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neck flattening
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=54795		 Page 1 of 1
Author:  mikemcnerney [ Mon Feb 21, 2022 11:31 am ]
Post subject:  neck flattening
What do people do to flatten your neck before gluing on the fingerboard. I do hav a LN jointer plane that I keep nice and sharp and I can usually remove a .001 inch. But I can't say I'm always perfectly consistent with it. I could clamp down the 'flat' back side of my radius disc which is 1. 5" thick, to the table saw table. Or I could use double sided tape abrasive paper to my jointer or table saw table and sand it that way.
Author:  Colin North [ Mon Feb 21, 2022 11:42 am ]
Post subject:  Re: neck flattening
I've normally used my L-N 62 ser at fine as possible (<1 thou).
Then use a small toothing plane on both surfaces, 'cause I uses epoxy.
Author:  Hesh [ Mon Feb 21, 2022 12:20 pm ]
Post subject:  Re: neck flattening
Whatever works and gets it pretty flat. The real important flattening is leveling and shaping the fret board prior to installing the frets where we use leveling beams that are capable of spanning the 1st through the 12th and have been precision flattened on a large, calibrated surface plate.

So planes, jointer, face down on a flat surface with 120 paper on it are all OK for this stage and I would recommend you consider getting, making and using leveling beams that are dead flat for fret work and board leveling. If interested just ask I can tell you how to make great leveling beams for peanuts AND they are commercial or better quality in terms of results. All the guys who took our classes used and have leveling beams.
Author:  SteveSmith [ Mon Feb 21, 2022 12:22 pm ]
Post subject:  Re: neck flattening
I used to use my Veritas low angle jack plane. Now I just use a Cutech 6" spiralhead jointer.

I should add that this the first step I do with the neck blank. Everything else is measured/squared off of the flat surface.
Author:  Pegasusguitars [ Mon Feb 21, 2022 2:11 pm ]
Post subject:  Re: neck flattening
Hesh- What is your recipe for the leveling beams? Thanks, Bob
Author:  meddlingfool [ Mon Feb 21, 2022 2:39 pm ]
Post subject:  Re: neck flattening
Edge sander for me.
Author:  Hesh [ Mon Feb 21, 2022 3:14 pm ]
Post subject:  Re: neck flattening
Pegasusguitars wrote:
Hesh- What is your recipe for the leveling beams? Thanks, Bob


Hey Bob - Sure we buy 1' X 2" aluminum tube stock (it's rectangular but called tubes...) and make one beam so it can hit the 1st and the 12th on the scale lengths that you use. So a bass guitar beam would be longer than a 6 string. Then we make one 6 - 8" long for doing the 12th through the last.

The edges on the ends and sides are "safed" breaking any sharp edge. Then we take it to a surface plate that is longer than your longest beam. We found 3M Frecut gold self stick paper to be super precise in thickness over it's entire span so we put 120 on the plate and use red magic marker to mark up the narrow, business end of the beam that we are going to flatten. This is like using "bluing" that machinists use. Same principal. WIth the 120 you will see with the ink where you hit and where you don't. Keep turning the beam around and use different positions on the surface plate too to minimize errors in precision.

When all the ink is gone go to 220 paper and repeat. 320 is really as far as you need to go but Dave took it to 1000 grit which I don't think is necessary.

Now you have the other side to do too and once both sides are done you can put 120 on one side and 220 on the other and Bob's your uncle. This is all I use and need for my fret dresses and refrets leveling wise. Just two beams.

Once you have the ability to level the board with great precision once you add the frets only the lightest kissing of the fret tops is required for a superb leveling. And of course very little recrossing is also required. This often takes me less than 15 minutes because the heavy lifting and shaping was done on the board.

The beams permit all manner of cool things that we can do with "the touch" and a little thought. For example I can use the beam on the treble side and gently pull the head stock toward me and reduce any relief. Conversely on the bass side I can add more relief pushing back on the head stock when using the beam. The pull and push might only be 2 lbs of force, the touch.

Most notably what results when you trace the string paths with the beams is a compound radius. People ask for compound radi at times and it's also found on some of the finest in their class instruments available such as Suhr guitars.

A great guitar should have less relief on the treble side and more on the bass side. F*ctories don't and can't do this level of precision with possibly the exception of Collings. Both of my new Collings Guitars (it's been a great year in the repair business...) have less on the treble side and more on the bass side as it should be. That could be chance or it could be because Collings is a dang good company that knows their stuff. My Suhr is like this too.

Now fall-away is possible with the short beam over the 12th and the last and adding a layer of masking tape to the end of the beam over the 12th ever so slightly elevating it and keeping that end over the 12th. This automatically induces fall-away while leveling. Pretty slick and works every time.

Now I just gave you more than a summary but the meat of the classes we used to offer and no longer offer. These were master classes in fretting and Dave Collins my business partner taught me these methods 15 years ago. I was fortunate to learn from an industry pro during a three year apprenticeship with Dave.

