You are currently viewing Kit Guitar Forum archives. To view the current forums go to www.KitGuitarsForum.com/board



Log-in
Register
Members


setting up the rim for the neck angle
Author
Post
blues creek guitars Authorized Martin Repair Ctr

Total Topics: 52
Total Posts: 1011
I just had a guy in the shop with a problem and if I can help avoid this problem for others I have done my job.
The top on most guitars will have a radius to create a dome. Often the 14 fret hump has to do with the way this is done as this will influence the build . The neck angle should fall in at about 1 to 1 1/2 degrees so the action will be good and the saddle height not to high or too low.
First thing you need to do is set the rims with the blocks in the mold or form. Then with the sides spread against the mold you want to square the top to the mold by making the top parallel to the mold and thus square to the neck block.
Once this is established you then will want to incoroprate this angle in the sides . I have seen some sites that do this on the top. I don't like that method as you are now removing wood from an area that is under considerable stress as the neck wants to roll from the string load. This , then focuses forces at the fingerboard extension on the top.
So with the side allready set with the angle we can keep the full thickness at this area.
So with the side squared you can now plot the angle. I measure 4 inches into the body. I then want to remove from this point 0 to 1/32 at the edge of the rim at the neck block. This plots to about a 1 degree angle. Then you can attach the top. rememebr that you want to visualize a slight uphill climb from the neck to the saddle.
When you are ready to check the neck location you can make a little sanding tool with some sandpaper attached to a 3 by 20 inch piece of ply. Put 3 inches of paper on one end and the clean side on the neck surface. One the neck is preset you can use this to clean the line of the fretboard on the top to make a clean transition.

May 27, 06 | 8:10 am
Andy

Total Topics: 57
Total Posts: 350
bcg, I'm just trying to visualise this process. You're removing a 1/32 to 0 taper [ from the outer rim towards the saddle ] just over the neck block, right ? Does this mean that when you glue the top down you end up with a slight depression over this area ?

Jun 15, 06 | 2:19 pm
blues creek guitars Authorized Martin Repair Ctr

Total Topics: 52
Total Posts: 1011
Hi Andy
Not just the neck block but you must look at the area of the fingerboard extension. If you don't have a 28 foot radius dish to set the proper form you can use this technique.
The area that you are working is about 4-5 inches from the top of the sound hole to the neck. This will help establish the neck angle.
john hall
blues creek g uitars

Jun 18, 06 | 8:34 am
Dennis Weatherly

Total Topics: 73
Total Posts: 651
John, would it be a good idea to mark this 1/32" dimension on the sides and be sure to sand down to it with the radius dish? That seems like it would ensure that we get the proper taper into the rim.

Sep 21, 06 | 10:28 am
Ken Cierp

Total Topics: 58
Total Posts: 2262
Hi Dennis --- since this dimension is always about 1/32 or less I have devolped this procedure that works very good. I think its pretty much the same concept as John uses but later in the process, since the top is just a veneer in the neck- fingerboard area thinning it a bit does not hurt anything.

http://www.kennethmichaelguitars.com/NECKSET.html

Ken


Sep 21, 06 | 1:14 pm
Dennis Weatherly

Total Topics: 73
Total Posts: 651
Well, I measured the fingerboard extension on the neck block and found that Martin had already built in the 1 degree angle for me. So I lined up the top of the block with the top of the rim (also already shaped by Martin) and glued it in place. Everything seems to measure out ok. We'll see what happens when I bring the neck and body together someday :-)

Sep 21, 06 | 8:26 pm
Ken Cierp

Total Topics: 58
Total Posts: 2262
Hi Dennis I find that very interesting -- do you have a photo of the block? Although it makes sense and should work great, I get a lot of material from Martin and I have never seen one like. Is this for a dovetail joint? Or MT?

Thanks Ken

Sep 22, 06 | 2:49 am
Dennis Weatherly

Total Topics: 73
Total Posts: 651
It is a dovetail block. I've been surprised at the amount of pre-shaping on both the neck and heel blocks. Both were cambered to match the side curvature. And the angle on the extension was also a pleasant surprise. One degree is not much, so I actually drew it out on paper and set the block over it to confirm my direct measurement of the block.

I'll know for sure when I set it in the radius dish. I figure that even if I measured wrong and it is at 90 degrees, I can mark 1/32" down the rim and shape it with the radius dish to get the proper angle.

I'll try to shoot some pics to share.

Sep 22, 06 | 9:11 am
Bill Cory

Total Topics: 158
Total Posts: 3584
Having learned on my first Stewmac 000 that I needed to avoid the hump at the body, I did back in June on my second Stewmac 000 exactly what Ken C has advised above: Sanded a "ramp" for the fretboard extension into the top. (I've mentioned it elsewhere in the past.) It worked very well and the guitar has a nice low action with no buzzes at all. On other kits, this hasn't been necessary.

I've found out the hard way that whether you need to do this has a lot to do with how I perform several early foundational steps starting with the very first: gluing blocks to rims.

As Al Carruth says continually: It's a system.

Oct 09, 06 | 7:12 am
KTHOM

Total Topics: 19
Total Posts: 244
Bill and everyone,
Is this why Seagull/Godin designed their "Compound Curved tops". Don't they have one radius for the bridge area and (?) another for the neck angle?

If you cut the upper top brace that fits under the FB extension to raise (radius) the top according to the need on the neck pitch...wouldn't it accomplish the same thing as sanding the top?

Then of course there's the cantilevered FB ext. on the Miss Antarctica and the old Howe and Orme designs. Those will ultimately make neck resets pretty simple in the short AND long run.

Oct 22, 06 | 7:53 pm
Ken Cierp

Total Topics: 58
Total Posts: 2262
Planning and execution --- not a hope and a pray!

http://www.kennethmichaelguitars.com/neckangle.html

Ken

www.kennethmichaelguitars.com

Oct 23, 06 | 4:17 am
SteveCourtright

Total Topics: 1
Total Posts: 81
Ken, I like your explanation directed to the arched shoulder brace. I have been struggling with this for a bit and now I understand. If this part of the soundboard has an arch (mine is 28') the guitar soundboard rises to meet the angled fretboard. Now, I understand better how this whole area of the guitar is supposed to come together. A person at Martin said these braces should be flat because "Aren't you making a flattop?" Now I don't think this is correct, unless they do something later to the braces or impart an arch to the top some other way!

Oct 23, 06 | 7:15 am
Ken Cierp

Total Topics: 58
Total Posts: 2262
Hi Steve, Interestingly, as my article indicates there are a lot of misconceptions regarding the actual functions and purpose of the various braces etc. Sorry to report that about 50% of what you read about guitar construction is factual. Most is passed down over time, consequently the trial and error method for fit and finish is the accepted process. As time goes by I plan to reveal the facts and science used to build a fine guitar. We would never build a “Lexus” based on hear-say nor should a guitar be built that way. The guy you talked to at the Martin factory was being a “Smart A**” and does not know what he is talking about. I use Martin components to take measurement all the time. The shoulder brace, while not “radius contoured” is in fact higher in the middle than at the ends --- it has to be! Even the so-called assembly manual from Martin has incorrect and misleading information.

Ken

Oct 23, 06 | 8:06 am



You must be a registered and logged in member to post in this forum