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May 2018 Update: Manufacturing, Schedule, Fundraising

It’s been a tough, but a good seven weeks. 

We’ve been making steady (although slower than we’d like) progress on manufacturing. We’ve been overcoming the various challenges around molding plastics, especially around the three most difficult parts: the speaker box and string assembly (done), the guitar body front (done), and the guitar body back (almost done). We’re about to cast all the remaining plastic and rubber parts of the guitar. 

We’re working to start manufacturing the metal parts in the guitar (strings, speaker grille, guitar strap button supports, neck button hinge, and input ports support).

We have a plan for finishing the electronics and firmware.

We’ve also starting to resume fundraising – working on our new investor deck, and getting introductions to angel investors.

On to the details.

In our last update, we were making progress casting the guitar body front. When we started on this part, we were most concerned about whether the detailed features on the inside of the guitar body – the ribs that provide structural integrity, hold the circuit boards, and the screw bosses that hold the speaker box and strings assembly in place – would form properly. However, these features formed well, almost from the beginning.

What was more difficult than expected was having persistent voids on cosmetic surfaces, particularly around guitar bridge, which is curved.

In between each attempt, we made modifications to the mold, cutting additional channels for the resin to flow:

We were also bedeviled by the mold leaking polyurethane resin out of the sides of the mold during the injection process, resulting in a number of attempts with insufficient resin to fully form the part:

To fix this, we modified the end plates by sawing out notches so we could wrap additional elastic bands around the end plates to keep sufficient pressure evenly across the two mold halves to prevent leaking:

Something else we discovered, to our surprise, was that using vacuum to evacuate air bubbles out of the resin was causing issues. Vacuum is supposed to pull bubbles out, but in a large mold with a large volume of resin, and in a large pressure pot with a lot of air, the vacuum pumps we were using weren’t strong enough to quickly evacuate all the air. As a result, they were just agitating/boiling the resin while it was hardening, causing more air bubbles to be captured in the part – the exact opposite result to we wanted:

Once we stopped using vacuum and cast using just gravity, by tipping the mold to enable the air bubbles trapped within the fine cavities to roll out, the quality of the parts increased significantly to the point.

Finally, on attempts 7 and 8, we were able to obtain repeatable, high-quality parts that were acceptable for manufacturing. Here is shot #8:

While there are still a few tiny surface imperfections, the part is fully formed, and smooth to the touch. (And once we paint the part, we shouldn’t have any issues with the finish.) 

We’re happy to be able to cast this part without using vacuum, and even happier that we didn’t have to procure and use a large pressure chamber. This means that our ability to scale up manufacturing of the largest, most complex part will be far easier and less capital intensive. (The pressure pot would have been the bottleneck, and our ability to scale up would be constrained by how many expensive, massive, 25-gallon pressure chambers we could procure and operate simultaneously.)

Now that we made the guitar body front, we needed to test that the speaker box and string assembly would fit. Fortunately, it nested in perfectly:

The guitar body front being successfully manufactured, we next turned our attention to molding to the final large, complex part: the guitar body back. We successfully created the first half of the mold:




We went to buy more silicone to make the second half of the mold… and UH OH, our preferred silicone was out of stock - and unavailable from any of our usual distributors! Apparently, the silicone manufacturer had been purchased by another company and the silicone was likely discontinued! This forced us to scramble around to find an alternate supplier with a silicone with similar properties as our preferred silicone. It took us a couple of weeks to source, procure and test different types of new silicone to ensure they had similar properties to our previous silicone. Fortunately, we were able to find a good replacement silicone, and then we were then able to complete the mold for the guitar body back.

Note that the bottom half of the mold and the top half of the mold are different colors – the result of having to switch suppliers and silicones:

And once we demold the master part... the mold looks good!

As a result of all the time and effort we put into making the guitar body front, we learned some lessons that we were able applied to the guitar body back. We didn’t try casting under vacuum, we went just used gravity. We used the same pressure plates that we had made for the guitar body front.

Fortunately, the leakage of resin from the mold was trivial:

And now the moment of truth…

Checking out the detailed internal features of the guitar body back:

OK, that looks really good for a first shot! Here are some other photos of the part, compared to the master part (in black):


And yes, the speaker box and string assembly fits nicely on the guitar body back:

And YES, the guitar body back and the guitar body front fit together nicely, with the speaker box / string assembly sandwiched perfectly in between! SWEET!

(Note the parts haven't been screwed together, as they would with a finished product, so there is a slight gap where the back and front come together in these photos.)

However, we still have some work to do on the guitar body back. Specifically, the battery bay has thin “fins” into which the battery spring terminals slide.

