Best practices for fastening speaker parts

[DLS79]

Have any of you used HDF or Baltic Britch plywood instead of MDF?

Woodworking is a hobby of mine, and I've come to hate MDF, the stuff you can buy now at the local big box stores is not nearly as good as it was 2 decades ago. If i need a sheet good, I almost always use Baltic Britch plywood even though its none trivially more expensive and a lot harder to come by.

 

[carbidetooth]

Have any of you used HDF or Baltic Britch plywood instead of MDF?

Woodworking is a hobby of mine, and I've come to hate MDF, the stuff you can buy now at the local big box stores and not nearly as good as it was 2 decades ago. If i need a sheet good, I almost always use Baltic Britch plywood even though its none trivially more expensive and a lot harder to come by.

You might find this interesting.

MDF and Baltic Birch and flatpacks, oh my!

I’ve been hanging around here a while, but only occasionally post. Some may know me from my YouTube videos where I mostly yap about DIY speaker building for which I have a weirdly unnatural attraction. I cut my teeth in the custom cabinet world, later making a living as a marine mechanic which...

www.audiosciencereview.com

Something to remember; The big boxes carry what sells. By and large, inexpensive sells better than pricy. As far as I know, HDF is not a moniker manufacturers use, although common parlance elsewhere. Ranger Board Platinum, my favorite high density MDF is marketed as that...high-density MDF. It is worlds different than garden variety MDF. Medex is similar.

 

[Chrispy]

This topic started on another thread and was initially about creating a speaker with a removable back…

First pass at removable back failed predictably. Tried to countersink some wood screws and most stripped on the first attempt to tighten. Have some nutserts and planning to try them next. Likely need to strengthen the MDF. @carbidetooth know you suggest epoxy but thinking I need something that harden the surrounding MDF better. Maybe wood hardener or some thinned wood glue? Suggestions?

Not a ton of experience but with my plywood boxes for subs I did use threaded inserts (glued in) so I had ability to pull drivers out as needed without worrying about stripping etc. I've seen some have had issues but even with multiple times accessing mine not an issue.

 

[carbidetooth]

And the saga continues.

This is the rig I set up for testing at 90°.

Held up my 25 lb. weight no issue

My rudimentary rotational shear setup

Torque wrench lowest setting is 15 in/lbs. Insert held till it clicked. I stepped it to 20 in/lbs. and insert began to shear. I assume at the interface between MDF and insert.

For reference, I drilled a root diameter pilot hole and inserted a coarse thread tapping screw. Never reached 15 in/lbs before (it appeared) to pull head down into core enough to split. Bear in mind this is pretty pithy cored MDF

My take-away is this. I'll continue to use this method for mounting smallish drivers, 6-8" using #6, #8, #10 machine screws. I have yet to experience a failure. This facilitates a radius on the backside of driver cutout and many choices for machine screw head styles. Bigger, heavier drivers might benefit having something with a flange, like a T-nut, on the backside of baffle.
The Rampa fasteners mentioned do have a North American Distributor in Canada and have some products that look useful for the speaker builder. I'll investigate further and update here.
For those interested, I made a video a while back that demonstrated how I do it. Although I cut hole with router, it could be drilled as well.

 

[restorer-john]

With all due respect, I don't find that info to be accurate. I've tried those inserts with little success. Both flanged and not. They will indeed displace material and split edges. I doubt they would work with the limited thickness we're talking about here. Have you actually installed them on an edge? The rest just doesn't apply to this situation

That's because they are not designed for cut edge insertion and as you say, they will simply pull out. Totally wrong insert for the task. They excel when inserted in surface applications on MDF.

Barrel nuts are used for edge to panel right angles and offer enormous strength. Two holes, no adhesives, no epoxies needed. Extreme precision not required.

 

[Chrispy]

Not a ton of experience but with my plywood boxes for subs I did use threaded inserts (glued in) so I had ability to pull drivers out as needed without worrying about stripping etc. I've seen some have had issues but even with multiple times accessing mine not an issue.

Second thought, somewhat has to do with the technique....I don't use a drill or impact driver to install. Maybe uninstall.

ps and thinking about that I do use the drill for appropriate pre-drilling of holes for the intended screws....

 

[DLS79]

You might find this interesting.

MDF and Baltic Birch and flatpacks, oh my!

I’ve been hanging around here a while, but only occasionally post. Some may know me from my YouTube videos where I mostly yap about DIY speaker building for which I have a weirdly unnatural attraction. I cut my teeth in the custom cabinet world, later making a living as a marine mechanic which...

www.audiosciencereview.com

Something to remember; The big boxes carry what sells. By and large, inexpensive sells better than pricy. As far as I know, HDF is not a moniker manufacturers use, although common parlance elsewhere. Ranger Board Platinum, my favorite high density MDF is marketed as that...high-density MDF. It is worlds different than garden variety MDF. Medex is similar.

I've seen HDF at a few specialty woodworking stores around the country, but in general it seems to be used more in industry.