Andrew's blog

Producing CNC milled combs revealed!

I design my combs myself and produce them using my CNC mill. Here's a breakdown of the process.

The combs are cut. Water is sprayed on the surface as the mill works to cool the bit as it cuts. Keeping the temperature down helps keep the bit sharp and prevents the finished comb from giving off a strong smell.

Fresh off the mill, the combs look a little rough....

After a quick rinse....

Each comb is held in place with support bridges. Here, I have cut them free.

Then wash away the debris.

The rough combs need to be sanded polished and flattened. I first start working on the outer edges and tips of the tines.

Here the outer edges and tines are smooth.

Next, I flatten the top and bottom sides. I check for flatness using a reference. This comb is not flat and needs to be fixed.

After a little work, it's flat.

At this point, the combs are starting to look nice.

Next, I round off every edge. The front (tines, viewed from the side) is rounded.

...and the corners...

Next, I painstakingly work on the inside of every tine. I make sure each one is shaped for comfort.

These tines are comfortable on your tongue.

I start the process of lacquering the tips of the tines. I apply many thin coats instead of only a few thick coats. I do this to ensure the lacquer doesn't chip or crack. My aim is that they last a lifetime.

This is after one coat.

After several coats...

If it's dry and it looks wet, it's done!

Next, I polish the sides and back of the comb. The last step is to flatten the comb one last time to ensure it's going to deliver peak performance.

Combs get wrapped up immediately and are ready to be shipped.

Mysterious embossing instructions - Can you see the light?

I offered some Mysterious Embossing Instructions which included a clue you can download and print out.

This video explains the clue I gave, my reason for offering it in this way and a demonstration of how I use indirect light and a three-dimensional view to make quick and effective work of embossing harmonica slots.

With this method, you get benefits similar to using a microscope and a light-table but avoid the respective disadvantages and limitations of those devices.

Mysterious embossing instructions

Embossing decrease the space between the reed and the edges of the slot. With higher tolerances can come better performance - the harmonica responds better and plays louder.

The thing about embossing is that so much can go wrong. Fixing the damage can take more time than it takes to do the actual work of embossing the slots.

So how to you "walk the line" to get maximum benefit without creating problems for yourself?

Some folks advocate special tools. Some use a light table. Others use a microscope - sometimes.

All those things can work well. But every method has its disadvantages.

For example, a fast-acting tool can overshoot the mark causing you to work against yourself. A light table only shows you two dimensions and as the reed passes through the slot in three dimensions, you can be left confused as to what you are seeing. A microscope can be overkill - you may not even need one if you have good eyesight. You certainly don't need to use magnification to do most of the work - if anything, you would want to shorten your view of the slot instead of zooming into one segment. But if you are over 40 years of age, using some form of magnification is probably good idea.

Let me share a secret with you: You can get top-level results using simple methods that don't rely on fancy technology.

How?

I'm not telling you. I don't make a habit of keeping secrets, but this is something I have never shared before in public.

I am happy to show folks the basics of how to tweak harmonicas and I have a strong preference for some methods, but there are may ways to get a task done. You don't need to know this secret to do a great job. This method's advantage is that it makes things easier and saves lots of time if you do it correctly.

Again, I'm not going to tell you what it is. I will, however, give you a clue.

Here it is. Print it out. (It's a way of looking at embossing.)

Contact me if you think you have it figured out. I'll let you know whether you are hot or cold. I'll add the most interesting responses to this page as they come in.

Good luck and don't hesitate to contact me!

2014/11/24 - Stephen C. described the way he holds the reed plate to "get a pretty good sense of what's going on in the space between the reed and the plate" and he's very close to what I describe!

2014/12/25 - Jaime G. wrote about "aligning tip edge with edge under rivet (to emboss) with a secure and efficient method."

EDIT: The mystery is over! My explanation can be found here!

"Where can I get that engraver?"

I get asked about the blue engraver you see in my YouTube videos. I use it for tuning.

It's from a local store and they no longer sell that model. I bought a few of them when they were clearing them out. They seem to last forever.

From the product description:

Hold the engraver as a pen and apply a minimum amount of pressure. Do not apply excessive force when engraving, as a higher speed will result in better engraving. Free speed: 11,000 to 12,000 RPM.

Here is the new model:

The newer models come with a smaller tip. I like the bigger tip - it's gentler and I can get really close to the side of the reed and not have to worry I am going to cut through the reed. What I do looks a lot more like chamfering once I am done.

Here are the two types of tips you can easily find on Ebay:

With the big gentle tip, I feel I can take off a lot of brass or stainless steel without distorting the reed.

One thing about some engravers is that they can have a little or a lot of run-out.

What is run-out? It's an inaccuracy of rotating mechanical systems, specifically that the tool or shaft does not rotate exactly in line with the main axis.

A lot of run-out will make the tip wobbly and difficult to use. You will distort the reed using such an engraver.

Hold the tip up to the light and watch it spin. If it stays straight, you've got a good one.

If the tip wobbles, I suggest you find a better engraver. Many cheap engravers made in China can have a lot of run-out while some will have almost none. I bought five of them for $2 each and threw four away.

I never got used to using files even though I spent a lot of money on some of the finest files. Early on, I wrecked reeds, bent them out of shape and overshot the mark using files. I found it a lot easier to use the diamond-tip engraver. I suppose there are many ways to get the job done!

Use any method that brings you success!

Tweaking harmonicas: Measure what you change

This is about methodology.

I made yet another harmonica tweaking video.

Here's a video demonstrating some of the things that are straightforward to quantify so that you can make changes that have a measurable benefit.

Some of these things include:

Tuning: It's easy to measure the pitch of a reed and whether it's in tune with another reed. Play all the octaves available and listen for "beating".

