Filling Some Neck Gaps

Friday, June 12, 2009

Between work and some much-needed early summer-time chores, I did not get a lot done this week - but I did get a little.

After posting last Sunday, it dawned on me that I had made yet another mistake - while gluing the neck to the body, one of the things you need to do is to locate the neck at the proper depth with respect to the top of the head-block. Now this might seem pretty straight forward, but I can assure you it CAN be messed up. It’s not perfectly clear from my photos, but the head-block and top of the dovetail in the neck are in different planes - the neck plane is 6 degrees out from the top of the head-block. This means that, at best, only one edge of the two will line up while the other will be offset - no big deal provided that you align the correct edge. So which is the correct edge? The back one (closes to the tailblock - and even that is not EXACTLY the correct one) - and here is why.

The plane of the fretboard on the neck has already been established when it comes time to glue these two pieces together. The top of the head-block has not - it is flat with respect to the body. Once the glue in the dovetail joint dries the head-block needs to be sanded to match the fretboard plane. Now obviously (when your smart enough to think about it in advance) you need to align the neck so that all of the sanding is done to the head-block. I did not do this. I aligned it so that the top of the head-block was below the fretboard plane which, had I done nothing to correct it, would have meant creating a new plane for the fretboard. Not a good idea.

So what I did was to cut and add a thin shim (made from a left-over piece of maple side-wood) that matched the outline of the head-block. This, once glued to the head-block, I was able to sand it down to match the fretboard plane. Since this is located such that it is going to be almost completely hidden from view and then stained so dark that it will be almost impossible to detect, I feel pretty good about this fix.

Now, as I noted in my last post, I also needed a shim on the back of the neck. Just like the one I did on the front, I created a shim using another piece of maple side-wood and glued it to the neck. After sanding it to match the contour of the neck and the plane of the back, I think it looks pretty good, too.

I’m afraid I am not going to get to work on my mandolin next week at all (work, work, and more work), so (for all my followers) I apologize. I hope to post again in a couple of weeks.

Neck Joint Cutting - Almost

Thursday, May 28, 2009.

Well, I am rapidly approaching the end of May and it occurs to me that I have been working on this now for just over five full months. As I look at what I have to show for the time, it doesn’t seem like much. When I look back at this blog, though, the road has been pretty long and I have already learned a bunch more than I ever expected.

I’m good with it and I can only hope you are, too. So lets keep going.

I am a bit disappointed in how little I have been able to get done in the last several days, but its not like I have been sitting still. I glued my soundboard on to the rim and spent a great deal of effort to create a jig for cutting the joint in the headblock where the neck attaches. My disappointment comes from the fact that for all my work, I am not going to be able to use the jig I made but will have to cut the joint differently than I had planned, but I’ll get to that later. At the moment, I want to show you something I came up with.

A couple of annoying little problems I ran into when using the hot hide-glue were that the glue cooled down too quickly and I was having to heat it downstairs in the kitchen and run with it upstairs to use it. When it began to cool off, I either had to run back downstairs again or stop where I was. Not fun. Then one day as I was browsing through the posts on the Mandolin Cafe, I ran across a thread where others were sharing how they dealt with this and other hide-glue problems. One of the things that caught my attention was how some folks make up their glue into plastic squeeze bottles and place steel nuts in with the glue to add weight and hold heat. What a cool idea. So that is what I did.

For my bottle, I took a nearly empty Elmer’s Glue bottle, washed it out, and poured in my heated hide-glue. I then put in four nuts - small enough to go through the mouth of the bottle but big enough to not interfere with the glue reaching the nozzle.

Now that I had an improved glue delivery system, I needed an improved heating system. While I could have purchased a single electric cooking eye or one of the glue pots you can buy at Stew-Mac or LMI, I did not want to spend that kind of money on it. Instead, my wife happen to find a “personal coffee heater” at a yard sale.

Using this, along with a glass bowl of water, I no longer have to run up and down the stairs. This is the rig I used to heat my glue when it came time to glue the soundboard to the rim and I must say I am very pleased with how well and quickly it works.

