Good way to induce back bow without a vice clamp?

Chrisk-K · #1 01-05-2011, 08:36 PM

I need to induce back bow to my Geddy neck because the neck relief, even with the truss rod maxed out, is too much for me.

I don't have a vice clamp. What would be a reliable method to induce back bow? Can I simply apply force to the mid area of the neck with, say, my knee?

iamlowsound · #2 01-05-2011, 09:44 PM

Is it something that a neck shim would fix?

Lowsound

Beej · #3 01-06-2011, 09:00 AM

Chris, I don't advise doing this. Although I have saved more than one neck with clamping, I have also lost more than one neck doing this. I always inform people of this before doing the work. It involves heat, careful preparation and time in the clamped position.

I'd try shims first. If you're really set on doing this, a few of us could walk you through how we do it, but I do want to emphasise the risks...

Rocky McD · #4 01-06-2011, 09:45 AM

Does this neck have an upbow with the strings removed and no tension on the neck?
In other words, in it's natural state? If so, it may be repaird, but as Beej said it is not without risks. I have always believed that a neck that has a Fender style arched truss rod, you should be able to produce a very slight "Downbow" with the truss rod tension and no string tension. You may be able to repair this neck with a truss rod nut spacer or, it may need to be clamped and heated for several days. I have been able to repair some but the neck may not respond to clamping pressure. The GL neck is very thin and therefore very weak and many people have had problems with these necks. I suggest you check the straightness without strings and without truss rod tension and see what the natural state of the neck is.
Rocky

lowendblues · #5 01-06-2011, 09:57 AM

A short asnwer would be a 1"x1", 2 wood blocks, and a cable tie. Works like a charm.

Chrisk-K · #6 01-06-2011, 10:11 AM

The neck is straight under no string tension. My Geddy neck seems too weak to handle even low tension Hi-Beams (040-100) with the truss rod maxed out.

Should I place a shim at the neck pocket closer to the pickup? I can visualize doing so will create slight downbow.

If that doesn't work, I'll definitely try the 2 wood block method.

bassy7 · #7 01-06-2011, 01:58 PM

First of all.... Have you tried helping the rod to induce some back bow while you turn the truss nut? If the rod really needs to be cranked down, you shouldn't rely on the truss rod to make the neck move that far. You can help the truss rod straighten out the neck by putting a little back bow pressure on the neck while you tighten the rod.
To sum- truss rods are better equiped to hold a neck in a certain shape than they are at forcing it into that shape.

I don't have any direct experience with this type of issue but the first thing that came to my mind was compression fretting. It involves a complete re-fret and it is certainly not the first aproach one would take, and maybe not the best solution for your situation- but its possible that it could solve your problem. Just keep it in mind if other options don't yield successful results.
Hope you get this solved without to much of headache.

JLS · #8 01-06-2011, 06:32 PM

Quote:

Originally Posted by iamlowsound

Is it something that a neck shim would fix?

Lowsound

Please (GOD!), be joking...

Zooberwerx · #9 01-06-2011, 07:03 PM

Quote:

Originally Posted by JLS

Please (GOD!), be joking...

What he said.

Is the truss rod nut removable? If so, remove the strings and truss nut and place one or two spacing washers on the rod. Lube the truss nut well, replace, and gently tighten while applying light pressure on the neck. I can usually introduce some degree of back bow. Restring, tune to pitch, then back off the truss rod until nominal relief falls into place.

Riis

walterw · #10 01-06-2011, 07:15 PM

^ that.

shrigg · #11 01-20-2011, 09:11 AM

After a Fender makes a cross country trip it often arrives to me with way too much bow and the trussrod appearing to be "maxed out..." pretty much unplayable by my standards. I remove the neck, loosen the trussrod completely and clean and lube it if necessary. Then I clamp the neck into a backbow, enough to notice the neck move quite a bit as you tighten the clamp. This reminds the trussrod how the neck relief should be. Then I tighten the trussrod all the way, unclamp everything and string the bass up. Usually the relief comes out very close to perfect using this method.

Jimbob Jones · #12 01-20-2011, 09:47 AM

+1 to lowendblues, zoober, shrigg etc.

If you decide on the washer approach, make sure you don't have a dual action rod, as you can't take the nut off of one of those...and if you do manage to remove it, you almost definitely won't be able to get it back on again.

It's even worth just trying this: get a friend to hold the body down on a table while you push the neck into a backbow, tighten the trussrod while still pushing down on the neck. Sometimes all the rod needs is a little help in getting the neck to the position you want it in, then it will hold it there.

shrigg · #13 01-20-2011, 09:53 AM

+1 Yes, I've done it this way by hand without even taking the neck off. Great for basses that have the trussrod nut at the headstock end.

bobunit · #14 01-20-2011, 02:01 PM

Many have suggested placing washers or spacers on the truss rod, but where do you find these that will fit this application? I have 79 Stingray that is in the same boat (too much relief, truss rod maxxed).

Zooberwerx · #15 01-20-2011, 06:07 PM

Quote:

Originally Posted by bobunit

Many have suggested placing washers or spacers on the truss rod, but where do you find these that will fit this application? I have 79 Stingray that is in the same boat (too much relief, truss rod maxxed).

Depends on the instrument. My last retro-fit required a 5mm steel washer....I would have preferred brass. I did have to do a minor grind on the outer circumference, though. Found what I needed at Lowe's in the metric drawer.

Riis

rojo412 · #16 01-24-2011, 09:58 PM

I fix almost everything with bicycle parts (because I work there). There are many washers that work well for something like this that are readily available at a good, local shop that recycles.

If that fails, a good hardware store with EVERY SIZE AND THREAD of screws probably has some. There's one of those a block away, just in case I need something wacky.

rumblethump · #17 01-26-2011, 02:01 PM

I've ended up making my washers. My everything hardware store did not have a direct fit. Got the smallest lock washer that would fit down the shaft, with the teeth on the inside. Grind off the teeth and it fits/works, but a real PIA to make. Screwed up 4 before finally getting 2. It did fix my problem. Now with flatwounds the neck can be adjusted perfectly straight.

mongo2 · #18 01-26-2011, 02:07 PM

Quote:

Originally Posted by rumblethump

I've ended up making my washers. My everything hardware store did not have a direct fit. Got the smallest lock washer that would fit down the shaft, with the teeth on the inside. Grind off the teeth and it fits/works, but a real PIA to make. Screwed up 4 before finally getting 2. It did fix my problem. Now with flatwounds the neck can be adjusted perfectly straight.

I've used split locks that I straightened using a couple of pairs of pliers.