Henry Scott Yocum Memorial Amplifier Build

[SilverSport]

gorgeous work!

 

Bill

[thebes]

A fitting tribute and a very kind sharing of your skills and designs.  Thank you.

[jorjen]

On 7/26/2018 at 3:36 AM, wdecho said:

Being a woodworker I can really appreciate that wood and quality of build. Great job Matt. I should say woodworker at heart, more heart than woodworker now. 

Ditto!

[ToolShedAmps]

Howdy all, my next step in building an amplifier is cutting all of the 1/8" (3mm) 6061 Aluminum plates and milling/drilling them. DISCLAIMER: for you DIYers out there, I do not advocate that this be done at home by those of limited skill or unfamiliarity with the tools I use. I take NO responsibility for any mishaps that may occur. This is highly dangerous, please consider risk vs. reward before attempting to replicate ANY of my processes. This works for me, YMMV.

 

I develop all of my layouts on 11" X 17" graph paper for all of the amplifiers I build. This helps visualize the amplifier and gives me a blueprint to work from. I use a Diablo "non-ferrous" blade mounted in my table saw to perform all of the cuts. I proceed slowly and clear the aluminum chips from the top of the saw after every single cut. Additionally, there is normally a burr created on the edge of the cut that must be sanded off prior to each subsequent cut to allow the plate to sit flat for the next cut. This process takes quite a bit of time so plan accordingly. Eye protection is MANDATORY, I wear safety glasses AND a full-face shield. Wear long-sleeved shirts, hot aluminum chips can and will burn you.

[ToolShedAmps]

Here are all of the plates necessary to build Scott's amp. The top and bottom plates are cut oversize by 1/8" to allow precise fitting to the wood base (you'll see how this is done later). I use 100 grit loop-back sandpaper discs mounted in my trusty DeWalt random-orbit sander for all of the initial sanding (including the deburring of the plates between cuts).

 

 

[Guest wdecho]

All my tube builds started with a Bud Industries aluminum box, a step up from what I use to use a cake pan. 

[ToolShedAmps]

I physically layout all of the dimensions and drilling locations from my "blueprint" to the plates with a mechanical pencil, clear 18" ruler and machinists square. After the layout is complete for each plate, I use a spring-loaded marking tool to create a dimple at each drill point for the bit to start from. This is very important as it prevents the bit from "walking" off the desired drilling location. Using one of my two drill-presses, I mill each hole accordingly (note: DO NOT USE ANY CUTTING FLUID AS IT WILL DISALLOW THE "RESIST" FROM ADHERING TO THE PLATES FOR THE ETCHING PROCESS). Go slowly, wear hearing protection. I use titanium nitride coated twist drills, step-bits, and hole-saws to mill the aluminum. Chamfered counter-sinks are done using carbide end-mills mounted in the drill press.

[thenewold]

Dig it! Thanks Matt for sharing the process. 

 

For those who haven't heard Matt's amps - I recommend getting your ears on one. 

 

[ToolShedAmps]

This is the tool of choice for cutting any hole that isn't round. I've found that Olson 15 TPI blades work best, and at very low speed (strokes per minute)..... this takes forever, but no other method I've tried works as well. Note: It is far easier to cut aluminum "on-the-flat" with a scroll saw than it is to cut a curve. In the photo you can see that I have drilled a 3/16" hole in each corner of the IEC connector cut-out to allow for only flat cuts. Final clean-up of the square cuts are done with files.

[ToolShedAmps]

Completed cut-out....

[ToolShedAmps]

Then the back of each plate is sanded again with 100 grit to remove any burrs from the holes followed by sanding the face with 150 grit using the random orbit sander to prepare the surface for the application of the "resist" for the etching phase of the process. Here is what the plate looks like after sanding. Make sure you remove ALL of the layout marks with the sander as they will act as a resist and you'll have extra lines in the etch....

[Coytee]

First I've seen & heard of this thread (and reason for it)

 

Nice job and all those accolades....but really.....  how heartwarming!

