Bruce Barnett wrote:
> [email protected] writes:
>
> > Just a quick question and forgive me if it annoys you, how deep into
> > the wood should a screw go? A 1/3 of the width of the wood? 2/3s?
>
> There is no single answer.
>
> Some times when I want to mount a flat board to a faceplace for my
> lathe, I use 1/2" #10 screws and shorten/sharpen them so the strength
> increases while the requirement for penetration decreases. (This was
> for a design where the side with the screw holes is never seen). The
> shorter the penetration - the more usable wood I end up with.
>
> I can give an example where the longer the screw - the better.
>
>
Argh I'm new to woodworking, I don't know the terminology, so bear with
me please.
I'm making a freestanding shelves unit. I'm using shelf boards that are
sold per piece, and then I'm using two rather thick and long pieces of
timber (I think it was 5cm x 8cm x 2.4m) so that I would make it stand
upright and then fit the shelves on it. To do that I'll be using those
L-shaped pieces of metal. Two for the two pieces of timber to make it
stand and not fall on its face, each one of them (the metal L-shaped
things) will be ~30cm, facing away from the wall - the shelves will be
standing against the wall but not attached to it. Then I'll use smaller
pieces of those L-shaped metals to attach the shelves to the long
pieces of timber.
My question really is about the two long pieces of timber, when I
attach the L-shaped metals to them on which the shelves will rest (and
will be screwed, but I know I'll just use 12mm screws for those because
the shelves will be 20mm and will rest on the metal anyway), how deep
into the long pieces of timber should the screws go to make sure the
shelves don't fall off, and how long should I choose the screws to be?
Should they go a 1/3 of the way in, or 2/3s?
I should say that I'll be using the shelves for books, so I expect that
they'll have to bear some weight.
Many regards and thanks.
>
> --
> Sending unsolicited commercial e-mail to this account incurs a fee of
> $500 per message, and acknowledges the legality of this contract.
---<| screws are measured from the very pointy end of the tip to the flat
end on the fartherest side
---|) screws are measured from the very pointy end of the tip to the flat on
the underside. Same with machine screws, and lag bolts I believe.
generally in 1/8" increments, so don't bother looking
I constantly trim the ends off with a dremel for max penetration. Tip
rarely matters. Pre-drill is often needed
the deeper the better, esp. in end grain, mdf, particle board. I'm not
happy if I'm more than .020" away. About a 7 pieces of paper.
In machine screws fine threads are stronger than coarse, e.g nf>nc.
when push comes to shove, add more depth rather than force width
wood screws come in numbers #8 is commonestly, 6, 10,12, 4, 14. smaller is
smallerestly
simialry sizes use like screwdrivers
they come in silver, gold and black
Gold ones snap, esp. the small ones. Don't use these.
Black ones rust. Don't use these either.
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when they get longer the increment changes to 1/4", then 1/2". Don't look
for those.
The length of the unthreaded shoulder just undre the head is designed
according to an ancient recipe of a max of 1/3 third the shank length or a
minimum of n inches or whatever. Don't look. Sometimes it is better to buy
a shorter screw with more thread. Don't ask. and definelty don't ask about
washers.
The radius on the underside of the head of machine screws is controlled to a
very high tolerance also. In metal to metal contact m/c screws should have
calculations made such that enough threads are engaged so that the tensile
strength breakage point is converely supplemenatry.
The coefficient of friction, µ, of a titanium and carbon or low allow steel,
but not corrosion resistant steel between a nut and a bolt is .08 (+/-20%)
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actually everything about any screw you can buy is predetermined. I read
Machinerys Handbook. There are pages upon pages of indexes on everything
you could want to know. Its a book about a book. Then its a book. There
are no surprises in fasteners. Its just easier if you can just pick up one
screw that ain't gonna do it and if you have a basic knowledge you can count
the ways to get where you are going. You can shop at HD without moving your
feet. But the calculations! You ask. It gives. Before you can ask. Its
not big onn wood though, there is a bit of info. I'm not looking.
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whats really intersting though isn't recognising that there is a 1/2"
unthreaded shoulder on all screws from e to f lengths, 3/8" before, 3/4"
after, none here, etc. but being about to recognize where the potential
breaks are. Where logic makes a U-turn - it is natural - I sold screws for
a while. This Q isn't rocket science. But you bettter beieve that it is.
You could literaly spend the rest of your life gathering info - and yes, you
would need a genius IQ just to even think about it.
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Brian Henderson wrote:
> On 24 Feb 2006 16:35:06 -0800, [email protected] wrote:
>
> >Just a quick question and forgive me if it annoys you, how deep into
> >the wood should a screw go?
> The only real answer is "deep enough to do the job".
I agree. Whenever I screw I bury the wood entir...err...forget it.
JP
Fri, Feb 24, 2006, 4:35pm (EST-3) [email protected] doth query:
Just a quick question and forgive me if it annoys you, how deep into the
wood should a screw go? <snip>
All the way.
JOAT
If you have something to say, raise your hand.
Then shove it in your mouth.
On 24 Feb 2006 19:27:10 -0800, [email protected] wrote:
>how deep
>into the long pieces of timber should the screws go to make sure the
>shelves don't fall off, and how long should I choose the screws to be?
>Should they go a 1/3 of the way in, or 2/3s?