Bending: Bend the 3 draw (or any other bend) with as little force as you possibly can. You will find a "blind spot" somewhere in the middle where the workload is handed off from the draw reed to the blow reed as you bend down. How much work is needed to "skip over" this blind spot can be felt, albeit subjectively; it tends to be more work on lower key harps. We learn to "skip over" this blind spot early on when we are learning to bend. A well-playing harp can be played with very little breath force without having to work hard around the "blind spot".

Reed shape efficiency: By playing a single reed using your lips on the plate off the comb, you can get sensory feedback on how easily the note responds, how much flow you need to make the note sound strong, and how loud the note is. A well-shaped reed will make the whole reed plate vibrate when you play it.

Reed shape efficiency (again): By bending the single reed's note down, you can determine if the reed is prone to squealing. That's a great indicator of how efficiently the reed is set up.

Sending harmonica reed plates by mail (the safe way!)

I usually prefer to work on a harmonica along with its comb and cover plates. However, there are times when I only require the reed plates. This can save on shipping costs because reed plates can be sent through regular mail.

You do need to be careful to package them in a way to try to avoid damage or loss. If you just drop reed plates into a plain envelope, I probably will receive an empty envelope with a hole in it.

Here's a safe way to package reed plates for transit by regular mail. Please be advised that although this is a great way to package them, regular mail is a lot less safe than sending them as a parcel with insurance. I cannot assume responsibility for list or damaged goods. It's up to you to make the choice whether the cost savings is worth the risk.

Step 1 - Place the reed plates back-to-back. Make sure the reeds are on the out side of both plates.

Step 2 - Wrap them up in wax paper.

Neatly fold the paper around the reed plates.

Step 3 - Use wide packing tape and stick the reed plates to a piece of cardboard. Make sure the reed plates are under a "bubble" of tape and completely covered.

Step 4 - Repeat the process for any other reed plate sets you are sending. Position the plates so they are parallel and centered on the cardboard.

Step 5 - Cover the first piece of cardboard with about piece of the same size. Make a sandwich.

Step 6 - Tape it up. Wrap the tape around the cardboard in both directions.

Step 7 - Put the cardboard sandwich into a bubble envelope and you are ready to send it!

Research and development of optimized combs

I have an ongoing process of quality improvement and I devote some time and resources for research and development on certain projects. I've enlisted the help of a number of players to do some testing. I need the input of different players to determine if a particular change to a comb design is indeed an improvement that can be measured.

In cases where the improvement is felt across the board, the change becomes part of my standard design.

In some cases, the change is subjective. Some may love it while others may hate it. In that case, I can offer the new feature as an option so that customers can get a truly customized comb, made to order with or without any desired design tweaks.

I recently had some testers compare two combs. Both were identical except for the hole spacing. The Hohner Rocket boasts wider spaced holes and I wanted to provide that experience without making the comb tines too thin.


Wide openings and standard openings

The tines are only thin at the opening and become a normal spaced channel to provide less compressible volume a little further down. This is to improve responsiveness. The hole openings are 40 per cent wider than standard Marine Band comb openings.

Feedback is trickling in and I am considering it carefully.

My next test will involve resonance chambers. I feel the consensus is that thinner combs offer better response because there is a smaller compressible volume between your lips and the reeds. But thicker combs offer a larger resonance chamber and some prefer the tone of a thicker comb. Here is not-too-thick comb with enlarged resonance chamber. The aim of this design is to get the sound of a thick comb with the responsiveness of a thin comb.


Comb with built-in resonance chambers


Comb with standard shaped tines

I will be looking for more testers in the near future. I need to finish getting feedback from the first test as well as tweak the "resonance chamber" design before I call for more testers. Stay tuned!

***Update 2016/05***

I have come to the conclusion that resonance chambers have no real benefit and some drawbacks, namely that they can interefere with the performance of some bends/overbends. The original, classic comb design with straight chambers provides the best, smoothest performance.

Although this doesn't result in any innovation, it does provide some helpful evidence as to what makes a harp play well. I believe this project was time well spent.

Acrylic (Plexiglass) harmonica parts

Acrylic is horrible on the environment to make in terms of the chemicals that are put into the air but it is sustainable once it is produced. It can be recycled or re-purposed. That being said, my community does not recycle acrylic. It goes into landfill.

So when I stumbled upon a small amount of discarded Plexiglass, I decided to give it a new home. After some tinkering, I found a way to produce some pretty nifty combs and French Tuners!

Once the sides are flat-sanded for air tightness and the tips finished to a smooth matte surface, they look like they are made of ice. Canadian-made ice combs for sale!

I am offering these combs at budget prices. They look terrific, offer quick response and sound great, but they don't offer the same juicy timbre as my Dark combs. They are most certainly a huge upgrade from stock combs and will add some punch to your harps.

If you want a comb that gets the job done at an economical price, this is the comb for you.

Limited quantities available. Click here to order. (Sold out!)

Video: Replace Marine Band nails with screws and install new comb

This is a quick and easy way to install a flat comb in to a Marine Band harmonica. The stock comb has dimples to make room for the ends of the rivets which hold the reeds. My combs provide more surface area to make an airtight seal with the reed plates and the rivet ends need to be flattened.

This is a harp in the key of G. The end result is a fantastic harmonica that is loud and responsive. I was happy with the instrument but was not satisfied with the 4 overblow due to the shape of the reeds (out-of-the-box profiles).

I spent a few minutes and did some re-shaping of the blow and draw reeds to make them more efficient. It's much more work than just gapping. But the end-result is a 4 blow that is not tight and plays normally with hard pressure as well as a solid - and bendable - 4 overblow.

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