The leveling beams work so well that what results is the ability of the fret plane to have action as low as 2.5/64th" for the high e at the 12th and 3/64" for the low e at the 12th. Of course a light touch is required with action like this so it doesn't rattle. Our jazz players love our fret work for this reason and the shredders go ape **** over it also loving it.

Steve S. here came to our classes when we offered them and made us proud as punch going back to his shop he's done a lot of fret work now and is paid for it too. I smile every time you post about this Steve, thanks man!

So it's really kind of a bread and butter thing for us and Dave is considered to be the top authority on fret work by a number of the top name luthiers today.

Anyway it's tried and true we've used this method hundreds of times with always stellar results and no issues.

Let me know Bob if I can help I'm happy to. Also this is a natural for you an experienced builder to want to refine fret work. A goodly number of our students were well known builders one with over 350 at the time guitars "in the wild" love that expression.

Thanks
Author:  Hesh [ Mon Feb 21, 2022 3:15 pm ]
Post subject:  Re: neck flattening
Sorry for the high-jack Mike, my apologies.
Author:  TerrenceMitchell [ Mon Feb 21, 2022 3:41 pm ]
Post subject:  Re: neck flattening
Hesh wrote:
Pegasusguitars wrote:
Hesh- What is your recipe for the leveling beams? Thanks, Bob

Once you have the ability to level the board with great precision once you add the frets only the lightest kissing of the fret tops is required for a superb leveling. And of course very little recrossing is also required. This often takes me less than 15 minutes because the heavy lifting and shaping was done on the board.



I'm curious about how you support your necks during the fretboard leveling process. I've always had trouble getting a truly flat surface due to flex in the neck and the lightly supported higher frets that will hang over the body. Even seems to happen when I temporarily attach the neck to the body for leveling. My goal is to be able to get the fretboard, attached to the neck, level enough that I don't have to do fret leveling.

Thanks!
Author:  jfmckenna [ Mon Feb 21, 2022 6:54 pm ]
Post subject:  Re: neck flattening
Very simple for me. I use a jointer plane and check it with a straight edge till it's nice and flat.
Author:  Hesh [ Tue Feb 22, 2022 3:06 am ]
Post subject:  Re: neck flattening
TerrenceMitchell wrote:
Hesh wrote:
Pegasusguitars wrote:
Hesh- What is your recipe for the leveling beams? Thanks, Bob

Once you have the ability to level the board with great precision once you add the frets only the lightest kissing of the fret tops is required for a superb leveling. And of course very little recrossing is also required. This often takes me less than 15 minutes because the heavy lifting and shaping was done on the board.



I'm curious about how you support your necks during the fretboard leveling process. I've always had trouble getting a truly flat surface due to flex in the neck and the lightly supported higher frets that will hang over the body. Even seems to happen when I temporarily attach the neck to the body for leveling. My goal is to be able to get the fretboard, attached to the neck, level enough that I don't have to do fret leveling.

Thanks!


Hey Terrence happy to help.

We use leg vices covered in leather I may take a pic this am of mine and post. I support the neck in the middle region 7th - 9th fret and when leveling we are not applying any real pressure to beams because flex as you said is the enemy and we don't introduce hardly any if we let the beams and the paper do the work. I never press on the beams I just move them tracing the string paths.

Knowing as I do that some will not appreciate the following it's our experience and belief that the idea of leveling and shaping a precession fret board off the instrument with the exception of Fender style bolt on necks in unrealistic and rarely does what it is intended to do which is be as accurate as doing all fret work with the neck on the instrument where it's going to be when strung up.

Additionally fretting the board off the neck is not accurate either with the exception of how Mario P. does it and he wrote an article about this that was published around 2010 IIRC. He has process controls in his methodology that increase his accuracy greatly. He also uses an arbor press and does two at once IIRC. Pretty clever as always from Mario.

If one does install frets on the board off the neck all bets are off when the board and neck are mated and more errors occur when the neck gets attached to the guitar. So just like in the repair world we install our frets on a board that has been leveled on the neck, neck on the guitar etc.

I should add that in the acoustic guitar world fretting accuracy is not as important for say a flat picking bluegrass player with higher action and 13's. For a finger stylist who wants low action it becomes very important and for a shredder on an electric it's essential and the show will not happen without very good fret work and low action.

So the guys here who may have banged them into the board and glued the board on the guitar and never leveled or recrowned let's bring the action down into the range that players wants it and they will see what I am suggesting here in terms of the need for accuracy. It.... will.... be..... glaringly obvious that leveling in a precession manner is essential.

Now if you picked up on the finger pressure and light pulling of the head stock that I mentioned in my first post you will see that we see the poorly supported neck as an "opportunity" to have a movable "fulcrum" to be used to add support where we wish and not have support where we wish to not have it.

