Straightening an excessive bass neck bow?

eSully

Hoping to get some help/opinion on this one, picked up a cheap bass a few weeks back (my first bass), 84 Westone Thunder 1-A. It's a lovely bass, love the different sounds you can get from the pickup configurations.



 Neck is really nice, The problem is there's a noticeable bow which is stopping me getting the action as low as I want. You can see how high the action is in the picture below and hopefully make out how pronounced the bow is. It is playable but I want to get it a lot better. 



So, I've changed the bridge saddles to new Wilkinson ones as the old ones were unadjustable. I thought after buying it I might be able to sort the bow out by adjusting the truss rod but there's already tension on the truss rod so that bow is there despite the truss rod being tightened. As the the bow is quiet pronounced a shim isn't going to do the trick I think, I did have a try but it made the higher frets unplayable although admitted I haven't give the bass a fret dress yet which it does need!

I see my options as:

• Live with it
• Shim the neck, fret dress and see if I can improve the action
• Buy a new neck and replace the current one!
• Try straightening the neck!!

I do fancy trying to get it straightened first so having watched the following video on youtube I was just wondering has anyone successfully straightened a neck using this method, if so, how long did you leave the neck clamped and did you use heat or an oven at low temperature as I saw on another video I can't find the link for right now? I don't know if this complicates things but as you can see in the picture below this is a three piece maple neck

cheers

Bridgehouse

Is the truss rod maxed out? If maxed there should be a back bow with no strings on

eSully

Bridgehouse said:

Is the truss rod maxed out? If maxed there should be a back bow with no strings on

Feels pretty maxed out to me although I'm no expert on setups, I didn't feel too comfortable trying to tighten it much further, it's been a few days since I had the neck off (been meaning to post this question earlier) but even tightened up without strings on I don't remember there being a back bow. Will take the neck back off in a bit and have another look. Cheers

Bridgehouse

eSully said:

Bridgehouse said:

Is the truss rod maxed out? If maxed there should be a back bow with no strings on

Feels pretty maxed out to me although I'm no expert on setups, I didn't feel too comfortable trying to tighten it much further, it's been a few days since I had the neck off (been meaning to post this question earlier) but even tightened up without strings on I don't remember there being a back bow. Will take the neck back off in a bit and have another look. Cheers

It might be tight - best thing is to put some pressure on the neck to straighten it, and adjust the truss rod at the same time. Try it in quarter/half turns and leave for an hour or so then try a bit more. Leave it over night once it's straighter, and if possible a tiny touch of back bow - you can always add a bit of relief back in later

eSully

Ok. I’ll give that a try this evening. Cheers @Bridgehouse ;

Bridgehouse

eSully said:

Ok. I’ll give that a try this evening. Cheers @Bridgehouse ;

Let us know how it goes!

Funkfingers

Those Westone basses are good - apart, perhaps, from the pickups and electronics.

If the neck itself is reasonably straight, a shim in the neck pocket will improve the action height.

If the neck is bowed, the Dan Erlewine video pretty much describes what needs doing.

prowla

From the photo, the neck does look bowed.

You can try taking off the adjustment nut and putting a washer/spacer there, but if there's an underlying issue (ie. the other end of the truss rod is compromised, or it's broken) then that might just make things worse and it'll need surgery to fix it.

If you try taking the action down or shimming whilst the neck is bowed, then you may end up in the situation where you can play the higher and lower notes, but the middle ones just snag on the top fret.

The first step is to get the neck bow sorted.

WezV

Make sure you actually check relief properly, sighting down the neck can be misleading.

also, try loosening the rod before tightening... sometimes they seize a bit and feel tight, then end up broke because someone tries forcing them.  Loosening it first prevents this and will give you a feel for how much tension it already has on it.

they are well made, so I suspect it will be fine

SteveRobinson

Also, a bit of lithium grease on the thread and washer will help matters no end.

prowla

Just put a capo on the 1st fret, press on the top fret and see the height of the string at the 12th - it should be about a credit (or business) card.

(Do it while holding the guitar in the playing position, not flat on its back!)

NeilMcG

You are unlikely to be able to successfully dress the frets if you can't get the neck dead straight (without string tension).

The advice from WezV and SteveRobinson is good. I'd also get a set of feeler gauges so you can see exactly what the relief is. The bass looks like a Fender scale, so a typical starting number is 12thou clearance measured at the 8th fret with a capo on the first fret and the string held down at the last fret.

