Iris Guitar Amp




Introduction: Iris Guitar Amp

I'm in a guitar builders guild - Guys Building Guitars - every year we display at the Dallas Guitar Show. I wanted to build a traffic stopping - never before seen [by me at least] combo guitar amp. After mashing about with fellow builders and a few nutcases I saw a picture of a human iris. That was perfect! The trick was getting the structure - the ridges and lines - oriented correctly and the correct colors close enough to be convincing.

The real challenge - I wanted the structure to be wood grain.

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Step 1: Find the Wood...

I am a curly maple fan - full disclaimer I'm a figured wood fanatic - and thought the maple would be up to the task. I live in Dallas - not exactly the figured wood capital of the US. By the time beautiful wood gets here it has been through a number of hands all looking for the same thing - wow wood. I spent a couple of weeks hitting every wood source in the area with no joy. Over the last few years I started to collect figured wood like some people collect stray dogs buying what caught my eye whether I had a project in mind or not.

One tip for 'seeing' the figure on raw wood - wet a section with water.

A new Rocklers opened a few miles from my home and I added them to the weekly wood sweepstakes. They had some curly maple and I went though the entire stack [always a good idea] and found this 12" x 120" piece at the back. One thing handy about Rocklers [and many of the 'crafter' wood stores] is most of their wood planks are 3/4" thick so you don't have run them through a planer or drum sander for your project. If you need thinner stock the drum sander and planer companies will be happy to help you. Another option some of the specialized wood sellers have a full shop and they can plane, rip, crosscut and resaw [bandsaw] for you for a lot less money than buying equipment.

One helpful tip that makes cutting wood faster, more consistent and safer is to cut long planks into more manageable pieces. I cut the 120" long plank in half.

Step 2: Cutting the Iris

While I did ace calculus in college back when no internet existed and dinosaurs ate the slow and unwary, my math skills deteriorated much like my hair and midsection. I have access to AutoCAD which informed me I needed each piece to have a total angle of 12° and a base width [small end] of 1.16". This would yield 30 [yup THIRTY] pieces with a hole of 10.5" in the center of the array. Why so many pieces you wonder as you ponder my sanity and safe distances from me? To keep the curly figure of the plank aligned to the center like sun rays. The small end width was important as a 12" speaker [11.1" hole in the wood baffle holding it in place] would be the pupil.

I had to recreate the jig to get some pics to illustrate the process. The first is the jig, the second pic is the initial cut to get the 6° first cut. Then the plank was turned over and moved until the edge of the cut aligned with the line furthest from the saw blade.

Another important tip when maximizing the beauty of figured wood - NUMBER THE PIECES AS THEY ARE CUT! This simple step will save you mucho time NOT playing 'Let's make a match' with your cut pieces.

Step 3: Test Fit

Since I'm working with wood - which the more figure the piece has the more 'squirmy' [warp, cup, twist] when it is cut - I eyeballed the cut width instead of trying for 'perfection'. I knew the last piece would need to be fitted i.e. cut down.

BTW - the true definition of the Art of Woodworking is artfully fixing the inevitable mistakes that WILL happen. I look for wood that has detects - cracks, knots or fissures - as these natural defects appeal to me. This coupled with my impulsive full speed ahead! building style affords me lots of time and creativity to apply the art. I was informed on another project of the Japanese art of Wabi Sabi where a deliberate defect is introduced in an otherwise perfect creation. Theirs is planned, mine usually starts with oops!

Step 4: Glue Up

Now on to the fun - gluing up angled pieces. First let me start by saying you can never have enough clamps! As you can see from the pics many things can be used to aid in clamping. I've used a crescent wrench to align a squirmy trim piece's front edge while keeping the back edge clamped in place.

I glued up pairs, then pairs of pairs then... you get the idea. The final four sections of 30 pieces required wood blocks to be screwed to the back to act as clamp fixtures. Also several 'bow' clamps were used to hold the inner sections flat.

Step 5: Success

Here the glued up iris is in all its glory. Too bad most of it will be cut away.

Step 6: Cutting to Fit

Now for the really nervous part - cutting to fit the existing combo cab. I built a fixture to hold the iris still whilst making the first table saw cut. That was easy. The remaining cuts needed to be square - this is where a great saw sled comes in handy. Forget using your fence as you can clamp the wood in the sled or put in a stop block for repeatable cuts. Plus, with a bit hand / saw blade awareness the sled can help you keep those valuable digits away from mortal peril. The other beauty of the sled is you can 'nibble' your way using the saw cut on the sled floor as a reference to a good fit as you are moving the wood and not the fixtures.

Step 7: It Fits!

With a few nibble cuts and some strokes of 80 grit sand paper in a block it fit. One thing to note - if you plan to make the piece removable it is best to have a smidge of play in between the bits. Wood expands and contracts with humidity and can cause much unhappiness. I used a few thousandths [a human hair is .005" to .007"] of gap and planned to secure the piece to the speaker baffle with a few screws from the back.

Step 8: Color Time

One thing that struck me about blue eyes is how much orange is present. Also the depth of the structure and hues of blues, oranges and yellows. I wanted to minimize the air brushing as much as possible and only used it for the jagged edges on the pupil side and some white highlights. I needed to have at least three colors present on the wood itself - light blue, orange and some yellow - I'll explain in the next step. The others - dark blue, white and black would be airbrushed on top of the dyed wood.

