straighten a neck

[watanabe71]

I've seen some times ago a company's website where they show a machine for straighten warped neck. I've googled again fot it, but i can't find it any more... If i remember right, you can send to them your bass and they put the neck into that machine for some times and it start to strighten the neck, slowly slowly slowly... I was thiking that it can be ok for that vintage Fender neck with that "hump" after the 15th fret where the trussrod doesn't work so much.
Franco.

[Turnaround]

Originally Posted by watanabe71

I'vI was thiking that it can be ok for that vintage Fender neck with that "hump" after the 15th fret where the trussrod doesn't work so much.
Franco.

The upper end "hump" (also called rising tongue, ski jump or flip) is usually addressed by removing the frets and planing the fingerboard. In less severe cases it can be dealt with by dressing the upper frets.

I have seen various means off dealing with warps, but straightening a warp is often not a permanent solution. The reason the wood warps in the first place is that it is reaching equilibrium in its environment. That means the wood is adjusting to the stress and relative humidity it is subjected to. Yes you can force the wood into a new alignment, but it will continue to adjust to its environment, which means it is likely to go back to the same "warped" position. So unless you can modify the humidity of the environment and/or change the stresses on the neck, the problem is likely to return. Fortunately we can do something about the humidity, but tension from strings is not negotiable.

There are exceptions. Steaming wood allows you bend wood in unnatural ways. But maple is not one of the woods that steams well, and most necks are maple.

[GlennW]

One of my basses has a similar problem. If you find the website showing the machine please post it. I've sketched out a jig I'm going to try, but a picture of something that's been used and proven would be interesting.

I'm planning on securing the neck pocket end of the neck and bringing the rest of the neck down with a level on top of the frets bracketed to a turn buckle underneath, and use a blow dryer for heat.

[Turnaround]

Originally Posted by GlennW

I'm planning on securing the neck pocket end of the neck and bringing the rest of the neck down with a level on top of the frets bracketed to a turn buckle underneath, and use a blow dryer for heat.

A blow dryer (hair type) won't provide enough heat. You will need something like a heat gun that's used for stripping paint. But you will then have to worry about scorching, fininsh damage, etc. Not for the faint of heart.

[62bass]

Originally Posted by GlennW

One of my basses has a similar problem. If you find the website showing the machine please post it. I've sketched out a jig I'm going to try, but a picture of something that's been used and proven would be interesting.

I'm planning on securing the neck pocket end of the neck and bringing the rest of the neck down with a level on top of the frets bracketed to a turn buckle underneath, and use a blow dryer for heat.

I've done it on several basses. I used a homemade jig consisting of a piece of hardwood about 2 1/2" x 1 1/2" the length of the neck, held off the fingerboard by two small blocks of wood at each end, with a clamp to put pressure on the back of the neck and the long piece of wood. I clamp it just enough for a slight backbow and apply heat with heat lamps. I leave it clamped up for about 6 hours and let it heat slowly and add a little more tension on the clamp when it's warmed through.

You have to do this with caution. Too much heat and you risk ruining the finish on the neck or scorching the wood. Too much pressure will put in too much backbow which the tension of the strings will not straighten out. Too little heat and the repair won't last. I get it so the wood is hot enough that I wouldn't want to hold it for long--sort of uncomfortably warm-about the temperature of a hot cup of coffee. After about 6 hours of this gradual warm up and then staying at a constant temperature, I turn the heat lamps off and let it cool overnight before removing the clamp. I believe what this does is sets the wood in the neck and also softens the glue holding the fingerboard on, which rehardens upon cooling. When it cools the neck has a new set to it.

It's worked for me on a bass that no amount of work with the truss rod would fix, even adding washers on the truss rod. While I'm at it I take the truss rod nut right off and add a couple washers anyhow, as you'll probably need them after this adjustment. I did this on a 69 Jazz that someone had left tuned up for 20 years in a closet right over a heat duct. Worked fine, and that was one bad bow that the truss rod would not take out by itself.

I also did it on my Fender P from '78 and even on a very old Martin acoustic guitar with no adjustable truss rod.

I lucked out each time.

I've seen this repair described a few times by luthiers. Some use an alcohol lamp for heat. Whatever heat you use, you have to moniter the heat and it's not something you want to set up and then leave while you go for a day on the beach. For safety sake you should keep an eye on it.

