| Official Luthiers Forum! http://www.luthiersforum.com/forum/ |
|
| Neck Angle FAIL! Please help. http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=43392 |
Page 1 of 1 |
| Author: | GustavBuhund [ Wed May 07, 2014 7:53 am ] |
| Post subject: | Neck Angle FAIL! Please help. |
Hi All - I haven't been posting much, but I am constantly lurking. I am working on my #7, a Sinker Redwood/Grafted Walnut OM. I cut the neck tenon with a version of the Woolsen neck jig. When I made a test-set of the neck before finishing, a straightedge on the unfretted fretboard just barely skimmed the top of the bridge, which is what I usually aim for. I finished the guitar, and fretted, mounted and glued the neck without checking if there was any change, (D'oh!) as why would there be? When I put the first string on, I realized that there was a problem with the neck angle, as the string was touching the 20th fret. I put the straightedge on the fretted neck, and was shocked to find that the ruler was now 3/16" OVER the bridge! Firstly, I am trying to figure out how this happened. Secondly, I want to know what I can do to fix it. It seems FAR too big of an oops to shave down the fretboard and re-fret. (Also, the fretboard is bound, so that creates other issues) The fretboard and neck were glued with white glue, so they should come off pretty easily, but I'm trying to figure out the root of this problem before I go tearing the whole thing apart. Shop is at 40-45% RH year-round. Thanks for chiming in, Eric |
|
| Author: | Hesh [ Wed May 07, 2014 8:49 am ] |
| Post subject: | Re: Neck Angle FAIL! Please help. |
Hi Eric: Necks need to be refitted during final assembly because things do change as you have observed. Why things change can be a plethora of reasons of which some may be RH issues as to when the box was braced, etc., green wood, and even the process of finishing which is not a precise operation by any means where film thickness may vary. Just the slightest amount of film thickness variance in the area where we fit the heel is magnified by the length of the neck and can also result in what you are seeing. I always fit my necks before finish, like you did, but I also tape off the body and fit them again after finish and things do change and you can see this in that the second fitting has always been required for me as well. We talk about 1.5 degrees of neck angle on a typical steel string which is meant to be a ball park and not a final answer to what the angle for the specific guitar needs to be. What to do now? Remove the neck, thank yourself for using a bolt-on because that's easier by far, and refit the neck by flossing the heel cheeks as need be until you have the intended neck angle. Here's a link to one way to fit a neck that works for me: http://www.lenaweelutherie.info/page6/page31/page31.html In summary nothing may be wrong so cut yourself some slack please in that the second fitting is always necessary even if it's just a check for proper angle before bolting and gluing the neck in place. Hope this helps. Had to tell a client yesterday that their new Washburn needs to be returned, over set neck beyond the point of being capable of being properly set-up without compromising the integrity of the bridge saddle slot with a very high saddle. It happens and looks like this one never had it's second and final fitting either. |
|
| Author: | DannyV [ Wed May 07, 2014 10:43 am ] |
| Post subject: | Re: Neck Angle FAIL! Please help. |
What Hesh said. I've used his toots a lot. Thanks Buddy. A couple of things. I don't see how the string can touch the 20th and be 3/16 over the bridge. It's pretty easily correctable if it's just over set. I made a heavy aluminium pate with slots for the frets dado'd out. The best thing I had for heat was an old iron and surrounded the area with damp rags. Only done it once but the neck was off in about 2 min. I only use a few drops of white Elmer's glue......... now. It sucks to get material off from the fret board side of the heel to correct an over set. You might start with a very sharp chisel and the a hard sanding block and then floss. Personally, I like to glue the bridge, bolt on the neck and string them up. Then you know exactly where you're at. Another thing that I think makes a difference, if you use a finish that builds up like nitro, make sure you get an even coat where the heel will sit. I'm pretty sure it can make a difference. Good Luck, Danny |
|
| Author: | theguitarwhisperer [ Wed May 07, 2014 10:50 am ] |
| Post subject: | Re: Neck Angle FAIL! Please help. |
If it's 3/16ths OVER the bridge, hen he would need to have he saddle TALLER by that amount (roughly) to lift the string off the fretboard. Something changed. The top sank or the UTB sank or something. |
|
| Author: | Michael Lloyd [ Wed May 07, 2014 12:14 pm ] |
| Post subject: | Re: Neck Angle FAIL! Please help. |
My first thoughs: Trying to picture the string running from the nut to bridge and touching the 20th fret. Sounds like the fretting bowed the neck. Check for a flat straight neck. Use the truss rod accordingly. |
|
| Author: | Don Williams [ Wed May 07, 2014 12:57 pm ] |
| Post subject: | Re: Neck Angle FAIL! Please help. |
