Working the Angles

Hevvy metal siine!!!!
Here is another SketchUp render for you, showing the dimensions and pieces for the frame of the cabinet:
Shown above are multiple cuts of 1"x1" lumber glued and screwed into a structure. Here is the list, so there is no confusion:

• 28 1/2" x 5
  
• 26 1/2" x 3
  
• 13 1/4" x 1
• 13 1/2" x 3 (For crap's sake, cut these longer so you have room for your angle)
  
• 12 1/4" x 4
  
• 10" x 6 (You can replace one of these with a thicker piece for the middle if you want)
  
• 7 3/8" x 3

This particular diagram is from revision number 4 of the cabinet design. The completed frame is actually revision 5, as it encompasses some changes made on the work bench. The only obvious change is the 10" stud in the middle; you can see this in the pictures from my previous post. The diagram shows another 1"x1" in the middle, but I chose to mount a 1"x3" piece in a slightly lower position. The main reason for this is mainly overkill... I want to be damn sure that this thing will vibrate as one unit. I was told by a local musician that the old Marshall cabs had terrible vibration issues when they first came out, so a lot of people just ended up cracking them open and screwing a 2x4 inside to brace it. I wanted to be prepared, is all.

How did I get that angle, you say? By utilizing mathematics skills that I have not even thought about for at least five years!

tan(Ø) = (opposite side) / (adjacent side)
tan(Ø) = (13 1/4") / (2 5/8")
tan¨¹(tan(Ø)) = tan¨¹((13+(1/4)) / (2+(5/8)))
Ø = 78.794°

sin(Ø) = (opposite side) / (hypotenuse)
sin(78.794) = (13+(1/4)) / L
...
L = (13+(1/4)) / sin(78.794)
L = 13 1/2" (You can check that against the dimensions pic at the top of this post)

You know, when you're in High School you actually think that there could be no practical use for the crap they shove down your throat.

Okay so the angle is roughly 78.7°... but you don't actually cut an angle that wide while you're working with wood. The easiest thing to do is to offset that from 90°.

90° - 78.7° = 11.3°

So, cut your angled pieces at 11.3° with the front and the back of the pieces being 13 1/2" long. If those two sides don't match up, you should get someone else to cut your wood for you. Also, cut your very top long piece with that same angle. If you look closely at the pictures, you can tell that it isn't a square 1"x1" piece like the rest of them. It matches up nicely with the angled pieces.

I probably won't get around to cutting the birch ply until this weekend. It's going to take three people and very steady hands to cut it without screwing the whole thing up. I can predict that my next adventure will involve pictures of three dudes hovering a massive sheet of plywood over a table saw. You should stay tuned.

Full circlebox

Today I worked on the frame. Today was also the day that I learned the hard way how to measure your cuts.

In case you haven't noticed, I'm not a carpenter.

This is what I started with:
This is what I ended up having before I got tired:
Note the look of dissatisfaction on my face. This was about the time my Dad came down and reassured me that I was off to a good start, but reaffirmed my unwillingness to continue building from such a crooked mess of a frame. He also convinced me to stop using dowels, because it hasn't been 1920 for almost 90 years.

So, after going to supper and eating some crappy fish and chips, we ripped most of it apart, re-cut some pieces and started gluing and drilling screws in instead of dowels. We were done the frame within an hour and a half. This is the result, in blurry-basement-blackberry-photo style:
This frame is quite solid, and the glue hasn't even set yet. By tomorrow you will be able to throw this down a flight of stairs and end up paying to fix the stairs. Hopefully the end result will be able to damage cement walls. Brutal.

I'll post more information about the frame when I have time to discuss the lengths and angles.

Evan

Intro

Hi,
My name is Evan W. Isnor. My friends call me Evan, so I guess you can too. I hail from the Annapolis Valley in Nova Scotia; I play the guitar and I love heavy metal.

I'm in the process of building an angled speaker cabinet to house four 12" guitar speakers, and to compliment my super badass Randall RH150G3 head. It will be modeled after the Marshall 1960AV, but only in regard to overall dimensions. I'm going to start writing and posting pictures here; I thought a blog would be a neat way to document it.

For the last month or so I have been planning and researching for this project, and Google SketchUp has been my guide. Here's a 3D render of the cabinet showing the box and internal frame:
The initial list of components:

• Large 4'x8' sheet of 3/4" shop grade birch plywood (It's actually really nice!)
• A solid 3/4" birch board for veneer strips to hide the rough plywood edges
  
• Two 2x4's, cut into 1"x1" strips (You can get 3 from one 2x4)
  
• Dowels and carpenter's glue
  
• Perforated Steel for the grille (18 or 16 gauge holes, we'll see what I can find)
• Recessed handles (a la Marshall 1960AV)
• Recessed plate for 1/4" speaker jack connections
  
• 14AWG speaker wire
• 4 x Eminence Governor (16 ohm) guitar speakers.
  

The project is underway, currently on day 2 of work. Yesterday I went up to my grandfather's place and he helped me slice up the two 2x4's for the framework. We cut 1"x1" strips and cut them to length for all of the pieces I need. When I took the pieces home I started building the frame. I will post later with pictures of this, showing my progress for the weekend.

Evan