What's the preferred means of fastening smaller drivers to an enclosure?
I have used t-nuts on midbass and tweeters, but I have come into some Visaton B80s. These have a 104.4mm frame diameter but the cutout needs to be 87mm.
Consequently a t-nut will not work without sticking out into the cutout - which concerns me for stability.
I guess small wood screws, but I'm concerned about maintainability if I need to remove the driver for any reason from an MDF baffle
Any alternatives?
I have used t-nuts on midbass and tweeters, but I have come into some Visaton B80s. These have a 104.4mm frame diameter but the cutout needs to be 87mm.
Consequently a t-nut will not work without sticking out into the cutout - which concerns me for stability.
I guess small wood screws, but I'm concerned about maintainability if I need to remove the driver for any reason from an MDF baffle
Any alternatives?
These are the times that your imagination may be of help. In this case, you are not really using the screws for much of a mechanical support since the driver doesn't have so much mass as a larger driver. Most of the intent would be about sealing the driver to the enclosure. I would rabbet the edge to accept the driver, but slightly deeper so that a permanent ring could be epoxied to the cabinet. Having done that, you can then use a very thin double coated gasket to place the driver onto the cabinet. The gasket must be of a weaker type of hold that what is holding the metal/plastic ring epoxied in place. This way the driver can gently be pried out of place if needed.
I have a baffle (from a 'standard' RAW with the B80 and RS225-8) which is 25mm ply. It has an aggressive chamfer on the inside.
I'm considering replacing it - its not installed yet - mosylikely MDF like the rest of the cabinet. Ideally I'd like to also 'drill' for a 104,, tweeter, so I can change between them and see whether I prefer the full-range or a conventional design.
The question stands for future projects anyway, most likely MDF.
Currently 25mm but I would probably generally use 18 or 25.
Yes, its a Visaton B80.
Yes.
And replaced with what?
I do actually have some 'Mason Mate' rubber nuts. They are also a possibility, and might be easier to use. I'd still have to route a flat area into the chamfer on the back of the driver cutout, but at least they install from the front.
Rubber nut
Threaded inserts.
MDF is particularily bad at losing T-Nuts. With proper plywood, good screws usually work fine.
dave
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So just use the sort of things I'd have for the spikes, but M4 or M4? And very short bolts?
Aren't they generally rather thick? The B80 is problematic because the flang depth is very modest - only about 8.5mm, with the mounting holes in the middle (ie 4mm from the edge of the hole through the baffle).
Its a problem for the rubber nuts, which my calipers measure at 7.8mm diameter. All the threaded inserts I've seen are pretty sturdy.
This sort of thing can be so much more work than expected. MDF has plus and minus applications. Another idea if you the space on the baffle is to make a ring of strong material that is larger than the tweeter size. That means you can attach this more reliable quality material permanently to the MDF baffle and the allow yourself to choose a better way to attach the tweeter. I used Corian once for just such an application. In my case, I was able to use T-nuts without incident. Yes, they had to be modified and permanently epoxied to the rear of the Corian, All while keeping the holes of the tweeter aligned by mounting it during this process. To be clear, this is done before the Corian plate is affixed to the baffle. Once done then epoxying that Corian plate to the baffle will yield a stable strong mount for the tweeter and can be removed multiple times without any trouble. It is more work up front that pays off in the end.
Note that the B80 is not a tweeter - its a full tange driver.
B80 datasheet with dimensions
The tweeters I have need a much smaller hole through the baffle and generally have wider flanges and do not seem to be a problem. They also don't need roundover or chamfer on the back of the baffle.
Having said that I have another driver that is likely to be tricky too - also a small full tange (a Peerless).
I use threaded inserts (like the one on the left in this pic). They take up less space than t-nuts, so they can go closer to the edge. It's also possible to install them from the front, which can make things easier if the back edge of the speaker cutout is rounded over.
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As others, I am not a big fan of TEE nuts or "hurricane" nuts unless I have access to the rear. A failure with these can be fatal. Inserts are a better option in that they can be removed. In my experience, however, they can make a total mess out of plywood and can degrade MDF with all the stresses they create. For small drivers, screws. Don't oversize the cut out so the screws have a fighting chance.
I also use a "wood hardener" or "wood strengthener" product liberally where any holes are made.
The hurricane nuts from PE are unusual in that they have a fine thread. 10-32 I think. The SHCS screws can be really tricky to line up if the concentricity or drill angle is even the slightest bit off.
I also use a "wood hardener" or "wood strengthener" product liberally where any holes are made.
The hurricane nuts from PE are unusual in that they have a fine thread. 10-32 I think. The SHCS screws can be really tricky to line up if the concentricity or drill angle is even the slightest bit off.
Absolutely true! Misalignment can make a fool of us. And at times, we aren't building speaker from scratch. We are trying to resurrect something that is already assembled (though many times less than in a great way) If I have to use T-nuts, it is likely that I will grind off the points and make a hole slightly larger than the T-nut. Then the Trick icky part is to get all of these bolts aligned. I suppose making a template directly from the driver would help. No matter what it is all Voodoo until complete. When I make a baffle for a new build it is almost always 1 1/2" hardwood and the problem is moot.
I've sometimes glued T-nuts in place, sometimes ground the prongs a bit finer if I thought that they would split the wood, and sometimes ground a flat on them (so they have three prongs) if they were going to be close to the edge. I now mostly mount drivers from the inside, often holding them against the front baffle with springs, but it does mean you need a trap door for access .
The wood hardeners are ideal for old cabinets with a particle board construction. I am thinking specifically about a pair of Infinity Quantum I had a long while back. It is amazing how many desirable brands used that crap. Nice veneer, but lurking inside was 30 year old particle board that all the glue seemed to have degraded.
I used "Git Rot", a thin two part epoxy intended for weathered and degraded wood on boats. Works on water-damaged particle board kitchen cabinets as well. You could probably replicate that with fiberglass resin and a thinner. Soak that stuff into the dry particle board and it will hold a screw. Need to look at the ingredients.
I used "Git Rot", a thin two part epoxy intended for weathered and degraded wood on boats. Works on water-damaged particle board kitchen cabinets as well. You could probably replicate that with fiberglass resin and a thinner. Soak that stuff into the dry particle board and it will hold a screw. Need to look at the ingredients.