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Setup Advice
http://luthiersforum.com/forum/viewtopic.php?f=10101&t=31717		 Page 1 of 1
Author:  Stuart Gort [ Sat Apr 02, 2011 10:42 am ]
Post subject:  Setup Advice
I've done a lot of setups....trying to make less than perfect guitars play well. I've done a fair amount of fret work but I've never actually started off with a really nice, even application of new frets.

After my first guitar I made a series of new tools that revamped the way I was making the neck, making the fretboards, gluing the fretboards, and sanding them prior to fret intallation. I now have four new necks fretted and all are quite a bit better than anything I've ever worked on to date. When I view down all four fretboards (no truss rod tension) there is a consistent tiny backbow on all four necks and the frets look as though I could just string things up play without leveling.

So....this result is very exciting...but I have a question.

What technique would you use if starting out on a very good footing with new frets? I've seen some factory videos where I could tell they were setting the truss rod to create a slight backbow prior to leveling. This seems counterintuitive to me as I'm inclined to set it as absolutely flat as possible and level from there. Thinking through it more, however, maybe adding a slight backbow prior to leveling establishes where on the neck that the truss rod will have its' effect and will also indicate where the neck is going to bend under string tension.

Anyway....I'd sure like some sound advice before I hack into these necks. :)
Author:  Tom West [ Sat Apr 02, 2011 11:18 am ]
Post subject:  Re: Setup Advice
Zlurgh: Think this thinking comes from when the rods used were mainly single rather then double acting rods. If you end up with a back bow that the strings can't pull out at least straight you are in trouble. So you put back bow in with rod and level your frets,back of the rod and the neck will end up with a forward bow. Thus you are assured that you have adjustment and not the dreaded back bow when you string up your guitar. My take on why it's done.
Tom
Author:  Colin North [ Sat Apr 02, 2011 11:30 am ]
Post subject:  Re: Setup Advice
All I've ever done (and advice I've seen) is to straighten the neck with the truss rod and then level the frets.
That's starting with slight back bow or forwards.
I don't want to assume anything - do you have double action truss rods?
Author:  Pat Foster [ Sat Apr 02, 2011 11:36 am ]
Post subject:  Re: Setup Advice
Stu,

I'd suggest starting flat. I don't see how you could be assured of level frets any other way.

Lately I've been trying the frets as is, without levelling. They're better than most factory jobs and refrets I've come across, very close to level, but I'm not quite there yet, so I go back and just kiss the tops of the frets to get them optimal. Levelling with a straight board is key, though IMO.

Pat
Author:  meddlingfool [ Sat Apr 02, 2011 12:26 pm ]
Post subject:  Re: Setup Advice
Are you absolutely certain they were tightening the rod? What I do is put a hint of tension on the rod before radiusing/profiling the FB. Then, when the frets go in causing a slight backbow, I can release the tension to get a dead level neck. Then I take a flat block with 240 on it and just kiss the fret tops going t side to bass side, not nut to bridge. Not having to aggressively level and recrown is the norm, having to is an indication of failure to properly install the frets. There are some who like to grind relief into the fret tops, but I'm a proponent of flat flat flat...
Author:  Stuart Gort [ Sat Apr 02, 2011 2:21 pm ]
Post subject:  Re: Setup Advice
In the video they laid a straight edge on the neck and then adjusted the truss rod until they could swing the straight edge back and forth from the middle. When I first saw this it was firm in my head that they were doing this prior to leveling...but if they did just prior to stringing the instrument that would make more sense...setting the truss rod tension with a straight edge as a starting point. I'll have try to find that video again.

I use double acting truss rods.
Author:  Stuart Gort [ Sat Apr 02, 2011 2:29 pm ]
Post subject:  Re: Setup Advice
Pat Foster wrote:
Lately I've been trying the frets as is, without levelling. They're better than most factory jobs and refrets I've come across, very close to level, but I'm not quite there yet, so I go back and just kiss the tops of the frets to get them optimal. Levelling with a straight board is key, though IMO.


That's probably what I'll end up doing too. I have some radiused blocks I made from aluminum. I think I'll start with 600 grit to see how close they are.

We are on another medical journey Wed. so I guess I'll see you at the May club meeting. :)
Author:  Terence Kennedy [ Sat Apr 02, 2011 2:50 pm ]
Post subject:  Re: Setup Advice
For leveling I put six lbs. of weight on each shoulder with the peghead supported to simulate string tension, get the fretboard flat with the truss rod, and level with one of the Stew Mac leveling bars with 600G stuck to it. I'm OK with just a little drop off at the end of the board. I have not had the best luck leveling with a radius block.

If touch up is needed I do it after stringing up using those sanding flats from L or U shaped extruded Aluminum we've all talked about so much in the past.
Author:  murrmac [ Sat Apr 02, 2011 5:05 pm ]
Post subject:  Re: Setup Advice
Terence Kennedy wrote:
For leveling I put six lbs. of weight on each shoulder with the peghead supported to simulate string tension, get the fretboard flat with the truss rod, and level with one of the Stew Mac leveling bars with 600G stuck to it. I'm OK with just a little drop off at the end of the board. I have not had the best luck leveling with a radius block.

If touch up is needed I do it after stringing up using those sanding flats from L or U shaped extruded Aluminum we've all talked about so much in the past.


Just a bit confused here, how does that six lbs on each shoulder replicate string tension ?
Author:  Howard Klepper [ Sat Apr 02, 2011 6:15 pm ]
Post subject:  Re: Setup Advice
Zlurgh wrote:

So....this result is very exciting...but I have a question.

What technique would you use if starting out on a very good footing with new frets?


The same as old frets, but less of it.

If you have a forward bow when you start to level, your leveling device (file here) will bump the top and bottom frets as you move it, and this makes it hard to feel and see when you have the fret tops aligned. Perfectly straight is OK, but so is erring a tad on the backbow side, for better feel and better visual feedback about the high and low spots.
Author:  Terence Kennedy [ Sat Apr 02, 2011 6:17 pm ]
Post subject:  Re: Setup Advice
I've been setting it up like the picture below and putting six pound weights on each shoulder of the upper bout. That comes pretty close to duplicating the position of the neck under string tension on my guitars. Kind of a poor man's StewMac neck jig. I've also found it helpful for a final check of the neck set before string up and also for checking the drop off at the end of the fretboard under string tension while fretting. And yes, this is for steel string instruments-thanks Filippo.

Image
Author:  nickton [ Sun Apr 03, 2011 11:37 pm ]
Post subject:  Re: Setup Advice
The Cumpiano/Natelson book mentions putting a back bow in and then flattening, but many don't think it's necessary these days so I never tried it. I might this time, because I have a bit of struggle with the higher frets so far.
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