Sunday, September 1, 2013

Building a Bass Guitar Kit, Part 3

(You'll find Part 2 here: (click here!))

OK -- the body is painted.  All that is left now is to sand and polish it.

As with the painting described in the previous blog post, I will strongly recommend John Gleneicki's book, "How to Create a Factory Finish with Just a Couple of Spray Cans!".  There are also some YouTube videos you can watch (for technique).  You'll find plenty on YouTube.  One series I like is by Joseph Tubb (although much of what he does in his series is not applicable to this project).  But for sanding and polishing technique, I recommend checking out parts 7 and 8 of his series.


And part 8 is here:   



I used sandpaper grits of 600, 800, 1000, 1200, 1500, and 2000 (all sanded wet, not dry).  These finer grits were available at the same auto-paint store where I purchased my paint.

(Click on image to view in its entirety)

Here are examples of the shine as I worked.  Note that the reflections of straight edges aren't exactly straight, indicating a very slight waviness in the overall finish.  I'll try to do better on my next body!

(Click on image to view in its entirety)


One problem with using wet sandpaper -- if you aren't careful, water can get under the paint and cause swelling.  Here's an example of what happened when water got under the paint at one of the holes where I'd originally screwed the body to the "stick" (which was then removed for these last sanding steps):

(click on image to view in its entirety -- the problem is to the right)

I also had water get under the paint at some of the pick-guard screw holes.  Fortunately, drying out the area with heat (and applying pressure, such as pressing hard with thumb) can bring the raised areas back down.  I used an incandescent bulb about 6 inches from the surface to dry out these types of mistakes.

By the way -- you might first try plugging holes (and covering open areas, such as the one above) with, say, candle wax, to waterproof them.

Another caution:  if using a wood sanding block, the wood can warp if it gets wet, and your flat block will no longer be flat!



After sanding, I used a swirl remover (Mequiar's, shown below), follow by a 3-M rubbing compound (not shown).  Both were purchased at the Auto Paint store.  The foam polishing pad came from Stewart-MacDonald.

(Click on image to view in its entirety)

When the body was polished to my satisfaction, it was on to final assembly, followed by bass setup.

For bass setup, I recommend first checking out the four great videos by John Carruthers on YouTube, in which he explains the steps necessary to setup a bass guitar:

First:  Truss Rod Adjustment:   

Second:  Bridge Action Height Adjustment:     

Third:  Nut Action Height Adjustment:     

Fourth:  Intonation Adjustment:     


For reference, here's my summary of the setup steps shown in the four videos above:

1.  Truss Rod
     o  Capo at first fret
     o  In playing position, fret the E string where the neck joins the body (16th fret?)
     o  At about the 7th fret use a 0.015" feeler gauge to measure string height above fret.
            To raise string, turn truss rod counter clockwise.  Opposite to lower.

2.  Bridge height
     o  Remove capo.
     o  In playing position, at the point where the neck joins the body (again, 16th fret):
            Adjust E-string saddle screws so that the string is 4/32" above the fret.
            Adjust A-string saddle screws so that the string is 3.5/32" above the fret.
            Adjust D-string saddle screws so that the string is 3.5/32" above the fret.
            Adjust G-string saddle screws so that the string is 3/32" above the fret.

3.  Nut Action Height
      o  For each string:
             Measure height above the first fret.  If greater than 0.022":
                  Loosen string and remove from nut groove.
                  With appropriate file, file in a slightly downward direction (towards tuner) until
                  desired string height reached.

4.  String Length
       o  In playing position, adjust the Saddle Length Adjusting Screw so that the open note and
           the fretted octave are the same.


By the way, during the final assembly and setup I found a few more problems:

1.  Some pick-guard screw holes are stripped (nothing done at the moment, the screws seem to be holding fine).

2.  Truss Rod difficult to adjust.  This neck's truss rod seems to be angled down slightly, so only the short end of the hex driver can engage it, rather than the long end.  Unfortunately, the small diameter of the hole in the wood means that the hex driver can only subtend a small angle of movement when adjusting the truss rod.

3.  During setup, the E string saddle bottomed out.  I fixed this by raising the neck slightly with a shim in the neck picket made with two back-to-back business cards (to get the appropriate thickness):

(Click on image to view in its entirety)


4.  While tuning, I found that the D-string was a little too wide for the slot in the string tree, and it would stick in the slot while I tried to tune it.  The slots were also a bit uneven and had sharp edges at the slot ends (where I was worried about the wire catching).  So I smoothed the front and rear slot entrance/exit edges and widened the two slots with a small file.



