The Speaker Guy
			Dedicated to really cheap audio enthusiasts
				Anatomy One
I have a table saw, compound miter saw, drill press, belt sander and a router at my disposal, and I found them very useful for this project. An unexpected ally was my propane torch.
I purchased a 4? by 4? sheet of acrylic from Tap Plastics. I picked up a brochure with a few tips on working with acrylic. It was here I first read of using a torch to polish the edges of acrylic. The store attendant did not know if my simple plumber?s propane burner was sufficient, he said he usually used MAP gas. But we decided I could try on a scrap first and go from there. I was very pleased with the results. If the edge of the acrylic is sanded to a smooth satin finish, slowly passing the flame across the edge a couple times yields a glossy transparent finish.
Acrylic plastic is ?glued? with a solvent which is a combination of ether, methylene chloride and a couple other nasty things. I found this ?glue? went a long way. I purchased the small syringe bottle recommended in the store?s brochure. This made application relatively easy.
I organized my cut list such that I needed to rip one 6? width and two 5? widths. To make handling the 4? sheet easier I actually ripped off 16.5? first, then divided this into the three required pieces. All this was done on the trusty old table saw, Unfortunately the blade, although carbide-tipped, is slightly old too. I experienced much more chipping on the edge than I thought acceptable. At that point I figured I would be sanding a bit more than I wanted. More on this later.
I then took the 4? lengths and cut them into the finished pieces using the compound miter (chop) saw. This blade left a much more uniform edge. I proceeded through the cut list, checking off the pieces as I made them and I made sure not to mix any scrap in with the good stuff.
I clamped my belt sander into a stand, and proceeded to sand all the edges smooth. This was not going to be as easy as I thought. On the upside, I found that sanding acrylic actually cleaned the sanding belt! One troublesome property was that as the acrylic was sanded it heated up, just like a piece of wood would. Acrylic, unlike wood, gets soft when it gets warm. I found that I could only sand each edge for about 10 seconds before the belt wanted to grab the piece from my hand. I ended up sanding every piece three times, and I still thought the edges were only marginally smooth. This was especially true for the edges cut using the dull table saw blade.
At this point I decided to make only one prototype, and set aside the pieces which I cut for the second speaker. The upside of this is faster completion per se, and I decided to ignore any small cosmetic issues because I had all the chips which would hardly a work of art in the first place.
I added a bevel to one end of each of the three pieces in the port area. Although I was using marginally thin material, I was not bracing the sides, I was not going to add any batting and I entirely neglected the affect of the increased radius in the port at the U turns, I decided I should not tempt fate and leave these square edges projecting into the audio stream. I belt sanded the edges to roughly a semicircle, then flame polished them to a reasonable finish.
I peeled the blue plastic from all the panels and started gluing them together. I found I could hold each piece long enough for the glue to tack, about 3 to 5 minutes. Soon I had all the pieces together except for the one side which capped them all. I went back and added extra glue to all the edges and let the whole thing set for about 30 minutes. I then repeatedly applied the glue sparingly to the edges which were to glue to the side. After about 5 minutes the edges were reasonably soft and saturated with glue, and I placed the side piece on top of the entire assembly.
I placed some wood on top to protect the plastic and clamped down in a few places. I then dabbed a bit more glue where it seemed necessary and let the whole thing set for another 30 minutes. At that time there are no remaining glue fumes and no tackiness around the edges.
Now here is something you can?t do with MDF. I took the cabinet to the sink and I filled it with water. This exposed a couple of leaks, so I dried it off and re-glued and clamped the trouble spots. This fixed the problems.
I then cut the holes for the driver and the terminal cup. For the driver I used a fly cutter in the drill press. For the terminal cup I had a hole saw of the proper diameter which I also used in the drill press. Drilling large holes in acrylic takes time, as the tool quickly gets hot enough to melt the plastic. Patience is a virtue. I touched up each of the holes with a drum sander, and then flame polished them.
I had some nice silicon rubber weather stripping I used to seal the two holes. I was very pleased with the results. The stripping stuck very well to the acrylic, and I?ll be able to open it up easily for service.
I attached the driver and the terminal cup to the enclosure with ½? brass wood screws. Luckily I practiced with a scrap first. Even with a generously sized pilot hole, driving the screw into the acrylic caused cracking and chipping. So I came up with this technique. I drilled the four pilot holes slight smaller in diameter than the screw body. I then carefully inserted the screws about ½ turn until they were held firmly by the acrylic, but well before the onset of cracking. I used the propane torch to heat the head of each screw for about three seconds, and then drove the screws into the acrylic. I used a heat shied to prevent damaging the cone or the surround. I did leave some minute bubbling on the edge of the terminal cup.
This technique was used to attaché the terminal cup, then I soldered the wire from the terminal cup to the driver, and then attached the driver to the housing. The great thing about the clear acrylic is I can inspect the seals from inside the speaker, and they look great.
	I finished up by flame polishing the exposed edges of the enclosure.