You won't need to shim the neck unless you run out of downward adjustment on the bridge saddles before getting the action low enough.

eSully

Thanks everyone, well I've popped the neck off and had a look again. There's definitely still a light bow with the neck off and under truss rod tension. I've checked the truss rod and it does seem to be working fine, there's no issue loosening it completely and in fact when I gave it a good tighten I did hear the neck creak. I've included pictures below but they don't quiet do it justice, in person the issue is clearly around the 12th fret. The neck is pretty straight up to that. I did check the relief at the 12th earlier by the way and I think you could get a few credit cards in there! That's why I don't think a shim will do the trick.


*I don't know how well it can be made out but there seems to be a back bow up around the 1st few frets. The bow that's causing the action to be so high is around the 12th!



So, at the risk of disgusting the respected luthiers on here, this is my makeshift clamp for the neck. I loosened the truss rod up, clamped the neck in the area I think the bow is happening at until there was a light back bow then tightened up the truss rod until it was snug. My plan is to leave it overnight to settle. Let me know if what I've done is completely the wrong thing to do and I'll get it out of the clamp. Apart from that I'll put it back on in the morning and see if there's any improvement.

eSully

Funkfingers said:

Those Westone basses are good - apart, perhaps, from the pickups and electronics.

Surprised by that, Although not a bassist and I don't have anything else to compare it to I was actually really impressed with the pickups and the range of sounds you could achieve by playing with the active/passive and tone settings. It's a great solid bass, if I can get the action sorted it'll be perfect for me.

eSully

NeilMcG said:

You are unlikely to be able to successfully dress the frets if you can't get the neck dead straight (without string tension).

The advice from WezV and SteveRobinson is good. I'd also get a set of feeler gauges so you can see exactly what the relief is. The bass looks like a Fender scale, so a typical starting number is 12thou clearance measured at the 8th fret with a capo on the first fret and the string held down at the last fret.

You won't need to shim the neck unless you run out of downward adjustment on the bridge saddles before getting the action low enough.

I don't have the guages but I did do a cursory check of the releif and it was quiet high. I did replace the saddles and there's a little further I could get them down but even then the action would still be very high. It definitely needs a fret dress but as @prowla said I'd prefer to get the neck straightened a bit better first

prowla

A rough sequence:
1. Neck bow.
2. String height...
2.a Bridge.
2.b Shim, if required.
2.c Repeat.
3. Nut (if it's too high).
4. Intonation.

GSPBASSES

If none of the above has worked so far, I presume the truss rod is working, but has not got the strength to put in some back bow in to the neck. If it's a one-way rod remove the nut and the washer. Then, if possible, put at least one or two extra washers on the rod. Then put the nut back on but don't tighten it.

 

Presuming you haven't got one of these http://www.stewmac.com/Luthier_Tools/Types_of_Tools/Jigs_and_Fixtures_for_Guitar_Building_and_Repair/Erlewine_Neck_Jig.html

 as this would make the job a whole lot easier, if you know guitar tech who's got one, it might be worth a phone call to see if he would sort it for you.

 

  Now for the kill or cure.

Clamped the neck to a bench, see photographs below. Now pull another clamp on the headstock, making sure you protect the wood, then slowly close the claim down so the neck bends backwards. Now tighten the truss rod no real pressure just so it comes to a stop, then about a quarter turn. I would then leave it overnight, next morning give the rod about another quarter turn. Remove the clamps and with any luck the neck will have some back bow, I still wouldn't use the neck for a few days. If this procedure doesn't work then you may well have to have a new neck.

If that works then its just a case put it back together and reset it up the best of luck.

eSully

Thanks @GSPBASSES ;, well looks like I'm taking generally the right approach, I've clamped it differently but it's the same effect, I'll follow the advice on here and update in a few days, Cheers all

prowla

Wow - I would've thought that you put the pressure at the 1st frst, rather than risking the headstock being weak?

eSully

Final update, it worked!!, I was away from home all last week so I decided to leave it clamped in the shed for the week and check it when I got back. Last night when I got back I had a few minutes free to pop the neck back on and tune it up and the difference is night and day. Without any setup or shim the action is noticeably much better and the bass easier to play. Should be even better once I have a chance to set it up better.

Thanks All

Bridgehouse

Great news! Glad it's worked out well..