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

[Prostheta]

So, the pocket is absolutely spot on. Very pleased with that, both in locating and dimensioning. The left inlay was the undersize piece cut with the 1,0mm burr. The right inlay is the piece cut with a 3,0mm burr. The flat edges and missing parts are simply because it was a tiny undersized scrap. I just needed to find out what sort of runout that cutter would produce across the minor diameter.

[Prostheta]

Fingerboard pocketed, ready for inlay. I'd better rattle out the accuracy issues beforehand though. I'm sure it'll be fine.

12th fret inlay. The rest that are full cat eyes with centre spots will have the centre cut and added separately. Just makes it easier for me....

 

19th, 17th, 15th.

 

Ugh, everything looks so rough at this stage, especially up close....!

 

[Andyjr1515]

It looks pretty neat to me, @Prostheta .   A good demo of your pantograph's set up accuracy.

But I have to say, starting with the chamber and then cutting the inlay rather than the other way round would slightly freak me out...

[Prostheta]

Understandable! I've done enough testing with the pantograph to know exactly what its weaks points are, how they express themselves in the end product and generally working around that. I think that for the most part it runs okay with anything larger than a 1,0mm cutter, and that size can only be used for cleanup passes both because of runout and fragility. A truer running spindle would break fine cutters less. I think there's a slight error margin in the pantograph as marked out on the board, however it does cut 3:1 without distortion. Generally my workflow was to have the 1,0mm cutter in place and lining that up with a hole lightly punched in the centre points with a scribe. As long as the board is aligned along the horizontal, the template can be re-centred with respect to the pilot. Any errors here are reduced by three also, which gives a comfortably small margin of error. Light is an issue thanks to the arm shadowing the working area, so an LED light would be a consideration for a subsequent iteration of the pantograph. An adjustable pilot would be a boon, however this has the potential to introduce slop through another mechanism being added. The pinch setup with a bolt closing up a split in the arm works very nicely as long as one has a 10mm a spanner on hand.

There's a few errors in there, and you can see that the burrs do not leave a straight sidewall. This is hardly a worry given how easily Ebony fills in. I tested a spare 12th fret inlay I made a while back from acrylic, and that drops in very nicely. As long as the final pearl inlays are done with a degree of patience (say, two roughing passes, one finish pass, hand filing) any inconsistencies in the board will be of no consequence. The larger concern I have at this stage is that some of the pockets are too shallow. 1,0-1,5mm pearl soon sands through if I don't adjust to use the greater majority of the depth.

[Prostheta]

I'd like to redesign the pantograph in aluminium, maybe even seeing if G&W might be interested in supporting it as a product. They can certainly produce the acrylic templates!

[komodo]

Watching this one closely. I also have the anxiety of cavity first, as well as cutting without hands directly on the cutter controlling it. That said, I've used pantographs in other situations and understand it's accuracies.

In my inlay, it became about the size and complexities (and resulting problems like blowouts). My accuracy slowly went downhill, and my eye focused on getting it in without catastrophic failures.

[Prostheta]

It's certainly strange, yes. The disconnect becomes less problematic as long as you can hear the cutter working (to gauge whether it's engaging or bogging down) and have a plan of action for the cut. The finer details often end up uncut until the finer cutters (for example, around the central part of the eye and the outline) which needs a slow approach, but it's still a very nice working method. Making a second version of this out of aluminium would be amazing. Not sure if I can do this with extruded profiles yet, but that would be less costly than many fully CNC cut plates.

[Prostheta]

Not really much progress to add today, at least, not until this evening after I've dropped by my workplace to do a couple of jobs.

I did however drill the side out for the Electrosocket. I don't think this came out as well as it could have done for a couple of reasons. Whilst the end result looks good, let's look under the hood....

 

Electrosockets need a 25mm recess for the lip and a 22mm bore for the body. This is surprisingly difficult if your Forstner bits don't want to play the game. Firstly, it has to be borne in mind that Forstner bits are guided by their rims and only started by the spur. That means once the 25mm recess has been started, changing over to a 22mm cutter is problematic if its spur doesn't engage ahead of the rim. Generally it won't, and it'll start walking out all over the place until the rim and/or spur establish themselves.

