[nlitworld]

https://www.amazon.com/Z-Threaded-Hex-Flanged-Internal-Threads/dp/B002KSTB9G/ref=mp_s_a_1_1_pp?dib=eyJ2IjoiMSJ9.DKLveC3dR3N9vHYxlfeaY9NfnlwDYj31B35715WGYh2gFbBpSrOUhtmLtwNlxjfFiihsLeHlhgWlEvSeJD6kaLy2BVLKjDZZc00NTpOy_iWwkrFsOMheM92UJXzTfPBTU7DMAjBgjLoY7ra7u7cK4_EqqoFmQUQDtkNhc7aXygnxtnt2VvNXrQAzDHEkM0tm1gHRoHPfJAJJMDwmXUGPRw.FaWey68HlfdNpSJEMiB0OjlYZparrPadBH2GLzscl-0&dib_tag=se&keywords=Threaded+Inserts&qid=1749937231&sr=8-1

Threaded inserts work great. 8-32 threads make bolting easy, and panhead black bolts always look super clean. Screw these in with a pinch of epoxy and they're locked down for good. Just double check all your pre-drilled holes are EXACTLY where you need them or it'll be tough to thread in the bolts.

[Peter J]

This might be helpful. I did it on CNC but have done many times manually. Ask questions if you have them.

https://www.youtube.com/watch?v=GCRc_XyQidw

[fishboat]

Thanks Peter(&nlit),
That's pretty much what I had in mind.  I've used threaded inserts in many projects and they work well. 

(btw.. Yesterday morning I read through your "X-Otica and sub" build thread from 2016.  Sort of a tour-de-force of speaker building.  Nice work!  The thread was a great help.)

The issue this time is I'll have so little meat(MDF) left between the insert bore hole and the inside of the flange..like less than an 1/8th in, probably closer to a 1/16th inch.  I can use 8-32 inserts that cuts the bore hole size down from 9/32 to 15/64, but still that only increases the bore hole to flange ID distance by  (1.5)/64ths..not much help.


I taped some thin fiberglass cloth all the way around the inside of the flange edge this morning and set the coax into the baffle.  It just nicely fit without binding on the cloth on either side.  This indicates I can epoxy a strip of fiberglass cloth to the inside of the flange to reinforce the thin edge around the insert holes.  I'd think epoxy/fiberglass cloth, besides wetting the inside edge of the flange with penetrating epoxy prior to applying the cloth, would make the edge fairly strong in spite of being so thin.

I'm sure anyone who has built a set of Super Vs, and made the coax baffle to spec, has dealt with this the same issue.

[Peter J]

I think the idea of reinforcing band on the inner surface of thru-hole is a great idea.
Similar problem, but this only mounts a port tube, so not much strength needed.

[fishboat]

Yep..that's the issue.  Ouch on the bit that cut that hole.

I just slathered the inside edges of the MDF flange with some old CPES (cold penetrating epoxy) I found in my epoxy/fiberglass cloth-supplies box from..like..25 years ago.   I mixed some of it up yesterday and it seems to cure yet.  Epoxy can last a long time.  Even Medex MDF is like a sponge. The epoxy sunk in as fast as I could apply it.

Tomorrow I'll apply the fiberglass cloth and slather some standard boat-grade epoxy to the MDF edges.  Hopefully that will strengthen things up a bit.  I'll run some test installs on MDF cutoffs to proof things out before diving into the real thing.

[Zuman]

In a similar situation (different cabinets and drivers, though), I inserted and epoxied t-nuts in the mounting positions and then ground off the portion of the flanges that intruded into the driver mounting holes. I used - obviously - correctly-threaded machine screws to mount the drivers and used Blue Loctite on the threads. Everything is still solidly in place after several years.

Just a further explanation of why I used this approach...
With a t-nut inserted from the INSIDE of the cabinet, the insert tightens when you screw the driver in, as opposed to the screw trying to pull a regular insert out of the mdf.

[fishboat]

Just a further explanation of why I used this approach...

Yep, makes sense.  I'm trying not to have hardware on the back side of the coax baffle though as it'll be visible (there is no box-cabinet to hide them).   You can get ez-lok threaded inserts with a top flange on them too that would work the same way.

