[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.