it. It's 8" long and *should* level the board completely getting rid of the ca glue bumps. I want to stick to plan, remove as little wood as possible and most importantly, EVENLY, from the surface of the board. A luthier has seen what I 've done up to now, measured the curvature of the board and thinks it's a pretty good job overall (he's a well reputed luthier mind you, but I have to confess I didn't mention that there are still little glue bumps he can not see haha). I am turning the truss rod until the board is near flat but with a little curvature still remaining, then the tough part: Using the radius block, remove as little wood as possible, evenly. Any ideas? I was thinking about using a weight on the radius block and doing full passes from top to bottom so that even wood is removed. Also thought about drawing and refreshing a grid with some chalk to track my progress, not sure if that will help or will be invisible after one or two passes. I don't have the expertise or more tools to do this "by the book" and I might have to go to a luthier after all, but hell, I 'll give it a try. Any help/ideas/corrections/pointers are welcome.

If you want to see my gruesome doings on that neck, voila:
Invalid Link Removed

Thanks!
 
#3
Did your luthier tell you to use a straight guide for the edge of the sanding block to keep the block aligned on center so you do not develop a twisting radius? Did your luthier tell you that leveling a fingerboard with relief in it will not allow you to ever get it level without a lot of removal? Leveling needs to be started with the board as flat as possible so you can get a level and flat platform. Did your luthier tell you about sanding conically after the board is level to develop even string pathways? If your luthier did not tell you these things, he is doing you a disservice by even talking to you?
 
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#4
Everything done on this neck has been done by yours truly. The luthier just took a quick look and checked straightness and radius at top/bottom of neck while the bass was there for some routing work.
 
#5
That is the point I am making, just looking without any of the simplest common sense pointers, is not helping you achieve your goal, and will cause you more work in the end. These things I mentiond are critical to having a good playing fretless, so take your time and try to accomplish what you are after.
 
#6
Find a piece of extruded aluminum, like 20-80 or a good tablesaw fence, anything like that. It should be at least 16 inches long, preferably 20+. Stick sandpaper to the edge of it and use it to flatten the fingerboard. Remember to loosen the trussrod first. This is what I do for fretless or frets. Remember a fretted board from the factory hasn't been flattened to any near the degree of a fretless board.
 
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#8
Before you do anything, I think you should seriously pay attention to what Musiclogic is saying. Although the task may seem simple, doing it without paying attention to all the little things can make you seriously regret things later. Hand sanding has probably crowned your CA "frets"

If your neck still has a slight bow in it, even after loosening the truss rod, it depends on how much that bow is to continue. If the bow is a quite a bit, I would consider chopping that sanding block down its length and make it 4". As I understand it, your trying to level the CA with the board, and not trying to level the entire board and making the bow go away. So a shorter sanding block will remove lesser wood, level the CA with the board, and keep the slight bow your instrument already has. A longer sanding block will make your neck straight and level but will obviously remove more wood, IF your neck has a bow.

Remember again, all this is considering that your truss rod, after complete loosening still doesn't yield a straight neck..!! If your truss rod is a dual action, then you can make your neck straight, and use your sanding block as is.

The good thing is you didn't a coarse grit already.

EDIT: If your board has a compound radius, pay attention to Musiclogics conical sanding bit..
Best of luck.
 
#9
Conical sanding is critical to any good fretless or fretted. Most people do not take into account the string paths following a cone not a cylinder, so if you use a radius block only your radius is cylindrical not conical, thus impeding the proper string pathway. You must do your final leveling with the pattern of the string paths to get a proper consistency of action. Conical leveling of fb's and frets is the step that most miss and thus can never get a good low action without hours of touchup work. It has nothing to do with single or compound radius, it is needed for both. Look at the string travel and you'll come to understand this more.
 
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#10
Musiclogic said:
Conical sanding is critical to any good fretless or fretted. Most people do not take into account the string paths following a cone not a cylinder, so if you use a radius block only your radius is cylindrical not conical, thus impeding the proper string pathway. You must do your final leveling with the pattern of the string paths to get a proper consistency of action. Conical leveling of fb's and frets is the step that most miss and thus can never get a good low action without hours of touchup work. It has nothing to do with single or compound radius, it is needed for both. Look at the string travel and you'll come to understand this more.
Click to expand...

Thats a good piece of info that I never even thought of. Thank ya sir.
 
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#11
Musiclogic said:
Conical sanding is critical to any good fretless or fretted. Most people do not take into account the string paths following a cone not a cylinder, so if you use a radius block only your radius is cylindrical not conical, thus impeding the proper string pathway. You must do your final leveling with the pattern of the string paths to get a proper consistency of action. Conical leveling of fb's and frets is the step that most miss and thus can never get a good low action without hours of touchup work. It has nothing to do with single or compound radius, it is needed for both. Look at the string travel and you'll come to understand this more.
Click to expand...

