Finishing the Chassis, Part 2

Pix here:

http://www.diycustomamps.com/images/...e/chassis_pt2/

The face plates arrived Monday night, a couple of days before they were expected. My first thought was that they looked great. BNP Lasers does a good job. My second thought was: damnit! I made the holes for the volume and tone pots a little too big. The Alpha pots I'm using are 5/16" diameter and I specified 3/8". Slightly too big. One function of the face plate is to center the components. The holes in the chassis can be a little bit bigger than the component and having a face plate fixes this. So I had to measure very carefully to get the holes for the two pots in the chassis concentric with the holes in the face plate.

Tuesday morning I spent about two hours finishing the chassis. First, I fitted the front face plate. It was just a matter of taping the face plate onto the front of the chassis, tracing the holes with a fine-point Sharpie, running a center line down the front of the chassis, measuring and marking the locations of the holes with a tape measure and locating the center with a square. One I got the hole locations marked I used a center punch to mark the hole and drilled a pilot hole with a 1/16" bit. Then I drilled out the hole to the correct diameter with a stepped bit. The volume and tone pot holes came out great. The pilot light hole had to be drilled out a bit bigger to get the pilot lamp assembly to sit in the face plate hole correctly.

Once I got the front face plate done, I moved onto the back face plate. The back face plate has a rectangular hole for the IEC inlet. This is the first time I've used one and it looks much neater than drilling a hole, using a grommet and knotting the cord inside the chassis. I made a template out of 3/4" MDF using the hole in the back face plate as a guide. I roughed out the hole using the template taped to the chassis with double-sided carpet tape. I removed most of the material in the hole with a drill bit and further cleaned it up with a jig saw. I then used my laminate trimmer with a top mounted bearing on a flush cutting bit to cut the hole to size. Finally I used a file to clean up the corners. The hole in the chassis is kind of rough, but that is okay as the IEC inlet and back face plate cover it up. It came out great for a first effort: centered and aligned.

The other two holes were drilled out in the sam manner as the front plate: marked, located with a center punch, and drilled out.

Next I finished drilling the holes in the chassis to mount the chassis mount capacitor can and the tube sockets. With these it is a matter of using the socket it self to locate the holes, marking them with a Sharpie, locating the center with a center punch, drilling a pilot hole, and drilling them to size with the correct size drill bit.

The last step was attaching all the components to the chassis: the transformers, the front and back components, the tube sockets and the cap can.

The next step will be to start wiring. First I will need to attach the leads to the output transformer as it has quick disconnect terminals instead of flying leads. Once this is done, I can install the eyelet board and begin wiring the circuit.

Stay tuned.

tung