Several things I have learned over the years coloring wood is stains tend to have a more subtle coloration as they contain oils [or water] and have a lower ratio of color to carrier. I have found water based dye to be superior as the ratio of color is much higher. I used General Finishes's orange & yellow and have fallen in love with Rit fabric dyes - as they have many more hues to work with. Yes you can mix to try to achieve the color you want. I find it easier - as the opportunistic cockroach I am [some call me lazy] to find the closest hue on the shelf and make it work. Rit's Aquamarine was the base color for the blue.

Step 9: Bias Relief Structure

If you've ever tried to use multiple colors of dye you probably noticed they don't play well with others - no boundary or design respect with bleeding and running helter skelter everywhere. This presents several challenges -

  • The iris needed to have at least three colors on the wood itself.
  • Wood tends to be brownish and doesn't play well with colors like blue, green or purple. Yellows and oranges and some reds work OK.
  • I wanted some depth or 3D that would be consistent from any angle.
  • I need the orange and yellow to stay where I want them and [very important] not be overrun by the blue.

The solution was to carve structure into the wood - generally where the curly figure was boring or not present, bleach the wood with a two part solution - caustic lye and 10% hydrogen peroxide. The lye is strong enough that if you get some on your skin you WILL know it very soon - so gloves and eye protection. I used a Dremel tool with a variety of bits to carve the valleys & such into the wood, then bleached. I started the yellow mostly on the edges and then applied the orange to the remainder. I didn't worry about neatness on the outer edges as the iris would get sanded.

Step 10: Seal the Structure Colors

I am a big fan of two part 5 minute epoxy and CA [super glue] as wood filler / fixers. To seal the structure I used epoxy to fill the carved structure 'flat' to the surface. Then with an orbital sander and 80 / 150 / 220 grit disks sand the surface smooth again. Bleach again. Use 400 grit to 'knock' the raised wood grain off. Whip out the Rit dye and with a piece of lint free [squares of tee shirts for me] SCRUB the dye into the wood. Blend it as you go for a homogeneous color.

Step 11: Blue

Here it is with just the blue rubbed in. Wood grain looks OK.

Step 12: The Beauty of Two Part Automotive Clear

The iris has had three coats of clear slopped on with a brush. Then wet sanded with 400 grit - leave the edges alone as they will 'take care' of themselves. Otherwise you will sand through the finish and have naughty words floating about - don't ask me how I know this.

Step 13: Airbrush Pupil Area

The pupil is black and is very jagged in its transition to the iris surface. Black airbrush paint and a spray jig to mimic the jags.

Step 14: White Highlights

More airbrush paint and a three part stencil. I also blurred in some translucent orange. I then 0000 steel wooled much of the paint back to blend it in.

Step 15: Supernova on Acid

As I started putting color on the iris I began to think it looked more like a supernova on acid than an iris. At this point I am three weeks into the project and am still in the I'm not sure this is going to work, holy crap!?! phase. I post all of my builds on two guitar sites - the Marshall Forum and The Gear Page for feedback. I posted the latest pics with the on acid comment and my Wabi Sabi buddy said I needed to have a bit of white on the corners to aid in recognition. I argued that the scale would be wrong and he adroitly countered with - ITS ART!

Step 16: He Was Right...

I added white to a couple of corners and then quickly had a few more coats clear sprayed on. Mostly as the project was done but primarily so I would leave it alone and stop trying to fix it by doing the just a little more... My Wabi Sabi buddy commented for the realistic effect the white needed a pink tint to simulate blood flow. I responded IT'S ART!

Step 17: Off to the Guitar Show 2017

The iris did what I wanted - attract attention to our booth. It was fun watching people walk by in the gotta keep moving so I can see EVERYTHING! guitar show strut pace a few steps past then stop and turn to look.

Step 18: Further Insanity and Musings

This is a 1x12 combo guitar amp - meaning the amplifier and one speaker are in the same case. Previews for the new Mummy movie came out around this time and when I saw Sofia Boutella's iris do the cellular mitosis splitting into two iris's I thought Now I gotta build a 2x12! Luckily sanity returned and I didn't.

One of the fun - really, honest, most of it was fun - things about this project was plowing ahead not knowing if it would turn out. I tend to be a get an idea and start building whilst I figure it out on the way. This approach helps me figure the design out, reveal options I didn't know I had and force artful fixes of mistakes sometimes leaning in an whole new direction.

I leave you with the best quote I have ever heard about woodworking which applies to any creative impulse. A friend on mine who taught himself how to build acoustic guitars from scratch replied to the question 'How did you learn to create such beautiful things?' His reply - 'Because I'm willing to screw this crap up on the way to the beauty.' [I cleaned up the language a bit]. His other quote 'Its wood, if you don't like it burn it and deny it ever existed!'


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    3 Discussions


    2 years ago

    Nice work.

    Although I have to say that I think it's a waste of such nice maple to paint it, especially given the trouble you went through to find it. That's just my opinion though!

    One tip if I may: next time you have to clamp things in a circle, you could try a modification on a frame clamp (see pics attached)


    2 years ago

    I tried this and all was going well. Then I got to

    Step 9: Bias Relief Structure

    Thats where It failed. It was a good try though!


    2 years ago

    Bravo sir, Bravo. That looks unique enough to win. Let us know how you come out.