Double bass rebuild - not for the faint of heart!

[The Guitar Weasel]

Neck fit is getting closer - this is all hand tools shaping so it can't be rushed. Looking a bit rasp-rough at the moment ... but lots more wood to come off still. 

 

One issue that has been highlighted is how bodged the previous neck re-glue was and how 'out' the original neck pocket was built. I wondered why the neck appeared to have been glued in without being fully seated in the pocket - in other words glued to the sides but not even touching in a lot of the bottom of the pocket. Well that would appear to have been a bodged attempt to face the neck properly down the centre line of the body. with the new neck properly seated and its mating face at exactly 90 degrees in all directions the neck and the fingerboard (strapped on with tape for the test) point way too far over to the bass side f hole. The whole neck pocket must be out of true with the centre line. The solution is to plane and use a cabinet scraper to deliberately take the back of the heel down on one side - thus pointing the neck/fingerboard once more along the centre line. 

 

 

 

For those into tools - the lion's share of the wood stock removal on this project has been done with the 'rip' side of a 250mm Japanese Ryoba hand saw. I really can't speak highly enough about how good these saws are. Maple is hard - and a bitch to hand saw - but not with one of these. The Ryoba cuts like a sharp breadknife through a fresh sourdough loaf ... so satisfying. 

Edited May 16 by The Guitar Weasel

[The Guitar Weasel]

So while I'm waiting for the neck bolts to arrive I might as well do a bit of tidying up. 

The bottom front edge of the bass had taken some nasty damage to the laminations - but all easily fixable. I sawed down some birch ply down to one lamination and let it in with hide glue and then scraped with a cabinet scraper. I'm not worried about small gaps and visibly repaired cracks - I'll mix some fine powder birch sawdust with glue and fill the cracks. Okay the finish is buggered in this area ... I could touch it in - but I'm leaning towards a full refinish.

 

The end pin hole had been reamed out massively and was also at the wrong taper for the new endpin - it nearly fell into the bass! 

 

 

So I made and glued in a liner from thin mahogany stock

 

 

And I'm using the incredibly slow method of bedding the endpin into the hole by double stick taping sandpaper around the pin ... it works well and is way cheaper than an end pin reamer - still got some to go! 

 

 

I've ordered an ebony saddle to replace this ... er ... 'wood' one 🙂 

 

 

Edited May 21 by The Guitar Weasel

[The Guitar Weasel]

So this is where we are now - 

 

The neck joint is fully trimmed and VERY tight fitted - it's gone back to the correct depth leaving exactly 27.6mm of overstand as per the original. 

The underside of the fingerboard end to belly is also exactly like the original - this is testament to my grandfather and father's advice measure a job twice - have a cup of tea - then measure twice again - then have another cup of tea to think about if you are actually doing what you need to be doing:  the four measure/two tea method (or coffee if that's yer bag).  

 

So the possible order of the the list of jobs still to do: 

1. Scrape a small amount from the bass side of the neck heel face to correct the slight wonkiness of the original neck pocket that had the fingerboard way off centreline. 

2. Bore the pilot holes in the neck heel out to 8mm and cut the wider area to sink in the cap head stainless bolts and washers.

3. Shoot the face of the neck with a sharp hand plane to prepare it for the fingerboard. There is a verrrrrrrrry slight back-bow ... but I will try to leave a bit of that in to pre stress the neck back a tad to resist string tension.

4. Glue the fingerboard to the neck - hot hide glue, properly warming the neck and fingerboard to extend the 'open time' - and I'll co-opt an assistant for that job as it has to be done fast and right! 

5. I'm pretty set on an access hatch in the treble side cutaway - so that will be next probably.

6. Making the neck inner clamp plate - yep I'm going to try that method: a plate bored and tapped M8 and secured to the inside of the neck block 

7. Fitting tuning machines to peg box and some much needed final neck shaping ... the replacement neck is like a tree trunk! 

 

Then technically speaking the neck can be bolted on, the end pin, wire and tailpiece installed, the bridge shaped and fitted, the nut fitted - the sound post re installed ...

