Cabinet assembly question - large cabinet(~16 cu.ft.), MDF, butt joints with timber cleats. Would glueing, clamping and nailing the panels and cleats be OK for domestic use?
Marshall
Cabinet assembly question - large cabinet(~16 cu.ft.), MDF, butt joints with timber cleats. Would glueing, clamping and nailing the panels and cleats be OK for domestic use?
Marshall
Plywood would be better, MDF is not very stiff. I think I'd try OSB before I used MDF, as it's stiffness is supposed to be closer to that of plywood, yet it price is closer to MDF.Originally Posted by mah
Audio_by_Goodwill
Michigan, USA
MDF is already cut. Will add bracing and panel damping.
If you're using a pneumatic nailer or stapler, i'd say "go for it" but if you have to drive and set the nails by hand with a hammer, i'd opt for screws in a heartbeat. Hand nailing on something as rigid and hopefully precise as a speaker cabinet will likely loosen 3 to 5 fasteners for every one that you drive. My fastener of choice for MDF is coarse thread drywall screw. It's a pain in the butt, but i strongly recommend pilot drilling all screw holes to depth with a bit size equal to no more than the root diameter of the screw, about half the thread diameter with a coarse drywall screw.
A hint for your exposed MDF edges, fill them with epoxy, it adds strength against corner chipping, and gets rid of that grossly porous area for painting or gluing veneer on.
In my experience(and i've built a couple boxes) there is always a difference in sound between ply and MDF boxes, and which is "better" IMO, is very dependent on the driver being used. The only hard and fast rule, is that the larger the box, the more influence the material has on the sound.
I like working with MDF, it's extremely uniform, and is very easy to work, and has the best surface finish of any sheet stock you can buy. It's price is an added bonus.
Plywood, when we're talking a true veneer core plywood is superior by a big margin where overall strength and durability are concerned. Good plywood is expensive however, and can be cost prohibitive for the hobbyist/experimenter.
OSB, unless it's a specialty product like Advantech is something i would avoid simply because of it's lack of edge strength. Looking into the edge of standard OSB, it is the most porous of all sheet stock, and for the durability of corners and edges, the bond and composition is too coarse making it more easily damaged than MDF. Specialty products like Advantech would be far superior as they are much more dense, and contain significantly more resin. It's also ~30 bucks a sheet putting it in the plywood cost category.
Real birch plywood cannot be compared to any of the above materials. Birch veneer core plywood is a totally HARDWOOD product. By a good margin it is the heaviest, and strongest sheet stock you can buy. It also requires that all of your tools be at peak sharpness, and all fastener holes must be clearance and pilot drilled. It will also cost you 2 to 4 times what a good fir, spruce, or pine plywood will. Don't be fooled by places like Lowe's or Home Depot that pass off birch faced pine or spruce ply as "birch plywood" the only birch present are the two micro thin face veneers, the rest of the material is softwood. You will pay real money for real birch ply, generally $80 and up per sheet depending on supplier and the specific material.
FWIW, the two best sounding factory Altec boxes in my stable are both MDF construction, 9849-8D's and 620A's, they're also the most heavily internally braced Altec boxes i'm aware of.
No debate intended here, just my .02 and experience with sheet stock.
Not all vegetables make good leaders.
Agree 100% on every point with the caveat that screwing, nailing weakens joints plus create resonant 'hot spots' that theoretically need to be avoided, so if used at all should ideally be kept to a minimum for initial panel locating, then removed once clamped and filled with a matching sawdust/glue mix.
Note too that if a high aspect ratio cab, and especially if using MDF or other massive material with a Fs down in the cab's BW, then ideally 'X' frame bracing that ties all six sides together spaced at a golden or acoustic ratio to average out the new, smaller 'panels' resonances. At minimum, there should be fairly massive bracing tying the baffle, rear panels together around the woofer with a double thickness cab top plate.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
How about drilling out to a common diameter, maybe 3/8 or 1/4 and filling with wood dowel, glued in of course?then removed once clamped and filled with a matching sawdust/glue mix.
This has worked well for me in the past on visible exterior screws, if the dowel is cut squarely to the proper length, it can be tapped down with a block until flush, requiring no sanding and no waiting before paint or veneer.
Resonant hot spots had never really occurred to me, but since a screw left in place retains most of it's original clamping force, it makes perfect sense. I guess i should be doing this with all screws from now on.
I've just always had issues with filler shrinking or popping off screw heads, and the drying time is no fun either. So, my cheap and available solution was to pull the screws and glue pieces of dowel in their place, they can even be kind of attractive under a natural finish.
Not all vegetables make good leaders.
Ooops, sorry I didn't read the question carefully enough.
Audio_by_Goodwill
Michigan, USA
I'm with Bowtie on the drywall screws. I think my cabinet shop was a very early user of those, we did them early 70's.
Anyway, if you can rent an extra drill, one for pilot holes and one to drive keeps from changing bits a lot.
I used to draw a line where the screws went, then use a compass to subdivide it so the screws are equally spaced...
Then just drill and drive...it goes pretty quick...
Your neighbors called. They like your music.
Here are some 16ft^3 boxes I just built. OSB - glue and screw. Drywall screws - lots of them and plenty of Tightbond II.
Framed like a house. You can see the basic frame and the box. I agree, the edges of OSB are fragile. I'll be doing inlays of hardwood on the corners. This is a GM design MLTL.
416-8A woofers.
Greets!
Haven't forgotten you, my PMs are stacked up off the screen ATM. Have you sent THE letter yet?
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Posting Permissions
Bookmarks