Mid Bass Horn Design 80-800 Hz

[Steve Mac]

Pic of Router Bit Needed
The cutting shank is shorter than the one I have and the ball bearing guide is closer to the cutter, both qualities allow the ability not to need spacer pieces and to keep the ball bearing on the guide piece only.

[jnorv]

I think you got it.

Jim

[bfish]

Originally posted by Steve Mac:
...The only weirdness is that I can decide whether I want to fill the edge or sand the edge...

<font size="2" face="Verdana, Helvetica, sans-serif">Just a suggestion...stage your depth of cut to fall between ply layers rather than in mid-ply.

[jnorv]

you still need to run the router base at 20 degrees to the face. Try it on a piece of particle board first.

Jim N

[Steve Mac]

No angle needed at all! That's the beauty of this!
Yes, there will be error material.
But the cut is accurate on the edge at one point
of every cut made. Exactly as a CNC router would do.
Anyway 4 cuts and a little sanding...story over.
Ya gotta appreciate how simple this is.

[Steve Mac]

Originally posted by bfish:
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Steve Mac:
...The only weirdness is that I can decide whether I want to fill the edge or sand the edge...

<font size="2" face="Verdana, Helvetica, sans-serif">Just a suggestion...stage your depth of cut to fall between ply layers rather than in mid-ply.</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yep, that's a good idea.

Waiting for the bit so I verified the dimensions for the cutouts in the rear chamber and drew out the speaker holes. I could have printed out 2 11x17 papers and taped em together to have a mounting hole template but I just carefully measured. Took one speaker and verified the pencilings are spot on:
Rear Chamber speaker mounting

One thing I noticed on the speakers is that the surround material overlaps into the frame's speaker holes:
Speaker Surround Material

Now, should I slice the edges of the surround material inside the holes with an exacto knife so the bolts don't pull at the surround material?

[bfish]

Originally posted by Steve Mac:
...Now, should I slice the edges of the surround material inside the holes with an exacto knife so the bolts don't pull at the surround material?

<font size="2" face="Verdana, Helvetica, sans-serif">Most definitely. I use a pointed blade, and ride the hole edge to remove all overlap.

While you're there, closely inspect the gasket segment joints, to ensure no air leaks. Inside of the bolt pattern is all that matters.

[Steve Mac]

Okay, more work...cutting out the speaker holes:
First, cut the big holes out first:
Speaker Hole Cutouts
...so it's easy to clamp boards to prevent blowout on the speaker bolt holes:
Using the cutouts to clamp
Then drill away:
Drilling the speaker holes
Then if you did this right the back looks good:
Back View

Guess what arrived today:
Guess?

[bfish]

Yeah, that order online, 3 day delivery thing sure is sweet.

I've alway wondered about using a std roundover bit to radius the cutouts, 100% externally, and on the straight cuts internally...

[Steve Mac]

Originally posted by bfish:
Yeah, that order online, 3 day delivery thing sure is sweet.

I've alway wondered about using a std roundover bit to radius the cutouts, 100% externally, and on the straight cuts internally...

<font size="2" face="Verdana, Helvetica, sans-serif">Don't know yet but I THINK I don't wanna roll over the side exterior edges if the side walls intersect them right at that point. OTOH, I hope the side lines and wedges and side walls hit this line close...

Well, eureka I've finished the compound angle pieces...and what a pain in the a_r_s_e they were.
This first pic shows how I decided to trim without spacers for each subsequent slice. Screw it, I tried spacers but they don't work as well as eyes and hands:
Pencil marks

I cut 5 slices and then by hand took the grinder bit in my drill and just shaped them by eye.
Piece of tin acting as a side wall

Here's a pic of the cut

And another pic

All 4 pieces

The only pain is I had to make a template to cut the last piece which is just as well, I should keep a master.

Now, I have another difficult decision which is how to fill the sides of the wedges to mount the side walls...this could laborious. I should just enjoy the moment...I've wondered how I was gonna cut this angle from day 1.