Opinions on screws vs. simply gluing/clamping joints? (1 Viewer)

[Mark.Louis]

Am new to the DIY world and am probably asking a question covered earlier, so please forgive me. I am doing my first subwoofer using Tempest in sealed box (can't get away with size of a vented design). I have basic tools now (circular saw with straight edge, drills, orbital sander, and maybe getting a router).

What I don't have are any clamps, and based on my visit to lowes and HD, they can get pretty expensive when large enough to hold a SW box together.

With 3/4" MDF, will using wood screws hold the butt joints together sufficiently tight/strong enough while the glues dries. Aside from percpetions of this "low rent" approach (vs. elegant approach of doing DAdoes, discuits, clamping, etc). are there any sonic or structural problems that arise from using wood screws? For example, will the box vibrate more with screws?

Thanks for the input. For those who recommend the glue and clamp method, any advice as to where to buy clamps more cheaply than HD will be greatly appreciated.

Mark

 

[Anthony_Gomez]

Screws will be fine. Just make sure you pre-drill ALL the holes, or the MDF will split. Also make sure you counter sink them. Get some bondo or putty to fill in the holes when you are at HT.

 

[Brian Bunge]

Actually, screws will countersink themselves in MDF if you use a drill with enough power. Having said that, I've had nothing but trouble when using screws. Even with pre-drilled holes I've had MDF split on me. It'll work though if you have no other choice.
What might be worth while is to buy a couple of the Merle Band Clamps from MLCS Woodworking. They're on sale right now (2 for $44.95) so this would be a good time to buy some. For building boxes it's best to take the little red things out. A couple of these could help you glue up your box in no time.
BTW, our very own Hank Frankenberg uses these with only glue and butt joints on all his enclosures. And I can assure you his cabinets are top notch.

 

[Ronnie Ferrell]

You can not beat Harbor Freight for bar clamps. 24" bar clamps for $4.99 each! You can get 6 of them for the price of one Jorgenson K-Body. They are nowhere as nice as the K-bodies, but they get the job done. Check their web site to see if you have one in your area. 2 to 3 times a year that have them for 1/2 price at the local stores. The price is already a steel before the sale!
Also, the only time I have had problem with screws and MDF was with a tapered countersink/pilot bit. Make sure the countersink/pilot bit has a straight shaft. I picked up a set of 4 Ryobi countersinks at Home Depot for around $5. They are made for quick change chucks, but work with any chuck.
I use 1.25" #8 wood screws with 3/4 MDF.
Ronnie

 

[Patrick Sun]

Clamp-n-glue
stronger than screw
plus less work
more time to lurk

 

[Brett DiMichele]

I have to say that I also had nothing but problems with the
MDF splitting using the glue and screw method. I predrilled
and countersunk every hole and most of them split the MDF
even though I used a depth stop to make sure the holes were
of sufficient depth.

The new box will be strictly glued butt joints with some
internal Dado work for the internal braces.

 

[Hank Frankenberg]

As my shadow Brian said, butt joints and glue - no screws. Screws are extra expense, time and labor and won't make a stronger joint. That's assuming you have accurate, 90-degree smooth saw cuts on your panels, leaving no gaps.
Speaking of top-notch cabinets, how's it going Brian?

 

[PaulDF]

I glued and screwed my cabinet as I had no clamps on hand. Though this was my first sizable cabinet building experience, I have had no major problems with the screws so far. But I have had minor problems.... The screw holes were hard to fill, and the MDF kind of swelled along the length of the screw. Took me a LOT more work to prepare for the high gloss finish coat, but its almost done and it looks pretty impressive. Next time I'd try something different, but I still might use a couple screws.