So what this results in is a 22mm bore that isn't necessarily dead centre in the position started by the 25mm cutter. There's a few ways around this, however experience of having done this a few times shows that there's diminishing returns unless you do this very very regularly, and by this point I would consider having a tool re-machined for the purpose. The downside is that the 22mm hole may be biased to one side and hence needs a little work for the socket to fit comfortably and with squarity.

Sinking a bore with a 25mm Forstner bit into endgrain Oak is a terrible job at best even with the correct sawtooth rim, so I decided to cheat a little. Firstly, I established the initial 25mm cut. I followed this up with the nerve-wracking 22mm cut, enough that the rim establishes itself. I then swapped over to a drill bit designed for door frames; a 5mm pilot with a 15mm spot-facing collar ("karmipora" in Finnish):

 

These do a great job by being directional enough that the centre bit goes from A to B correctly (difficult with a Forstner bit outside of a drill press) then the main cutter removes most of the excess. Going back to the 22mm Forstner leaves far less material to remove, and works since that cutter is now guiding off its rim rather than needing establishment from a central point.

Being difficult to control directionally for deeper cuts (without a pillar drill) Forstners do leave a poor finish on the sidewall requiring a bit of cleanup using sandpaper. As long as the initial 25mm cut is safe and unaffected, the outward finish should be flawless. As it happens, I decided to slightly deepen the left hand side of the recess a hair for symmetry. Time to order one of these Electrosockets in Gold at some point! The Kobiconn DPDT-switched jack socket fits neatly within the main 22mm bore as long as the plastic corners of the square body are filed slightly. A lick, nothing more.

[Prostheta]

Alright. So yesterday I managed to make up the plywood templates for the cavity recess and cover plates. These will be kept to one side as it's pretty much a low priority job at this stage. Firstly, I need to figure out what I'm making the cavity covers from. Thick 2mm brass would be a nice option, but a pain to cut. This is still within the realms of routing as long as one doesn't have a large excess of waste to remove, and the brass isn't going to get into electrics. The same rationale applies to the cavity cover recess. If I decide to use a thinner stock laminated to constructional veneer or even ABS, I'd prefer to sink the recess the exact depth based off how deep this turns out.

I also used a pin router to deepen the components recesses in the cavity. These look a bit rough at this stage as I only had an upshear bit of the depth required. The template was aligned to the front of the body, so a bit of misalignment was to be expected. I'm too too bothered by this, however I think I would do this differently in future. The taper of the body (45mm at the front, 55mm at the rear) means that the usual methods of routing from the back surface as a reference datum leaves the cavity misaligned with respect to the front. This doesn't matter a huge amount, however it results in controls sitting at an angle to the face of the instrument, and a difference in wall thickness  leaving the rearmost controls more proud than those at the front. Short of using a pin router for all of the cavity operations - so that everything is perpendicular to the front plane - this is an operation that should be done prior to the tapering operations. Given that this would be impossible due to the front and rear laminates being applied after this, pin routing was the right way to go here. This said, a template set that would allow for multiple stage pin routing passes would make the process more efficient, cleaner and more accurate. The difficulty in aligning a template "blind" on the front face for cutting component recesses hit a couple of mm off one sidewall (inconsequential in anything other than cosmetics) and left uncut material in others. I also think that the round recesses for the potentiometers would be better if they had a channel linking them up to give the wafers more breathing room. As it stands, I would need to ensure that the soldered points don't catch on the copper shielded surfaces. It can be fixed. The entire cavity needs time with some 80 grit paper to smooth off surfaces prior to burnishing in copper foil.

 

I set up a pillar drill with a 14mm Forstner bit so that the depth stop prevented the bit cutting straight through, but allowed the spur to make a pinhole through the headstock's rear face. Once all five of these had been cut, I flipped the workpiece and cut through from the rear with a 12mm Forstner bit. It may be unnecessary work on some level as the tension of the tuner bushing pulling it into squarity does most of the alignment and retention work. It's a nice exercise though. Same as the Electrosocket recess, doing this at any level of regularity might be best served by having a 14mm drill bit re-ground with a 12mm lead-in. If I get chance, I will show how this is done.