And if I want to I can whack a set of strings on there to see what I have! 

 

Yep I'm going to refinish her ... but I think it's worth putting the old girl back under tension for the first time in I believe over 40 years to make sure she doesn't go BANG before I spend a lot more time making her look beautiful! 

 

[Paddy Morris]

Amazing job you're doing.

[bass_dinger]

I am enjoying this build diary, very much.  Well done for saving a damaged instrument from the scrapheap.

 

I must say, seeing the complexity of the build has cured me of the foolish notion that I could also buy and repair a double bass.  

 

 

[The Guitar Weasel]

2 hours ago, bass_dinger said:

I am enjoying this build diary, very much.  Well done for saving a damaged instrument from the scrapheap.

 

I must say, seeing the complexity of the build has cured me of the foolish notion that I could also buy and repair a double bass.  

 

 

My regular daily work is in either building new pickups to customer's sometimes strange requirements - or restoring valuable PAF pickups etc from the 50s ... this stuff is like big Lego! 

 

Seriously though ... it's meant to encourage not 'put off' - I think any reasonably competent DIYer with some hand tools and who is willing to learn (there are lots of bits and bobs of knowledge available online) can do as well or better than I have here. Patience and an eye for the end goal are the most important things. 

 

I was born a bit stubborn ... that helps too ... man went to the moon when I was a kid, I refuse to believe I can't fix a musical instrument that's essentially made of tree!   

[PaulKing]

Nice job.

[The Guitar Weasel]

So ... shot the face of the neck level and smooth with my trusty Stanley No 4 plane. It's still thick as a tree-trunk but I will sort that after I've glued on the fingerboard. 

 

 

First time it's moved as a unit with the neck bolts in ... no nuts yet (oooer Missus) ...  but the fit and neck socket were tight and tidy enough for me to lift the bass. 

Checking all is well with the bridge height ... and should be no issues. 

 

 

So in preparation for drilling the tuning box peg holes I disassembled the tuners and mounted them as a template.   

The holes are 14mm so I've had to order a bit specially ... bah! 

 

 

Couldn't resist a quick shot of her looking a bit more like a bass again - yep the cap heads of the neck bolts will be let in ... luckily with the same 14mm drill as needed for the tuner holes - happy day! 

 

[Hellzero]

Superb job so far! 👏🏻👌🏻👍🏻

[The Guitar Weasel]

Just now, Hellzero said:

Superb job so far! 👏🏻👌🏻👍🏻

Thank you - I had a bit of spare workshop time - so I did a bit in the day today ... makes it zip along when you can knock a couple of intensive hours off the total ☺️

[The Guitar Weasel]

Well I've been putting off drilling the tuning machine holes .... it's basically a horrible job ... I used a 14mm twist drill bit in a variable speed power drill ... going as slow as I could, and eyeballing the correct 90 degree angle of drilling. Easy to go wrong, so slow but sure was the way. 

Well after a grimly intense 20 minutes I had the holes drilled and the tuners trial fitted ... only to discover a problem ... the rollers were WAY too long for the width of the pegbox. Not only would the holes for the steel rollers have had to go all the way through both sides of the box, but even then the tips would have fouled the brass plate on the other side! This is galling as the neck and tuners were supplied as a unit and clearly supposed to be fitted together. 

See image below ... the plate furthest away was stood off about 1/4 of an inch with the 'bearing hole' drilled as deep as I dare. 

 

 

I did however still have the set of tuners I replaced on my Stentor bass stashed away  ... which, while individual on the Stentor as opposed to set and 'all on a plate' with this set ... the rollers were also 14mm diameter and fitted a pegbox the same width as the one on this Chinese neck. 

As luck would have it the tuners were identical except for the Stentor ones rollers being brass and actually fitting properly. RESULT!!! So I swapped the rollers over between sets and everything fitted perfectly! 

I could of course have used my bench grinder to shorten the steel rollers ... but who wants to work that hard? I think keeping the brass theme is nice too. 

 

 

I trial fitted the nut as well and was toying with the idea of gluing it in place as an 'end stop' to make the positioning the fingerboard for gluing a bit easier and faster. 