Yeah, this really sucks when it happens. My condolences! I lucked out on my latest build... As Hesh and others said, things change, and it isn't always apparent what. This latest guitar was dead perfect in the white, literally. No gaps with the heel or the bottom of the FB extension, and the perfect angle in both directions. It sighted down the center-line perfectly, and the corners of the fretboard hit the rosette symmetrically. I was happy as can be. Then came the finish, and all that changed. I had a little issue with a slight gap at the bindings on the heel/side joint, and even under the FB extension. The reason... I had stripped back the finish on the bindings because of color issues in the middle of the finishing. Fortunately, some judicious sanding of the heel edges and the finish under the FB, and all is well. Still dead on center too. I do worry that I will have to reset soon though (not strung up yet) as the straightedge is resting just barely over the bridge top, about 1/64" or so, maybe a hair more. I usually shoot for a little more than that. IF you haven't glued on your bridge yet, you can reset the neck, and make a bridge with the saddle pushed back a bit to compensate for lost length on the reset. Or, you could fill the saddle slot and mill it back a bit. Good luck... |
|
| Author: | GustavBuhund [ Wed May 07, 2014 3:26 pm ] |
| Post subject: | Re: Neck Angle FAIL! Please help. |
Happy for the bolt-on! Got the neck off no problem... had to chisel the heel a bit due to the sheer amount that had to come off the top to even things out. Still not perfect, but brought it down to about 1/16th over the bridge. Will work on it more this week and post results. Thanks for all your suggestions! Eric |
|
| Author: | bluescreek [ Thu May 08, 2014 5:41 am ] |
| Post subject: | Re: Neck Angle FAIL! Please help. |
Lets address a few basic parts for clarity to this discussion. A neck pre set Setting a neck without a fret board attached to the neck. B Neck block position Measuring the height of the neck , off the top at the point of the neck block where the rim and the neck meet. In most cases , the point of the 12 or 14th fret , or the connecting point of the fretboard. C saddle position This is where the saddle would be measured off the point on the neck where the nut is located , so this would be based off the scale length you are using. D neck plane this is the top of the neck where the fretboard is attached. E Center line There are 2 center lines we are working to , One is the one off the neck and then the fret board the 2nd is the top. We will set the bridge on the top to the center line off the neck. F Clearance from holding off chamfer or bevel the edges of the sides where they open to the neck block. The male/female corners have to be cleared . The sides , if left sharp may fit into the corner of the neck and that interferes with the mating surface of the mortise and tenon. This is one thing that can really make a mess out of the neck. OK Lets get started. When you start to do the PRE SET of the neck , this is done as the body is in the white just as you close the box. We want to get the neck set so when we are done with the finish process we will attach the neck after the finishing . I don't finish the neck on the body but will do them apart and then attach them . So let us assume we are doing a raw neck that has just out of the box. You will need a good measuring device , I use a 36 in scale, and it has a straight edge. I also use a smaller scale so I can measure the top and the neck plane. Also some wide tape. We start with the neck in the block. I clamp it tight so I can measure the neck center line to the top center line. I also measure how how the neck is out of the block. So please for sake of discussion we will call this at this point 1/8 in. This is an example of what I may see as I am setting a neck. You will have to adjust a bit to what you acutally have but I hope this will clarify some of the discrepancy in the past posts. Here We Go The neck is clamped in , I measure the neck at the block along the rim of the guitar and see a 1/8 in rise. I then mark the point of the nut line on the neck. This is just a general point. If I am within an 1/8 we will be close enough for this exercise. I lay out a piece of tape in the area of the saddle. Let us assume that we are doing a martin long scale ( 25.4) So I now have A neck at 1/8 about the rim B point of the saddle ( 25.5) make it easy C laying the straight edge on the neck I see that the neck is 1/8 off the top at the point of the saddle. D Center line off the neck measured at the tail end of the guitar is 1/4 in to the bass side. What does this mean ? This neck in this situation is dipping down and needs to be adjusted so we raise the neck to get the proper neck angle , and also the neck is canted to the bass side and will have to have the heel adjusted to swing the center line of the neck in more of a line with the center line of the top. This is done by removing wood all along the heel do let the neck swing. NOTE: this is needed on any neck and the joining method doesn't matter. So what must we do? There are a few things that we have to do and the most important is start by