[fishboat]

Looks like I'll be using 8-32 inserts for the coax mount instead of the 10-32 inserts I wanted to use.  I received both sized inserts yesterday.  The 10-32 inserts are MUCH larger than the 8-32s.  There won't be room for them I don't think, at least not that I'm comfortable with.  The 8-32 inserts and associated bolts seem strong enough with a couple test runs cranking them down until something gives (the MDF, with no epoxy in the bore hole).  The coax requires 8 bolts to mount..the combined strength should be fine. I'll mount the coax with the bolts having a healthy coating of blue thread-lock on them.

I've always used 1/4-20 inserts on other projects.  Never dealt with 8-32 or 10-32.  I never would have guessed there would be so much difference in size.  The 10-32 in on the right.



I soaked the edge of the MDF flange with CPES yesterday.



 and just finished applying a thin fiberglass cloth to the MDF edge with epoxy. 

[fishboat]

Given this is a build thread, I suppose I should back up slightly and fill-in a couple details of how I got to where I am now.

Most of the interior pieces of the Super V.  The side panels are just 2x4 foot pieces of 3/4 and 3/8ths MDF.



Next is the prep for gluing up the coax baffles.  The baffle is two 3/4" panels glued together to yield one 1.5 inch thick baffle.  I decided to use a few dowels to keep the panels from slipping around during glue-up.  I've done glue-ups in the past where the pieces tend to "travel" as I've tightened the clamps.  That can be a real panicked mess.  The dowels made the baffle glue-up uneventful...although is was still a mess, but a controlled one.  One thing that helps me when doing a glue-up like this is to keep both pieces of the glue-up in very rough size and have one piece smaller than the other and ""inside" the larger piece.  That way after the glue dries I have at least one edge that is clean, straight and square.  I can use that edge on the table saw fence guide to cut the piece down to final size.  Using a panel cutting jig on the table saw is also a BIG help to get perfectly square pieces.






This is a circle jig I rigged up.  I found similar examples on the web and it seemed easy enough to build.  The 1/4 inch steel rod cost me $5, the rest is scrap pieces.  The OSB under the router will be the wood template I'll use to to shape the 4 side panels(two @3/4 & to @3/8 inch MDF) with a flush trim bit.  OSB is cheap, flat, and holds a good sanded edge for template routering.







The sub boxes that attach to the sub baffle were next.  When I make multiple shop-grade cabinet drawers, or in this case enclosures for the subs, I set up a simple perfectly square corner on my bench to brace the pieces square to each other.  I then use a right angle clamp to position & secure the two sides flush with each other.  Next comes a drill guide for the pilot hole, then glue &  whatever screw I'm using.  All of this is particularly needed when screwing-gluing MDF as it likes to split when screws are driven in the edges.   



I used trim-head screws with an 1/8" pilot hole drilled the full length of the screw.  Trim-heads work well as they don't force the MDF apart when driven home.  I also tip just the very end of the screw with just a little toilet-bowl wax.  It's cheap and very slippery and soft..easy to get on the screw and stays in place.  The screws drive in super easy.  And no splits!  In addition, I use a small dremel tool mounted in a drill to prep a countersink hole for the screw head.  The shape of the countersink hole mimics the trim-head screw.  The smaller the countersink, the less repair work is needed later.











Finally, up to today at least, I started working on the template for the sides of the Super V.  This is a 1:1 ARCH E sized (typical blueprint or architectural drawing size paper) printout that I'll use to make the 1/2" OSB template that I'll then use to shape the MDF side panels.  I'm making a number of small changes to the shape of the sides.  A number of the changes are discussed up-thread.  I made the 1:1 PDF file of the sides way back in 2013 before the above discussion was done. I was using the free version of Sketchup 8 back then and there was a way to create 1:1 files directly.  I think that option is long gone in the free version now(without printing out a dozen+ office sized sheets and taping them together).  Though I don't have it, I think SU Layout does this now..in the paid version.

[tremrej65]

Good job. Thanks for the great "in progress" pictures. Always interesting.
Cue to rotate picture: upload the picture in your gallery. In there, there is a tool to rotate the picture after it is uploaded. Then you can include the picture in a post from the gallery.

[fishboat]

Cue to rotate picture:....

I am linking the pics from my gallery and have spun the pics at various angles and it seems to have no impact.  However, I've now linked the photos from an external source and all seems OK. 

[fishboat]

Change-up..

The reality of making the speaker side template out of 1/2 OSB is staring me down.  I've made lots of templates over the years, typically out of whatever scrap sheet good I have laying around.  Masonite (hardboard) is good(though very thin), but there's different requirements for templates made for tracing vs one used for repeatably guiding a router bearing.  My past templates have never been on this large of scale. 

