Fretboard Radius Jig

[Andyjr1515]

I mentioned this jig in my 'Piccolo gains two strings' thread and a couple of you were interested in a bit more detail.

I have come to the conclusion that life is too short to hand sand fretboards.  Challenges include:

• It's bloody hard work
• Even with all of the precautions, tips and tricks employed, it is still too easy to end up with a board that is either thinner one side than the other or uneven or dipping at one end or another

The Alembic-esque 6 string electric recently completed nearly did for it and me!  A brittle figured ebony bond.  Took my time (did it over 3 days!), used chalk to ensure evenness, used a guide rail for the radius block, regular checks.  And it STILL ended up a mm slimmer on the treble side than the bass!!!  And it absolutely killed my increasingly arthritic hands.

So I shamelessly stole and modified a design I'd seen a photo on Google Images by LedBelliBass, originally posted on the HomemadeTools.net website.

This is the finished article in use:

Basically, the router is bolted to a ball-bearing fitted tray, which itself sits on a simple carrier - which has radius templates either side.

 

Here's the router tray:

As you can see, the radius templates are detachable, making it easy to fit alternative templates with alternative radii on.

For those with good eyesite, the template fitted is 11" radius but - because the router bit is going to be an inch lower than this - it will actually rout a 10" radius on the fretboard. Similarly, the second set you see on the right of the picture is radiussed at 13" to produce a 12" fretboard curve.

Now - on LedBelliBass's original, the bottom carriage also ran on ball bearings, to to me, that seems to be too free moving...and I hate routers to be too free moving!

Next post, I'll show the simple rig I used for the lengthways movement

 

[gary mac]

It looks great and if it saves your hands some stress and strain, then that's a marvelous thing. 

[Andyjr1515]

The idea of LedBelliBass's original design was to allow both routing each radius strip then index along the length AND alternatively routing along the length of the fretboard,  indexing round the curve at each pass.

Because I wasn't sure what would be easiest, I decided to allow the same. 

My base was an old IKEA box shelf.  Dead-flat, quite light to handle, just the right width (by pure fluke) and melamine covered so actually quite slippy.  All it needed, therefore, was a couple of pine strips glued along the length at the same distance apart as the bottom carrier:

 

I also guessed that if I was doing the multile lengthways passes, I would need to index it relatively securely - so I just drilled a hole in the bottom carrier and, indexing the top carriage by 1/4 of a router bit's width at a time, drilled through to the top carriage to use an old drill (not the breakable cocktail stick shown in the photo!) to hold it in position:

Those of you much cleverer than me will have worked out that these holes will only work with one radius template pair.  Correct - I will drill another peg hole and indexing holes, above or below, for each different radius I use.

 

Next post I'll let you know how the prototyping went...

 

[Andyjr1515]

So - before subjecting my beautiful and eye-wateringly expensive piece of snakewood to the devilish and destructive router bit - I thought I'd better try it out on some scrap maple.

It seemed to work!  And the radius did, indeed, seem to be correct

One challenge was that I would need a decent selection of flat spacer lengths to raise the blank to pretty much the exact height...because lowering or raising the router bit will, of course, change the radius.  

The other thing noted was that the visibility was pretty limited.  I used one of the spare Bosch palm router holders that comes with the kit - it's the one that nobody uses that can hold the router at an angle (does ANYONE use that one?????) and maybe the standard base would give a bit more visibility.

Anyway - it worked

So...onto the eyewateringly expensive snakewood!

[Andyjr1515]

Rather than do the documentary-makers favourite ploy of artificially creating drama with the 'and all was going well....and then they hit a serious problem!' yawn approach, let's just say:

It worked

The snakewood was fine

 

There were, however, a couple of builder and user errors in the live trial.

As a precaution, I worked out that with the thickness of the snakewood I would be able to try two or even three passes, so I deliberately started on the thickish side rather than trying for finished thickness first go.  Good job I did!

First I tried routing lengthways and indexing at each pass.

• Very easy
• VERY quick
• But unexpected groove steps at the edge of two of three of the passes (didn't take a photo!! )

Wasn't sure why that was happening.

Second go, I changed to routing the radius and indexing manually each pass along the length.

• Took a bit longer but still very easy
• But....    "Hmmm...that's odd"    :

Perfect at the sides but digging in in the middle??

Then realised that the two unexpected results were linked:-

                        Basically, the two radius templates are probably not quite identical.  One of them is higher in the portion at the top of the radius.  Result - the carriage will therefore tip and so the router bit is now angled and hence it digs in along one edge.

It's easily fixed and was acually less serious than it looked - 10 mins with the sanding block gave me this:

 

The second issue was pure rooky operator error.  Once I got into the joy of each of the 100 passes of 'zip, index, zip' I forgot.  I forgot that this, of course, is still a satanic router!  And instead of slowing my cut feed right down at the far end (which normally I would do) - I just zapped past the finish mark at the same speed as the previous 100 passes.

And *PING*

...the very last cut of the very last edge pinged off a 15cm sliver of snakewood off the side.

Luckily , this was an un-slotted fingerboard and so this became the nut end.  Could have been a disaster and I should have known better!

