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The time has come to radius my fingerboard. I was thinking about doing compound radius by hand, but it's pau ferro and likes to tear when planed, plus it has wood inlays that might tear as well, so I decided to sand a fixed radius instead, and possibly shave it toward compound with a flat sanding block at the end.

But now I've run across a decision point... do you glue the sandpaper to the radius block, or just wrap it around and hold it? And if you glue it, then how do you get it off when the sheet is used up, or you need to change grits? Do you even change grits, or keep a single coarse grit on the radius block, and use flat blocks for smoothing with finer grits?

Advice and experiences would be much appreciated.

Personally, I find gluing the paper on is best. If you simply hold the paper onto the block, it doesn't accurately conform to the shape of the sanding block.
I use 3M Gold & Klingspor self adhesive paper for this work. The 3M paper is aggressive & fast, but wears quite quickly. It is also wider, & fits the Stew Mac sanding beam in one piece.The Klingspor lasts longer & is not quite as aggressive.
Both papers remove easily with a little heat from a heat gun. Just make sure you rub off all the old adhesive before applying a new strip.

You can create a compound radius on a fret board simply by using a non-radiused sanding beam such as these from Stew-Mac:



You can easily make your own too but the key is that it is precision flat over it's entire length. Using a sanding beam (non-radiused) such as these and sanding the fretboard in the direction of the individual string paths will produce a compound radius fretboard and there is no tear-out issue from say using a plane incorrectly. This method is how I level my boards now, not really leveling but sanding in a compound radius and it's also how I level the boards for refrets that I do.

I have the radiused sanding blocks and the aluminum one too from Stew Mac but sadly since I no longer use a set radius in my own boards these very nice tools are now relegated to being gluing cauls...

I use a belt sander with a 30 inch sanding platen to do a compound radius. I check each end with radius gauges, and the overall length for straightness with a full length straightedge, making sure that each individual string plane is straight and true, since that is the purpose for a compound radius.
I also use the belt sander to radius 5 and 6 string bass guitar necks.
It's faster and easier than using short blocks, in my opinion, and super accurate, although with care and LOTS of elbow grease, you can get equally good results with the blocks, it just takes longer.

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Old growth, shmold growth!

The (Guitarwhisperer) I like your belt sander idea and even though using a sanding beam as I do works fine it is not fast as you indicated.... It may be TAS time again at Heshtone Global headquarters....

+1 for the ole 6 X 89 belt sander!

Another + for the 6 x 89 sander! Once you have one, you'll wonder how you did without it.

Chuck

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Assortment of 4 inch sanding blocks with various ban sawed radius
2 x 4 x 24 douge fir sanding beam. jointed all 4 sides.
various sand paper grits and double sided tape.
elbow grease.
4 to 6 min.
cheap like borscht, nice and quiet on the brain....very peaceful communion with the wood.

vs.

6 x 89 belt sander...
+- $1K, floor space and noise \
and a dust collector
ear muffs and an electrical bill.
Then there is building the friggin jig to hold the fret board while radiusing...been there done that.

All really great for production peoples I guess. Or those of you who took early retirement with a big buy out package.



blessings
Padma

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Audiences and dispensations on Thursdays ~ by appointment only.


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Padma, no early retirement or buy out here, in fact still trying to make a living building houses during a double dip recesession/depression. I've got 40+ years of communion with wood 8 hours a day. Not looking for any extra when I get home. As for $1k for the sander, so happens mine is homebuilt.

You probably used more electricity band sawing your radius blocks than I would sanding a fretboard, with the same amount of saw dust, requiring equal dust collection.

Chuck

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Ya but Chuck...I only have to make my blocks once.


Padma

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Audiences and dispensations on Thursdays ~ by appointment only.


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Padma,,, that's true only if you use the same radius on all of your instruments?

Chuck

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As a matter of fact Chuck...I do. I guess you missed the "assorted" part of the post.

How about pics of that big belt sander you build...me always like see pics of DIY stuff.


blessings
Padma

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Audiences and dispensations on Thursdays ~ by appointment only.