These fins didn’t form fully, and two of the silicone fins ripped when we demolded the guitar back. As a result, we have some re-engineering required on the battery bay and the mold to solve this issue.

In the meantime, we’ve made the molds for all the remaining plastic parts of the guitar by claying up the master parts and building the silicone-pouring mold boxes.

The guitar neck front and back:


The 90 buttons on the fretboard:

The knobs, and various other internal parts:

Light pipes for the LEDs in the guitar neck:

Rubber parts that secure and dampen the guitar strings:

The battery bay door:

And then we poured silicone to make the molds: 

We’re demolding early next week, and should be able to start casting the remaining plastic and rubber parts of the guitar over the next few weeks.

The other mechanical parts of the guitar the metal parts: guitar strings, speaker grille, guitar strap button reinforcements, neck button reinforcement, input port reinforcement and battery spring terminals.

Here is a photo of the guitar strings, over the metal speaker grille (mounted on an earlier design of the speaker box/string assembly):

The guitar strap button reinforcement:

The guitar strap button reinforcement and the neck button reinforcement:

The input ports reinforcement:

We tried sourcing the metal parts from local metal fabrication shops in Southern California, but the quotes we received were exorbitant for small runs. We’re now exploring sourcing them offshore, and we’re awaiting quotes from several different metal fabricators, and are hoping they’ll be a lot more reasonable. More on this in future updates.

Now that we have a clear path forward on the mechanical parts – especially on the large plastic parts – the electronics and firmware now represent the biggest hurdle for us to overcome to start shipping guitars. While we’re pretty close on both electronics and firmware, we still have a ways to go to cross the finish line.

We need to do a circuit board revision for the strings board (the PCB that processes and filters signals from the piezoelectric transducers that record the string actuations when you pluck or strum one or more strings). The challenge we’ve been facing is that the piezoelectric transducers are hyper-sensitive, so when you pluck a single string, all 6 strings fire. We’ve determined that by adding a simple resistor-capacitor circuit (also known as a “low-pass filter”) to each string, we should be able to filter out a bunch of the false-positive string actuations. We need to rev the firmware for this.

The second major task on the firmware is to finish porting the existing firmware from the current Arduino microprocessor over to the STM32 ARM microprocessor (MCU) on the main PCB. We’ve done most of the work to “bring up” the new MCU, but still have a bit of work to finish before we start porting the firmware.

Finally, we need to add a couple of minor new features to the firmware: adding support for the LEDs on the neck, and adding a third encoder (that switches the guitar’s mode between “Magic” and “Traditional”). More on this also in future updates.

Once we have all the parts – mechanical and electronic – we’ll have to figure out how to assemble the guitars in an efficient manner. We’ll also have to test and configure each guitar, flash the firmware on, and calibrate the piezos in the strings.

We’ve been relentlessly focused on approaching manufacturing in a capital-efficient manner. We know that some of you would rather we go to a high-volume factory and have them do most of the heavy lifting and move faster. Of course, if we had the capital to afford that right now, that would certainly make our lives easier, and make the process go faster. The silver lining for us is that we’ve found less capital-intensive ways of manufacturing, which makes our business more sustainable. And when we’re ready to scale up, we can always move our production over to a contract manufacturer (onshore or offshore) with a higher throughput, particularly with injection molding the plastics.

Regarding schedule, it looks like we should be able to start manufacturing all the plastic and rubber parts starting in June. We’re hoping to receive some samples of the metal parts in June as well. The firmware work will be ongoing over the next few months, as will ordering and receiving the circuit boards. So, if all continues to go well, it currently looks like we should be able to start shipping initial units either towards the end of Summer or early Fall.

Lastly, we’ve finally started to fundraise again. We had taken a hiatus from fundraising to focus on manufacturing. Now that we’ve validated urethane casting as a viable manufacturing technique to produce high-quality plastic parts, and have more visibility into unit economics and our ability to scale up production, we’re now going back on the road to raise capital from angel investors. We’ve revised our investor deck and are getting introductions to angel investors. If you are, or know of any angel investors who might be interested in investing, please have them email us at invest@magicinstruments.com.

(Disclaimer: This is not an offer to sell or a solicitation of any offer to buy any securities. Offers are made only by prospectus or other offering materials. To obtain further information, you must complete our investor questionnaire and meet the suitability standards required by law.)

As always, thanks for your continued support!



March 2018 Update - Making the Guitar Body Front

Hi everyone,

I hope you had a good month! It’s been a long and hard month for us (with a couple of illnesses on the team, but nothing serious). But we’ve made some  progress and are excited to share the news with you.

After we successfully cast the most complex part of the guitar last month - the string assembly and speaker box - we’ve turned our focus to molding and casting the guitar body.

