Welcome to my blog! I thought that I would try my hand at writing about various aspects of mandolin making on a more or less monthly basis. I say 'more or less' because new submissions will largely be based on wether or not, I have the time and inspiration. New entries will be posted here with the latest one at the top so you can quickly see if there has been any activity since your last visit.

Wow! I can't beleive that I'm into my third year of blogging here! In order to keep things from becoming too unruly, I will begin seperating each year of blogs onto its own page. Just click on the links below in order to read my past postings.

 

Oliver's blogs 2017

Oliver's blogs 2016

 

 

 

June 12, 2018

While French polishing creates a fairly high gloss on it's own, it usually needs some buffing and polishing to look it's ultimate best. The spirit varnish finish on my mandolins is so thin that machine polishing would be too aggressive. The risk of burning through the finish is just too great. So, after the varnish has been hand applied using the French polish method, I hand polish the finish using a soft cloth with some polishing compound added.

Although my finishes have the appearance of great depth, they are actually very thin. Basically, in French polishing, vapor thin layers, which fuse together to form a singular film, are slowly built up until the film is just thick enough to produce a smooth gloss. The warm, yet crystal clear nature of the natural resins in the varnish, creates the illusion of a thicker film with greater depth, and clarity than any sprayed lacquer, although a high gloss lacquer finish is in fact, the heavier finish. With a sprayed lacquer finish, extra "insurance coats" must be sprayed on so that when sanding back the finish, the risk of sanding through is minimized. Also, when machine buffing and polishing is to be used, the finish must be sufficiently thick for the same reason.

There is an old saying amongst violin builders regarding the varnish. It goes like this, 'not too hard, not too soft and not too thick! The reason for this is that no matter how great your varnish recipe is, a heavy film will hamper the wood's resonance.

Unlike some makes of mandolins, when I say that my finish is hand applied and hand rubbed, I mean it in the truest sense of the term, because for me, achieving the best, most resonant sound, is my absolute, number one raison d'être.

Hand Polishing the Finish

 

Until next time, thanks for reading.

Oliver

 

 

 

May 8, 2018

First, let me apologize for missing last month's blog post all together and for being a little late on this month's as well. In my defense, I did stipulate in describing my blog, that it will be "more or less monthly" and it is titled "Oliver's Random Musings". As everyone knows, life can get busier than one had planned on. One of the things that made me busier than usual will be the topic of this month's blog.

Over my 40 plus years of instrument making, I have tried a number of ways to rout the binding channel or "rabbet" around the perimeter of an instrument. Until now, none of them were completely satisfying to me. At first glance, this may seem a simple matter of running a router around the edge of the instrument. The problem is that on arched top instruments (and the backs of flat-top guitars) there is not a nice flat and square to the side, surface for the router to register on. Just running a router around the perimeter would create an out-of-square ledge for the binding to fit into. So when I got my latest idea, which I like to claim was inspired by the famous "Canadarm" on the U.S. space shuttle, I just had to take some time away from building mandolins to build this new gizmo to rout binding channels.

In case you don't know what the "Canadarm" is, it's that long arm-like manipulating crane that you see in use on the American space shuttle. It was developed by "The Canadian Space Agency" (yes, Canada has a "space agency") in co-operation with NASA. Here it is in operation.

 

Granted, my version is a little less sophisticated but to me it's just as awe inspiring.

The actual idea for my "Apiti-arm" came from one of those articulated task lights that are so useful for a number professions. You know, the kind of light that you can position any number of ways while the actual light fixture stays perfectly vertical. The key being that the light on the end of the arm stays perfectly vertical as the arm is swung around to any desired location. Now I've had this idea floating around in my head for some time now but I could never find an easy enough way to build and arm that would be capable of holding the weight of a small router until finally I came across a ready made articulating arm of the perfect size in a surplus store. What a score!

Now, I did need to make some modifications to it so that I could mount a laminate trimmer to it and I also needed to make a base that the arm could be mounted to as well as a holding mechanism for the mandolin but when it was finished, it worked like a dream! It well exceeded my expectations. Below is a photo of it in action. (In the distant, far left, you can see the light that inspired it.)

 

 

With this set-up, I can reach into almost all of the twists and turns of an F-model mandolin except into the scroll area. In this area, the ledge must still be cut by a combination of free-hand routing and a variety of hand tools. I really enjoy the challenge to my skills that this brings. It literally takes me hours to carefully cut the scroll's binding ledge and get the lines just right. Here's a look at the nearly completed scroll binding channel.......

 

 

and here's a look at the binding being glued into place.

 

 

Bye the way, the mandolin pictured above is being custom made for a special client. At this time, I'm not at liberty to say more but I hope to give a full report in the not so distant future.