Still not decided on that one. The end of the fingerboard has been cut slightly out of the 90 degrees so I'll have to address that first - whichever order I fit nut and fingerboard and nut. 

 

busy busy busy 😁

 

[The Guitar Weasel]

So the evil day of cutting the 'access' hatch came. I'd racked my brains to find a mechanised way to do it ... but there was simply no way. This was going to be protracted and painful. 

I made up a saw doohickey using a chopped off coping saw blade ... with a screw holding it into a little handle and waded in. I used a school compass to mark out a circle, a tiny drill to slot a starting hole and found to my surprise that the C panel was only about 1/8th of an inch thick. This meant that I could only cut on the back stroke ... ie the wrong way ... and it took a very very very very very very long time ... and absolutely crippled my wrist! 

 

Mr Blobby had clearly been about with the glue inside!

 

 

And done 

 

And a new sound post will need to be made ... the original wasn't even a gentle push fit ... it took a bit of 1/4 inch scrap wood to get it to wedge into place. Something has shrunk methinks! Well it comes to us all with age I suppose. 

 

 

I shall make up a reenforcing flange to glue around the access hatch (probably three or four laminations of thin ply) and due to the really thin nature of the C panel I will have to make some bracing ribs for the hatch cover - as well as a decorative knob (ooer Missus) to be screwed onto it to facilitate easy removal against the pull of the ring of neodymium magnets I intend to set into the flange and hatch cover to keep it in place and stop rattles. 

 

[PaulKing]

Was the soundpost too loose then, if I understand right? Well ... it should be, with no string tension to hold in place. Although maybe a 1/4" air gap is  tad exaggerated....

[The Guitar Weasel]

17 hours ago, PaulKing said:

Was the soundpost too loose then, if I understand right? Well ... it should be, with no string tension to hold in place. Although maybe a 1/4" air gap is  tad exaggerated....

To my understanding the sound post should be gentle push fit ... enough to keep it in place while string tension goes on certainly - then it is clamped by the belly pushing in under that string tension. 

This bugger ... and it should be the right one as it was inside the bass ... was not even a push fit ... unless you jammed scrap wood under one end. 

 

Someone in the bass's past could have put a wrong sound post in - lord knows. But the post should be firm enough to be able to take all the strings off and it not fall over so long as you keep the bass on its back and don't bounce it around. 

I will be cutting a new one. 

Edited Wednesday at 10:57 by The Guitar Weasel

[Owen]

No problems fitting that new post now

[The Guitar Weasel]

 

So I had to engage in a glue fight to get the fingerboard glued on ... hide glue everywhere including my bench, the floor, my hand towel, countless rags to clean up squeeze out ... er and my eyebrows!  

 

 

So from this ... to this ... 

 

A couple of hours on the bass before work today  - went in for 7.00 as I wanted peace and quiet to do the glue up ... with no phone ringing! 

After 'gluemageddon' and a couple of hours of clamping ... 

 

Neck  bolts snugged up to a pair of temporary nuts ... and technically the bass could be strung up and tested tomorrow ... but I've a few more things to do yet.

The nuts are temporary as I found the stainless steel neck bolts I had bought are about 10mm too long to tighten fully ... gurrr ... more on order from Accu. 

 

I glued in the nut and started doing sone assessment of how much needs to be trimmed off the bridge feet to match them to the belly curve. not much as it goes.  

 

Looking forward to hearing its first notes in perhaps 30+ years soon. 

Then it'll be looking to a re finish. 

 

 

 

 

 

 

 

 

 

[Stub Mandrel]

1 hour ago, The Guitar Weasel said:

Accu

 

Are you a billionaire?  😁

[The Guitar Weasel]

2 minutes ago, Stub Mandrel said:

 

Are you a billionaire?  😁

Lol we use Accu quite a bit ... they are a really good solution for difficult to find things - like tiny M1.6 Allen headed cap machine screws ... we use these to replace drilled out rivets in some old Hofner pickups when we rewind them ... as we invariably have to! Handy on some old DeArmond stuff too.