Neck Reset and cutting the heel

[Frank Beard]

I've been enjoying the helpful knowledge on this forum for a while and have finally joined, although my level of expertise is well below most of the regulars.

I've done several neck resets with good results but I want to continue getting better and I need some help. After cutting the heel partially with chisels, I finish up by pulling strips of sandpaper, with strapping tape backing, through the joint. I'm having trouble getting the bottom of the heel to fit as tightly to the body as the top of the heel. I usually end up with a hairline gap at the bottom 1" of the heel. IOW, when I pull the sandpaper all the way through, it cuts more from the bottom of the heel than the top.

Should I try removing the sandpaper before I finish pulling it through, or should I pull the paper down for a ways and then sideways and out of the joint?

I hope this is clear enough to get some help, making the joint fit tightly and without a gap.

Thank you,
Frank

[Magnus Hultin]

I will follow this one closely, I have experienced the same thing. And I actually think You are on the right track, Frank. It seems like the paper eats more intensely as its pulled out the last bit.

Magnus

[Jeffrey L. Suits]

I think that the sandpaper is too thick w/ that backing, and that it's probably user error; you have to pull *just right*, or you'll get this problem. You are relieving the inside of the neck heel, right, so that you're only sanding the shelf at the edge of the mating surface?

[Jim Bancroft]

I just take a narrow strip, 3/4" wide approx, of about 150 grit paper and pull it straight through the joint, and exit at the heel cap. I start about a 1/2" below the fingerboard extension. To get a tight fit, make sure the neck joint tapers back enough from the edge that makes contact with the body. If it doesn't then the inner edge can make contact with the body and not allow the very outer edge of the heel make contact with the body.
I don't use any backing on the sandpaper, it's not needed. I have applied masking tape on the body where the sandpaper is sliding, but it's really not necessary. The finish doesn't seem to get scratched by the paper backing.

Jim

[Frank Beard]

Thanks for the tips so far guys. I've tried both with and without the sandpaper backing, with the same results. Maybe I need to try easing up on the light pressure that I'm applying to the neck joint, just before the paper exits the joint. I've been using the right amount of pressure to allow for good cutting power without any binding or jerking.

I'm still a little foggy though, because the idea is to make a straight cut and by pulling the sandpaper completely out the end of the joint, the bottom of the joint will naturally be cut more than the rest of the heel, which results in the problem. What am I missing here? .............besides experience. ;-)

[Jeffrey L. Suits]

If you aren't pulling straight, that is, if you lift up at all at the end of the pull, this will happen.

Also--are you judging w/o the shims in the dovetail? That can pull the heel in enough to close a hairline.

[Ronnie Nichols]

The undercutting of the wood at the outermost portion of the joint where it actually meets the body is critical. ( I learned this from Frets.com) That way (as someone already stated) you only have a small amount of wood to remove. I also think most folks tend to use too fine a grit of sandpaper. My years in the auto body repair business taught me this. Amateurs often try to cut plastic body filler with too fine a grit paper. All they ever accomplish is to sand the edges down and leave the center too high. A coarse paper will cut through more evenly. I'd recommend using someting around 80 grit (or coarser)to cut through evenly. Discard the paper if you even suspect it is getting dull. A strip of masking tape on the back of it works alright for me since I use the stikit type paper with glue on the back. You can also tear off a small strip of the paper with a cloth backing (like a belt sander uses) that will not break so easily. I recently built a jig to hold the neck while I recut this angle. I can control the angle of the cut and it enabled me to do a more accurate neck reset. Since the body is normally pretty much flat where the neck joins, the angle is the critical measurement. There is a formula for calculating how much to take off, but I've found that I can set the neck up in my jig to the existing angle and then readjust the angle before recutting. The jig is basicly a guide for cutting with a flat chisel with the bevel up. It has worked well for me. If you think this angle is hard to cut, you should try to fit a banjo neck to a body where everything fits properly without any shimming or loose lag screws. All the different angles and shapes will make you appreciate the flat guitar joint.
Ronnie Nichols

[Frank Beard]

>>>If you aren't pulling straight, that is, if you lift up at all at the end of the pull, this will happen.

I do pull straight with just a tad of downward pressure, in an attempt to cut straight..............I still remove a little more from the bottom 1" of the heel.


>>>A coarse paper will cut through more evenly. I'd recommend using someting around 80 grit (or coarser)to cut through evenly.

Well, I've been using 180 or 220 grit after chiseling the correct angle and have experimented with 400 grit for the last pulls. The finer grit causes less damage to the edge of the finish on old guitars.

I have no problem achieving the correct angle for a successful reset. I'm just trying to make the bottom part of the heel fit perfectly, without the hairline gap that's always there, after I pull the sandpaper through the joint.

Frank

[Mike Mancini]

Frank,
This is coming from an amateur (I'm not a luthier) and I have done only a few neck resets but how's this for an idea: using your chisel, cut the new neck angle, but leave it a little shy of the angle you want. Then use the sandpaper strips to fine tune the angle as you fit it to the body. The sandpaper strip procedure, by its nature, will always remove more from the back end of the heel than from the fingerboard side because the back end gets the full sweep of the sandpaper. The fingerboard side gets essentially nothing, the midpoint gets sanded by half the strip. That's how the angle gets changed, no?

Mike

[Frank Beard]

>>The sandpaper strip procedure, by its nature, will always remove more from the back end of the heel than from the fingerboard side because the back end gets the full sweep of the sandpaper.

Gosh Mike, you've explained my problem more clearly than I've been able to do. Yup, it's the old full sweep. ;)

btw, I do chisel first and then fine-tune with sandpaper. I read where some well known luthier's do ALL the cutting with sandpaper so there still must be a trick to avoiding the full sweep and still cutting the heel straight.