Fretboard radius, sanding blocks

[Jehle]

I've seen in several places now where people have made their own sanding blocks to radius the fretboard. I'm wondering how this is done.

My first thought is that you might use a jig and a band saw. Perhaps a block mounted at the end of stick that is then rotated on the band saw to get the proper radius. Are there other ways to make such a sanding block?

[Brian]

I'm waiting for that answer myself sure would beat payin Stew Mac for a set.........

Plus I think it would make a great tutorial

[Guest AlexVDL]

Why not use a piece of thread (the length is the radius) tied to a nail and a pencil to draw the radius on a little piece of wood. And cut out the round part with a contour saw or just sand it with a beltsander. repeat this a couple of times and align the pieces and glue them together, just like the image below.

It's just a thought... it could work

[LGM Guitars]

to be honest, for the $8 stew mac charges, I can't be bothered, their's are CNC cut, you KNOW that it's accurate. I made some, but compared to the stew mac ones, well, it's just way cheaper to buy them if you consider your time worth money.

just my 2 cents worth

[Brian]

to be honest, for the $8 stew mac charges, I can't be bothered, their's are CNC cut, you KNOW that it's accurate.  I made some, but compared to the stew mac ones, well, it's just way cheaper to buy them if you consider your time worth money.

Hum let's see $30.00 minimum order plus they hit you with $8.25 S&H or in your case Canada add another $4.00 on S&H

I'm just tired of buying stuff to Ebay or sell off when all I want is an $8.00 part to begin with.

[LGM Guitars]

I just waited until there was a few things I needed, then throw in the block, I always need something hehehe

[Jehle]

Why not use a piece of thread (the length is the radius) tied to a nail and a pencil to draw the radius on a little piece of wood. And cut out the round part with a contour saw or just sand it with a beltsander. repeat this a couple of times and align the pieces and glue them together, just like the image below.

It's just a thought... it could work

<img src='http://people.zeelandnet.nl/alinde/fretboard sander.jpg' border='0' alt='user posted image'>

Alex, you are quite a wiz with the computer graphics. If your career as a meatloaf impresonator doesn't pay off, you can always get a job in computer graphics.

My idea was similar to that, but I was thinking more about cutting the arc directly (rather than scribing the arc first like you suggested). I've seen Norm Abram on the New Yankee Workshop cut large circular arcs like this with a large jig.

Basically it's a huge slab of plywood with a nail in the center. A rigid wooden rod slips over the nail to mark the center. The other end is used to guide the saw for cutting the arc... Time for me to do more web surfing on it.

I'm on the case, even though I don't need to do this step quite yet. I just love to make jigs. And pain. I love pain too.

[Jehle]

This is the closest I could find on Norm's site... Look for "Band saw circle jig". Bit scant on the info... but it's sorta there.

http://www.newyankee.com/fanmail/search_sh...hop_notes2.php3

Here's the same idea with a router. Seems like you should be able to cut out the circle bit and keep the concave "leftover".

http://www.woodworkingtips.com/etips/etip102000sn.html

I don't have a router yet though. :|

[GhesQi J]

I also made my fretboard sanding block myself (430 mm radius). I used a block of (hard) wood and a beltsander to achieve the radius. Very time-consuming, but simple and effective.

The radius of 430 mm was drawn in AutoCAD and (partially) printed scale 1:1. Then I glued the piece of paper on the block, and belt-sanded to the printed hairline.

The idea with the router would also work very well.

Cheers,

Joten

[KeithHowell]

Have a look on www.buildyourguitar.com for a easy method of making radius sanding blocks to any length you like. I have made a 9.5" and a 12" and they work great.

[mikecnyc123]

What if you have a guitar with a compound radius? Do you have to use a few different ones?

[KeithHowell]

Yes you use a few different blocks. All the math is on www.buildyourguitar.com so you can make any radius you like. You could possibly, I haven't tried this, make a block with one radius at one end and the other at the other end with the side supports smoothly interpolated between them. The block should then have the compound radius you require.

Keith

[cajunboy2k]

The easiest way for me to make a radiused sanding block was to purchase a short piece of 12" PVC pipe (or what ever size you need). Then I cut it lengthwise and shortened it. glue it to a piece of wood, and tak sandpaper to the underside. WA- rock LA radiused sanding block.

[Brian]

Yes but wouldn't a 12" PVC pipe just give you a slightly tighter version of a 6" radius?

I thought about that idea myself but figured finding a dealer that would sell me a 12" length of 36" dia. pipe (figuring it is 1/2" thick on the sides) to give me a bunch of 17.5" radius blocks might get a little pricey..........

Guess I'll have to call around and see.

