Back Bow

[QweziRider]

I have a back bow problem with a finished neck (Rickenbackaer, to be specific). Would a repair question on an existing bass be out of place here, seeing primarilly project guitars are discussed?

[Southpa]

How did you assess the back bow? Did you totally back off both truss rods with the strings still in tension, (Ricks have 2 rods don't they?) and its still back bowed?

[Primal]

Ricks do indeed have two truss rods.

[QweziRider]

Oh yeah, it's definitely back bow.

Trying to shorten the story, it started with a wave at the 12th fret. Straight from 12-20, slight hump at 12, and a normal amount of relief between 12th and 1st frets. Moderately annoying. Been scouring through Rick forums and talking with people there who recommended removing the rods, straightening them (some are apparently curved, as mine were considerably, from the factory while others are straight), and resinstalling. Did just that and the odd wave was gone.

Now there's considerable back bow. Using a straight edge on the frets, the straight edge is on frets 1-12 and starts to rise off the frets until about 2mm off at the 20th fret. I've re-curved the rods, turned them in the channels 180 degrees, kept the rod nuts completely loose, tried heavier strings (.045-.130, I usually use .032-.100), strung it with only one rod in. Nothing has cured the back bow save for the heavier strings, and they only do enough to make it playable for the weekend, not where I'd really like it set. I've always had Ricks set dead straight with very light strings and had no problems.

This leaves me down to heating the neck as the last thing I can find to try, unless there's a better idea here. I think the knowledge level is considerably higher here on how to repair something than a forum of mostly players, which is why I thought I'd throw out the question.

One other note, this was once a 4 string Rick and was converted to a 5 stringer. I don't think that should be an issue because I'm under the impression Rick used the exact same neck configuration for the 5 and 4 stringers. The guy that converts them has done numerous Ricks with no ill effects (he and others who have his basses say). And he clearly remembers this one already having that odd wave prior to conversion for the person from whom I bought it. Plus, I would think if the 5 strings added too much tension, the back bow should be cured by that, should it not?

Kind of at my wits end on this and wondering if neck heating described in this forum will work on a finished neck or if there's a better idea.

Thank you very much.

[Southpa]

Backbow is nasty stuff, especially with Ricks, but apparently somewhat common with Ricks because of the lighter gauge strings used and lower action than other bass guitars. There are a few ways to correct your problem, some are relatively simple some are more radical, and may be only temporary, depends how much memory your neck wood has. What you need to do it try to make your neck wood forget where it was.

Hard to describe so I'll try to illustrate. Stewmac shows how to tighten stubborn truss rods by clamping here:

http://www.stewmac.com/tradesecrets/ts0000.hzml

Thoroughly heat the neck beforehand and reverse the clamping so the 2 contact points for the carpenter's level are on the back of the neck and your main clamp area is at the center of the fretboard. Tighten the clamp and check the fb with a straightedge, adjust as necessary and leave overnight. Hopefully the neck will "forget" where it was and assume the new shape ie. some relief when string tension is applied.

A more radical approach is to remove the frets and plane the fretboard flat. I read up on a board member's progress at trying to relieve a back bow in a neck he was building. Instead he removed the fretboard and planed the face of the neck flat but went beyond the limits of proper neck thickness. End result was having to construct a new neck.

[QweziRider]

Aha! Very clever. Makes perfect sense and is no longer a daunting thought. I'll go search the forum for proper heating devices now. Thank you!!

[soapbarstrat]

I think the knowledge level is considerably higher here on how to repair something than a forum of mostly players, which is why I thought I'd throw out the question.

First thing I'm curious about is how the guitar is being stored (what kind of stand, hanger, etc) ?

Often you can get better answers over at MIMF (Musical Instrument Makers Forum, or Many Irritated Members Fled). I wouldn't give up yet on the removable t-rods, since most necks don't even give you that option, so take advantage of that as much as possible.

That kind of heat will trash the fret-board finish. Before doing that, I would start pulling frets, and see if that starts taking back-bow out. But, at first I would pull one fret, and measure the fret-tang and slot size. That would tell me if it makes any sense to continue pulling more frets (if the tang to slot is a tight fit, it can be changed to a less tight fit, which often takes away back-bow). Of course, in the end, even if you get further with the T-rod manipulation, the fret-board surface will probably have some slight dips and rises, which will require the board surface to be leveled flat from end to end, but you want to do all you can to keep the wood removal to a minimum.

[Jon]

One other note, this was once a 4 string Rick and was converted to a 5 stringer. I don't think that should be an issue because I'm under the impression Rick used the exact same neck configuration for the 5 and 4 stringers.

If you don't mind me asking, what's the string spacing at the nut and at the bridge?

[QweziRider]

First thing I'm curious about is how the guitar is being stored (what kind of stand, hanger, etc) ?

I cannot vouch for how it was stored prior to March, but these days it hangs in a Hercules stand by the head, body supported from the back at the bottom, hanging at about a 10-15 degree angle. Humidity is pretty constant 40-50%. It's been the same with the odd 12th fret wave apparently for at least a year or so (I am told). The back bow did not take place until this weekend when I did remove and straighten the truss rods.

Which, although still a back bow, does seem more straightforward to correct than the wave did.

[QweziRider]

If you don't mind me asking, what's the string spacing at the nut and at the bridge?

1/2" at the bridge and 3/8" at the nut. Surprisingly comfortable, actually. The only thing difficult is serious slapping, which I couldn't do well in the first place, so no great loss there.

[soapbarstrat]

Life is cruel. I can't pick winning lotto numbers, but after reading your posts, I was 90% sure your bass was being hung by the headstock. Seen similar before. Not going into guitar wall hanger debate. Been there, done that.

[QweziRider]

Thank you for all the quick replies this afternoon. You all were very helpful.