Here are a couple of pictures of the finished Bass:





Conclusion:

The bass kit was much more work than I anticipated, from fixing problems that originated at the factory (in China, I believe), to painting the body and dealing with all of the little heart-stopping issues that arose (runs, sand-throughs, etc. etc. etc.), to the extra expense of new strings, guitar-specific tools, etc.

So I have to ask myself, was it worth the effort?

For me, the answer is, without a doubt, yes.

Sure, the kit had numerous issues, but because of these issues, it provided an invaluable (and inexpensive, compared to the price of quality basses) learning platform.  Now if I need to do a bass guitar setup --  no problem!  Frets uneven?  I can handle it.  Sealing, painting, and finishing the body?  A lot of work, but I can now get a color scheme I like, rather than one forced upon me by a guitar's manufacturer.

In short, I'd do this again.  But next time I would prefer that the kit be a lefty PJ bass, or better yet, a lefty Rickenbacker knockoff!

However, if your goal is simply to purchase an inexpensive bass, my advice would be to find a used one.  With the tools and paint that I purchased, I easily spent several hundred additional dollars above the price of the original kit.  For that kind of money, you can get a decent used bass.

I would also like to point out that this kit is a left-handed bass kit, and it's quite possible that a number of the issues I mention in this and previous posts are due to the fact that it is left-handed and thus the workers might not have had experience with any changes-to-procedure that might have been required for the manufacture of the left-handed body and neck.  In other words, the right-handed kits might be better!

Disclaimer:

This was my first time doing any of this:  fret leveling, painting, etc.  Before you tackle your own project, do your research!  Don't depend solely upon my experiences.


Links to Bass posts of mine...

Sonic Blue Bass (part 1 of a 3 part series)

Mellow Yellow Bass

Short-scale Telecaster Bass

Bass Guitar Painting Jig

Repairing a G&L Butterscotch Blonde Paint Chip

G&L ASAT Bass Strap-button Extender


Building a Bass Guitar Kit, Part 2

(You'll find Part 1 here: (click here))

OK -- Problems with the body have been fixed, now it's time to paint the body!

First, what paint to use?

Do I go with lacquer rattle can paint from the local hardware store?  Or how about a Nitrocellulose finish?  Or perhaps auto paint?  Or normal house paint?  And can I use one type of paint and another manufacturer's clear coat?

I started researching the web and I was soon confused with conflicting recommendations and advice -- a true plethora, and not in a good sense.

Fortunately, I came across a book that was a huge help in winnowing out the useful information from the noise:  "How to Create a Factory Finish with Just a Couple of Spray Cans!", by John Gleneicki.

For me, a neophyte painter with little experience, this book was GREAT!  John explains the different types of paints (enamels, acrylic lacquers, and urethanes), their pluses and minuses, and gives some simple rules of what not to do.  For me, this information was well worth the price of the book.

He also spends quite a bit of time discussing the steps and techniques that should be followed when painting with spray cans.  Again, for me, this was all valuable information.

I decided to go with an auto-body polyurethane paint and clear coat, rather than, say, nitrocellulose (although that is a more classic finish), because I was worried about the nitro's durability and also its tendency (or so it seemed to me) to yellow with age.  Although auto paint was more expensive, it also dried much more quickly (days compared to a month or two).  That convenience, and the fact that many guitars are now finished with polyurethane, pushed me in that direction.

 As for colors?  For me there was no doubt:  Sonic Blue!

So off to the auto paint store (I went to one in Sacramento) to purchase my materials, shown below in the order in which they were applied:
  • The first can is Spray Max 2K Glamour High Gloss Clear Coat, used to seal the body of the bass guitar before primer or paint are applied.
  • The next can is white primer.  I used Transtar 4633 White Primer (the auto-paint store clerk told me there would be no issue using this with my color coat or with the Spray Max clear coat).
  • Then the can of the urethane base color:  Sonic Blue, mixed at the store.  Sonic Blue originally was a 1956 Cadillac color, and I gave the man at the counter the Du Pont Color Code for that color (code: 2295).  Interestingly, when he printed the label for the can, it said "Fender Guitar Company," not Cadillac!
  • Followed by two additional cans of the Spray Max 2K Glamour High Gloss Clear Coat.
Eye protection and a respirator are shown, too:

(Click on image to view in its entirety)

Here are two more pictures of the Sonic Blue label on the can:
(Click on image to view in its entirety)

(Click on image to view in its entirety)


The body, drying, after being sprayed with the first can of clear coat (sealer/fill coat):


This layer is meant to seal the body and fill the pores (needed, because of prior sanding).  It was then sanded down to a smooth surface and the primer applied:


The primer was then sanded and the color coat applied.  Note the respirator.  Use one!

