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Filling small gaps & lines http://luthiersforum.com/forum/viewtopic.php?f=10101&t=45184	Page 1 of 2

Author:	Cablepuller [ Thu Feb 19, 2015 8:19 am ]
Post subject:	Filling small gaps & lines
Hi Im getting near final assembly of neck and body I have small gaps around neck joint and also small hairline gap fretboard to neck on dry fit stage. Not done any finishing yet awaiting your advice i have spent along time on the neck joint and the angle is perfect and its a very strong joint, most of the cheeks are flush just the outer edge isn't due to my beginner skills. please dont shoot me down but that neck joint is as good as im going to get it this time and i cant loose anymore wood or sleep !! Questions are should i start finish with neck and body separate or glue it all up then some how fill these gaps then put a finish on ? And what can i fill with? thanks humbley in advance

Author:	kencierp [ Thu Feb 19, 2015 8:31 am ]
Post subject:	Re: Filling small gaps & lines
Can't say what would be the best approach without pictures -- but one thing for sure do not use any kind of gap filler until after the wood is completely sealed otherwise you'll cause a stain where ever the filler has touched. Worse thing is the blotch might not show until you are well into the finishing process.

Author:	Goodin [ Thu Feb 19, 2015 8:51 am ]
Post subject:	Re: Filling small gaps & lines
What kind of finish are you planning to use? If you do a film finish like lacquer or varnish that will build up, then the gaps may disappear, depending on how big the gaps are and how much finish you apply. I am also assuming you are finishing the neck and body separate. If you still have gaps between the neck joint you can fill them with paste filler colored to match after you have finished, like Ken said. It will never look as good as a tight fit though. You can use a shim to take care of the gap under the fretboard. All that said, man I still think the best solution is to walk away for a few days, come back to it when you are calm, and get that neck joint fitted properly. You will be glad you did.

Author:	Cablepuller [ Thu Feb 19, 2015 9:33 am ]
Post subject:	Re: Filling small gaps & lines
Cant sand anymore really and have left it for days before to rethink but still cant seem to get it flat...think i must of messed with it too much before i got good advice on here on how to sand slowly and level Still its a solid fit despite how it looks and the angles good Just need to know how whether to finish the parts separately then fill or seal it all then glue it up then fill/finish Think im going to use tru oil final finish Cheers

Author:	jfmckenna [ Thu Feb 19, 2015 9:44 am ]
Post subject:	Re: Filling small gaps & lines
Try the sand paper floss technique. Cut a one inch wide strip of 120 grit (or so) paper and with the neck lightly secured in place pull the strip through such that it conforms to the shape of the body while sanding that shape into the heal. What kind of joint is it? Also you could remove more material then necessary from the center of the heal face so that the edge lines are the only thing touching. That's a bit of a cheat imho but it works and it would make flossing faster. You are really very close with it as it is.

Author:	Glen H [ Thu Feb 19, 2015 9:58 am ]
Post subject:	Re: Filling small gaps & lines
CP, it doesn't look from the pic that you have attached the fingerboard yet. I'd recommend attaching the fingerboard, confirming the neck angle and then come back and give the neck cheek-body fit another go. IMO, always finish the pieces separately, then attach, then if you still have gaps, run a very, very small bead of elmers glue (or any other glue that dries clear) along the seam.

Author:	Nils [ Thu Feb 19, 2015 10:27 am ]
Post subject:	Re: Filling small gaps & lines
I generally fit the neck by adhering some sandpaper to the body around the mortise, and then gently work it for about 10 mins or so. Carbon copy paper is great too. If you put it in the gap and then pressure the joint, you'll find the contact points.

Author:	meddlingfool [ Thu Feb 19, 2015 10:50 am ]
Post subject:	Re: Filling small gaps & lines
Cablepuller... Have you cut relief channels into your neck? Is it a dovetail? The only part of the heel that should touch the body is the outside edges. As well, the corners of the pocket should be checked for smoothness. I'm at a coffee shop right now, but if you have a little patience, I'll put some pics up in a bit. Pretty sure I must have a dovetail or two kicking about amongs the detritus. Assuming it is a dovetail...

