I've had to put the build on hold... I had an accident and cut the extensor tendon of my right middle finger. It will probably be a few weeks until I am able to continue with wiring the heaters, etc... :-(

After drilling the holes I installed the sockets. I decided to use Belton top mounting sockets instead of ceramic but probably not for a good reason... I was thinking of getting a set of hole punches because it had a 3/4" punch. Then I realized it was a punch of a 3/4" pipe and did NOT make a 3/4" hole. Instead I bought a set of step drill bits. 

I used #4 bolts with kep nuts to mount the sockets. I was originally going to rivets to mount them but the shield base on sockets did not allow me to seat the rivet securely.

Then I installed the standoff terminals in the chassis. I used the T91 standoff from Surplus Sales of Nebraska. You can save some money by using the Diallyl Phthalate (DAP) products. The standoffs will be used for a couple of things. One pair will be used for a ground bus, another pair will be used as a convenient way to connect grid-stopper resistors to the sockets and another is to support the ground bus behind the input jack and potentiometers.

Cutting a square hole sucks. I am using a IEC socket for my power cord instead of a fixed cord so I needed to cut a rectangular hole. I've seen people use jig saws for this but since the back of the chassis is only 2.5 inches I didn't have good support for my saw. Here's what I did instead... I started by outlining my hole on masking tape with a marker. Then I drilled holes close to the lines. Then I used a file to square things up. After examining the hole, I realized I still had a ways to go. The masking tape and the file didn't work very well together so I put the backplate in place and used the centering punch to scratch the outline into the chassis. Then I broke out the Dremel tool (no pictures). To be honest, this didn't work very well, but it got me pretty close to what I wanted (no pictures). Finally, I broke out the file again and cleaned things up. The chassis is a little scratched up but that will be hidden behind the plate.

Product idea... someone needs to make a IEC jack that fits into a round hole. If you know where I can buy one let me know. Also, if you know of a better way to cut rectangular holes, please leave a comment.

I don't have a lot of experience with metal work. Most of my past projects have either come with pre-drilled chassis or I have used a service like Front Panel Express. That or I just didn't care what the chassis looked like and drilled holes where ever without any concern for cosmetics. However, I want this amp to look professional so I'm being careful about things.

I printed my face plate on paper (I'll create a separate entry about making that later). I tried using an automatic centering punch that you press to strike, but it didn't make a clear enough mark for me. It would probably do fine in wood but it didn't work very well in aluminum.

I bought a hardened steel punch from home depot. I like it because the point is easy for me to see and get in the correct position. I've used others that are more shallow and I have ended up missing the center of my guide lines. I then used a 3 pound sledge hammer make the indentation in the chassis. Really, you just need to let the hammer drop - there's no need to wind up.

After marking where to drill I removed the face plate print out and wrote the size of the holes using a black marker. The next step was to drill 1/8" pilot holes. This allowed me to come back with a step-drill bit to make the larger holes. My step bits are not labeled so I had to use my calipers to determine which step was which. Next I used some pin-striping tape to keep me from drilling too far by accident.

The holes came out pretty clean. There were some sharp edges on the back side that I was able to clean up using a file. If I had a deburring tool, that would have been even better but the file worked fine.

Not much to say. Start at one end and work your way down. Take your time and follow the layout. Check things twice... I messed up and installed the 1.5K resistors instead of 1M resistors in a few places. I should have paid closer attention to the stripes and values.

I want to go back and add some solder to the top of the turrets so they look pretty, but all of the joints seem to be pretty solid so its not really necessary.