The Latest in Summer Fashion


When painting, do NOT hold the can over the body as I'm doing here if trying to get to the bottom of the guitar, because...


...a paint blob might fall on it!!!  Look for the dark streak in the center of the photo.  Don't worry, I and the paint job recovered (after my heart restarted).

(Click on image to view in its entirety)

Base coat applied and drying:



One of the problems when painting outdoors, especially under tall pine trees, when the wind is blowing!  Fortunately, I was able to flick these two pieces off with a needle.  But another hear-stopper.


This I couldn't flick off.  Oh well!

Following the color coat, the first can of two cans of clear coat was applied.  Note:  the color coat was not sanded before the clear coat was applied.

A run following application of the first can of clear coat.  Fortunately, following the steps in Gleneicki's book, this is very easy to fix.

(Click on image to view in its entirety)


While sanding the first clear coat, I accidentally sanded through it, the base coat, and down to the primer.  No way to recover, as I had no more base color paint.  Fortunately, the areas were all very small and the white primer was similar in color and luminosity to the Sonic Blue.  But I decided to apply a third can of clear coat, because, clearly, I had not applied enough along the bottom of the bass with the first can -- this area is the most difficult to reach if holding the body by the stick attached to the neck pocket, and so careful attention must be paid, as I discovered!

(Click on image to view in its entirety)

Although, difficult to see in the photo below, the last can of clear coat left little lumps in the paint under the pickup pocket.  This is better seen in the next picture...

(Click on image to view in its entirety)


...here (below).  Look closely -- you can see the little zit-like lumps left by the last can of clear coat, brought to relief as I started sanding.  I believe their appearance was because I was determined to use everything in that last can, and this "stuff" came out at the very end.  Next time, I'll stop a bit sooner.

(Click on image to view in its entirety)

Fortunately, they weren't a problem, as they sanded out (and with three cans applied, there was plenty of clear coat on the body, so no worries about sanding down (and through) the color coat).

And here's the body, awaiting sanding and polishing.



By the way, I strongly recommend that you first plan out your steps and then make a checklist so that you are sure to follow them.  The checklist will also help you remember what you had done if you decide to paint another body in the future.

Here's mine.  From it you can get an idea of the steps I took with each can of paint, and how long I waited between each.

(Click on photo to enlarge)


Disclaimer:

This was my first time doing any of this:  fret leveling, painting, etc.  Before you tackle your own project, do your research!  Don't depend solely upon my experiences.

Next Installment:  Sanding, Polishing, and Assembly! (click here!)


Links to Bass posts of mine...

Sonic Blue Bass (part 1 of a 3 part series)

Mellow Yellow Bass

Short-scale Telecaster Bass

Bass Guitar Painting Jig

Repairing a G&L Butterscotch Blonde Paint Chip

G&L ASAT Bass Strap-button Extender

Building a Bass Guitar Kit, Part 1

Although I play a Fender Jazz bass, I've always been curious as to how the Precision bass sounds and feels, especially with its wider neck.  Normally, one would just go to the local guitar store and try out one of their many basses.

The problem is, I'm left-handed.  This makes test driving a P bass almost impossible: of the three guitar stores in my area, not one had a lefty P bass (if they had any left-handed basses at all!).

So, if I wanted to try a P bass, I pretty much had to purchase it, sight unseen.  And without the chance to play a bass first, I didn't want to spend too much money on something that I might find clunky and awkward to play.

During my search for an inexpensive P bass I came across a P bass guitar kit.  And I thought, "Why not?"  I could paint it a color I liked (rather than being left to the limited color selection of most left-handed guitars).  And as for the assembly, well, how hard could it be?

The kit was ordered from Canada, and after a bit of a wait, it arrived:

Christmas in July

First things first.  After inventorying the parts (discovering a few minor discrepancies) I started assembling it.