Isn't compound radius the same as conical radius.. Following string paths will yield a compound/conical radius. This helps in the action of the strings on the higher frets. Whereas a single radius depends on the fretboard taper. Too much of a taper and a single radius will drop the fretboard height the wider the board gets, which is at the higher fret region.

Musiclogic said:
It has nothing to do with single or compound radius, it is needed for both.
Click to expand...

That is not true..While I completely agree that a compound radius gives the best consistent string height/action, if you follow string paths while sanding a single radius fretboard, you will end up converting it to a compound radius. So if the OP's bass has a single radius, he should just use the sanding block unless he wants to mod it and go for conical radius..

But we are deviating from the OP's topic. :p
 
#13
suraj said:
Isn't compound radius the same as conical radius.. Following string paths will yield a compound/conical radius. This helps in the action of the strings on the higher frets. Whereas a single radius depends on the fretboard taper. Too much of a taper and a single radius will drop the fretboard height the wider the board gets, which is at the higher fret region.

That is not true..While I completely agree that a compound radius gives the best consistent string height/action, if you follow string paths while sanding a single radius fretboard, you will end up converting it to a compound radius. So if the OP's bass has a single radius, he should just use the sanding block unless he wants to mod it and go for conical radius..

But we are deviating from the OP's topic. :p
Click to expand...

Yeah, I am not going to give a dissertation on how the fret paths are ALWAYS conical, and how level is achieved beyond what I have already posted. If you do not understand how the fret paths are always conical unless the nut spacing is the same width as the bridge spacing, then everything I have already posted has been a waste of time to start with.
 
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#14
I have actually been saying the exact same thing..just a different way. I understand that an instrument without neck taper, or identical spacings at nut and bridge will have its strings follow a cylindrical path, whereas the strings of any normal guitar or bass WILL follow a conical path only because of the string spacing difference at the nut and bridge. I mentioned how the fretboard taper affects the action negatively on a single radius board, which is the same as you saying different string spacing at nut and bridge.

No differences here mate :)

U stated that conical leveling is required on single as well as compound/conical radius fretboards which is TRUE for great action, BUT this information can make the OP alter his fretboard geometry while he's trying to remove the least amount of wood possible.
 
#15
Ok, I'm going to try to split the difference. I think the difference between compound radius and conical fingerboard sanding is more in method and degree than in design since a cone has a compound radius by definition.

When I radius my fingerboards I apply a single radius. If I modified my radius machine a bit I could apply a compound radius, but I've never bothered trying that. On the other hand, when I do all the finish sanding I use a long flat sanding bar that is only about 3/4" wide. I sand lengthwise on the fingerboard but always following the string paths. The effect, I think, is of a slight compound radius where the radius is larger at the bridge end than the nut.

If you think about it, if you don't do this, you'd have an effect like if you tightened a string along the length of a cylinder then move one end slightly. It's going to want to buzz in the middle, if you get my drift...
 
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#17
suraj said:
I have actually been saying the exact same thing..just a different way. I understand that an instrument without neck taper, or identical spacings at nut and bridge will have its strings follow a cylindrical path, whereas the strings of any normal guitar or bass WILL follow a conical path only because of the string spacing difference at the nut and bridge. I mentioned how the fretboard taper affects the action negatively on a single radius board, which is the same as you saying different string spacing at nut and bridge.

No differences here mate :)

U stated that conical leveling is required on single as well as compound/conical radius fretboards which is TRUE for great action, BUT this information can make the OP alter his fretboard geometry while he's trying to remove the least amount of wood possible.
Click to expand...

No, no greater amount of wood removal is required, as I stated, and then Karl stated, you do the final leveling with the string paths, conical leveling, which is proper technique for every fretboard, flat, compound, or single radius. This makes sure the board has an extra degree of level along the paths of the strings.

Yeah, I am sure we were both talking in circles....LOL. but meaning the same thing...no worries, between all of us, there was plenty of info bestowed on the OP and others...LMAO :p
 
#20
Musiclogic said:
No, no greater amount of wood removal is required, as I stated.
Click to expand...

I guess I'm still a little confused:confused:

The reason being, I recently radiused a fretboard at a single 16" radius. If a place a straight edge anywhere on the board, but parallel to the centerline, I get no light from under the straight edge. But when I place the straight edge along the string paths of the outer strings, it wobbles ever so slightly, giving the mild buzzing in the middle effect warning. This finding was expected, obviously. But wouldn't more wood be removed, from the edges if i level with the strings paths, as the straight edge rocked and showed that more wood exists in the middle ? :eyebrow:

by more wood here i mean veeeerrry little more :p

pilotjones said:
Flat fretboard. Done.

:eek:

:p
Click to expand...

im sure the OP's already done that :D and is now drinking some beers and looking at his thread go..:ninja:
 

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