taking a pencil and marking the lines of the heel at the neck joint. Most Martin style kits will have a neck block that has a slight radius on it. So mating a flat heel cheek off the neck to the radiused neck block can be problematic , so I will flatten this area. Now to mate a flat to a flat is much easier. Next I will make a few hash lines on the neck heel as a reference line so I know how to work my neck heel in adjusting the fit , angle and center line, Now with the mating area flattened we can start making adjustments to the neck . DO NOT TOUCH THE DOVE TAIL So using the hash marks , you want to adjust the neck angle first. In the back of your mind you know that the bass side of the neck heel will also need adjusting later but for now just do one thing at a time. Trying to do too much can cause you more confusion. Using the lines ( I usually do 5) work the heel down. In my video you will see that I do this with a sanding block. Also NOTE: that this is about a 5 to 1 move. If we need to move this neck angle up 1/8 in. That is .125 so you don't want to take more than .025 in . WORK IN SMALL INCREMENTS . So you want to only work the first 3 to 4 hash marks. Work both sides. CLAMP IN THE NECK and look close at the joint so you have the neck tight as you can to the body. You may see a slight opening up near the top but as you get the neck heel adjusted this will close up. This is a constant work the joint and test the fit and measure. As you see the neck angle working up , always be aware of the difference of the height from the neck joint to the saddle position. so after a few tests you have the neck at A 1/16 in and the height off the point of the saddle at 5/32 this is a difference of 1/16 = ( 2/32 ) that leaves a 3/32 rise at the point of the saddle If you are between 1/16 and 1/8 in you are within the spec for this pre set. So you have the neck angle. Now you need the center line. So lets say you now check the center line of the neck to the top and you see that you now have 5/16 off to the treble side. You may be thinking What the Hell did I do now Relax , this is a result of you working the heel and one side may have more wood removed than the other side. As someone said this is the joint from heel , I would say that this is a joint that makes you scratch your head. So now you have to make the neck swing to bring the center lines together. I would say that if you are within 1/8 in to the center line of the top at the tail block you are fine. NOTE: When you look at the heel and how this adjusts the center line , the distance off the heel from the neck center line may only be about 1 1/8 in , and the distance from the neck heel to the tail is about a 20 in distance , this will make the move ratio about 19 to 1. So 5/16 in is .3125 and you want to move this back to center and you are leaning to the treble side you will want to take off only 1/19 off this 5/16. That would be about .016. this is not much . Most issues with this joint are often caused from over adjusting. Also keep in mind that joint must be tight for taking measurements NOTE: if the neck feels loose DON"T TOUCH THE DOVETAIL but USE PAPER AS A SHIM AT THIS POINT> by using the paper shims , you are not changing the physical dovetail joint yet. You can add paper easier than removing wood. You can also put more on the bottom than the top. THE POINT IS TO GET THE JOINT CLAMPED TIGHT! ok you now have the basic tools for adjusting this neck. You have now adjust A and C of the ACE equation A angle C center lin Now with all this you can use a strip of sand paper and floss the heel at the body to clean up the fit. NOTE: once the angle and center line are established you no longer need to touch the heel of the neck. This is the plane that locates the heel. OK now we do E of ACE Elevation. I use chalk but you can also use carbon paper So with chalk mark up the neck block where the neck tenon will fit in the mortise . Now carefully set the neck in the block and clamp. NOTE: the lower part of the tenon is what you want to see covered in chalk. THIS IS A PINCH JOINT. NEVER WORK IN THE NECK BLOCK. Once you pull out the neck look to see where the chalk is and just remove that. It won't take you long to see how this works. VERY SMALL ADJUSTMENTS ARE NEEDED. If your neck fits below the top you will need a shim . So lets recap HEEL this makes the adjustments of the neck. Look at the neck and just think about the mating surfaces and the relationship to how the neck would move by adding or subtracting material. This is the whole crux of the neck setting procedure. The tenon is the part that locks the joint together. NOTE: the angle of the tenon , in relation to the mortise is critical to understand. Look and this in the block and you can see that the "sway" of the dovetail locks into the neck block. You want the tenon to be parallel to the mating mortise. In reality you can even make it a bit more angled so the lower part of the neck tenon sets into the neck block. If you flatten the angle you will loose this pinch and bind of the mechanics of the joint. This is where the neck joint can really frustrate the heck out of you. Please let me know if any of this need clarification. On a side