So, once the glue on my soundboard assembly had dried, it was time to focus on the neck joint.

In Mr. Siminoff’s book, he details two methods for cutting this joint; one method is his own development (the one I settled on) and the other is the classic dovetail joint. In order to cut the Siminoff joint, you need to create a jig that both elevates the head block to about a 6 degree angle and allow it to rotate in both directions so that you can cut a “V” joint with your bandsaw. Early on, as I looked over my bandsaw and the materials I had on hand, I knew that creating this jig was going to be a challenge, but I figured I had what I needed. Sadly, though, I was wrong. Fortunately I never cut into or damaged anything important in the process of learning I was wrong. All I lost was time.

While I was able to eventually cobble together a jig that allowed me to just get the head block up to the saw blade, I found that I just did not have enough room to allow for the rotation without hitting the bandsaw with the scroll.


Even though I was not able to use it for anything other than a learning experience, I decided to go ahead and put up some pictures of how I put it together. You will probably notice that there are a lot of extra holes and cuts that don’t look planned (they weren’t), but I had to take it apart several times before I got enough clearance to clamp, rotate, and cut even as much as I was able.





So now that I realize I cannot use Siminoff’s joint, its time to learn about and attempt a dovetail joint. From what I read, it looks like this should be one I can cut, it simply takes a lot of touch-feel work to get it right.

I will let you know how it goes.

Installing the Peghead Veneer

Sunday, April 26, 2009.

Yesterday I got a few honey-do list projects done and then got to spend a little time prepping and gluing the new soundboard together. I chose not to include pictures of that since they would be of little difference than the ones I posted for the first. That was about all I got done on Saturday.

Today, while the soundboard glue continues to cure, I took to the task of gluing my peghead veneer onto the peghead. Since, once the instrument is completed, the veneer will be butted directly against the nut and, since the nut is perpendicular to the fretboard rather than the peghead, the first step in this process is to prep one edge of the veneer to the angle of the nut.

I had done this a couple of weeks ago using a drawing from Mr. Siminoff’s book, so all I had to do today was to verify the angle still looked good to me. Holding against the peghead as if glued on, the angle of the edge appears to be perpendicular to the fretboard as it should be. Looks good.

On to the next step - sanding the peghead smooth to make it ready for gluing.

As you may recall, the last thing that I did on the neck and peghead was to install the circular scroll reinforcement. When I put the neck aside, I had not sanded down the reinforcement. So that is what I did. Since the reinforcement still protruded quite a bit, I started by using my hand-plane to remove the majority of the protrusion. Once it was close to level, I switched over to sanding with 320 grit paper on my orbital palm sander. This process only took a few minutes and now, with a silky smooth surface on which to glue, I was ready to get back to work on the veneer.

I started by match-marking the centerline on the nut and point edges of the veneer to match those on the peghead. Now that I had my reference points, I was ready to mark the outline of the peghead onto the veneer using my pattern and a mechanical pencil.


That completed, I retraced the same pattern onto the peghead itself.


With matching patterns on the peghead and the veneer, I was able to lay the veneer on the peghead, verify they lined up, and then clamp them in place so I could drill for alignment pins.

The alignment pins are nothing more than finishing nails with their heads cut off that are located in the “junk” area of the peghead blank. By putting them in during the gluing process, I am assured that the veneer will align exactly where I want it, without slipping, while clamping and the glue setting. I cut off the heads of the nails so that the gluing caul (a 3/4” piece of plywood) would push them flush with the veneer without interfering with the clamping itself.

After cutting out a hole to roughly match the truss rod pocket, I was ready to glue.

Once again using hide-glue, I liberally applied the glue and clamped up.


After taking these shots, I also added one more clamp right over the truss rod pocket.

MISTAKE (I stopped counting) - Just after I had applied my glue and started clamping, I realized I had not cut a hole in my gluing caul over the truss rod pocket. This hole would have allowed me to clear out any glue that oozed into the truss rod pocket. Now, I will have to wait until the assembly is dry and chip/sand/scrape the glue out. Not too bad (I hope), but still a pain nonetheless.