 

Also, the Macassar Ebony truss rod cover. This sits flush with the headstock, however I'm tempted to add in a 0,5mm chamfer around the top edge and bring it up by that amount. I imagine this would be best done using magnets in the cover and small grub screws in the headstock. Using the smallest magnets I have means the headstock can be removed using a larger magnet to overcome the attraction between cover mags and the screws.

[Prostheta]

Bonus! Looks like I ordered a gold Electrosocket a while back. Still not 100% happy with the fit. I'm going to do something about that later, however I think that this is something best done at the end of the game prior to finish sanding.

 

Control layout. The rotary switch needs the shaft reducing in length. Testing the pointer knob shows that the six position markers all line up.

 

The cavity, modified as mentioned earlier. Again, I'm not 100% happy with this even though the functionality isn't hampered in any way. I'm going to make a judgement call on the pots based on what type of knobs are going to get used. I have a pair of splined CTS pots that might (I'm going to check after this post) fit original Aria Pro II knobs. The entire cavity is going to end up shielded with copper tape except for the recess where the preamp fits. That will be a small cutout of black foam rubber as the preamp isn't otherwise secured from movement. The batteries fit over the top, side by side. These will in turn by cinched in place with a piece of black foam rubber fitted underneath the cavity cover.

[Prostheta]

Bummer. It seems that the CTS pots I have are 450k for Les Pauls. Options are always limited when it comes to 25k pots and odd knob splining. Depending on how desparate I get, option to convert the splined knobs into solid-shaft with a grub screw is always there, providing that I can relocate the seller of those brass collars on eBay....

These I guess:

https://cbgemporium.com/products/knob-insert-brass

 

....however this wins out for locality.

https://www.thonk.co.uk/shop/knob-insert-for-diy-knobs/

 

edit: interesting. It must have been some sort of feverish dream, me thinking that I had a pair of original knobs. Back to the drawing board. Everything seems to be deciding not to play the game today. 

[ScottR]

Meticulous.

SR

[Prostheta]

Thanks Scott! It's going well where it counts, but there's a few areas as mentioned that I'd improve if I were to do this again without restrictions of tool access, time and money.

Truss rod cover time. This is too small to do with a router. Feasibly it could be done with a pin router with the stock CA'ed to a plywood base or similar. I elected to scribe the outline, chalk it to reveal the lines, do the flat edges on a belt/drum sander and file the radii in by hand. The chamfer was done on a router however. Three 4mm magnets were glued into small blind holes drilled under the cover, and three corresponding M3 grub nuts sunk into the truss rod access recess. These can be raised/lowered to align the truss rod cover visually. After chamfering, the cover was sanded through 500, 800, 1200 and 2000 grit before polishing with aluminium oxide paste. A thin wipe with Tru-Oil and we're good.

[Prostheta]

Alright. This one's going on a short break whilst I wait for pearl and fretwire to hit the ground. I'm going to re-slot the board to depth and that's about it until then.

I've also done a few tests of my waterslide decals and how they work under Tru-Oil. At least, this is the finish I will use in lieu of a better option. Considered shellac, and I'll do a test to see how it affects contrast, however Tru-Oil is pretty convenient and more protective than shellac. I don't want to go down the route of using heavier finishes at this stage.

The decals' ink is soluble in alcohol and petroleum distillates, so the solvents in Tru-Oil need consideration for use under and over a decal. The area where a decal will be applied ideally needs to be flat and filled, and a good build of oil already made. The smoother the surface, the better. After applying the decal, Tru-Oil is wiped very quickly once over as a film and left to dry. Not soaked or wet. Once that film has dried, repeat a couple more times to seal the decal from subsequent oil finishing. I've noted that the decal film I use is slightly visible even after sealing, so I'm going to see how it reacts after a heavier coat. If still visible, I'll take a view on how to deal with that.

[ScottR]

1 hour ago, Prostheta said:

The decals' ink is soluble in alcohol

Doesn't that eliminate shellac as an option?

SR

[Prostheta]

Not really. When you're doing very fine singular wipes of shellac the same as applying a film of solvent/oil, it takes a second or two for the alcohol to melt the ink. That's why doing it wet is too much (surface tension might push/pull the ink around as the oil/shellac settles) and doing multiple passes in one session the same. I've done shellac over decals before and it just takes patience and a fine touch. No scrubbing!