The body and neck both needed sanding -- I believe they were coated with Polyurethane, but the surface of both the body and neck was very rough, and the kit supplier recommends that they first be sanded down (starting with 180 grit, then 240, and finishing off with 320).

Also, you need to drill 17 holes:  4 holes for the mounting screws for each of the four tuners, and 1 hole for mounting the string tree.  All in all, not terribly difficult.

Here's how it looked when fully assembled.  Not bad!

It played well enough that I decided to continue with the project.  But before painting the body (which would be the lion share of effort and additional cost), I first needed to tackle some of the issues I found during the assembly process.  Specifically:
1.  Parts Discrepancies:
  • No Allen-head Wrench (for truss rod adjustment).
  • Springs instead of compression foam pad for pickup height adjustment.
I contacted the kit supplier and they sent me an Allen-head wrench to replace the missing one.  The springs versus pads were no big deal, and probably due to old documentation.

2.  Wrong nut:  it looked like a right-handed bass nut hand been flipped around and installed in the neck.  This would be fine if the string channels were flat, but they weren't.  They were cut to slope towards the tuners when the nut was installed in a right-handed guitar.  The problem was:  in a left-handed guitar, they sloped in the the opposite direction, not towards the tuners, but toward the bridge.

I contacted the kit supplier, and, although they didn't have any nuts for lefty basses, they did send me a nut blank.  Not sure if I wanted to try cutting nut slots, I also looked around on the internet and found an Allparts nut listed on Ebay with the correct width and a flat base.  It was this nut that I installed.

Let me add -- the kit supplier was very willing to work with me to resolve the nut and the missing Allen-head wrench issue.  The other problems (listed below) were more problematic, because they weren't the fault of the kit supplier.  Instead, I believe they are due to lack-of-attention at the manufacturer (China, I believe).

3.  Obscured fret dots.  Not a big issue.  But required some cleanup.

(Click on image to view in its entirety)

4.  Bridge Mounting Holes:  Angled and various depths (illustrated below with small dowels in the holes).  Not a big deal, just sloppiness on the part of the manufacturer.


5.  Rear strap button hole:  not centered and drilled at an angle.


This was more of an issue with me, so I:
  • Drilled it to make the hole slightly larger and then pressed-fit a wooden dowel into it.
  • Counter sunk the dowel.
  • Filled the counter-sunk cavity with Bondo.
  • When the Bondo dried, sanded it flat.
  • Then drilled the correct hole.
Note:  Bondo is great for patching small holes and dents in the body.

6.  Incorrect Wiring:  The bass had Jazz bass wiring (in which the pickup was connected to the wiper of the volume pot), rather than Precision bass wiring (in which the audio jack is connected to the wiper of the volume pot).  I fixed the wiring to be P bass wiring, per the photo below (note the paint job!).
 

7.  The through-body holes for the four neck screws were too narrow.  This meant that, when screwing in the four screws to attach to the neck to the body, these screws were also cutting threads in the body wood, not just the neck wood.  Threads in the body wood prevents the neck from being sufficiently tightened to the body -- the screws snug up to the body first, rather than pulling the neck in as tight as it can go.

The obvious fix is to widen the diameter of these four body holes so that the screws would pass freely through the body.  I used a 13/64 drill bit.

8.  Fret Buzz when fretting either the E or A string at the 8th fret.  The 9th fret was noticeably higher than the 8th.  I tapped it down with a rubber-headed hammer, and this fixed that problem.  Buzz fixed!

But with that fret now lowered, I quickly discovered other frets buzzing.

Oh boy!  My chance to learn how to level frets! (Said with a distinct lack of enthusiasm).

Still, why not?

So I purchased a fret rocker and got to work, but I quickly discovered that the fret leveling issues where more significant than I imagined (or, more likely, I was making them worse by attacking them one fret at a time), and I needed to open up the wallet and add to the arsenal.  Here's my fret-leveling kit now...