Author:	Cablepuller [ Thu Feb 19, 2015 11:06 am ]
Post subject:	Re: Filling small gaps & lines
Hi its a bolt on martin style neck

Author:	meddlingfool [ Thu Feb 19, 2015 11:20 am ]
Post subject:	Re: Filling small gaps & lines
Any neck joint will still need a relief cut in the area beside the tenon... Can you take a picture of the neck off? I don't know what a Martin bolt on looks like...

Author:	Cablepuller [ Thu Feb 19, 2015 11:30 am ]
Post subject:	Re: Filling small gaps & lines

Author:	meddlingfool [ Thu Feb 19, 2015 12:20 pm ]
Post subject:	Re: Filling small gaps & lines
Ok, I totally see part of the problem. Stand by..l

Author:	meddlingfool [ Thu Feb 19, 2015 12:30 pm ]
Post subject:	Re: Filling small gaps & lines
Ok, you need to cut a relief channel around the base of the tenon. The only part of the heel that should touch the rims should be an 1/8" strip around the very outer edge. My photo is a dovetail but the concept is the same for a straight tenon. The parallel lines following the heel shape is what should be left, the squiggly lines are what should be cut away. Pare it carefully with a chisel, so that when you do your sanding, only the space between the parallel lines needs to be sanded. That's how to get that seem tight.

Author:	Goodin [ Thu Feb 19, 2015 1:13 pm ]
Post subject:	Re: Filling small gaps & lines
Ed and jfmckenna beat me to it but thought I would post anyways as a "+1" for their ideas. Cut away material like the pic above with a SHARP chisel (you're cutting into end grain), then floss, while checking neck angle (left-right, up-down). Check out this great tutorial: http://www.bryankimsey.com/ (go to neck resets page 4)

Author:	Cablepuller [ Thu Feb 19, 2015 1:36 pm ]
Post subject:	Re: Filling small gaps & lines
Meddlingfool thankyou...had no idea about the relief channel... going to give it a go ..how deep should this channel be Thanks

Author:	meddlingfool [ Thu Feb 19, 2015 1:42 pm ]
Post subject:	Re: Filling small gaps & lines
Well, 1/32 - 1/16. Just deep enough so that the sides don't touch it and to give you a little wiggle room for flossing..l

Author:	Greg B [ Thu Feb 19, 2015 2:19 pm ]
Post subject:	Re: Filling small gaps & lines
I carve out about 1/16" relief, but in this case I'd suggest about 3/32" to give you a little more room. There's a relatively large gap near the top. It's no big deal if the neck ends up a tiny bit shorter at this point. I'd suggest getting it fairly close now, checking for side to side and action, and then attach the fingerboard and do it again to get it perfect (or reasonably close... ) Attach the neck loosely, and floss with sandpaper strips only, holding the neck in place with light hand pressure. Don't pull up!! drag it down a bit against the body. Trying to chase this with a sanding block would be an exercise in futility. BTW I think Robbie O'Brien has a video on this.

Author:	Hesh [ Thu Feb 19, 2015 3:32 pm ]
Post subject:	Re: Filling small gaps & lines
Hey CP a couple of things: First click on this for a toot on how I fit necks. The only thing that's changed since I threw this toot together is that I now use a 1/4" uber sharp chisel to make the relief cuts that Ed is describing to ya: http://www.luthiersforum.com/forum/viewtopic.php?f=10102&t=15022%22 Relief cuts make a gapless fit way easier to get. Next the advice to attach the fret board AFTER you make relief cuts and fit the neck is a very good idea and important for determining neck angle. Last, for now finishing a guitar with the neck on is way harder especially if you have never done it prior. It also is a "best practice" in my view to finish the neck and body seperately because come neck reset time you won't have some hip shootin, opinionated repair guy such as I.... calling you every name in the book for finishing the guitar with the neck on. It makes it very difficult to do a clean job and more finish repair is generally needed if the instrument is finished with the neck on. Hope this helps CP!

