What screws to use , they keep backing out

[ehall8702]

Exactly what title says. What options are out there to keep the speaker mounting screws from backing out? Used course and fine thread drywall screws used bigger medium thread screws and I literally can watch the screws back themselves out while I have volume up high . Thought about t nuts and loctite but wanna see what other options I have.

[Epic]

I've gotten to the point where I pretty much always use bolts and threaded inserts. I dont like T nuts or wood screws myself

[Triticum Agricolam]

My experience with both T-nuts and hurricane nuts has been poor.  It seems like they cross-thread really easily and when that happens you are going to have a bad day.  I won't touch either of them any more.  

I've gone to using #10 pan head sheet metal screws for most stuff and the SMD Blackjack screws for really big subs.  The key to getting screws to bite well is to make sure they aren't just going into MDF.  Plywood holds screws REALLY well while MDF never seems to hold screws worth a darn in the long run.  I avoid MDF altogether, but if you want to use it you can make just the baffle out of plywood.  If you don't want to do that or if the box is already built you can just glue some blocks of 3/4" plywood to the back side of the baffle where the screws go through, then just make sure you are using long enough screws to reach all the way into the plywood blocks.  If you wanted to be fancy you could make a plywood ring in two pieces and glue that inside.  

One thing I really try to avoid is any drywall screws or deck screws.  They are plenty strong enough for the job, but the back side of the head where it is tapered really isn't the best thing to be putting through the hole in a basket,  you want something with a flat contact area.  This is why I prefer pan head screws or cap head screws, even better if you can find them in square drive.  

[Skullz]

When you use use bolts or screws in wood, you want to use some super thin CA glue in the hole and as mush as the wood will take. Give it a minute or two to dry and use a drill or impact to run the screw or bolt in and out a few times with some gloves on as it will heat really quick and really hot, now what you have done is to make the wood as strong as metal with threads that act like they are nuts.

EDIT: You do want to run the screw or bolt in the hole first to cut some threads.

[PaCiFiKbAllA]

I used 2” SPAX screws...the gold ones that require a star bit.  Never had an issue with screws backing out....but that may be due to the slight angle my sub sits at.

[ehall8702]

I am using big flat headed metal screws, have used them many times in the past with no issues but a problem now. Going to make plywood rings for the back and use some ca glue in the holes also. Thanks for the good feedback and advice guys!

[twalker182]

19 hours ago, PaCiFiKbAllA said:

I used 2” SPAX screws...the gold ones that require a star bit.  Never had an issue with screws backing out....but that may be due to the slight angle my sub sits at.

I used SPAX as well and 2 years later....have never had an issue.

[SnowDrifter]

Speakers or subwoofers?

 

If subwoofers: brace your baffle more and use spax #8 multi material construction screws

[ehall8702]

41 minutes ago, SnowDrifter said:

Speakers or subwoofers?

 

If subwoofers: brace your baffle more and use spax #8 multi material construction screws

Subs, it's a pain in the ass to post a pic or I'd show ya what screws I'm using, but they are about the same as backer screws ( double thread design) but with a flat edge that touches the basket of the speaker. Never had a problem with em before, but my baffle is only 1" usually it's 1.5" so I'd figure that's my issue. For door speakers I use Phillips panhead self tappers. I'm going to try plywood rings behind and some glue inside the holes. If that doesn't work I will be refacing the box with plywood I guess.