Been waiting 5 wks for delivery of amp and speaker to finish my sub,so while waiting i have been searching forums for snippets of info to help with my first build. After seeing ads and threads about using t-nuts to fix the speaker to the box i have purchased some locally, bloody typically just read a thread with around 8or 9 replys saying don't use t-nuts as they are rubbish, that they do'nt hold very well and if you try to remove the bolt it pushes the t-nut out at the back so it will just spin. Nearly all recmmended ordinary rough thread screws. Any comments from experienced builders
Decent steel T-nuts are simply not a problem regarding spinning as far as I know. I wouldn't use the grey alloy ones at all. The moment you have slightly loosened a standard nut on the back of something then the nut will just rotate until you grow old. Particularly if the thread is covered in wood dust. The small size of the standard nut also means it will slowly force itself through the baffle material using the pre-bored hole as a weak spot. You'd have to use a washer behind the nut to resist this pressure. Look for a crown shaped t-nut with large fierce teeth in thick steel and a good length of thread and you shouldn't have problems. I don't like those nuts with a large thick flange. With a few tiny teeth moulded onto the side of a thick projecting stub as an afterthought. I tried a Google image search and didn't find the excellent type used on my Linn speakers so I can't offer a link. Nimby
Are these the beasties Pronged T. If they are a loose fit in the hole then they will push out so make sure they are a snug fit. I've not actually used them yet in MDF but in standard wood they work great.
I think the 'problem' is mainly associated with MDF. I always use evo stick contact adhesive to glue the t-nuts to the MDF.(put the glue around the edges of the hole before hammering it home) - no probs so far. We use T-nuts with plywood all the time at work and never have trouble. Cheers Rob