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Screws that should not be screwed

edwin's picture

I am continually suprised at how often I see people who should know better recomend the use of drywall screws for building construction, and a variety of carpentry and cabinet work, other than the hanging of drywal. I have seen it in both Fine Homebuilding and Fine Woodworking  as well as other magazines and TV shows (along with the use of flat head screwdivers. So what to use for round head screws or pan head screws?).  

There are a host of reasons for not using drywall screws in lieu of wood screws for attaching wood to wood or hardware to wood, but I will touch on only a few and suggest that editors start to address this issue and that practitioners of our wonderful trade and craft do some resurch on their own

Probably the most important reason is that drywall screws are not very strong, They are hard and sharp and easy to drive but they have very thin shanks and  britle making the heads easy to break especially when driven with an inpact driver.   Secondly, the threads go all the way to the head making them difficult or impossible to draw two pieces of wood tight . Other charicteristics such as bugle heads, lack of corossion resistance, very sharp points and  ease of spliting wood make them unacceptable for much other that drywall.

Buggs me too. (post #190941, reply #1 of 6)

But whatcha gonna do?  Bad advice is everywhere nowadays.  I'll add that I don't always understand why so many screws are used where nails would be a better choice. 

When the patent on philips (post #190941, reply #2 of 6)

When the patent on philips recess expired, Paul Piffin invented the now well known Piffin screw. The classic Piffin screw,  having a Rockwell C of 65.7 (so the recess wont strip), has a yield strength of 123 ksi, and is very strong, but ultimate is only 123.56 ksi, hence not a lot of margin for design error on individual strength, hence the reason to use lots of them...

Contrary to 'the purist viewpoint', since Piffin screw are cheap and can be bought by the 40# box, it is easy to just use lots more of them rather than resorting to more pricey less hardened screws.  I personally like a hard screw now and then.

Use to hold wood together is a good use on pine, hemlock, and other relatively soft woods.  The need to predrill on teak, oak, apitong, cocobolo, and hickory diminishes their use with those woods as the labor to pre-drill more htan offsets the higher cost of less frangible fasteners.

In the manufacture of predinhnal sheathed errenoalreefers, Piffin screws are unsurpassed, as the trip mechanism on the percrodalgernater does require a frangible pintle prong.

And let us not forget the 'lets get back at the GC for no bonus'!  A Piffin screw thru a piece of hardboard makes an excellent improvised caltrop.  A few of these in the area of GC's car will be sure to cause that esteemed worthy a slight delay for unscheduled maintenance of traction devices on his next non-perambulatory trip.  A few of these strewn in the path of any Marathon or the Tour de Fancais also makes for exciting times.

As for hanging cabinets:  Piffin screws are unsurpassed !  A HO who looks inside the top cabinet is sure to notice the 14 heads per foot fasteners holding the exotic pressboard cabinets flush against the wall board - and you DO need lots of any type screw to hold your typical loaded kitchen cabinet up to just drywall. 

In closing, Piffin Screws should be the Maine screw in everyones kit for those myriad tasks eveyone dreads.

As for drywall itself, why bother with Piffing fasteners, any old nail gun is quicker.  You can use 8d linkers very effectively for drywall as you can be sure of recalls due to the long nails popping in a year or so - just after warranty expiration.

Thank goodness (post #190941, reply #3 of 6)

all the smart knowledgable guys didn't leave.  Otherwise we might never get a good answer.

whew.

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I hardly ever use nails (post #190941, reply #4 of 6)

I hardly ever use nails (don't have any power nailers), but I don't use drywall screws for anything structural.  Mostly I use GRKs.  Never broken one of those and never had one strip out.  I would like it better if there were more sizes available with a naked shank, but if I really need to pull two pieces together I can drill a clearance hole.

For most purposes I like the bugle head, since it countersinks itself pretty nicely in most cases, and (where visible) the appearance is pretty good.  I do keep some cabinet screws around for when I need a round head, though.

Keep in mind that you can't easily tell on TV whether a drywall screw is being used or a structural screw of some sort.  Before I switched to GRKs I used deck screws, which often have roughly the same color as DW screws and would be hard to distinguish on TV.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

How about deck screws? (post #190941, reply #5 of 6)

How about deck screws?

Greg

Hello Son, (post #190941, reply #6 of 6)

I'm proud of you!

 

http://www.google.com/url?sa=t&source=we...

 

Now go forth and screw the deck out of everything.

 

 

Oh Well,

We did the best we could...