 

But, with a couple of tweaks of the jig itself on the radius templates and some self-flagellation for being an idiot, I declared the rig a success!

And a couple of days later, this was what the fretboard blank looked like - whereas, before, I would have still been sanding!    :

 

 

 

[honza992]

Andy, thanks so much for posting this.  A radius jig is next on my list of things to build, once I finish the two work tables, the work bench, wood rack....oh and the unfinished guitar and bass that keep on looking at me making me feel guilty.  But sanding radii is pretty much my least favourite part of a build, so I shall be re-visiting this thread shortly, compass and stubby pencil in hand.....

[Andyjr1515]

Just now, honza992 said:

Andy, thanks so much for posting this.  A radius jig is next on my list of things to build, once I finish the two work tables, the work bench, wood rack....oh and the unfinished guitar and bass that keep on looking at me making me feel guilty.  But sanding radii is pretty much my least favourite part of a build, so I shall be re-visiting this thread shortly, compass and stubby pencil in hand.....

Great!

If I work out ways of improving it, I'll post the changes

[TheGreek]

I thought magicians weren't supposed to reveal how their magic works...

[honza992]

Andy I've reached the point of radiusing the Jazz bass I'm building at the moment and like you I just can't face doing it by hand. It's no fun. 

I think you've used this a few more times now. How has it worked out? Are there any adaptations you would make? 

[rubis]

This is great stuff

I’m about to have a go at making a 60’s style veneer fingerboard neck and i think this may be adaptable to produce a concave as well as convex radius 🤔

thanks Andy

[Andyjr1515]

On 03/09/2018 at 11:29, honza992 said:

Andy I've reached the point of radiusing the Jazz bass I'm building at the moment and like you I just can't face doing it by hand. It's no fun. 

I think you've used this a few more times now. How has it worked out? Are there any adaptations you would make? 

There are some changes I would make...in fact the biggest change is that I'd buy a G&W rig instead of building my own!  It came on the market after I'd built mine...

[honza992]

Just now, Andyjr1515 said:

There are some changes I would make...in fact the biggest change is that I'd buy a G&W rig instead of building my own!  It came on the market after I'd built mine...

I've seen those and was tempted....the only issue I could see (other than the cost, clearly) is that the base of the radius jig itself aren't wide enough to take a 5 string bass fretboard.  The max width is 70 mm (I checked with G&W) which isn't really wide enough.  I can't understand why you would go to all that trouble to spec, design and produce (what I presume is) a top quality product, but not make it 10mm wider.  What luthiers only make 6 string guitars?  Surely a 5 string bass is the minimum you would design for.  Very very odd.  And a great shame, and opportunity wasted. 

[Andyjr1515]

3 minutes ago, honza992 said:

I've seen those and was tempted....the only issue I could see (other than the cost, clearly) is that the base of the radius jig itself aren't wide enough to take a 5 string bass fretboard.  The max width is 70 mm (I checked with G&W) which isn't really wide enough.  I can't understand why you would go to all that trouble to spec, design and produce (what I presume is) a top quality product, but not make it 10mm wider.  What luthiers only make 6 string guitars?  Surely a 5 string bass is the minimum you would design for.  Very very odd.  And a great shame, and opportunity wasted. 

Yes - thought the same. However, when you draw out the sweep of the router itself, a wider one becomes a much, much larger jig so maybe they judged better to start with the most common size. 

[honza992]

Now you have a router table, have you thought about using router bits?  They're available in the UK and (reasonably) cheap...

https://www.amazon.co.uk/Yonico-13005-Radius-Guitar-Radiusing/dp/B06W2M7892/ref=sr_1_1?ie=UTF8&qid=1536173060&sr=8-1&keywords=fretboard+radius+router+bit

I've got a similar  12" one and it cuts scrap beautifully.  I'm still trying to work out though how to fit it into my normal work flow ( I normally glue the board on first, which is problematic).  I think you radius then glue? Supposedly that's more easy to do.  

[Andyjr1515]

59 minutes ago, honza992 said:

Now you have a router table, have you thought about using router bits?  They're available in the UK and (reasonably) cheap...

https://www.amazon.co.uk/Yonico-13005-Radius-Guitar-Radiusing/dp/B06W2M7892/ref=sr_1_1?ie=UTF8&qid=1536173060&sr=8-1&keywords=fretboard+radius+router+bit

I've got a similar  12" one and it cuts scrap beautifully.  I'm still trying to work out though how to fit it into my normal work flow ( I normally glue the board on first, which is problematic).  I think you radius then glue? Supposedly that's more easy to do.  

There are lots of possibilities now I have the table, John!  I got a set of bearings as you suggested - brilliant!

Never seen those bits before - I'll investigate

[Christine]

57 minutes ago, Andyjr1515 said:

There are lots of possibilities now I have the table, John!  I got a set of bearings as you suggested - brilliant!

Never seen those bits before - I'll investigate

What bearings are those?  I'm new to router tables too, I'm used to a spindle moulder and a ring fence.

[Andyjr1515]

John suggested using progressively smaller od top bearings on a guided trimmer bit to be able to creep up on the final size when using a template - a bit like a reverse version of using guide rings   Works well!