As always, thanks for reading,

Oliver

 

 

 

 

 

March 8, 2018

I'm a little late with this month's blog post. I've been busy (busier than usual) creating content for my new Instagram account.

Last week my wife Jody came to me and said, "you should be on Instagram". "Insta what?" "Instagram. You need to be working the social media like a regular person". I responded that between all of the other hats that I need to wear, I already have difficulty in getting enough actual shop time. She said that if I create the content, ie; photos, that she would do the posting and otherwise manage the account and so the Apitius Mandolins Instagram page was launched!

This is a giant step for a guy like me. I don't even have one of those hand held thingys that does everything and tells everyone. I still have the same wall mounted rotary telephone that I've had since, well, I'm not sure exactly. I don't recall not having it. It's worked without fail, even after a lightning strike on the cable that comes into my house. Why would I need to replace it? It's perfectly fine. See.

I will admit that some years ago, I had to add a "touch-tone" phone, the kind with the push button technology, in order to be able to deal with some businesses and the government people. So here's what I have in my office.

Luckily for me, Jody, remember Jody, Jody's my wife and "bestie", Jody's got one of those cellular phones. Turns out, you can't even post to Instagram with an "old fashioned computer" like mine. So, I'm slowly being dragged into the twenty-first century, kicking and screaming. I guess I'm just an old fashioned guy with old fashioned values whose lucky enough to have a guide into the "new normal".

 

 

February 1, 2018

A well made string nut with accurately spaced string slots that are also filed to a depth which provides the lowest action possible is one of the pillars of a professional set-up. I can see no reason to have an action height at the nut, that is any higher than necessary to prevent string buzz. Some players may prefer to raise the bridge up a little more than necessary to prevent buzzing just because they like the feel of (as Bill Monroe would say) a "manly" action. Personally, I like a low action at both ends of the string. How low you can go will depend on three factors, how well the frets are dressed, the string guages used and the individual player's attack. A player who strikes the strings aggressively will require a taller bridge height in order to avoid buzzing than someone with a lighter touch. String height at the nut should be the same or slightly higher than the height of the first fret whether you play hard or soft. Excess string height, especially at the nut will make fretting a note more difficult than it need be and even worse, it can cause intonation issues as the string needs to be excessively stretched to make good contact with the fret, thus raising its pitch.

Good string to string spacing as well as good spacing between the courses also contributes to a good overall set-up. Although I have heard other schools of thought on this, I contend that the gaps between the four courses should all be equal as well as the gaps between the string pairs themselves. To achieve this requires some tedious but basic math to layout the slot locations on the nut. Simply using a divider to lay-out the centers of the string pairs equidistant will not do. This would result in less of a gap between the courses of the heavier strings than the lighter ones due to their varying diameters.

In order that I did not have to do the tedious math every time I needed a different nut width and/or string guages, I came up with an Excel© spread sheet that would do the calculations for me just by entering the known and desired variables. I have included a working version of this nut slot spacing calculator below.

To use the calculator, double click on any of the buff colored boxes and enter the value you would like. The white boxes will be automatically re-calibrated when you "off click" in a blank area of the web page. The calculator is presently filled out with metric values but you can use decimal inch values as long as all of the values in the buff boxes are changed to decimal inch. In other words, all of the values in the buff colored boxes must be in the same unit of measure.

 

 

 

 

 

Once I have the measurements that I want for the nut slot locations, I enter them into a special Illustrator© file and print off a very accurate template.

Thanks for reading,

Oliver

 

 

January 5, 2018

Happy New Year everyone!

On top of the holidays being very busy, I came down with a nasty cough/cold/flu that I just couldn't seem to shake. After 4 weeks I was still under the weather and losing productivity in the shop and so I finally saw my doctor who seems to have whatever it was on the run now. I am presently well behind schedule in my mandolin making and I'm grateful for my customer's patients and understanding. I apologize to my readers for re-posting this blog from July 9, 2016. I just could not find the time to create an original post this month. I consider the following to be one of the most important of all my blog posts and I think it's worth re-reading.

 

July 9, 2016

In today's blog, I'm going to do my best to demystify the relation of wood to humidity. I'll start by describing what we mean by terms like humidity and relative humidity. Humidity is a term for the amount of bound water molecules in the air. If you measured the amount of water in a defined volume of air, say a cubic meter, without regard to temperature, that would be the absolute humidity. (usually expressed as grains per cubic meter) In the real world, what is important is the relative humidity and not the absolute humidity. Relative humidity refers to the amount of water molecules that can be bound in the air at a given temperature.