The guitar body is composed of two large pieces - the front and the back. (We’ll refer to these as “front body” and “back body” for brevity sake.)
The front body is the larger part of the two body pieces, as it also contains the side walls of the guitar. It is the single largest part of the guitar, in terms of both size and weight - and it’s a challenging part to mold and cast.

The front body serves three crucial purposes. First, it’s the front of the guitar, so it’s the first thing you see and notice. It needs to look good, which means it can’t have any significant deformations on the surface. (We plan on painting the part, so surface finish and color consistency aren’t deal-breakers right now.) Second, it provides the mounting and enclosure for the string assembly and speaker box, the main electronic circuit board (the brains) of the guitar, and the various control knobs and input ports. Third, it needs to be sturdy enough to survive various knocks and bumps and everyday wear and tear that come with regular playing and transport.

As with the string assembly and speaker box, we fully expect to go through a number of iterations, where we cast a part, review and analyze the imperfections, and modify either the mold, or the casting technique, to hopefully overcome the remaining issues until we’ve achieved our target quality level for the part.

We begin with taking the “master" part - the black front body from our last prototype, and embedding it in clay, to make the first half of the mold. We’re going to mold the more difficult internal-facing side first, so the guitar exterior begins face-down in the clay. In the photo below, you are looking at the guitar interior.

The detailed pattern of ribs serves to hold the electronic circuit boards and provide structural strength against flexing. The four holes (in the bottom right corner of the part) are where the posts of the guitar controls (volume, instrument sound, etc.) protrude through, and are capped by knobs on the outside of the guitar. The large rectangular empty space in the middle is where the string assembly and speaker box will be mounted.

We’ve built a cardboard box around the clay that will enclose the liquid silicone and enable it to cure (harden).

Next, we mix the two parts of the silicone (the silicone and the catalyst) and start pouring the liquid silicone into the box:


We then put the silicone under vacuum to draw out any trapped or suspended air bubbles. We let the silicone cure for around 48 hours, remove the cardboard box, and turn it upside down to extract the front body from the clay:

We then rebuilt the box and poured liquid silicone on top of the front face to form the top half of the mold:


After degassing the mold in the vacuum chamber and waiting another 48 hours for the second half of the mold to cure, we got our chance to see whether the mold had formed properly. We separated the two halves of the mold:


And a big sigh of relief, the mold formed well. The front face of the guitar front body looks smooth, with no air bubbles or voids in the silicone:

Here it is again, along with the master part:

We demolded the master part to examine the bottom half of the mold:


and… voila, the bottom half of the mold also looks good!


All the ribs and screw bosses looked to have formed nicely.

Here is another look at both halves of the front body mold:

OK, let’s try to cast some guitar bodies!

First, we had to create end plates for the mold so we could keep the two halves pressed together, to avoid any bulging from the polyurethane resin as it is injected into the mold:



We mixed up the polyurethane resin and the catalyst:

We injected the polyurethane into the mold and put it under vacuum to evacuate the air bubbles:


We waited for the resin to cure, and we opened the mold:


And then we demolded the part fully:


And the first thing we did was turn the part over to check whether the internal features had formed properly:

All the structural ribs and screw bosses formed properly and accurately. There were a couple of tiny voids, nothing that we are concerned about.

However, some of the curves of the body didn’t fill in properly, especially around the bridge. The mute bar also had a major missing void.

You can see the unfilled areas when we hold the part up in the sunlight: 

Over the next few days, we modified the mold by cutting small channels to enable the polyurethane to flow more easily to the affected areas.



And we tried casting the part again:

The second attempt at the part was a definite improvement over the first attempt. Although some voids are still present, they are much smaller:

The interior looks pretty good:

But, still not at the level of quality that we’d like for this part.

So, back to improving the mold and casting the part a third time:


The voids around the bridge and mute bar are yet even smaller:

So this is where we are currently. I think one or two more attempts at modifying the mold and casting this part should get us to the right quality level.

If that doesn’t work, we always have the option of putting this mold into a pressure pot to pressurize all the trapped air bubbles away, although that would require a capital investment of around $20,000 in a large pressure vessel and an industrial air compressor. We’re trying our best to not have to incur that expense.

After the front body comes the back body, then the neck (front and back). (All the remaining parts after these are small and nowhere as challenging as the guitar body.)

Overall, we’re continuing to make steady progress. We wish we were going faster, of course, but with limited resources we’re doing our best.

