<--click any picture to enlarge

This is my temporary soldering station - a card table to which I taped a piece of heavy cardboard to protect the surface from burns, etc..

While this is how I'd like them to look, there are several obstacles to fabrication. Among the most challenging are the wooden dowels on either side of the woofer pipe. I'd have to mate them to the curve of the woofer pipe by either milling the back side of the dowel concave to match the pipe (or some variation of that), or I'd have to mill a flat in the 4" woofer pipe to accept a flat on the rear of the dowel.

(NOTE: In a previous iteration of design, the long dowels served a purpose, now they're just decorative. In the end, I decided to not use the woofer pipe dowels.)

The electronics would be housed in the lower chamber, and large air holes and slots in the first horizontal plate would provide good ventilation. The second horizontal plate would hide the holes from view and from poking fingers. The bottom surface will likely be a truncated 15" diameter circle. The upper layer in the "layer cake" would be circular, going with the round theme offered by the pipes.

Just kidding!

Total cost of this order was around $160.

The conduit comes in 10 foot lengths, so there's plenty of spare pipe to experiment with. Each conduit is a reasonable $6 at a local mom-and-pop hardware store.

The DMM is a $45-ish unit purchased online from MCM electronics. It doesn't measure inductors, but there are none in this project anyway.

The local glass shop cuts a couple pieces of acrylic for me for $6 each. I planned the holes and geometry using CorelDraw software, printed the plan to a laser printer, and used the printout as a template to mark holes and cutouts. This file, saved in TIF format, is available for download here (1.8MB TIF file), Note that the circuit board shape may have changed since I built mine. If you are following these notes for your own construction, double check your own boards first.

So far, so good.

Be sure to account for any mounting bolts in the assembly. I didn't, and the caps came VERY close to contacting the bolt head that held the woofer pipe in place. Close call!

It was an interesting experiment though. I may employ the light-pipe concept in another project someday.

Tip learned in a later project: Rough cut the round part using a jig saw or a band saw leaving about 1/8" extra material. Then trim the remaining material using a router and a larger 1/2" router bit in one pass. It will produce a smoother surface and reduce sanding compared with multiple small cuts necessary with the 1/4" upcut bit. It's faster too.

This was another tip learned the hard way after building a previous pair of speakers. I LOVE Zinsser Bulls Eye Seal Coat now.

I dry-fitted the unfinished parts to check fit, and to preview how things might appear after assembly. Not bad!

I used thin 1/8" pieces of MDF for creating the initial template for the irregularly shaped woofer. Because its shape is a truncated circle, I routed a full circle in the thin MDF, then positioned additional straight pieces next to the flats of the woofer.

 I allowed about 1/32" clearance from the edge of the speaker to the flats to accommodate any small errors.

I tacked these parts together using wood glue, and let it dry overnight. Then I lifted the woofer out leaving the opening with the desired shape and size. This formed a temporary template that I could use to route a stronger template in 3/4" MDF in a following step.

In retrospect, the first through-circle for the woofer should have been routed in a somewhat larger area piece of material. The flats didn't have much overlap for gluing.. By the time I was done, this thing had all sorts of "wings" glued up to make sure it didn't fall apart when routing the final pattern in thicker material.

I used this thin template to route the pattern deeper into a stout 3/4" piece of MDF. To route the final pattern, I used a pattern bit with the follower bearing at the top. I purchased a short 1/2" diameter by 1/2 inch long pattern bit with the bearing at the top from MCLS online. I bought their Katana bit #16509 to do this work (see picture of it being used below for the final routing of the dress plate).
 

I used a short 1/2" diameter by 1/2 inch long pattern bit (with the bearing mounted at the top) purchased from online store MLCS. I bought their Katana brand to do this work. MLCS have good prices and fast delivery.

I had to be careful that I didn't cut the woofer through-hole away before the outside was done. The center for the outside shape is included in the hole. If the hole had been cut first, I would haven't been able to cut the outside shape concentric.

Here are the (sorry!) partly hand-drawn plans for the MDF rings that get stacked to make the woofer mount. It is a substitute for the Fernco fitting in the Pluto. These were made from both 3/4" thick and 1-1/8" thick MDF. The 1-1/8" thick MDF was a stair step from Lowes.

When drilling the center pin for the Jasper circle cutter, I also drilled some 1/8" holes for assembly pins to be inserted later. Two MDF blanks were temporarily pinned together at the center (where the Jasper pin was to go) and two other holes were drilled in the "meat" of the rings so that they would align properly during final assembly.

Think through the drilling of pin alignment holes so that you don't end up with an external hole where you don't want one.

This illustration also shows how I had to increase the center to center distance between woofer and tweeter pipe to accommodate the extra diameter of the MDF woofer mount. It's thicker than the rubber fitting.

Note the alignment pin holes in the "meat" of the MDF ring. These were drilled at the same time the Jasper Guide center pins were drilled, and align exactly with the holes of an adjacent ring because the rings were drilled together.

The box of steel dowel pins was purchased online from McMaster-Carr

The necked-down portion of the Fernco fitting is shown in a dashed green line. My design provided a little more "breathing room" for the woofer magnet. The dashed red line shows the inside profile if a 45 degree chamfer bit had been used on the inside of the MDF ring. I used a steeper 30 degree bit to make a sharper angle down to the 4" pipe to further help woofer breathing.

The wood is ordinary poplar.

I used a 1/2" round-over bit in my router table to round each end.

To apply, I used two coats of polyurethane over the bare wood, then stained, then applied more poly as a top coat. This is an unusual method to prevent blotches and dark grain that I got when using the stain normally. The stain behaves oddly over the polyurethane, looks like it won't level out, but does. I also found that I couldn't "brush-up" an area that I had just stained. Difficult and messy, it still provided the appearance that I sought.

Note the long cooling slot on the bottom piece. In the final assembly, it is positioned directly over the amp's heat sinks to provide straight-through air flow for maximum cooling. Two other cooling holes can be seen also. These provide an additional air escape path for cooling the amplifier.

Note: Steve Roehrig on the Orion/Pluto user group reported success using a similar jig, but he used his drill press instead of a Dremel-type tool. He employed a router bit mounted in the drill press for the flange trimming. This might be superior to my method because of the rigidity offered by a stout router bit + drill press. Also the speed can be slower to prevent melting of the plastic while trimming.

It was perfect. No tweaking needed.

The purpose of this piece was to hide the air vent slot and to hide the PVC end caps.

The three screw-mounting holes were located by cutting a strip of paper and positioning it around the pipe's periphery. Then I unfolded it, measured out three equally spaced marks, and used it to mark the pipe for screw holes. I didn't bother to drill pilot holes in the MDF for the small screws.

All fits well. Good to go.

Here's a top view of one finished Pluto. (Click to enlarge any picture)