 

[Ronnie Ferrell]

As everyone has said, clamp and glue only is easiest, usually. On large projects, I use both screws and clamps. The screws are mainly to hold the project square and flush while I'm clamping. The screws are a lot cheaper than buying a brad nailer and compressor, though they are on my wish list! Also a band strap like Brian suggests would help a lot with this. I really need to get one... or two!
It is an added expense for the screws unless you don't have any clamps to start with. Then screws are A LOT cheaper to use, especially if you do not plan on doing any other woodworking besides building the sub.
Also as everyone has said, screws do not make a joint any stronger. But to answer your question, I don't feel they make it any weaker either. I used screws all the time, before I got all my cheap Harbor Freight bar clamps.
If you are worried about the acoustical properties of the screws, then remove them and fill the holes after the glue dries. I always do this because I usually don't counter sink them enough and they stick up a little.
I always drill the pilot hole (not the countersink of course) from the opposite side of the top piece of MDF. Then I flip it over and do the countersink and the correct depth into the second piece of MDF. This way I know the screw will enter the center of the 3/4 MDF edge, even if I do not have the drill perfectly perpendicular to the work.
After making the countersink and pilot hole, I drill out the hole in the top piece so the screw can slide through and bite into the second piece of MDF. That way the joint can pull up nice and tight for the glue to form a good tight bond. Before using screws, test it out on scrap pieces of MDF several times. Try to find out how close to the edges you can get before the MDF will split. I also over tighten and strip out some of the screws in the scrap just to get a feel of how tight I can tighten the screws before on the real project.
Hope that helps!
Ronnie

 

[Aaron_Smith]

Even if you use the screw method, you may find yourself wishing you had clamps just to hold the workpieces together while you drilled the holes for the screws. I second the opinion on Harbor Freight, most of what they sell seems to be junk but you can get decent bar clamps there for CHEAP- just last weekend I got 6 24" and 4 30" for around $40.
I didn't want to spring for the clamps either but I'm glad I did. In addition to making the speaker building process 10x easier, you'll be amazed at how many uses you have for your clamps around the house!

 

[Ronnie Ferrell]

you may find yourself wishing you had clamps just to hold the workpieces together while you drilled the holes for the screws.

Ooops, you right! :b

I do that too! I guess you will need at least 2 clamps if you are going to screw-n-glue instead of clamp-n-glue.

FYI: If you DO go to Harbor Freight for clamps, make sure you keep your receipt. The Pittsburgh clamps have a life time warranty!


Ronnie

 

[Carl_Berg]

Personally I hate MDF and use appleply or baltic birch. Being in the Pacific NW appleply is available and is awesome. Nice Maple face and 13 ply in 3/4 and weighs about 60-65% of what the same size would in MDF at many times it's strength. You can also get it all the way up to 1.5" thick (i believe like 27 ply in 1.5" - crazy)and it can be had in normal 4x8 sheets unlike most baltic birch which is normally found in 5x5 sheets.
So with that said I am a huge fan of the kegg pocket hole jig. All screws are hidden in the inside and you only need 2 clamps. Do the pocket holes first, use gorilla glue, clamp to a perfect fit, drive 2 pocket holes screws, move on to the next piece. No having to let everything setup between each piece and the strength that can't be beat. In addition no holes to fill or hide. In conjunction with apple ply or baltic birch you can finish a "rough" box and have it look very nice. The edges of multiply plywood looks very nice.
Overall I think it makes assembly way way faster - especially if you don't have all that many clamps.
This is my technique and the pocket hole jig is amazing for face frames of cabinets (as in kitchen or bathroom cabinets) as well. Very cool tool.
No I don't sell them just use it and like it lots .
Personally although MDF is very solid and inert I would stay away from it and go with the alternatives above. Unless for speaker cabinets in which case I would probly use a combination of MDF and appleply. It also is nowhere near as nasty a dust as that from MDF.
I built 2 maelstrom sealed subs this way and have been very happy with the result.
CB

 

[Mark Fitzsimmons]

Mine is glued, but since I didn't have clamps, I just screwed it all together to hold it in place while the glue dried.

If you are using screws at all, definitly put the glue there since it will help ensure the enclosure is air tight.

 

[Jack Gilvey]

Just butt joints, Gorilla glue and lots of clamps. The poly glue really fills any gaps in imperfect cuts (most of mine)and obviates the oft-recommended step of running silicone over the joints to seal a box. As strong as it gets, also.
I use a few Bessey K-Body clamps at corners to really square up a box and sprinkle a few cheaper ones liberally all over.

Nothing beats a nice butt.