Gary's first build: JB-5

Hi all y'all.

Didn't take long to find my first snag. :cool:

Started to do my mock build. Neck fits the neck pocket nice and snugly. Measured the distance from inside the nut to where the second (closest to the bridge) of the two dots indicating P12 at 420mm which sounds pretty much spot on.

So, place the pups into position, pick guard, wiring panel ...

And then I go to place the tailpiece so the the saddle for third sting is at 840mm from the inside of the nut, only to find that the hole for the earth wire is quite a bit further out, beyond the end of the tailpiece. :(

So, what have I got wrong here? What am I missing?

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You need to measure to the 'crown' or peak of the fretwire of the 12th fret, not the centre of the fret area. I'm guessing that will add about 10-12mm to your half scale and should give about 863-864mm'ish at full scale. As you've got a fretless you need to work from 34" scale using a straight measurement, so convert to mm's and go from there ().

Edit: Bass bridge placement guide.

Sorry, Scott, but there's no fretwires; it's a fretless. :)

At P12 there's two dots next to one another, along the top of the neck. I'm taking the the dot closer to the body would mark the actual position of where the note's intonation would be - in other words, if there was a fret, this would be its location. That's where my 420mm is.

But would 864 be closer to full scale on this body/neck combo?

Thanks.

I was updating my post as you replied, with a fretless you need to work straight from a 34" scale measurement (~863.6mm).

BTW your side dots will (most likely) be the same as the fretted version of the bass, so they are only showing the rough mid-point of the fret not the scale accurate fret lines and cannot be used for measurement.

Ok, thanks. Let me see how that flies.

Er, sits. :)

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Originally Posted by WeirdBits

I was updating my post as you replied, with a fretless you need to work straight from a 34" scale measurement (~863.6mm).

BTW your side dots will (most likely) be the same as the fretted version of the bass, so they are only showing the rough mid-point of the fret not the scale accurate fret lines and cannot be used for measurement.

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Hi Gary,
You might need to check the dot placement on the side of the neck. The dots on the fretless neck of the JB5 I recently finished were a bit out. Have a look at the fret calculator on the Stewmac website http://www.stewmac.com/FretCalculator, I found it very useful. It also tells you that, on this style bass the distance between the screw holes in the bridge and the nut should be 35"

I converted a JBA-4 to fretless. I'm pretty sure it's the same scale length as the JB-5. Obviously I had the luxury of measuring to the fret crown before I removed the frets, but...

I just measured to between the two 12th fret dots, and yeah, that's 420mm.

But since I removed the frets and filled the slots instead of starting with a fretless neck, I can measure to where the fret crown was. That's about 431-432mm (and the same from there to the saddle), which is in line with what WeirdBits said with the scale length being 863.3mm.

Gentlepersons, many thanks for that very useful information. It's all being placed somewhere safe.

So safe, that I will probably never be able to retrieve it again. :)

Seriously, great information, especially about the dot placement not being aligned with the actual intonation points. That most certainly is important and relevant data.

Muchly appreciated.

Sanding time.

Which means sanding questions time.

How does everyone do their sanding? Do you use a power sander of some sort, and if so, what type?

What about sanding the edges of a solid body instrument? How is that done?

Finally, how about the parts of the body that sit between the routing cavities? The cavity edges have a tendency to eat the sandpaper; how do you deal with that?

Thanks in advance.

I'd avoid power sanders as it's too easy to overdo it and leave marks. If you do, then use a finer grit than you'd use by hand. It's very easy for the grit to get clogged by dust, and a hard accumulation of dust is capable of leaving scratches in the wood - which you then need to sand out etc. So keep checking the sanding pad and clean or change the sandpaper if you start to get a hard build-up of dust in the grit. Power sanders are also especially good at wearing away at edges - like the cavity edges - so go lightly in those areas and preferably sand those by hand.

So I'd use a padded sanding block + sandpaper for the flat surfaces, and just sandpaper for the curved surfaces (unless you plan to sand the neck when you'd need to buy a concave sanding block with the correct neck radius for your guitar from a luthier supplies company). Just take your time, always go with the grain - or just very slightly across it, and don't press too hard. Lots of light back and forth sanding.

I would suggest that the dots on the side of the fingerboard are in the same place as on a fretted fingerboard, ie between the 11th and 12th fret positions.

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Originally Posted by Fretworn

I would suggest that the dots on the side of the fingerboard are in the same place as on a fretted fingerboard, ie between the 11th and 12th fret positions.

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Which, for a fretless, is perhaps less than optimal. )

Many thanks.

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Originally Posted by gstark

Which, for a fretless, is perhaps less than optimal. )

Many thanks.

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You could do vertical lines that match up with where the frets would be instead of the dots which are traditionally positioned mid point between the frets being marked.

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Originally Posted by wazkelly

You could do vertical lines that match up with where the frets would be instead of the dots which are traditionally positioned mid point between the frets being marked.

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Thanks, but no. That will never happen. Fretlines make the instrument unplayable for me. I either have frets, or not.

The incorrect (IMHO) placement is more of an issue in terms of correct bridge placement.

My '77P has the dots in the correct location, and I may undertake a little surgery to relocate these, but it's not a biggie. Having a full size upright sitting in the corner here, I'm sure I can cope. :)

Unfortunately the factory isn't as sophisticated as we would probably like. A fretless neck will just be a fretted neck without fret slots.

Hi buddy, I think you misunderstood what I meant.......on the thin edge of the fret board where dots are usually located you could add 3mm - 4mm vertical lines at the points where some of the frets may have been seated if it was a fretted neck.

If you play an upright it is a fair bet your ear is well trained to let you know when you are on the right spot or not.

Quote:

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Originally Posted by wazkelly

Hi buddy, I think you misunderstood what I meant......

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Thank you; yes, I did misunderstand. My apologies.

I did consider "relocating" the dots; scraping out the paint, filling the depressions, and then making new ones in the location as you're suggesting, but I couldn't be bothered. All that's needed is a bit of a guide, and I can cope with that.

With the grounding wire for the bridge/tailpiece, how do others connect this up?

My experience with things electrical, and especially living in an area where old Alfas and Minis corrode as you watch them, is that I am going to tin the end and secure it to the tailpiece through one of the mounting screws, rather than just leaving it as a stripped bare wire splayed out and contacting the underside of the tailpiece.

I'd appreciate the thoughts of others with more experience in this realm.

In most cases, regardless of bridge/tailpiece type, the ground wire just makes a pressure contact. A loop of bare wire under the bass bridge is all you need, but I often use a small piece of copper shielding tape to hold the loop where I want it so I can position it around a screw hole and/or ensure good contact etc. The important thing is to get a good electrical connection, best tested with a multimeter once it's in place.

Many thanks.