I picked up the OSB as it was the only thing in stock at the lumber yard I was at (the MEDEX MDF wasn't easy to find). 

I found a local place that has 1/4 and 1/2 inch thick handi panels (2x4 feet) of MDF, I just need one.  MUCH easier to sand MDF to a line compared to OSB.

[fishboat]

Good progress today.

While I wait on some supplies to come in for mounting the inserts for the drivers, I figured I'd continue work on creating the router template for the sides of the speakers.


It went much faster than I expected, thankfully. 

First..I made yet a couple more adjustments to the shape of the sides on the paper template.  I then cutout the paper template and traced the outline on the 1/2" MDF that will become the router-bearing template. 



I picked up some 20 TPI curve-cutting blades for my jigsaw.  The better the initial cut, the less work is required to clean up the cut surface later.  The blade did cut very well.





Once the MDF template was cut out the next step is to smooth the curves out to a uniform, non-bumpy (in boat-building terms) "fair" curve.  There's always a little unevenness when cutting curves with a jigsaw.  Much like painting, prep is the biggest deal. Once I get a uniform fair curve the downstream work will get easier.  You can see the ridges that need to be smoothed out.



Following boat(or surfboard)-building techniques..I made up a flexible longboard sanding tool out of some thin cutoff scraps I had laying around.   Longboards can be whatever length is needed. I made it about 15 inches long.



I epoxied some pieces of vinyl tile samples that I have in stock. It's good material for a multitude of uses.  In this case it cushions the sandpaper and helps the sanding process to a flat surface.  Some folks use thin cork for sanding block surfaces.



Next..I used doubled faced tape to tape a piece of 50 grit belt sander belt to the longboard face.  Last fall I(we) installed a vinyl plank floor in my better half's condo.  Prepping the subfloor involved belt sanding some humps down.  Heavy belt sanding generates lots of heat and the belts fail if they get too warm.  I have a number of trashed sanding belts around that have lots of good grit left.  It was nice to find a perfect use for one.   




The longboard bends in a "fair" curve as you sand curved edges and hits the highpoints on the curve first..which is exactly what you want. Sanding the bumps down to one, continuous, smooth curve.   



50 grit working on the soft MDF made short work of completing the MDF template.  I thought I might spend a couple days on getting a perfectly smooth-curve template, but I managed to complete it in a little over an hour. A pleasant surprise.

Finished (router-bearing) template:

[fishboat]

Got all eight Super V sides cut out (4 @ 3/8ths inch thick & 4 @ 3/4 inch thick to make 4 sides at 1.125 inch thick).

First, scribe a consistent line around the finished mdf template..using the old washer and marker trick makes short work of a good line that leaves room to work them down to the final shape-edge later.    Need more or less room around the eventual finished edge..use a different size washer.



All eight rough sides cut out.  Dusty work..did it outside.



Using the dowels again to keep the sides in register while gluing up.  Heavily glued panels tend to move uncontrollably as clamps tighten up.  The dowels keep that from happening.  The 3/8ths thickness panel will be on the inside of each finished speaker side.  The holes in the thinner panel will be covered by the final assembly of the speakers.



..and the glue-up begins.   I make a point of applying plenty of glue and particularly plenty of glue right to the edge of the bottom glued panel.  If there isn't glue squeezing out on an edge you need another clamp.



..rinse and repeat today until all four panels are glued up.

(Made a deal on some new power for these speakers when they're done.  What I have now, McCormack DNA1, is a bit of overkill.  Picked up a Don Sachs DS2 preamp and Kootenay 120 KT88 amp.  Runs 65watts in ultra-linear mode and about 35 watts in triode mode.)

[Tyson]

Jesus dude your new preamp and amp are world class pieces of gear.  With the Super V's you are going to have a spectacular system.

[fishboat]

 

Thanks..I kinda hope so.

Of course once it's set up then comes tube rolling. I'm going to have a mix of excellent (power tubes) and very good gain stage tubes to start with.  What I really need to do, once the speakers are up and running, is...nothing, at least for a while.  It'll be hard, but there will be lots of things changing on their own early-on so I really don't need to toss in more variables, or making decisions based on data that's constantly changing.

[fishboat]

OK, now that it isn't 98 degrees outside, back to work.

Cool out today with a mild breeze so I figured I'd reduce the speaker side blanks to their final dimensions.