[Prostheta]

Just to feed back into this thought process, @ScottR....after the first couple of film wipes to seal, subsequent layers can be rubbed on with a gloved finger without risk to the decal. As long as the initial film coats seal the surface, it seems pretty much impervious from there on out. The decal film itself seems to be the sticking point as I mentioned. I would suspect that the surface you apply the decal to must be absolutely smooth and the decal applied without voids or bubbles. The surface in my test was a Tru-Oil slurry-filled surface with oil layers wet sanded in with 600 grit paper. Still somewhat matte, which I think highlights the film and means the matte surface underneath stays that way.

This photo is under a wet layer of oil to simulate many film coats. If you look closely, the decal is not on a smooth surface and has microscopic wrinkles. Partly because of the 600 grit wet sanding, the wood grain (look at that parenchyma!) and less than ideal placement thanks to it being a test. No, I will not use this signature decal....it was made years back when I did a couple of A5 sheets of logos, notes, etc. These were specials for a client.

 

You can see how apparent the decal film is under oil. Mostly this will just need careful trimming with a scalpel before application. This was not done here.

[ScottR]

3 hours ago, Prostheta said:

(look at that parenchyma

I had to look that up....and it didn't tell me much in regards to wood. I've always considered those micro rays....a phrase totally made up by me, and zebrano is loaded with that stuff.

Sometimes you can use a small roller to apply decals bubble free. Head stock size may be pushing the limits though.

SR

[Prostheta]

I think that's the parenchyma anyway. I'm more than 30% certain. 

I'm continuing to do tests on scrap with spare decals. Whilst the results I have are not poor by any means, I think finessing the technique is worth the effort. It may simply have to be that I cut around the decal neatly rather than hoping it "disappears under the clear", in this case the oil.

[Prostheta]

Okay, so a little more on the state of play....

Tuners are all on their way in thanks to having a little pocket money to play with this month (moving house sucks balls financially). This leaves the things that are required to complete the project simple; the bridge, nut, a set of strings and the cavity covers. All minor details which don't actually need to be here for finishing up work otherwise.

Let's talk neck angles.

I've never really believed in discrete neck angle values on the basis that it sets up a very tight tolerance for one to hit. Sort of like painting a picture from a few metres away with a very very long brush, minor angular errors result in high values in terms of saddle height adjustment. Realistically, it just isn't necessary. An angular value is nice shorthand for representing how a body tilts back from the neck/string plane but it doesn't provide the best information to be working from. Really, it's better to work with the values you have and understand how best to apply those to the working methods you intend on using.

In my case here, I have a neck which has a flat glueing plane for the fingerboard. That drops back, so I simply need to correlate how far down I want that to drop at the bridge minimum intonation witness point so that it enables the best use of the bridge's saddle height adjustment range.

In the original SB-1000, this additional height was fairly large thanks to the super-high brass bridges which typically provided a saddle height of around 19mm from the base with maybe 5mm of adjustment. These bridges were recessed into the body, with that recess varying from model to model, year to year.

"Quickhook" type bridge, not from an SB-1000....Zamak alloy.

 

Rendering I did years ago on a campaign to make aftermarket bridges.

 

Here's a couple of SB basses (not SB-1000s) showing a very shallow neck angle and significantly-varying bridge recessing.

 

The neck angle is a combination of two factors; the "drop" from the fingerboard/neck seam to the body plane and the angle between the neck/string and body planes. The larger the drop, the less angle is required to achieve adequate string positioning at the bridge, and vice versa.

The bridge I have provisionally decided to use - Hipshot A style - has an adjustment range of 0.4"-0.63", or 10,1-16mm from the base. In this case I am a little circumspect about the provided values as each saddle is sat in ways of varying base height. I'm unsure whether this range corresponds to the centremost (highest) saddle or the outermost (lowest) and how much this might vary between them. This is definitely a case for having the hardware on the bench and deriving measurements from them rather than relying on spec sheets, however it's not a dealbreaker in this instance as the range of the unit is sufficient to work with.