(Click on image to view in its entirety)

Clockwise, from left:
  • Micro-mesh polishing pads for polishing the frets after they've been leveled and crowned.
  • Bass Guitar Neck Straight Edge (to ensure that the neck is flat and level *before* you start leveling frets).  Stewart MacDonald carries these, but I purchased mine from Ebay.
  • Brass brush (for cleaning files).
  • Fret File (for crowning the frets -- I purchased the Medium/Wide Double-edge Fret File from Stewart-MacDonald).
  • 320 grit sandpaper with adhesive backing (Stikit Gold Paper Self-adhesive Abrasive -- purchased from Steward MacDonald).  This is for the next item:
  • Fret/Fingerboard Leveler, 8 inch.  Stewart MacDonald carries these, but I purchased mine from Ebay.
  • Fret Rocker.  Another Ebay purchase.
  • Sharpie Pen.
(Not shown is the masking tape used to protect the fretboard during leveling/crowning).

When using the Fret Leveler it is important that you first adjust the truss rod so that the neck is flat.  And do this before you tape up the fret board.

Stewart-MacDonald has a good video on using a Fret Leveler:


   
Here's a picture of my Fret Leveler beam in action (again:  first adjust the truss rod to ensure that the neck is flat!!!).  No need to be aggressive when using it-- the weight of the beam itself is enough to sand down the frets.

(Click on image to view in its entirety)

Before I started leveling I first marked the tops of all of the frets with the black Sharpie pen.  As I leveled, the leveler removed the black markings from the high frets, and the low frets were yet be touched.  Below is an example of the different fret heights.  Note the areas that are still black.  The neighboring frets are still too high and must be leveled further.

(Click on image to view in its entirety)
 

Here are a couple of other fret-leveling YouTube videos that I found interesting, especially if you only need to level a fret or two.  If you search YouTube, there are more!

Leveling inexpensively:    

I like this guy's approach:     

Some additional notes:
  • When crowning the frets after leveling, again mark the fret tops with the black Sharpie.  When you finish crowning a fret, there should only be a thin black stripe left running along the fret's top.  You may want to practice your crowning technique on the high frets (e.g. 20th) first.
  • If you need to dress the ends of the frets, you'll need an appropriate file to do this.  Fortunately, the fret ends were fine on this neck -- no protruding sharp edges.

9.  Anemic and twangy sound when played.  I first thought this might be the pickups, but decided to try a different set of strings first.  Glad I did -- the difference was night and day.  It needs proper strings!
OK, those problems were fixed.  Now on to painting and finishing!

Finishing the Neck:

I decided on a clear satin Polyurethane finish.  The local hardware store had a can of exactly what I needed:



Fret board taped off, a thin coat of Poly applied with a cloth, and now to the drying...





After the polyurethane dried, I sanded it smooth with a very fine grit sandpaper to make the neck smooth and fast.


Disclaimer:

This was my first time doing any of this:  fret leveling, painting, etc.  Before you tackle your own project, do your research!  Don't depend solely upon my experiences.


Next installment:  Painting the body! (Click here!)



Links to Bass posts of mine...

Sonic Blue Bass (part 1 of a 3 part series)

Mellow Yellow Bass

Short-scale Telecaster Bass

Bass Guitar Painting Jig

Repairing a G&L Butterscotch Blonde Paint Chip

G&L ASAT Bass Strap-button Extender

Tuesday, June 25, 2013

Homebrew Horn Strap-button Extender for the G&L ASAT Bass

This is not my typical blog post, but it's a problem I recently became interested in, and others might find it useful.

Being a lefty, it's difficult to purchase a bass guitar.  Most guitar stores, if they have any left-handed basses at all, will only have one or two, and these are typically entry level models.  So it can be a frustrating endeavor if you want to find specific models to try out prior to purchase.

It's almost enough to make one switch to playing right-handed!

Almost.

I recently picked up (via the internet) a G&L ASAT bass.  The seller was too distant for me to try out the bass in person, so I took a gamble.  Overall it was a good purchase, but...the ASAT does have one flaw:  Because the horn is short, the strap button mounted on the horn has moved, horizontally, much closer to the guitar's center-of mass, compared to the strap button location on other basses (such as my Fender Jazz bass).  This shift in position of the horn strap button creates two problems:
  1. As this button moves horizontally closer to the guitar's center of mass, the guitar's weight distribution between the two ends of the strap (neck side and bridge side) shifts towards the neck-side end of the strap and away from the bridge-side strap.  That is, the neck side of the strap pulls down harder.
  2. The neck-side strap drops more vertically, thus, more of the strap is grabbing onto your shirt-front and pulling it down, resulting in shirt bunching.
The overall result, for me, is that the ASAT is not a very comfortable bass to play when standing up.