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Thanks all, many good suggestions. Those quartz blocks are a great deal, I think I'll pay the extra $5 for a 20" so it more than covers the fingerboard length, thus sanding the whole thing evenly instead of the ends getting a bit less. Looks like lighter weight than the StewMac beams as well, which is nice for control.

I'm with Padma, I'd rather sand with blocks than turn on a noisy, skin-hungry belt sander, even if it was free and I had the space for it (which I don't). Tempting to do the wooden beam, but the quartz isn't that expensive and I don't have to worry about it ever warping.

I can't decide if I should keep the radius block to get it started a'la Filippo, or just work it entirely with a flat beam a'la Hesh... I haven't unwrapped the radius block yet, so it should be fine to return to LMI for $20. But it would be convenient to stick 80 grit on it for the roughing, and then go at the compound radius with maybe 180 on the beam, and finish with 220-320 on smaller flat cork lined blocks since it won't be affecting the shape much then. No changing grits except when the paper is worn out.

Maybe I'll just do fixed radius with the block with 80 grit, followed by holding other grits against it by friction. Should hold on ok and sand evenly after the roughing, since it will have full contact then. Then think about beams for doing compound radius on the next one.

...now I just have to find some adhesive sandpaper or double sided tape. Tape would be quite handy for holding the fingerboard to the bench as well. I looked all over for it when I was out shopping a couple days ago, but nobody seems to have any larger than scotch tape. I guess I should have bought some anyway. A bunch of strips is better than nothing. I could Elmer's it, but then I'd have to scrub it off with water, risking warping the block. Grr. Back to the Padma beam being a good choice. Basically free, no waiting for shipping, and easy to re-joint later if I warp it with water.

contact cement.

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Audiences and dispensations on Thursdays ~ by appointment only.


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A 24" Aluminum level works also. If you have one laying around it can be trued up with some sandpaper on a table saw top. Not much weight to it though. You might find yourself looking for a sander after you see how much work it is sanding by hand. I have an idea or two for jigging up my 6X24 sanding station. But that's no help to you know.

Though at $10 for the eBay plastic gauges it hardly pays to make your own, these are pretty similar to Steve Senseny's gauges over at MIMF.


Cheers
John

Filippo-
That looks like a nice levelling tool. Thanks for the tip.
How do you remove the stubborn sandpaper bits and residual adhesive?
Since the beam is plastic, I guess my usual paper towel and solvent (lacquer thinner or acetone) method won't work?

Cheers
John

Naphtha/ lighter Fluid.

FYI: I posed the same question to the seller and received the following reply:
"Hi, excellent question! My beam is 93% natural Quartz with a
hardness of 7 on the Mohr scale; way higher than any steel
including razorblades. It is actually very easy to scrape-off
adhesive without scratching the surface. It is also 100% safe to
use mineral spirits, lacquer thinner, acetone etc to remove any
"leftovers", but I use Softscrub because it's all that's needed after
scraping. There is so little "plastic" in it's make-up that there is
actually zero worries about the problems you are concerned
about. Thanks! "

I see that the quartz beams are guaranteed flat within .0015". I would be a little concerned with that on a fretboard.
Nelson

Nelson-
.0015" (1.5 'thou) is pretty good compared to the straightedges I have (e.g. Lee Valley Alu .003", LeeValley Steel .0015").

What level of accuracy do you think is appropriate for this sort of work?

Cheers
John

John, I would really like to see .0005" flatness. The more variables that can be eliminated in fret leveling, the better.
The supplier states that he checks the flatness on a .0001" certified surface table.
I wonder if, with a little more work, he could guarantee .0005"
Regards
Nelson

Thanks, Nelson.
Pretty impressive precision requirement.
I wonder what the sandpaper thickness variation is, when doing this sort of work (paper stuck to levelling block).

Cheers
John

I suspect that a tolerance of .0015" is fine for most of us, but he does list his "Premium Reserve" sanding beam as having a tolerance of less than .0002".

http://cgi.ebay.com/Quartz-20-SANDING-B ... 4aa446e6ac

Alan, thanks for the heads up. Got one on order.

John, you're right in that the sandpaper alone varies and I would guess by a couple thou at least.

I like the extra precision in that it can also be used as a master flat surface for the shop.

Best regards to all.
Nelson