Members Audiopile Posted April 13, 2014 Members Share Posted April 13, 2014 I have some speaker cabinets (subs) that are equipped with threaded "inserts" for bolting the tower (column) speakers to the subs. A couple of these inserts are messed up.. the threads are all boogered up, and I thought "no big deal... pop out those tee-nuts and put in new ones"... But... but, but, but: After examining the back sides of those "tee nuts", I've discovered those aren't tee-nuts, but rather are some sort of threaded inserts... they look like tee-nuts from the top side, but from the underside, they certainly don't, and in-fact, they appear to be some sort of helicoil sort of device, although there's a socket-head (Allen Head) in the back sides that an Allen wrench fits into. And they don't "come out", or don't seem to come out with reasonable force applied by an Allen wrench to the underside. I suspect they're pressed or threaded in with some sort of bonding agent to stick them in "good". I've seen these things before, and seem to remember "dealing with" messed up ones, but I forget what the trick is. Maybe there is no trick, and stuff gets ugly fast when trying to improve the situation... I dunno... Does anybody here have a clue/advice? Link to comment Share on other sites More sharing options...
Members agedhorse Posted April 13, 2014 Members Share Posted April 13, 2014 Can you chase the threads with a tap? Those fastners are used in the KD furnature industry, like this: http://www.grainger.com/category/hex-drive-thread-inserts/thread-insert/fasteners/ecatalog/N-8nx http://www.fastenal.com/web/products/details/0123232;jsessionid=hvrcTKJZVlpyY4hLDzQP1F2Q64jC2qKkY7RhHl3y2hMDYyXfn1NR!379136172!403118208?isPunchout=false http://www.theinsertcompany.com/steel_hex_drive_inserts_for_wood_headed.shtml Most of these are zinc which makes their use in heavy duty applications, but I have seen them in steel as well. Link to comment Share on other sites More sharing options...
Members Rob_H Posted April 13, 2014 Members Share Posted April 13, 2014 Did you try re-tapping them Mark? You may be able to clean them up with a thread chaser or a tap depending how bad they are. Might be an easier solution than replacing if they are really solid in there Link to comment Share on other sites More sharing options...
Members Bobby1Note Posted April 13, 2014 Members Share Posted April 13, 2014 This might help; Link to comment Share on other sites More sharing options...
Members wesg Posted April 13, 2014 Members Share Posted April 13, 2014 I used some of those things Andy linked to when I made the front legs of my organ detachable. I found them at Home Depot in the screw aisle, in the plastic rotating display. It's basically like putting in an anchor, except they go into wood. If your cabinets are MDF you might have a hard time pulling out the old ones and getting new ones in the same spots. If I was putting these into vibrating wood, I would probably coat the threads with glue on the way in...your speaker manufacturer may have done the same thing. If you have nothing to lose - get out the breaker bar and use gentle but steady torque. Normally they are right-hand (normal) thread and the hex driver goes into the same side the stud/bolt screws into. Link to comment Share on other sites More sharing options...
Members Scodiddly Posted April 13, 2014 Members Share Posted April 13, 2014 Might be able to soften the (hypothetical) adhesive with heat. Maybe just stick a soldering iron to the metal and see if it loosens up? Link to comment Share on other sites More sharing options...
Members dbMontana Posted April 14, 2014 Members Share Posted April 14, 2014 Might be able to soften the (hypothetical) adhesive with heat. Maybe just stick a soldering iron to the metal and see if it loosens up? Works well for ski-binding screws. Link to comment Share on other sites More sharing options...
Members Audiopile Posted April 14, 2014 Author Members Share Posted April 14, 2014 Armed with the insight gained here by the helpful advice offered, I'm happy to report that I "figured it out" and was successful in removing the hex drive thread inserts at will. Initially I thought I'd replace them with t-nuts, but I'm now thinking I'll replace the messed up ones with same-same... as the threaded inserts seem to stand to reason to be a "stronger system" in this application than t-nuts. The factory installed inserts indeed appear to be zinc. I believe I'll replace them with steel inserts... maybe even go with a little bigger size. Chasing the threads of the messed up inserts wasn't an option as most of the messed up inserts had some or most of the threads pulled out or they were so galled up there wasn't anything left of the threads to chase. The inserts did have adhesive applied to them, as well as being socked in pretty tight, which I was able to un-adhere by threading a "longer" bolt into the insert and heated the bolt with a torch. Link to comment Share on other sites More sharing options...
