build thread 5-String Aria Pro II SB1000/R150-ish bass

[Prostheta]

Very true. Well, we'll learn something from the experience I guess. What that will be, meh. Who knows?

[Prostheta]

....aaaaaand we're back! The move was fair uncomplicated and it feels great having space plus a lot more organisation to get stuff out of the way. The next job on this bass is to get the fretwork sorted before gluing on the wings. Believe me, that second part feels really tempting right now. Being able to see more of that finish line is a positive reinforcement that will just complicate jobs like the fretwork! Currently hunting around for a non-crucifyingly high price on a 3,0mm diamond ball end Dremel bit and silicon carbide impregnated wheel for doing the fret ends. Meanwhile, the frets have been cut to length and are ready for a bit of de-tanging and grinding to better lengths prior to the end finishing. We're getting there.

I also located my camera battery charger, hence the silly bokeh off my fave 50mm lens. Thanks as always go to @Andyjr1515 whose help in getting me this Evo wire at a less-silly price was very very welcome. Its made all the difference!

[Prostheta]

Well, that turned out to be a waste of time and money. I decided to try out Highline Guitars' method of taking a Dremel impregnated rubber polishing wheel, dressing it with a 3,0mm/0,125" diameter diamond ball end bit and making semi-hemispherical fret ends that way. As with most information on the Internet, this method is a bit hit and miss.

 

 

I found that the dressing of the polishing wheel is very inconsistent. Once the edges thin out, they happily flop over and make it difficult to centre the profile of the fret you're working. It gets you some of the way, however the fine tuning ends up going back down the route of the method I've always used, and that's to "drag" the fretwire over an appropriately-sized crowning file, with each stroke starting almost parallel and ending up at 90°, then doing smaller strokes of the same to establish a hemisphere around the fret end. The most I got out of this technique is that I cheaped out and bought a set that included the correct arbor for the abrasive wheels and ended up with some compressed felt polishing mops which are great for polishing up a fret end.

First fret. If you look closely, you can see my reflection in the fret end

 

 

The biggest problem I've found with doing semi-hemispherical fret ends whilst dressing the fret off the neck is that the pre-bent radius flattening out on the board makes it next to impossible to accurately judge the correct fret length. Whilst this isn't a massive issue once you figure out how to eyeball each fret before placement, it can produce an uneven run as you look down the length of the finished board.

The way I approach this is to do the opposite of what I do when cutting raw fretwire pieces; work from the lowest frets upwards. Whilst cutting wire, it's best to cut the longest pieces first so that any undershooting can be remedied by placing that piece further down the board into a "free" position. 24th fret cut too short? Fine, it probably fits 23rd, etc. Offcuts from fret lengths (Andy kindly cut the fretwire spool into ~30cm pieces for me) can be placed at the head end of the board. When dressing fret ends, it's a subtractive process and one of caution. If a fret is dressed too cautiously and hence too long, it's fine to place it further up the board in a position that it fits correctly.

In this case I was dressing the wire for the zero fret, but it was a hair too long for that, but absolutely perfect for the 1st fret. The wire eyeballed as though it should flatten out with around 0,5mm grace from the fingerboard edge. Once the fretwork is complete, rolling over the fretboard edge marries this all up into a smooth and buttery zero-feel job.

[Andyjr1515]

That is, all said and done, a pretty stunning semi-hemisphere!

[Prostheta]

Thanks Andy!

This post is somewhat of a recap or addendum to the tutorial I did on semi-hemi fretwork:

 

Over time and heavy repetition, methods refine themselves. I tried the method shown in the YouTube video linked previously, however I found that the wheels used were absolutely inadequate. The best way for grinding fret ends in this manner would be to use a slow speed wet grinder, such as the back end of a Tormek grinding wheel. I'd love to invest in one of those, and I'm sure that the wheel would last me over a decade with occasional use before it got to the point of being useful for fretwork grinding! If I do Tormek my life, I might ask around some tool-bod forums seeing if any Tormek owners have old wheels on their last legs they would sell. Anyway.

For this build, I cut all my fretwire pieces largest to smallest. My cutters are a bit crap, so some ends mangle a little. Hardly an issue when the tang (most easily mangled) gets cut back anyway. A pair of needle-nose pliers pulls off the corner of a bent tang when straightening it, with modified nibblers as fret tang cutters undercutting the rest. If any pieces ended up too short for that fret position, they easily work for lower frets.

My first job is to clean up the fret end flat using a file, and using a diamond needle file to smooth any remaining tang. This removes any chowdering left by cutters, and allows the crowning file opportunity to work evenly from the get go, rather than it having to chew off one corner more than another.

 

After the end is clean, flat and even I run the fretwire against the file in my left hand vertically, with strokes about 45° either side in order to establish a round end profile. Having my bench against the window makes this (and most other) work quick and simple to observe.