Regarding schedule, we’re still on track for initial shipments this summer, although it’s looking increasingly like late summer. We’re continuing our efforts to raise funding, and if we’re successful, we’ll be able to accelerate with additional resources. (We’re currently applying to a couple of programs that provide funding to hardware startups manufacturing in Southern California. We’ll let you know if we have good news on that front.)

Thanks again for your continued patience and support! As always, we welcome your comments, questions, concerns and criticism.

Best wishes to everyone for a good Easter, Passover and Spring!

- Brian

February 2018 Update - Manufacturing the String Assembly / Speaker Box

Hi everyone,

The past few weeks we’ve been working on a number of different fronts for manufacturing the various components of the guitar: the plastics, the metal parts (including the strings, and parts to reinforce where the guitar strap buttons and input ports), light pipes, rubber parts, electronics.

This update will focus on our efforts to use urethane casting as a manufacturing technique for making high-quality plastic parts for the guitar. This update will also feature a LOT of photos.

First, we’ve been working to make the single most complex / difficult / high-risk part of the guitar - the string assembly / speaker box. This part performs two critical functions: 1) it holds the six strings for strumming, and 2) it holds the speaker in an air-tight cavity, which maximizes the speaker’s projection and volume. This part has numerous intricate features with thin walls, which increases the likelihood of trapped air pockets in the silicone mold, leading to voids in the part once it’s cast with polyurethane resin, cured, and de-molded from the silicone mold.

First, we made a two-part silicone mold from the master part. This involved putting the part in clay, and then pouring silicone to make half of the mold:

We mixed up some liquid silicone (to make the silicone mold):


We poured the mixed silicone into the mold box:

After the part was fully covered by the liquid silicone, we put the entire box in a vacuum chamber (a stainless steel vessel with a lid) to pull out any trapped air bubbles in the silicone.

We let the silicone cure, and removed the mold from the box:

We then removed the master part from the mold, and now have a high-quality silicone mold of the part:

Now that the mold was complete, it was time to cast the part.

We placed the two halves of the mold together, and secured them using flat plates:

We mixed liquid polyurethane resin with a catalyst:

Once this mixture was complete, we injected the liquid polyurethane resin into the mold, until it overflowed, so we knew all the cavities in the mold were filled with resin:


We let the polyurethane cure, and then we pulled the mold halves apart to examine our first casting.

 This first casting had a couple of major problems. First, the mold had bulged slightly open from the pressure of the injected liquid. This made parts of the string assembly too thick. Of particular concern was that the fins that hold the piezos for each string had all filled into to become one undifferentiated part:

On the bottom side of the part, a number of the screw bosses did not fill in properly, as air bubbles in the mold were not fully displaced by the liquid polyurethane:

To address these problems, we found thicker flat plates to bookend the mold halves, which should help keep the mold clamped together. We also made additional modifications to the mold by cutting little channels between the fins to ensure that the polyurethane would flow between them. We then attempted our second casting a week later:

 This time, the part was significantly improved. The mold halves had stayed together due to the thicker flat plates, so the part didn’t become too thick, and the fins for the strings were properly differentiated. 

Comparing the two parts side by side - the left part is the first casting, the right part is the second casting - you can see the spaces between the tabs that hold the strings:


 Also, the screw bosses on the back side are now all formed properly:

However, there was still one key section that still didn’t fully form properly - the part the holds the rubber parts that helps dampen the vibrations of the guitar strings and gives them a nice feel when strumming. This section had some voids due to trapped air bubbles:

To address these remaining issues, we made some additional modifications to the mold:

A week later, we tried another casting, and the problematic section is now properly formed.

Here is a photo of the three generations of parts side by side. (The part on the left is the first casting, the part in the middle is the second casting, and the part on the right is the third casting):

Given how well this third casting came out - we’re now confident that it’s possible for us to manufacture the most difficult and complex parts of the guitar using urethane casting. This third attempt at casting the string assembly and speaker box has yielded a high-quality part - one that can be used in a production unit.

Over the next few weeks, we’ll be making molds and casting the largest parts of the guitar - the guitar body front and back, and the neck front and back.

So what does this mean in terms of when we’ll manufacture and ship your guitar? At the moment, we're still thinking we’ll be able to start shipping units in Summer 2018.

Many of you have been asking for a more specific timeline one when we’ll fulfill your orders and when you’ll receive your guitars. Before we can answer that question with a greater degree of certainty, we still need to figure out how to best scale up production - how many production lines / sets of molds we can have working in parallel, how big of a facility we’ll have to rent, how many workers we’ll have to hire and train to cast the parts. And that also partly depends on how much capital we can raise over the next few months.

More on this in future updates.

Thanks to everyone for your continued support. As always, please let us know if you have any questions, concerns or comments.

Brian Fan
CEO, Magic Instruments