Members Bobby1Note Posted April 14, 2014 Members Share Posted April 14, 2014 Mark, was it a tapered insert by any chance? (tapered outer sides) Left-hand outer-thread? If it was zinc, did it have a "flange"? There's so many kinds out there, it'll make your head spin. Very handy though. I use them for making jigs in my woodworking shop. Link to comment Share on other sites More sharing options...
Members Audiopile Posted April 15, 2014 Author Members Share Posted April 15, 2014 Mark' date=' was it a tapered insert by any chance? (tapered outer sides)[/quote'] No, they weren't tapered... just straight. Left-hand outer-thread? Right-hand outer-thread, but threaded in from the back side of the plywood. If it was zinc, did it have a "flange"? Yes, although the flanges weren't much to behold... most of the flanges were cracked out or completely broken-off. There's so many kinds out there, it'll make your head spin. Very handy though. I use them for making jigs in my woodworking shop. As I'm discovering, there's many types available. But they do seemingly have a purpose... agreed: likely very handy to have on-hand for the right application. With that: I sense another cigar box addition to the hardware shelf coming on... and likely being another cigar box of "interesting looking stuff" that should look good/interesting piled on a pallet with all the other pallets of my stuff at my widow's estate sale (someday hopefully in the distant future). Well... enough of this speaker cabinet stuff... I have a sense of urgency to get back to getting the summer tires on the Chevy automobile car (which is tricky with 3" of motorcar vehicle ground clearance). Link to comment Share on other sites More sharing options...
Members Bill.ESC Posted April 15, 2014 Members Share Posted April 15, 2014 T-nuts are much better IMHO. Link to comment Share on other sites More sharing options...
Members Audiopile Posted April 15, 2014 Author Members Share Posted April 15, 2014 T-nuts are much better IMHO. what I'm pondering. The threaded inserts are bonded into the wood. Tee-nuts are backed with the flange. Which is better, I dunno... 90degree bonding throughout the wood or 180 degree back pressure? Or something else I'm missing? Link to comment Share on other sites More sharing options...
Members agedhorse Posted April 15, 2014 Members Share Posted April 15, 2014 The steel inserts properly installed are supurb. Especially on poplar and birch/poplar plywood. The zinc ones not so good. Link to comment Share on other sites More sharing options...
Members Bobby1Note Posted April 15, 2014 Members Share Posted April 15, 2014 what I'm pondering. The threaded inserts are bonded into the wood. Tee-nuts are backed with the flange. Which is better, I dunno... 90degree bonding throughout the wood or 180 degree back pressure? Or something else I'm missing? In plywood, the threaded inserts are vastly superior to T-nuts.(depends on the application) The steel threaded inserts like Andy mentioned, usually have a small circular flange, so the flange butts up against the underside of the plywood when fully inserted. The flanged insert can't be "pulled through" the hole, even when over-torqued. Plus, the fact that the insert has outside threads, prevents the insert from being pushed back down through the pilot hole. Very strong and secure. The outer threads are also deeper than those inserts which are not specifically designed for use with man-made lumber materials (plywood/MDF, etc) T-Nuts don't have outer threads. They do have a broad flange, and they're hammered in. Tiny "wings" on the flange, are driven into the plywood, which prevent the T-nut from turning, but, they're not as securely bonded to the plywood. http://www.homedepot.ca/product/10-32-tee-nuts-long-prong/955572 http://www.mscdirect.com/product/93442408 Link to comment Share on other sites More sharing options...
Members agedhorse Posted April 15, 2014 Members Share Posted April 15, 2014 There are also industrial grade T-nuts that have a slightly larger flange that accepts small screws to prevent pushing out. Link to comment Share on other sites More sharing options...
Members Bobby1Note Posted April 15, 2014 Members Share Posted April 15, 2014 I might add that the T-nuts I linked to above, are basically designed for applications such as furniture legs, where you'd have adjustable leveling feet under the wooden foot, or leg. The threaded " leveling foot " would be pushing against the flanged side, driving it against the wood. For a speaker cabinet, where you have a complete "through hole", and you're bolting something from the outside of the cabinet, you really need that threaded insert, and preferably with the flanged underside. And as Andy said, steel is best. Link to comment Share on other sites More sharing options...
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