 

Once the fret end is rounded, I repeat this operation more or less equally with the fretwire held at 45’ from the file face, rolling it over 45° either side, being careful not to take too much from the edge. This is intended to make a 45° sweeping face that tapers out at the edges.

 

The last of the filing with the crowning file is to smooth out those last two edges a little at around 22,5° and (hold up whilst I think...) 67,5° similar to this:

 

At this point I either spend a little time fettling with a diamond needle file or move straight to polishing. This is where I depart from the method displayed in my original semi-hemi tutorial. Instead of drawing the profile back over a sanding sponge, I cut the profile with a felt pad in a Dremel tool. I use Autosol, which is a paste of aluminium oxide. You can also use the various white wax metal polishing compounds out there. They're all aluminium oxide and good for the purpose. Autosol needs spreading into the wheel otherwise it sprays a bit, but hey.

This felt wheel was one of the (about) 1/2" wheels that come with most Dremel sets. It's done half the fretboard already. Compare that to sanding sponges which tear up and still need polishing. A smart person would have put some masking tape on the bench. I am however, not that smart right now.

[Prostheta]

I also did a little thinking on how to calculate the amount that a fret would expand sideways when pressed or hammered into a fret slot. I've not done the mathematics on this yet, however I know what I need to calculate. Let's see if I don't make too much of an idiot of myself here.

So, the variables we have are the width of the fretboard at any particular location, the point to point distance we want the fret to lay from that edge, the pre-bent radius in the wire and the target radius when the wire is located. The value we're deriving from all of this is the point to point width of the wire in it's pre-bent radius.

In more mathematical terminology, we're wanting to know how a change in the segment height affects the chord size, and calculating that backwards to figure out how wide the piece of fretwire needs to be so that it expands outwards to the correct size. I'm sure that it will be minimal, but let's play.

[Prostheta]

Oh well. I ran out of beermats and patience, so I took to CAD.

I drew a circle of radius 12" and trimmed it to an example width of 50mm, giving me an arc length of 50,056mm. I then drew an arc with a radius of 16" and an arc length of 50,056mm, aligning this over the trimmed 12" circle's arc. This shows exactly how much wider the segment becomes when the radius is flattened out by 4" for an equal arc length.

 

This is simplifying the issue for sake of illustration. I take 0,5mm to be my "acceptable margin" below which it requires physical measurement that the eye can't easily discern without distinct reference. If you can't see the difference that easily, you're far more likely to be chasing a ghost in the numbers that you'll not see in the finished item. Unless something in the finished item specifically highlights errors in measurement of this magnitude, we can look at shorter and simpler methods.

Basically, fret expansion isn't anything to be concerned about. At least, not at these fret widths and radii. The values may change more significantly at say, 6" radius flattened out to 7,25".

[Prostheta]

What we can take from this, is that the individual pieces of fretwire can be presented to the fingerboard after the initial end rounding has been carried out and again immediately prior to inserting the fretwire in order to ascertain whether the length is dialled in correctly. Doing this visually is sufficient, and beyond that it becomes a case of your eyes being the judge. Of course, we can still take the fingerboard width, subtract the space we want to ease the edges by and measure the fretwire with calipers. I think it would be reasonable to produce a spreadsheet of derived values for this purpose if one doesn't want to constantly measure to and from the workpiece. That depends on how confident you are that the numbers reflect reality.

Okay, let's crack on. Those last twelve frets aren't going to finish themselves!

[Prostheta]

Oh for reference, I am using an orange-handled Hosco TL-FF2 crowning file, and using the medium side rather than large. Fretwire is Jescar EVO 57110. The medium size is perfect for producing easy round ends on this size of wire. I think I want to get a diamond crowning file at some point soon, mostly because steel fret files often leave chatter marks that need additional work to remove. I'd rather use both than just the diamond file on its own (diamond shouldn't be used for shaping, only refinement) so it's a complimentary tool rather than an upgrade as such.

[komodo]

Man you smoked me. I just did them my hand one at a time after it was fretted. It certainly doesn’t look like it was done with a machine, but math woulda been tricky with the multi-scale frets.

[Prostheta]

I hadn't quantified things like how much frets spread out sideways, so calculated sizes seemed less than useful. Turns out it's a great way to do things. 

I'm sure calculating for a multiscale would be a little more complex. I can already imagine how to do this in CAD of course, which implies how to approach it mathematically. The angle of each fret and how the circular end meets the fretboard edge at a (secant?) is way more complex than I can remember or re-remember how to approach.

This fretjob has put all kinds of silly ideas in my head. One being how to make a fret grinder using a slow dressed grinding wheel, a DRO made from a set of digital calipers and a gear-reduced leadscrew advancement. Also, a mini cutoff chopsaw for cutting fretwire to length cleanly. I think too much.

[ScottR]

10 hours ago, Prostheta said:

I think too much.