note to this I also stated about screwing in the neck block. Let me say that the neck block should be set into the rim so the mortise is square and centered to the body. Also before you screw the neck block to the mold , you drill a 1/4 in hole through the mold. I use a screw that would be about 1/4 in short of the mold and neck block so I don't make the screw protrude through the neck block. I set the block to the mold with clamps and then using a washer and the screw lock the neck block into the mold. Remove the clamp and the screw will hold the neck block. I then apply the spreader. If you get the neck block in off center or square , you can make some adjustments to the neck tenon. To accommodate a tilt in the neck block you will have to adjust the tenon by taking some off the top on one side and some off the bottom on the other. If you are off center , you can always remove more off the tight side to move the neck over . |
|
| Author: | jfmckenna [ Thu May 08, 2014 7:28 am ] |
| Post subject: | Re: Neck Angle FAIL! Please help. |
Nice write up JH! Gustav I think now is the time to practice your neck resetting skills. Of course in this case you will be doing the opposite of what a normal neck reset is but it's essentially the same. Just remember that a little bit goes a long way so you will be removing material on the heal right up against the underside of the fretboard and tapering to zero at the heal cap. Use a sharp chisel and check your work constantly. When using the chisel 'aim' more towards the inside of the heal adjacent to the dove tail and then get the facing edges. A short straight edge can help you see where you went too low or too high. And of course constantly fitting the neck as you work will expose the same spots. Since this is a 'reverse' neck reset I'm not sure that flossing with sandpaper will work. And since ther is no entrance and exit to the surface that needs to be adjusted I would avoid the temptation to use a sanding block. At least for me anyway I tend to round things off when I sand. Good luck. |
|
| Author: | Tai Fu [ Thu Jun 05, 2014 1:36 am ] |
| Post subject: | Re: Neck Angle FAIL! Please help. |
I don't know if it's too late to say anything now... but I just thought of something. Make a really tall temporary saddle, get your guitar up to a playable action, set it up and leave it strung up for a couple of months. I guarantee you (unless your soundboard is extremely thick with very tall braces) that the action will rise a bit as the thing seems to settle a bit... I'd aim for about 1mm OVER your target when initially building the guitar because they do seem to settle, so if you get it just right the first time it will be too low when the guitar settles. I know 3/16" is still a bit too high but with some time under string tension it will change. I did get this advise from another professional luthier from Germany by the way. |
|
| Author: | bluescreek [ Thu Jun 05, 2014 5:46 am ] |
| Post subject: | Re: Neck Angle FAIL! Please help. |
Sorry Tai I can't agree with this for 1 main reason once you get the bridge saddle too high your stress on the top changes drastically , yes the top may rise but more importantly , there is a torque on the bridge that gets magnified by the height . This can really deform the top or just fold the saddle over. Once the neck is over set, it has to come off and be set properly. The reason I know this is I once decided that I can make the worlds best guitar by increasing the height of the bridge and saddle and go with lower gauge strings. Trust me , it didn't work. The torgue actually shoved the top in front of the bridge down in a few weeks. Things you learn when something fails. |
|
| Author: | Duhjoker [ Thu Jun 12, 2014 8:54 pm ] |
| Post subject: | Re: Neck Angle FAIL! Please help. |
You know I make flat top guitars with no sound holes which means I have to glue the bridge on and pretty much set your angle at the same time. Because of the order of the way I build I start set up as soon as the top is glued onto the sides and the bridge is set and before gluing on the back. I only had trouble doing it this way once because my top somehow ended up being higher at angle than the bridge. I ruined a neck and dang near slit a tendon on my fret hand trying to reangle the neck with chisels, which was dang near impossible. Now my point is that it's possible to set the right angle before finshing over all construction and it still be good when your ready to set up. Now of course my guitars are double florentine so it's a lil easier to mess with. Also I learned with a good sanding block you can actually reverse the angle or add more by sanding the head block. Takes some time and you have to bolt and unbolt the thing but it's easier than chiseling and takes a lot less time. Now I'm sure someone is going to negate this but this is what I've learned through my own exoerience. |
|
| Author: | Duhjoker [ Thu Jun 12, 2014 9:16 pm ] |
| Post subject: | Re: Neck Angle FAIL! Please help. |
Here's a link you should find useful. http://www.tundraman.com/Guitars/NeckAngle/ |
|
| Page 1 of 1 | All times are UTC - 5 hours |
| Powered by phpBB® Forum Software © phpBB Group http://www.phpbb.com/ |
|