I did some Googling and discovered that this is a known problem:  http://www.bassesbyleo.com/forum/viewtopic.php?f=4&t=385

There's a clever design shown in the above link.  Here it is:



Unfortunately, this extender seems to no longer be available (also, it's designed for a three-hole mounting system that is not compatible with my ASAT, whose neck-mounting scheme has 6 holes in a rectangular pattern).


Well, I thought, if I can't purchase an extender like the one above, why not make an extender myself? 

I did, and here it is:






The Design:

As you can see, the design differs from the original one shown in the earlier link.  This was dictated by my design goals, which were:

I wanted to keep the amount of metal I would need to purchase to a minimum, which dictated that the holes to mount the extender to the guitar's body be somewhat in-line with the hole for the strap button.

I also wanted to play around with the location of the strap button.  On my Fender Jazz bass (and many other basses), the button is above the 12th fret.  The ASAT's button, by comparison, is above (roughly) the 17th fret.  Was there a better location for that ASAT than above the 12th fret?

I also didn't want the extender to interfere with my fretting hand as it slid down towards the body, so the extender needed to quickly bend up above the neck (but not so quickly that it looked awkward).

Given these constraints, I decided to use the two holes below (shown sans screws) for mounting the extender.



Notes:
  1. The distance between the centers of the two mounting holes is 1.95 inches.
  2. The original "shoulder washers" will be left in their respective holes (as shown above), so that they'll be available if someone wants to remove the extender.
  3. The original screws are also used -- they have plenty of length to provide adequate grip.

I dropped by a local surplus-metals shop and had them cut me some 8 inch long pieces of 6061-T6511 aluminum flat bar stock (0.125" thick by 1.5" wide).  I drilled a hole in the lower corner of one of them, mounted it to the lower-middle neck mounting hole shown above, and rotated the bar about this mounting point until I had it in a position that seemed good.

Important Note:  Put something between the bar and the guitar body to keep burrs and other sharp bits of metal on the bar from scratching the body when rotating it.  Thick paper or cardboard should work fine (but use your own judgement) -- I cut a piece from a manila folder and put this between the bar and the body.

(I also purchased some 8" lengths of 3/16" thick flat bar stock, but it turns out the 1/8" thickness is fine).

Once the bar's position seemed good (I wanted to try mounting the button above the 12th fret and at the same height that the button was currently mounted), I then determined where I wanted to place the second mounting hole.  After drilling it, I also drilled some holes for experimentation with the strap-button placement (to give me a range of choices to play around with).


Here are my final dimensions:


(click on images to enlarge)




(The only important dimension is the 1.95" center-to-center distance between the two mounting holes.  You can play around with all of the other dimensions to suit your personal design esthetic).

Here's the bar mounted on the bass (for testing strap-button positions)


...and its view from the front (note that the strap-button is not in its final location). 




By the way, the strap button is held on with a 6-32 screw and nut with integral lock (star) washer.

I played around with the location of the strap button and decided that I liked it best near the 13th fret -- As the button is moved further out from the body towards the neck the guitar body will shift in the opposite direction.  I decided that I didn't like the way the tummy cutout was hitting me when the button was at its furthest location, and that a good compromise was with the button near the 13th fret.

If you like rectangles, you can stop now (although your fretting hand will probably run into the extender, however, as you slid it down the neck towards the body).  But I wanted something a bit more curvy, to go with the curves of the ASAT and to also put the extender out of the way of my fretting hand.

Here's the design I came up with:


Cut, File, Sand:

To make hacksawing easier, remove metal by drilling around the shape's outline.
 
  
Hacksaw!
You won't be able to hacksaw too far along the curves (at least, I couldn't).  Whenever you get stuck, just cut as far as you can go along the outline, then remove the hacksaw and make a new cut from the outside of the bar to the last hole that you cut through.  Or if the metal is still held to the body by a few thin channels of metal between the holes, you can use a pair of pliers to bend the metal piece back and forth until the metal at the holes fatigues and the piece breaks away.

Filed and sanded.  Ready for paint.

Paint and Backing:

The extender is painted flat black.  No primer was used because, well, the paint I used is supposed to contain both paint and primer -- it's Rust-Oleum Painter's Touch 2X Ultra Cover Paint+Primer (picked up at Home Depot).  (We'll see how well it holds up).