The fingerboard is 8mm thick in the centre and 6mm at the edges at the very end of the board. We'll work with that 6mm as the radius will be dialled in through saddle adjustment. Jescar EVO 57110 fretwire is 1,45mm tall. I want a couple of mm of drop from the fingerboard-to-body/neck seam to the body plane. We can call this 9,45mm at the edges and 11,45mm at the centre. Of course, strings have thickness and a height above the fret to their lower witness face. If I aim (by all means, this is a point for discussion, especially if I mess it up....) for the lowest saddle adjustment heights that would in theory have the strings resting on the fret crowns, saddle height adjustment will provide maximum range on top of any relief added in through neck upbow under string tension.

Still with me?

A point can be drawn from the side where the fingerboard ends and 2mm down for the drop and a second point at the bridge minimum intonation point. This second point is drawn so that the body plane here is a minimum of 10,1mm down from the string plane. Let's drop that decimal point, call it 10mm. So, taking the fingerboard and fret thicknesses from 10mm leaves us with 2,5mm. Not that much more than the drop at the end of the fingerboard itself. We could easily call this a zero angle if we wanted. I'm not so certain. It's fairly easy to align the seam of a wing being glued along a neck blank with an accuracy of half a mm over that sort of distance, especially if you mathematically extend that line out towards the back of the neck blank.

This is a point I've been rolling around in my head a little the last couple of days. The pickup.

Veijo Rautia at rautiaguitars.net (fantastic boutique pickup winder, plug plug) made me a complete one-off 5-string MB-1E pickup, and like the originals it has a radiused face (this makes me think of ramps, @ADFinlayson) and set back edges commonly used as playing anchor points. If there isn't sufficient space between the body and the strings, these recesses end up sat below the body of the bass which is weird. I've seen a number of Aria Pro II SBs where this is the case. How they ended up like this, who knows?

 

The bottom line is that I'd like to have a bit more breathing room for my own pickup. I could stretch this out of the A-style bridge at the expense of remaining adjustment range, which seems like too much of a compromise. The driving factor is the pickup requiring that room.

So the question is, should I instead consider a bridge with a larger adjustment range or one that is set further from the body? That makes me think of the Hipshot D style bridge. They're a fair move from the look of the original SB, but not one I think would be completely out of the question. Most importantly they're available in brass, which is a very defining aspect of the original basses. Gotoh make great bridges with slightly higher offset than the A-style, however the baseplates seem to be made from materials based on how they're being plated....can't find any Gold brass examples in 5-string!

I'm really thinking that a D-style with string-through ferrules is an option here. The alternative would be that I need to precisely measure and calculate how much the pickup will be recessed (if at all) and/or how close it would lay in relation to the strings.

[Prostheta]

On reflection, the D-style bridge seems to offer the most options and a backup of sorts. Having measured the pickup, any additional body angle over the dimensions calculated above are useful otherwise the design will be right up against the rails. Other alternatives would be a bridge such as the Warwick two-piece bass bridge which I'm not convinced by. At the very least I know that the Hipshot D style comes in brass and is an absolutely stellar piece of hardware from experience. Whilst it does veer from the original design intent of the basses this one is based upon, it's a (no joke intended here) gold standard in getting the angle I need out of a bridge in the material I require. It's just costs an arm and a dick.

[Prostheta]

My suspicions about the decal film were as I thought. It's the application to the surface that defines whether the film disappears well or not. I'm unsure if there's a better way.

I applied a 3/4" square section of decal film with no print and oiled over it aggressively, which is what I can't do to a printed part. This is testing the film at the extreme in my mind. It's hard to capture in photos, however it appears that the decal "darkens" when the lower surface adheres to the substrate and leaves a lightly milky spot where it doesn't. The simple fact of the matter is that I need to reduce the amount of unprinted decal as much as is reasonable for the finished application to reduce any of this being visible. It is visible, but it isn't.

 

[ScottR]

I wonder what would happen if you laid the decal on a wet film of oil.

SR

[Bizman62]

1 hour ago, ScottR said:

I wonder what would happen if you laid the decal on a wet film of oil.

And I thought he already did that and didn't want to make myself look besserwisserish to suggest that!

[ScottR]

Did he? I didn't see that, but confess that I might have missed a sentence or two here and there.

SR