The warmer air gets, the more water it can absorb. Relative humidity means, the amount of actual water in the air relative to the maximum amount of water that the air could hold at that temperature. So for example, if we have a volume of air with an amount of bound water in it that is equal to 50% of how much water the air could hold at that temperature, it is said to be at 50% relative humidity or, commonly abbreviated to, 50%RH.

Now, if we take that same volume of air and heat it up, it now has the ability to carry more grains of water but if the absolute amount of bound water remains the same, then the relative humidity will drop because it now has less than 50% of the water that it potentially can hold. This is exactly what happens in the winter months. The outside air is cold and say, at 50% relative humidity then we heat it up with our central heating and unless we are adding moisture to the inside air, the inside air drops in relative humidity. It is not uncommon for heated homes and apartments to get down to 15%RH (worse than desert conditions) if humidity is not added to the inside air.

Now here's how this relates to your wooden instrument. Wood, all wood, is hygroscopic which is a fancy term for saying that it picks up or releases water depending on the relative humidity of its surroundings. If the relative humidity stays steady at a given amount then eventually the wood will reach an equilibrium moisture content (EMC) with its environs. The exact moisture content (MC) of wood in equilibrium with a given RH will vary somewhat from species to species. The various spruces used in making stringed instrument soundboards will generally have an actual moisture content by weight of 7% when in equilibrium with a relative humidity of 37-40%RH. Problems arise because as wood takes on water it actually increases in size and as it gives up water or MC, it actually shrinks. This is a property of wood and remains a property of the wood as long as the wood is still wood. We cannot change that. What we can do is learn how to deal with that fact.

Imagine a spruce mandolin soundboard being glued to a rim in an environment of 40%RH. The soundboard is measured at say 250mm across at its widest point. Now the instrument is completed and is sold to a customer who takes it home in the winter time to his heated home. If that home is not being humidified and has gotten down to say 15%RH the soundboard will now start to release moisture which will then cause the soundboard to shrink. Going from the 40%RH at which it was built to 15%RH in a heated home will cause an actual shrinkage of the soundboard in excess of 1 full millimeter. The problem is, the rim does not change in diameter, in any significant way, which means that the shrinking soundboard, which is glued to the rim, feels itself under tension and somethings 'gotta give. Either a crack develops in the wood to relieve the stress or a seam lets go.

In the summer, when the humidity goes up beyond the 40%RH that the instrument was glued together in, the wood swells in size. This time, though the rim is holding things in place, the soundboard does have somewhere to go. It can bulge up causing the string action to rise. Although the soundboard does have some room to maneuver, there is a limit and if the RH gets too high, the stress caused by the expanding wood will typically lead to seams letting go. Since high humidity is very often associated with high temperatures, these conditions will also weaken glue joints while putting the stress of the expanding wood on them. In actual numbers, a spruce mandolin soundboard that was glued up at 40%RH will grow by nearly 3mm when at an equilibrium with an environment of 80%RH

The key to avoiding problems caused by excesses and extremes of humidity is to keep your instrument from being exposed to these extremes. Solutions for excessive dryness include using a whole home humidifier on your furnace, using a room sized humidifier in the room where you store your instrument or using a humidifying device in a case in which you store your instrument. My preference is in using a whole home humidifier. It requires the least amount of ongoing maintenance and is good for the human occupants of the home as well. A room size humidifier can do a good job if correctly sized and maintained. Using a device in your case is my last choice. I find that these require a lot of maintenance and monitoring. It is difficult to insure that your are adding the right amount of moisture and not overdoing it.

Here comes one of my real pet peeves and that is that the typical hygrometers you buy at the hardware store are very often very badly calibrated. It's OK for me, I have sling psychrometers to calibrate my hygrometers because it is my business to maintain proper humidity levels but it is not so good for the average person. Proper calibration of your hygrometer is essential in maintaining proper humidity levels in your home. Other wise you could be lead to believe that you are maintaining the the proper level, which by the way is 40 - 50%RH, when in fact you are not. I wish I had a good answer for this. Here in the Toronto area, I know of one music store, The Twelfth Fret, that will calibrate your hygrometer for free if you bring it in. Maybe there are other reputable shops in your area that will do the same for you.

So the main takeaway is, keep your instrument at a comfortable humidity level, avoid extremes and you will be able to pass it along to your grandchildren in perfect working order.

Here is a handy chart that I drew up. It plots the equilibrium moisture content of a typical spruce species vs relative humidity and also shows the actual dimensional change that occurs across a 250mm wide mandolin soundboard. Keep in mind that the maples used for the back actually have a larger coefficient of expansion than the spruce top. This is even more so in rift-cut and slab-cut backs which are popular for their figure.

Click on the image below for a PDF version sized for printing on 8.5 X 11 paper.


Thanks for reading,

Oliver

 


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