Setting up the template routering with 2x faced tape to keep things from moving as I work my way around the sides.   



Ready to route things down



Dust, lots and lots and lots of dust.  I felt bad creating this much dust even outside.





..and things went perfectly until just 5 inches from the end.  After 4 panels and 4 passes around each panel to get all the waste off I was getting a little tired (heavy router).  One second of lapsed concentration and the router tipped a little..oops.



If the sides were solid wood that would get a clear finish..I'd be crying.  But the side-edges are paint bound so no worries. Minwax's epoxy wood filler is made for divets.



Once cured, a little router and longboard sanding and we're back to the original edge.



With the sides down to their final dimensions, time to move on to building the two risers the speakers will sit on.  The original drawing had a flat base and the pieces above were cut at -3 degrees as needed to get the speaker to rock back from vertical by 3 degrees.  I found it easier to cut/build everything above the base with square edges and build just the base with a 3 degree tilt.



This is the glueup of both bases.  I'll cut the taper with a resaw bandsaw.

[fishboat]

For reference sake, this is where I'm headed

[fishboat]

Working on the speaker bases (3 degree angle risers) today. 




In order to re-saw the 3 degree taper into the bases I first needed to build basically a re-saw fence offset spacer to allow me to guide the cut along the fence while cutting the taper.

Rather than calculate the spacer needed I drew up a model in Sketchup. 



The spacer thickness determined in SU.



And the resulting re-saw spacers attached to the base-blank with doubled sided tape.  The two angled pieces ride against bandsaw fence and result in the desired tapered cut.



Everything was doubled checked from the SU model & model angles to the actual spacer thickness themselves so, in theory, this should have worked perfectly. Well, it didn't.  In theory, perfect, in real life, not so much.

I had to use a buddy of mine's bandsaw as my saw only had a 12.5 inch re-saw capacity and his saw could do 14 inches. My blanks were 13.5 inches wide, with a final width of 13 inches.  I did a couple practice cuts on the blank to see how the saw was cutting. The saw itself cut very well.  His saw worked perfectly and is carbide re-saw blade was tensioned properly.  The angle the blank was at wasn't right and yet all the calculations/model indicated it was exactly what it should be.  Not sure what was wrong, but..it doesn't matter.  The practice runs cut the blanks close to the final line and it was getting tough to get the blade to track right due to the incorrect practice runs. So, I stopped.  I still have more material to remove, but the blanks themselves are in good shape with respect to the final dimensions. 

It's probably hard to see the final dimension line, but there's more material to remove yet.



What do to? My next option to finish the cut will be a very accurate planer sled.  This should work very well. It will just take a little time to set up.

So, some progress today. One step forward, two steps back, such is life.   At least the base blanks themselves are still in good shape..I just need to get to the final dimensions.

[fishboat]

After the sort of failed attempt above, I thought about it off an on all last evening..how to do what I needed to do.  I thought of a few planer sled setup options, but nothing clicked with a "that's it".

I'm sure you've heard the saying, "sleep on it".  That actually does work.  Long about 3am I got up to hit the bathroom and the beginning of an idea popped into my head.  After a couple hours in the shop the final idea finally emerged from the fog. I'd like to say I knew exactly how to do this, but that's not the case. Sometimes the simple solutions are the hardest to find. 

If you've ever watched the woodworker(actually more of an artist that works in wood) David Marks(old shows are on youtube now), he's known for making unusual pieces that need unusual jigs to complete.  One other woodworker use to kid him about first making a jig to make  yet another jig he needed to finally complete a task on his project.  Occasionally there was a succession of three jigs made just to complete one task on a project.

Ok, so I made some wedges to mount to the planer sled using my tapering jig.



The wedges themselves match the angle I need for the speaker base risers but are 5/8ths on an inch less in height than the speaker base risers themselves.  5/8ths inch is(will be, rather than 11/16ths) the thickness of the narrow edge of the base-risers. (see the SU diagram above).  I made three wedges and mounted them with doubled-faced tape on the planer sled in an orientation opposite the taper on the base-risers.



Next..mount the base-riser on the wedges(2x tape), thick edge to the left. This yields a surface on top of the riser that's parallel to the planer sled surface. Simple, right?



Run the whole assembly through the planer a few times and the riser top surface is planed down to the final dimension line, perfectly..whew.



..and after all this, did it work?

Spec says 3 degrees of setback..close enough.