One of the last Super V builds

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nlitworld

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Re: One of the last Super V builds
« Reply #20 on: 15 Jun 2025, 03:13 pm »
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

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Re: One of the last Super V builds
« Reply #21 on: 15 Jun 2025, 06:52 pm »
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

Re: One of the last Super V builds
« Reply #22 on: 15 Jun 2025, 07:38 pm »
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

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Re: One of the last Super V builds
« Reply #23 on: 15 Jun 2025, 08:09 pm »
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

Re: One of the last Super V builds
« Reply #24 on: 15 Jun 2025, 09:30 pm »
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

Re: One of the last Super V builds
« Reply #25 on: Yesterday at 12:53 pm »
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

Re: One of the last Super V builds
« Reply #26 on: Yesterday at 05:54 pm »
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

Re: One of the last Super V builds
« Reply #27 on: Yesterday at 06:14 pm »
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

Re: One of the last Super V builds
« Reply #28 on: Yesterday at 10:07 pm »
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.




« Last Edit: Today at 02:35 am by fishboat »

tremrej65

Re: One of the last Super V builds
« Reply #29 on: Today at 12:47 am »
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

Re: One of the last Super V builds
« Reply #30 on: Today at 02:21 am »
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.