Test Staining and Cutting the Nut

Sunday, August 09, 2009

I haven’t been able to spend much time at all on my mandolin for the last couple of weeks, between travel and family time, so that’s why I have been a bit delinquent in updating this blog - but I have gotten some done and hope to get more this week.

I finally managed to get the rest of the binding on the body of the instrument and then get started on binding the peghead.

Because the binding needs to be held tightly while drying, especially for the first couple of hours, I used some wedges of scrap wood on the binding since there doesn’t seem to be a better way to get the job done is such tight quarters.

Here are a couple of shots to show how the back binding came out.


I made my first attempt at staining on the scrap soundboard I prepared earlier for this purpose. To begin I started by rubbing down the entire soundboard with water. I read that when using water-based stain that the dry spruce is bad for soaking up a lot the stain right where it makes contact which makes it difficult to “feather” it if you are attempting to create a sunburst, but by applying the water first, the stain tends to soak in less and give you a chance to feather it. It’s not much to see, but here is my soundboard after applying the water only.

Next, I made another really stupid mistake. I say stupid because there is no excuse what-so-ever for having made it. To create my sunburst, I purchased three different stain colors - Tobacco Brown, Red, and Amber - that are to be used from darkest to lightest from the outside edge to the center. Since I wanted to start at the outside edge and work my way inward, I intended to use the Tobacco Brown to begin. So what I did was I grabbed the Amber (the lightest color) instead of the Brown and rather than actually READING the label, I ASSUMED I grabbed the right bottle. Stupid. Anyway, since I promised to show both the good and the bad, here is how it worked out.

Using a glass cup and a cut-up piece of an old cloth diaper that my wife purchased with a bunch of other material at an auction, I applied the amber stain around the outer edge of the soundboard. As light as it turned out, I assumed I had simply not mixed enough stain with the water, so I added some more stain to the mix and did it again.

Still not dark enough - but not being smart enough to LOOK at the label on the bottle to see what the color was OR what the recommended stain-to-water ratio is, I add even more stain and tried it again.

Better, but not really what I was hoping for, I decided to try mixing some red in to see what that would do. I went to my other two bottles of stain, read their labels, and lo-and-behold, realized I was using the wrong color. Idiot.

By now, the wood was pretty well saturated so I broke out my heat gun and spent some time drying the wood in preparation for staining all over again. Once dried, I mixed up cups of both red and brown and tried it again. Here is how it came out.

I don’t really like the way this came out, but I have yet another scrap soundboard that I will test on again. This time I think I will try it without the hide-glue sealer and after doing a much more thorough job of sanding.

Setting the stain aside, I moved on to cutting the slots into the nut. Opening up and removing the appropriately sized feeler gauge blades from the set my brother-in-law donated, I used my Dremel with a narrow cutting wheel to create my nut saw blades.

For the smallest three slots I was able to locate blades that were either exactly the desired thickness or 0.001” small, but for the largest one, 0.043”, there wasn’t a blade thick enough. For this one, I chose to use two blades, 0.020” and 0.021”, and glue them together with super-glue before cutting the blade slots. I figured that the thin glue layer would be somewhere around 0.002” thick giving me the overall 0.043” thickness I needed.

Turns out that these little saw blades work quite well. They cut the bone pretty easily and holding them in the proper orientation was no problem. I imagine that professionally made blades or files would work just a little bit easier and quicker, but for the price difference ($6.00 vs. $50.00 or more) I really like these guys. I recommend this method to anyone looking to buy or make a set of nut slot saws.

Unfortunately, this is about all I was able to get done in the last couple of weeks. Hopefully I will be able to work on it more this up-coming week.

Fitting the Nut

Sunday, July 26, 2009

Not having parts and then having to make yet another unanticipated business trip have really slowed down progress this week, but I have been able to get a little bit done.

As you might recall, one of the last things I did last week was to seal my test soundboard with a mildly diluted hide glue formula. After it dried for a couple days, I spent about two hours hand-sanding it off to what looks like bare wood. It is my understanding that the goal here is to “clog” the otherwise open pores of the wood with the hide glue to prevent the stain from soaking in too much without inhibiting the stain from getting to the majority of the wood fibers. From what I have read of other people’s attempts at this, its almost impossible to sand it off too much. So, armed with my trusty 80 grit paper followed by some 120 and then 220 grit paper, I sanded off the dry hide-glue layer. Here is what it looks like.

One of the interesting things I found while sanding the glue off was that this is a really good opportunity to find and correct many of the imperfections in the contour of the top. The hide-glue dries just a little bit darker than the color of the raw spruce so each dip and valley, regardless of how shallow, shows up. I was quite surprised at the number of irregularities I found. I believe using this will really help the appearance of the finished mandolin.

With the fretboard now in place, it was time to install the nut. But before I could do that, I realized I needed a padded block to go under the neck while the mandolin is laying on its back to prevent hold the peghead off of the workbench. For this I picked a scrap piece of wood that measured about 1-1/2” x 3” x 4”, cut a shallow wedge in the center of the 4” long face, and glued a piece of soft leather to it. Here is how it looks.

NOW it was time to install the nut.

I started by measuring the width of my slot with my digital calipers. I measured both edges to make sure they were about the same, and much to my surprise, they were within .001” of each other.


I then measured my nut blank (bone - ordered and received way back).

Since the difference between the two was almost half the thickness of the nut blank, I decided to use my drill-press-drum-sander to get it roughly to size. (I used a piece of scrap would to verify the thickness before committing to the nut itself).

Once run through the drum sander, I measured again.

With less than 1/10th of an inch remaining to trim, I stopped there and finished sizing by hand.


I already new that the height of the blank would need to be trimmed but before I could do that, I needed to be able to mark the correct fret height on the nut and this could most easily be done once the nut was correctly sized to fit the slot.

Now to find a way to mark it.

I read somewhere that somebody had taken a wooden pencil, cut it down the center to create a “half” pencil and used this to mark the fret height - so that is what I did. Rather than try to cut the pencil, though, I used my drum sander again to sand away the unwanted half of the pencil.

Using my drum sander once again, I removed all but about 0.30 inches of material above the fret line and then hand-contoured it to shape before gluing it into the slot with Titebond. Here is how it looks now.


As you can see on the top photo above (if you look really hard, anyway) you can see I have marked where the notches for my strings will.

My brother-in-law read my last post where I wrote about buying and using feeler gauges for saws and offered up an old set that he had (and no longer used) for creating my “saws”. Not being one to look a gift horse in the mouth, I accepted and found that this set has a much wider selection of thicknesses.

And, last but not least, the remainder of my parts finally arrived late this week. Now that they are here and assuming I get to stay home a bit more this week, I should be able to get the rest of my binding on and try my hand at staining. I am really looking forward to the staining - if I am lucky, I may get to even try it on the mandolin, not just the test piece.