After the paint dried (I gave it 48 hours) I buffed it down with a soft cloth and then added a green felt backing to protect the bass body (felt is usually available at Arts and Crafts or Hobby stores and ought to be inexpensive -- a piece of 6 inch by 9 inch green felt only cost me 29 cents).

The felt is held in place with a spray adhesive (be sure to mask off the rest of the extender!).  I used a can of 3M Super 77 adhesive that I've had around the shop for a few years.  A very thin smear of Elmer's glue in lieu of spray adhesive would probably work fine, too.



After the adhesive dries, mount the extender onto the bass, attach your guitar strap and away you go!

Ahhhh...that's better!


A Bit of Physics (extra-credit reading):

So what's going on?

First, let's talk about the guitar's center of mass.  Where is it?  (Actually, we're really talking about the center-of-gravity, but in the case the two are essentially equivalent).

I found its approximate location by balancing the back of the bass on top of a pill bottle.  Doing this, I discovered that it runs along the center of the bass neck.  For a more accurate position, you can hang an object from a string, and a line drawn along that string must pass through the center of mass.

For example, the ASAT center of mass (the red dot):



For comparison, Fender Jazz bass center of mass:

It is the distance between these strap buttons and the guitar's center of mass which is important:  what happens when the position of the strap button is shifted horizontally with respect to the guitar's center of mass?

First, we need to recognize that, because the guitar is not moving (that is, it isn't falling towards the ground, nor is it rising towards the heavens), it is at equilibrium:  all of the forces acting upon it (gravity pulling down, my body pulling the straps up) sum to zero (this is one of Newton's laws of physics).

What are these forces?  For the sake of discussion, let's simplify them to be the following:
  1. There is the tension of the "neck" end of the strap pulling down (and, as shown below, it's also pulling horizontally to the right).
  2. There's the tension of the "bridge" end of the strap pulling down (and, as shown below, it's also pulling to the left).
  3. And then there's the force my neck is exerting, pulling UP, to keep everything from dropping to the ground.

 Here's a drawing showing how these vectors sum to zero:

(Click on image to enlarge)

What is important to me (and my neck and shoulders) is the vertical component of these forces.  The horizontal components cancel out without any effort on my part (they are equal and opposite), but I myself must counteract the weight of the guitar, transmitted to my neck via the "tension" on the two ends of the strap.  That is, the force I'm exerting pulling up equals the sum of the forces on the two sides of the strap (neck side and bridge side) pulling vertically down.

Of the two vertical tension components shown above (neck and bridge straps), it is the neck strap tension that we are affecting when we move its strap button left or right.  And, because the neck strap button is closer to the center of mass than the bridge strap button, it carries the majority of the guitar's weight.  What happens when we move its position?

Changing the position of the Neck strap button will change the angle "alpha" shown above.  As the neck button moves towards the center of mass, the angle alpha becomes smaller and smaller.  Assuming the angle of the Bridge strap doesn't change when we move the neck button (it does, but let's not worry about that), this means that the vertical component of "Tension, Neck Strap" increases (and therefore the vertical component of "Tension, Bridge Strap" must decrease, because they both must still add up to be the weight of the guitar, which itself is unchanging).  That is, as I move the neck button in towards the body of the guitar (and its center of mass), the "Tension, Neck Strap" vector's point moves down along the vector I've drawn for "Tension, Bridge Strap".

Here's an image showing this:

(Click on image to enlarge)

Note how the vertical component of the Tension, Neck Strap, has increased while the vertical component of the Tension, Bridge Strap has decreased by an equal amount.

On the other hand, as I move the neck button away from the center of mass and towards the fingerboard's nut, the force exerted upon the neck strap will decrease, and the bridge side of the strap takes up more of the weight.

And this is what we are doing when we move the strap button away from the body of the guitar:  we are lessening the weight felt on the neck-side of the strap and transferring that amount, instead, to the bridge-side of the strap.


Other stuff:

Link to post at TalkBass Forum:  http://www.talkbass.com/forum/f8/homebrew-g-l-asat-strap-button-extender-994333/


Links to other Bass posts of mine...

Sonic Blue Bass (part 1 of a 3 part series)

Mellow Yellow Bass

Short-scale Telecaster Bass

Bass Guitar Painting Jig

Repairing a G&L Butterscotch Blonde Paint Chip

G&L ASAT Bass Strap-button Extender