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March 2018 Update - Making the Guitar Body Front

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

16 comments

Apr 01, 2018 • Posted by EDDIE DUDLEY

i been waiting patiently for over a year now, can not wait to get my hands on that great guitar!! i am sure that i am going to be very happy that i waited so long for it!!!i just hope that i will not be disappointed!!

Apr 01, 2018 • Posted by Joseph Lemons

So will I still possibly get my guitar by July?

Apr 01, 2018 • Posted by Cordell

I agree with Stacy’s post. This approach seems more like you are pursuing a hobby instead of a serious business. I’d like to understand why?

Apr 01, 2018 • Posted by Ralph

Wow
Progress awesome looking great
Keep up the updates and I’m sure
I will be receiving my preorder later
In the summer of 2018? I hope !!

Apr 01, 2018 • Posted by MAX PRASAD

Thanks for the update. I love your commitment and perseverance. Being an entrepreneur myself, I appreciate the hustle. I can wait longer if needed for your product. You need to wait longer for the best things in life! :)

Max

Mar 31, 2018 • Posted by Marvic Farrugia.

This is awesome and worth waiting. Please if you need more funds let us know. Maybe we can pay half for the guitar in order for you to finish early.

Mar 30, 2018 • Posted by Chris

Great update, well done, I expect by now the last snags are resolved by for this component. Its all looking great,
Chris

Mar 30, 2018 • Posted by William David Barnes

Nice update and it was great to be walked through all of the steps. I’m not the most patient person in the world but if I’m going to wait, updates like this at least make me feel a part of the process and that’s important to me. Peace, have a great Easter!

Mar 30, 2018 • Posted by Elizabeth mills

Hi guys,

What’s the ship date?

Mar 30, 2018 • Posted by Paul Marsland

Once again thank you for keeping us in the loop. I find your UPdates very informative and educational.
Hope you manage to secure some more funding over the next few months,
Have a chocolate egg on me,
Paul

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