 

Kudos to you.

 

 

[ToolShedAmps]

Howdy All!

 

Whew! Lots O' plates milled and prepped for etching. Additionally, you'll notice an additional plate to the left of the original 14, this is a choke bracket I fabricated to mount the selected Transcendar choke on the inside of the chassis. The original end-bells on the choke had their little mounting feet oriented such that the choke would have to be mounted vertically, thus not fitting within the Euphoria chassis. The mounting bracket I fabricated started life as 1/8" thick 4" X 2" extruded rectangular 6063 aluminum. By making a cut @ 1 7/8" on the 2" flat, then flipping the piece and making the cut again you are left with two 90 degree "L" brackets @ 4" X 1 3/4".  Size them as you wish for different sized applications. 

[ToolShedAmps]

OK, so a bit back in this thread I stated that I cut the top-plate and bottom-plate 1/8" oversize and would explain why and how I size it to fit the wood base. The why: as accurate as I like to think I (and my tools) are...... the bases are actually more of a rhombus than an exact rectangle. My goal is to have the tightest finger joints possible, sometimes during glue-up the base gets slightly "out-of-square". No worries. This is the reason for the 1/8" additional material on the plates. The how: AFTER all of the milling (aside from the countersinks around the periphery) I match the plate up to the base and use a sharpie and straightedge to mark where the plate needs to be shaved. My tool of choice for doing this "shaving" is my trusty 1" belt sander. It allows me to draw the edge of the plate across the platen varying speed and pressure to trim just the marked area. This makes for a very nice fit. 

[ToolShedAmps]

I've been asked many times how I create the etched info/artwork on the plates of my amplifiers. I'll try to explain the process as best I can, those of you who wish to try to replicate the process can PM me for additional info. I'll try to keep this build-thread going without bogging it down with too much "white-paper" type drudgery. There's enough of that elsewhere.

 

In a nutshell, I create all of my images in Adobe Illustrator and Adobe Photoshop. I generate the same "layout" in digital format within Illustrator to match the physical plates and the graph paper layout. This then allows me to create the text/artwork EXACTLY as it will appear on the plates when etched. I size the circles slightly smaller than the actual holes (tube sockets) to use them as registration indicators when ironing the photo paper onto the milled plates. Yep, you read that right, I print the Illustrator file (inverted of course) onto photo paper using a laser printer. This is then IRONED onto the plate using a very hot iron. This creates a "ghost image" (ie., not good enough to act as a resist itself), you need to then put on your "artist" hat (if you have one) and dig out the little bottles of Testors gloss black enamel paint and some pretty fine brushes so that you can paint over the ghost image. I normally heat-set the plates in a household convection oven @ 180 degrees for 2 hrs. Here is a pic of Scott's plates after they've come out of the oven. In the next installment I'll go over the actual etching process/chemicals/precautions, etc. Cheers! Matt. 

[ToolShedAmps]

[ToolShedAmps]

Just a glimpse of the computer screen showing Scott's top-plate.

[ssh]

Beautiful, Matt! This is exactly what Austin described to me. I don't think it could be more perfect or fitting.

SSH

[ToolShedAmps]

On 8/21/2018 at 12:19 PM, ssh said:

Beautiful, Matt! This is exactly what Austin described to me. I don't think it could be more perfect or fitting.

SSH

Thanks Steve!  FYI, I've decided to upgrade the amp from the standard N.O.S. Amphenol tube sockets to the new CMC Bakelite sockets so that the family can't possibly insert the power tubes the wrong way. This makes it just a little more user friendly.

 

Cheers! Matt.

Edited August 22, 2018 by ToolShedAmps
Wrong name.... Doh!

[Guest wdecho]

I am enjoying this thread very much. I have learned a few things watching your methods and tools used. You have inspired me to do a better looking case for my new SET project. Below is a work in progress. Drilling holes, sanding, and finish is still left to do. Naturally mine is an amateurs job and not professionally looking like yours.  Keep the info coming for us amateur builders.