Homemade Voigt Pipes: Update 2

 "Never let the future disturb you.  You will meet it, if you have to, with the same weapons of reason which today arm you against the present." - Marcus Aurelius

The start of the Voigt Pipe project is here.  

The first update is here.

I put a couple more day's worth of time into building the Voigt pipe speaker cabinets this week, and made another significant error.  It's not one that can't be covered up - half of carpentry is learning how to hide your mistakes - but it is embarrassing.  

Onward then, with the Voigt pipe construction journey.  Always start with project grease.

This was the part where I had to cut seven degree angles on the end of each of these rear panels.  It was an unpleasant cut to make.  I don't have a large table to support the free end while cutting, so it's very difficult to keep the panel aligned and flat on the table, while also making a clean cut.

Below, the rear panel now has the same angle as the sides.

Below is where I screwed up with the fitting-together business.  The angled panels are supposed to be screwed into the sides of the rear panel, instead of attached inside.  Oopsie.

In the previous post, I mentioned using a thin sheet of plywood to make the curved transition from the vertical pipe to the horizontal horn opening.  Even a 1/4" thick piece of plywood doesn't bend very well, so I tested out the possibility of making a partial cut every 1/4" to see if that would work.  It will bend when you do this, but in the wrong direction!  Once you remove material, it bends backwards.  But with a little force, it can be made to bend in the other direction.

I spent nearly 30 minutes scoring the back side of two sheets of 1/4" plywood so that they could be bent into the curved shape needed.  It was a huge pain in the butt to move the fence 1/4" after each pass, but it was necessary to obtain a smooth curve in the wood.

Years ago, I lent out my router to a friend, and one of the router bits had come back absolutely black.  Maybe he was making cuts in cinder blocks.  This was the first time that I needed to use that particular router bit, and a test cut revealed it was doing more burning and tearing than cutting.

The replacement bit was $14.  Don't loan out your tools unless you are certain you want to replace them.

Below:  I free-hand cut a couple of slots in the side panels for the 1/4" plywood to fit into.  I left a 3/4" gap at the bottom for the bottom panel to fit into, and let the router blow out the back of each side panel.

Testing the fit of the curved piece with both sides.  Pretty straight for freehand-cut grooves, eh?

It was at this point (below) where I realized that the sides were supposed to attach to the outside of the back panel!!!  The front panel overhung the cabinet I'd already assembled.  I had to cut 3/4" off each side of the front panels.  It will still work fine, I'm sure.

Test fitting all the sides with the curved section in place.

Below: Trying to get all the joints aligned so that holes can be drilled for the screws.

Ta-Da!  One speaker cabinet assembled, more or less.  The opening for the horn has been cut, but the bottom panel has not yet been installed.

 

Below:  You need to take great care that everything is aligned and square at the bottom of the speaker so that it will sit flat and be square.  However, any errors in your panel lengths will show up at the top.  I will have shave some wood off, and then decide how to decoratively close up the top.  Nothing tacky, I promise.

Below:  Side view.  The left side of the box with the large hole is actually vertical.  The phone camera doesn't make it look that way, though.

If I had assembled this correctly, all the screws would be on the sides, the speakers would be 1-1/2" wider, and much narrower at the very top.  I'm not doing this over unless they are an absolute sonic disaster.  A second day in the shop led to the near-completion of the other cabinet.

So what's left?

• The bottom edge of each cabinet is a wee bit rough, and a small trim piece would improve the look of the horn opening there.
• The top of each needs to be planed down, and a trim piece designed and installed to close it up.
• Both need stain on the red oak panels, and wood wax on the front and curved birch panels.
• Mount the speakers and binder posts
• Install the fiberglass

Then it will be time to perform a sound check!