[billbass1]

Dan Erlewine's book, " Guitar Player Repair Guide " , litereley
help save my 1971 Guild JS II 's neck.
Has the photos and the technique showing how to do the fix.
After the fix, I now leave it in a stand where it hangs by its
neck, when I am not useing it.

[GlennW]

Thanks for all the input - I'll try the heat lamps; having never used a paint remover heat gun I'd rather not risk screwing up the finish. I have Dan's book, and looked before for neck straightening info - I'll look again.

I have two necks that need help. I was going to make a similar arrangement to what 62bass described because it's just a very bad bow, too bad for the truss rod to handle it. It's been straddling a couple of chairs face down with a bunch of weights hanging from it for going on a week (I know...). I'm trying to get it used to being close to where it should be. Started off with 41+ lbs and that wouldn't even get it straight. I've added more weights and now it does have a little backbow. I'll regroup and use the heat lamps and a jig with a C-clamp.

The other neck's a different story. It isn't bowed, but more like a hockey stick. Right where it leaves the neck pocket it takes a mild turn and the truss rod has no effect on it - it's pretty straight until it gets to the neck pocket. I'll try the heat lamps and a different jig on that one since it has more of a kink than a bow.

I'm going to try to get to it in the next few days.

[watanabe71]

Can you take and show some pics when you'll do it on your second neck?
Thanks,
Franco.

[GlennW]

Sure.

[62bass]

Originally Posted by GlennW

Thanks for all the input - I'll try the heat lamps; having never used a paint remover heat gun I'd rather not risk screwing up the finish. I have Dan's book, and looked before for neck straightening info - I'll look again.

I have two necks that need help. I was going to make a similar arrangement to what 62bass described because it's just a very bad bow, too bad for the truss rod to handle it. It's been straddling a couple of chairs face down with a bunch of weights hanging from it for going on a week (I know...). I'm trying to get it used to being close to where it should be. Started off with 41+ lbs and that wouldn't even get it straight. I've added more weights and now it does have a little backbow. I'll regroup and use the heat lamps and a jig with a C-clamp.

The other neck's a different story. It isn't bowed, but more like a hockey stick. Right where it leaves the neck pocket it takes a mild turn and the truss rod has no effect on it - it's pretty straight until it gets to the neck pocket. I'll try the heat lamps and a different jig on that one since it has more of a kink than a bow.

I'm going to try to get to it in the next few days.

Yes, the heat lamps and clamps will work, at least on the first neck. The other, I don't know. You may have to shape a wooden caul to fit the back of the neck so your clamp won't slip off or bend the neck sideways which you definitely don't want. Some C clamps with enough throat depth to work with are heavy and a real pain to get to stay in place. Also, as you turn the clamp it makes it easier to twist out of place. I've used 2 others which worked well. One was the old fashioned wooden clamp and the other a Quickclamp that adjusts by squeezing the handle. The Quickclamp just barely gave me enough force to pull the neck into a backbow.

Anyhow, make up some jigs and do a trial run without heat to make sure you've got all the bugs out. If everything works as you like, then clamp it just enough to induce a very slight backbow and turn on the lamps. Once the neck has heated through put a little more pressure on the clamp. The neck will feel soft and bend easy, specially a skinny J neck. Don't overdo it, watch the heat doesn't burn anything ( you might want to use 2 heat lamps for more even heat) and you don't want the heat just in one localized spot where the clamp is or you'll just put a sharp kink in the neck. You want to heat the full length of the neck so you get a gradual curve. On one bass I used a big electric ceramic heater that gave off serious infrared heat and heated the whole neck. I think once the neck is heated right through there's no real point in letting it sit under heat for too long. When it's heated through and sat for an hour like that, then shut the lamps off and let it cool slowly until it's at room temperature before removing the clamps.

I haven't read Erlewine's book or read any other luthier's methods of doing this. Someone in the business told me about it back in the 70s and I worked out the details myself.

As I said before, slack off the truss rod before you do this and be prepared to put 2 or 3 washers on the rod when you put everything together again. You'll need the extra purchase the washers will give you.

Good luck with it and let us know how you did.