Author:	jfmckenna [ Thu Feb 19, 2015 4:20 pm ]
Post subject:	Re: Filling small gaps & lines
I always finish the guitar neck separate these days but I used to finish it as a whole, especially Spanish guitars using the Spanish neck joint where you have no choice. Anyway the one advantage it does have is filling tiny gaps like that and giving it a nice finished together look. But one can also appreciate a very well fitted 'dry' joint too. I remember back in the day when I converted from Spanish heal to bolt on I had more then a few guitarists raise an eyebrow about the whole neck joint tone debate. My answer to them was that the butt joint makes contact at every point along it's surfaces and is essentially the same thing as wedging the sides in slots like a Spanish heal and that convinced them, I actually still have a demo block/heal and side sections. So I do struggle to do this till this day however digging out a 'blood groove' is a perfectly acceptable standard and something I will most likely resort to in the future. I have a combination sanding block, one to sand the curve in the head block and the congruent one to sand out the heal. It's easier on a butt joint obviously. It gets it real close and then flossing finishes it off. Lots of ways to solve this problem.

Author:	Cablepuller [ Thu Feb 19, 2015 4:25 pm ]
Post subject:	Re: Filling small gaps & lines
Thanks greg b and thanks hesh ..just looked at your link hesh and couldnt ask for a better guide.. Going to have a couple of days off the guitar as i had started to get into "must finish it soon" mode which isnt good Cheers

Author:	cphanna [ Thu Feb 19, 2015 8:13 pm ]
Post subject:	Re: Filling small gaps & lines
Hey, Cablepuller, Now, this is a very informative thread for everyone who is fitting a neck for the first time (and for others who still have problems). You've already received all the good advice you need. I know you can pull that neck in for a tighter fit, and now you know how to do it. Take a deep breath, take your time, be patient and I am sure you can get it to perfection. Press on, my man. You're doing just fine!

Author:	dnf777 [ Thu Feb 19, 2015 10:13 pm ]
Post subject:	Re: Filling small gaps & lines
I'm very new at this also, but one thing I learned the hard way is that when you start to floss-fit the neck, the depth of your tenon may start to contact the mortise base and (unless you recognize this right away) make the neck seem to wobble, and you may try to floss your way to a better fit, when in fact you will worsen the problem by removing more and more wood. I started doing that and got really frustrated until I realized what was happening, filed down some of the tenon base, and things got good again. One other tid bit I learned the hard way, is when you pull the sandpaper strip, make sure it is very straight, or even angled AWAY from the grit side, else you risk rounding the corners, and then have to take more wood to true them again. (ask me, ONE bad pull is all it takes) Sorry if I'm giving advice below your skill level. I don't mean to insult-- It is more a testament of my bone-headedness mistakes than anything!

Author:	George L [ Thu Feb 19, 2015 10:51 pm ]
Post subject:	Re: Filling small gaps & lines
Great advice above. This is not a difficult task if you approach it carefully and meticulously, paying close attention to what is happening to all the surfaces as you work. Be patient. Take your time. Have fun.

Author:	TimAllen [ Fri Feb 20, 2015 2:11 am ]
Post subject:	Re: Filling small gaps & lines
All good advice. One problem I've had is the sandpaper strips tearing while I flossed with them. Pieces of sanding belt are durable, but I don't have them. So I just back the sandpaper with a piece of thin plastic packing tape, and now it never tears.

Author:	Joe Sallis [ Fri Feb 20, 2015 8:28 am ]
Post subject:	Re: Filling small gaps & lines
One thing I find with flossing- the direction you pull the abrasive paper in takes off more material on the side closest to you as the paper is in contact with the neck wood for longer. Important to consider this when determining the neck angle.

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