[Dave M]

What would happen if you just used an existing item or object with the correct radius, and stuck some coarse sandpaper to it. You could use anything here. You don't need a full circumference, just a portion a couple times wider than your block. Steel pulley belt. PTO from an old tractor, architectural column on your front porch, snare drum shell, artillery shell casing, large tin or wastebasket. (Probably have to fill it with sand, or something to hold its shape) then you could just use that to dish out your block. If you looked around a bit, you could probably find some pretty close radii to what you want. Especially if you are near any junkyards.

Just thinking...

[Jehle]

Hmmm. That's an interesting idea. In fact, it gets me thinking about the issue as a whole. What are some special tools and jigs that people have made in order to make their guitars.

Don't get me wrong, I wouldn't mind buying everything that StewMac sells, but to build a handfull of one off guitars, it's not cost effective. A radius sanding block is just the begining.

[cajunboy2k]

The PVC idea works great for me. Besides where I get mine, it is measured from the inside diameter, not the outside. And it is also very cheap. $2.00 American for a 3 foot section.

[soapbarstrat]

Many years ago I made my own radius blocks ( 4" and 8") by planing pieces of oak flat, then roughing in the radius on a router table(rout the deepest channel down the middle and each channel next to it gets more shallow). Then I would sand the radius into the roughed-in blocks by moving back and forth over the radius block sanding jig I made , which was a piece of lexan held down over two rods with wing nuts. The more you tighten down the wing nuts, the sharper the radius. I would adjust for the proper radius by laying a radius guage that I made (1/8" plexi glass that has the radius cut by using a dremel with router base and the edge guide, with the edge guide's metal rods replaced with much longer rods to make the dremel like a big compass). I would adjust the wing nuts until I could no longer get a .002 feeler gauge to fit between the radius gauge and lexan curved top of the jig. Sometimes I had a .001-.002 gap here and there. Then I would put coarse sandpaper on the lexan and move the radius block back and forth to sand the radius into it. I'd switch to finer grits. I would have guides to make sure the block stayed straight while I moved it back and forth. Then I would lay the finished block on a piece of glass that has a .005 flatness tolerance to make sure the radius block didn't rock on that. And also would check the lengthwise flatness of the block with a precision 24" straight edge to make sure the flatness wasn't off by anymore than .003 or about that. I made a whole set. from 7.25" all the way to 20" . Glued handles on all of them and put a couple "coats" of danish oil on them.

I don't know if they were any better than the Stew-mac ones, but I used very old, stable wood. I would imagine the Stew-Mac ones would probably warp a little with age, which would really suck, although they'd love for you to buy a new one then, I guess.

I don't use my blocks much anymore. I found out that a long, narrow and flat block is much better, because it's better to sand in the path of the strings, which creates the best compound radius. Changing radius blocks as you go up the neck is also an inferior way of doing it.

Using radius blocks is like they often do it in the factory (even machines that do it). Using a long flat block with the right technique allows you to surpass a factory fret-job. Why duplicate a factory fret-job when you can surpass it ?

I've said all this before on other boards and a lot of guys don't like to hear it.

I even made a 13" block that is 10" at one end and goes to 16" at the other end. I used it and will probably never use it again. It makes the fret-board weird somehow. It's just not the proper way to do it, in my opinion. I think you end up sanding more off the board than you want to.

I think the reason why my fret-jobs were still turning out very good when using the 12" and 16" radius blocks is because I would then level the frets with a flat block, and I would go in the path of the strings.

If you don't understand what i mean about "in the path of the strings", think about how the outer E strings do NOT run parallel with the 2 center strings.

Hard to explain, so I'll shut up now.

[Dave M]

Martin Koch has making a radius block in his book. I just saw it at a buddy's house. Great idea, but hard to explain.

Take a flat board, and then lay up a pair of rails of a certain height down the outer edges of the board. Then lay a piece of thin ply down, and screw the middle of it down. This will curve it to the radius, and then screw and glue another piece of ply to it for strength and stability. I would suggest his book, if you can find it at your local library, or buy it. It's pretty good, although I would use Hiscock's book for making my first instrument.

I also tend to agree with soapbarstrat's post above, though. I don't like making compound necks with radius blocks either. Sometimes, I will use them to get a bit of wood out of the way, before my final working, but I use a flat sanding surface (Glass, or a flat benchtop) with a jig and pivoting arms to sand my radius. I do it the same way as the pro luthiers do, except that I can't afford the huge sanding belt table, so I just use sandpaper and a lot of elbow grease. The only problem is that my sanding strokes have to go across the grain, so I have to do some careful finish work by hand. I usually fix the position of the jig, and then slide the abrasive unnder the neck, although I am thinking of mounting some roller slides to my jig, and trying that next.

I do use radius blocks for making straight necks though, and they are great for that. I have actually been thinking of making a compound radius block, but trying to figure out how to use it makes my head hurt.