[GlennW]

The neck with the bad bow is under the lights now. It's jigged with a slight backbow. FWIW, the week it spent with weights hanging from it accomplished nothing that I can see.

Two 250 watt heat lights - one pointed at the fretboard, the other pointed at the back of the neck. I had them aimed at the sides, but figured this way more surface area would be heated. The fretboard side has a 2' level running down it edgeways, so I might shift that light every so often to heat the shadowed area. The bulbs are about 9-10" away.

If I'm doing something wrong, please let me know.

[62bass]

Sounds right to me. Check to see if the neck is getting warm enough.

[GlennW]

Thanks. I guess it's warm enough. I moved the lights a little closer. It's hot to the touch, too hot to hold very long, and the finish seems to be fine.

Edit: just checked it and it isn't looking like a back bow, more like a very shallow upside down V with the high point being the 7th fret (where the clamp is). A 2' straightedge will rock on it and be about 1/16-3/32" off the opposite end. I'm going to find something a couple of inches long to put between the c-clamp and the back of the neck so it will be more like a bow.

[GlennW]

The little block between the c-clamp and the back of the neck helped a lot, it helped to round it out a little - the straightedge would pivot on two frets instead of one.

I think it's ok now. After removing it from the jig this morning there was still a slight bow, about 1/32". I thought about doing it again with more backbow, but went ahead and strung it up. It's tuned up and doing fine. The only side effect was a couple of side dots grew a little from the heat.

It's one of these, a blue one made in May of 1998. I'm not crazy about the color, but it's in great shape. I might paint it white if I keep it, but not this year. It looks about a week old and was $91 on ebay. I have some ebay pickups to try in it - Muy Grande, SD 1/4 pounders, and SPB-2.

http://www.ibanezregister.com/images...0/gtr50-98.jpg

Thanks again for all the help.

I'll try to get to neck #2 this weekend. The jig for that one will take a while to make.

[62bass]

Great. See if you can rig up a way to get more of the total length of the neck heated.

Hope #2 turns out good.

[GlennW]

I was wondering about that while setting up the lights - didn't know if it would be better with both lights aimed at the back or one on the back and one on the fretboard. Either way, it's 100% better than it was - very comfortable full scale neck. It must have just sat a long time in a hot place.

I'm going to take your recommendation on the JF344s and also try the 1/4 pounder. I'm into flats anyway and think the TI's lighter tension (compared to LaBella) would be a practical choice for this neck considering its history. The pickups went cheap on ebay because they didn't have any leads, but they all check out alive with the DMM - should be an easy fix.

I've also come to my senses as far as the paint. It has by far the best finish of any of my basses and it would be close to foolish to paint it, but I will make a white pickguard (I have a scrap big enough) to replace the black one - it's just too dark as it is.

Thanks again.

[62bass]

Sounds good. I'm glad the repair worked. Yes, the JF344s do have a bit less tension and should work nicely for you. But, it's the sound of these strings that knocks me out. Completely unlike other flatwounds and they keep their tone for years. Give them a few days of playing to develop their tone.

I've always liked the Quarter Pounders. That should be a fine gigging bass when you're done.

[GlennW]

Neck #2 is in the jig and under the lights. I'll post a couple pics tomorrow as the OP requested. It took a couple hours to make.

I'm glad I put it off another weekend - instead of a turn buckle it uses a piece of angle for the bottom of the c-clamp; that way it can be moved closer to or further from the heel of the neck.

It isn't under a lot of pressure now. The 2' level on the frets contacts 1-10 (except 2-4). Frets 11-18 don't contact the level, 20 does, don't know about 19 but suspect it doesn't.

After an hour or so I'll look again and probably tighten a bit.

I'm trying to reverse the ski jump and end up with the most clearance at 20.

I think I should have used something shorter than a 2' level - it's blocking a lot of light on the fretboard. I might try something else if necessary.

[GlennW]

I think it's close, so it's going to set under the lights a few more hours.

I'm using a .005" thick plastic/paper tag for a gauge to check between the frets and level.

Frets 1-13; won't go (except 2-4 as before)
Frets 14-17; it will go
Frets 18-20; double thickness will go

It took some tweaking, but it's bending where I wanted.

[62bass]

Great. I'd like to know how that one turns out.