Gravity is a slight issue and behind the little flex that we have to deal with and if you think about this statement we are shooting for accuracy of our work of around .0005" and better and we achieve this on demand.

We were offered a PLEK for free because we are very well known as specializing and even blazing some trials with fret work and we turned it down. It's our belief that our methods provide superior results to a PLEK which is NOT hard to do since it's a CNC machine that really is no more accurate than a highly skilled human AND the PLEK in our view has design flaws too. We turned it down and didn't want one.

Collings Guitars uses a PLEK which is a great tool don't get me wrong and then they touch it all up with hand work and a skilled Luthier. More evidence that we are not alone in suggesting that skilled hand work can provide results second to none.

So not having to do fret leveling is not possible in my view with the best of processes but you can minimize the leveling of the frets AND recowning by strict process controls and a process that works well. And again flex is really not an issue for us and it may be because we are not putting pressure on the beams and our's are aluminum and not heavy either.

Question: Do you have the StewMac beam? We don't like it it's heavy as hell and might be why there is flex if you use it and it's steel making it more difficult to precision flatten and touch it up periodically. If you use this beam that may explain the flex you get and we get very little of. And people think I'm a shill for Stewmac :)

Let me know if any of this makes sense and if you have any questions Terrence I'm am very happy to help.
Author:  Hesh [ Tue Feb 22, 2022 3:14 am ]
Post subject:  Re: neck flattening
Here's a pic of my leg vice from my home shop. We have four of these in our Ann Arbor shop and could not work on a guitar without them they are fantastic. We have all the other vices too that people use and they are collecting dust in one of our "closets of doom..." since we like these better.

Funny thing to me at least about my home leg vice. You see the leather used, thick, quality black leather and a pouch too in the pic for repair tickets. When I retired from being a corporate exec. I took my Coach brief case and cut it to pieces to use the leather for Lutherie. I had a nice drink of single malt too when I cut it up to celebrate my retirement from one world and my official entry into the Lutherie world.

My vice is a reminder to me of sorts that people are also capable of being repurposed and useful for a very long time. :) That's my hope anyway.

Anyway these vices are used in some schools, some shops and have been around a very long time. I'm drawing a blank on the history but I think it goes back pretty far. The 2 X 4's are intended to flex when clamping down on the neck from side to side to prevent damage. We have never damaged a single guitar with one of these vices and have put thousands of guitars in our vices. They also eliminate the possibility of using my Heritage/Travelers insurance because we knocked a guitar off the bench although I managed to knock a counter top Martin off the bench once and it bounced on it's back on the floor into the air and I caught in in the air. No damage :) I am a lucky guy and Martin builds a great guitar.

So no guitars were harmed in the writing of this post :)

Also apologize again Mike, kind of pedantic here..... ;)
Author:  bluescreek [ Tue Feb 22, 2022 6:52 am ]
Post subject:  Re: neck flattening
Similar to Hesh but a bit different.
Once the neck is ready I use my granite block to true the neck plane for the fret board , and as a machinist I also have the 1 by 2 alum block machined true on my mill. I use 320 and 600 grit on the block.
Once I have the neck trued I think the most influential part is gluing the fretboard to the neck. I do not fret the fretboard till it is glue on as I will true the fretboard on the guitar. The big thing I learned is when gluing the fretboard you must be as flat as possible or you can glue a curve and twist into the neck .
I use my granite block and have 2 pieces of spruce about 1/4 wide and about 1/8 in thick. This I set to the taper of the fretboard and clamp using about 8 bar clamps. Then start at one end to the other. I do use tite bond original Once glue ( allow over night clamp time ) I can now true the fretboard. I do like a 1 by 2 alum block for flattening and I have the aluminum radius blocks from All parts.
I also have a machinist set up block that sets perfect on 1 to 12 fret.
The process of making and truing a neck is one of the most important parts of guitar instruction.
Author:  Hesh [ Tue Feb 22, 2022 10:56 am ]
Post subject:  Re: neck flattening
Just got home, I work nights now to avoid people/covid.

Here's a pic of my leg vice at work in Ann Arbor with a 60's all original, single owner Gibson SG that was made a few hours away from here in Kalamazoo. This guitar has never been serviced before and needed a bunch of things. Spent half a day getting her back to performing as intended and this did not include any fret work since this guitar had never really been played much.

But I propped it on my leg vice to show you how we intentionally use the vice as a fulcrum and on this guitar I have the 8th fret on the fulcrum.

This is also one of the narrowest necked electric guitars ever produced, too narrow and I don't have big hands at all and it's too narrow for me but I digress.

So leg vice and how I place the guitar while using leveling beams and of course the strings are not present when doing fret work unless it's a Martin requiring compression fretting and then I string them up about four times and tune to pitch in the entire process to check my progress in getting proper relief where I want it.
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