SR

[Prostheta]

I'd call the neck-body transition 75% complete. I'd like to dial in the immediate transition from the body to the neck more towards a 45° slope around the profile, however that's within "80 grit sandpaper range" as it stands. Current tools being used are my go-to rasp, a very old 10mm Sorby outcannel gouge and my Mirka DEROS loaded with 80 grit Abranet. The main foci here are keeping the sweep from the horns' radius trailing edge consistent so that the profile drops in with a similar 12mm radius to the shape itself. The neck profile begins to change into the heel profile around the 15th fret.

[ScottR]

I forgot about that cool zebra wood.

SR

[mistermikev]

that is an interesting idea with the grooved thingy for the dremel. 

yes, ooh la la zebra.

[Prostheta]

1 hour ago, mistermikev said:

that is an interesting idea with the grooved thingy for the dremel. 

yes, ooh la la zebra.

 

That's just how it ends up after polishing a few fret ends. The use of an abrasive wheel doesn't seem that consistent or predictable, so I opted not to use that.

[Andyjr1515]

How do you rate the Mirka Deros, @Prostheta ?

[Prostheta]

Sort of a difficult question Andy, since I've been used to having at least one around since they were released. I can on that basis give very deep insight into specific questions, however from my perspective I am very slanted towards saying that I feel like I couldn't be without one now. Whether they are worth the additional spondoolas is a good point. I would say that they are, however the machine is only ever going to be as good as the media you use with it.

I opted for the 2,5mm orbit on the basis that it is a finishing machine and not one for shaping, stripping or coarse removal of material. The 5,0mm orbit is fine, but a little too aggressive at times. 2,5mm is smooth, controllable and definitely in the range of what I call finish sanding. With an 80 grit Abranet it's nice for knocking off high spots on the neck shaft, 240 grit and it produces silky smooth flat surfaces (assuming they were flat to begin with of course, it's not for that). Drop on an Abralon pad and it becomes a different beast.

Still, I have to say that they're a definite shop investment. I find myself using it for all manner of things, which a good tool does; find itself more uses than you originally bought it for. Big ticket investment, and media isn't cheap. Forget the 150mm pad, go 125mm. Always use pad savers (€4 a pop) between the actual platen (€60+ a pop) and the media. One silly mistake (sanding without media loaded? Been there) and you could toast the expensive bit. You can always rip the pad saver off if you absolutely need a hard-backed surface behind the media for flat non-conforming sanding. Pad savers have a minute give to them, but not much.

I would rate it A+ on a scale of one to yes.

[Prostheta]

I've got do some running around to acquire a 10mm diameter cutter to complete the pickup rout. As you can see, the tenon is still flat and in line with the fingerboard. Dropping in the pickup rout this way makes it perpendicular to the strings, not the body. Most of the contouring around the inside of the horns is completed.

[Prostheta]

10 minutes of roughing in with a super sharp spokeshave, cleaned using a cabinet maker's rasp and flexible piece of plywood backing an 80 grit Abranet pad. I'm aiming to follow the carve using the sharp edges to "prove" the contour, following it to make sure there's no humps or valleys. So far, very smooth. This is maybe 25% of the way there though. I feel it's still a little light and short on the horn end. The seam between the Zebrano and the Oak is an additional guide as to the changing contour's trueness.

[Prostheta]

The belly cut was refined further using the rasp, then shaped using Abranet 80 grit around a medium rubber drum from my spindle sander. Occasionally I scribble with a pencil to highlight (lowlight?) low spots. The drum is kept oriented perpendicular to the flow of the contour. After refining, sanding is taken into the direction of the contour with a flexible backing block and the same Abranet. Once I'm happy with the feel of the contour, the same is repeated with 120 grit, then fine sanded to 240 grit.

It's still quite a way from the finish line, but I'd say it's 75% there.

[Prostheta]

It's a little soft in the transition to the face and edge, however nothing a bit of block sanding with 80 grit can't fix. I might have to make a dedicated concave sanding block for this, so I'll describe how I make one of those a bit later.

[RonMay]

@Prostheta, This is looking great.

 

Ron

[ScottR]

5 hours ago, Prostheta said:

flexible piece of plywood

I can't say I've ever run across anything like that. Is it just really thin?

Your wood choices are going to look great with finish on them. What is your plan for that?

SR

[Bizman62]

52 minutes ago, ScottR said:

I can't say I've ever run across anything like that. Is it just really thin?

3 mm 3 ply Baltic birch is very flexible across the grain as the centre veneer is thin enough to flex yet strong enough to prevent the two from cracking. At 5th grade we built Fortuna games at school (the flipper type without paddles) and made the sides and the end curve by gluing two layers of 3 mm Baltic. The radius was something like 15 cm so pretty tight.

There's also 3 ply sheets for hobbyists like glider or doll house builders, starting from 0.4 mm with 0.1-0.2 mm increments at the thin side, made of various woods like basswood, linden or birch.