You are getting people all mesed up about a handful of screws for
God's sake. Do 2/3 and forget it. If they don't work your project
was doomed for failure from the start; 1/3 wouldn't work if 2/3
wouldn't. Make an adult decision.
"bent" <[email protected]> wrote in message
news:[email protected]...
> ---<| screws are measured from the very pointy end of the tip to the flat
> end on the fartherest side
> ---|) screws are measured from the very pointy end of the tip to the flat
> on the underside. Same with machine screws, and lag bolts I believe.
> generally in 1/8" increments, so don't bother looking
> I constantly trim the ends off with a dremel for max penetration. Tip
> rarely matters. Pre-drill is often needed
> the deeper the better, esp. in end grain, mdf, particle board. I'm not
> happy if I'm more than .020" away. About a 7 pieces of paper.
> In machine screws fine threads are stronger than coarse, e.g nf>nc.
> when push comes to shove, add more depth rather than force width
> wood screws come in numbers #8 is commonestly, 6, 10,12, 4, 14. smaller
> is smallerestly
> simialry sizes use like screwdrivers
> they come in silver, gold and black
> Gold ones snap, esp. the small ones. Don't use these.
> Black ones rust. Don't use these either.
Take a look here for good screws and a wealth of information that may be
contrary to your terminology and way of thinking.
wrote:
>
>
> Just a quick question and forgive me if it annoys you, how deep into
> the wood should a screw go? A 1/3 of the width of the wood? 2/3s?
The correct answer is "deep enough".
All depends on what you're screwing to what. You're looking for a one
size fits all answer and there is no such thing.
Joe Barta
[email protected] writes:
> Just a quick question and forgive me if it annoys you, how deep into
> the wood should a screw go? A 1/3 of the width of the wood? 2/3s?
There is no single answer.
Some times when I want to mount a flat board to a faceplace for my
lathe, I use 1/2" #10 screws and shorten/sharpen them so the strength
increases while the requirement for penetration decreases. (This was
for a design where the side with the screw holes is never seen). The
shorter the penetration - the more usable wood I end up with.
I can give an example where the longer the screw - the better.
--
Sending unsolicited commercial e-mail to this account incurs a fee of
$500 per message, and acknowledges the legality of this contract.
> Argh I'm new to woodworking, I don't know the terminology, so bear with
> me please.
>
> I'm making a freestanding shelves unit. I'm using shelf boards that are
> sold per piece, and then I'm using two rather thick and long pieces of
> timber (I think it was 5cm x 8cm x 2.4m) so that I would make it stand
> upright and then fit the shelves on it. To do that I'll be using those
> L-shaped pieces of metal. Two for the two pieces of timber to make it
> stand and not fall on its face, each one of them (the metal L-shaped
> things) will be ~30cm, facing away from the wall - the shelves will be
> standing against the wall but not attached to it. Then I'll use smaller
> pieces of those L-shaped metals to attach the shelves to the long
> pieces of timber.
>
> My question really is about the two long pieces of timber, when I
> attach the L-shaped metals to them on which the shelves will rest (and
> will be screwed, but I know I'll just use 12mm screws for those because
> the shelves will be 20mm and will rest on the metal anyway), how deep
> into the long pieces of timber should the screws go to make sure the
> shelves don't fall off, and how long should I choose the screws to be?
> Should they go a 1/3 of the way in, or 2/3s?
>
> I should say that I'll be using the shelves for books, so I expect that
> they'll have to bear some weight.
>
> Many regards and thanks.
>
Better questions bet better answers. That is a much better question.
20 or 22mm. Go as far as you can without coming out the other side.
Wood screws have a tapered profile and their bite come from the thread (or
depth there of). Since the very tip of the screw (the first 4mm (1/4'")or
so) is narrow the threads can't be to deep and it can't get much bite. What
I am saying is that the 1st 1/4" of screw doesn't give you any significant
holding power.
If your screw is 2 inches (5cm) long that's not really significant, if your
screw is 10mm, that's nearly half your screw.
As others have said, it's tough to comew up with a simple rule.
On 24 Feb 2006 16:35:06 -0800, [email protected] wrote:
>Just a quick question and forgive me if it annoys you, how deep into
>the wood should a screw go? A 1/3 of the width of the wood? 2/3s?
Depends on what you're screwing, what kind of wood you're using and
how strong it has to be. For a joint that doesn't need to be very
strong, you'll need less "grab" than a joint that's load bearing.
Screwing into soft wood is different than screwing into hard wood.
The only real answer is "deep enough to do the job".
[email protected] wrote:
>
> Just a quick question and forgive me if it annoys you, how deep into
> the wood should a screw go? A 1/3 of the width of the wood? 2/3s?
>
> Thanks and many regards.
>
You mean thickness? The standard solution is the
screw should be 3 times as long as the thickness
of wood piece it hold. Often not an option.
Maybe you are asking how deep can you screw it
without a bulge in the wood. If so, and you drill
pilot holes, the screw tip should stop about 1/8"
to 1/4" from the wood surface that is visible and
to be finished.
[email protected] wrote:
>
> Just a quick question and forgive me if it annoys you, how deep into
> the wood should a screw go? A 1/3 of the width of the wood? 2/3s?
>
> Thanks and many regards.
>
Wouldn't that depend on the thickness of the wood? Wouldn't it depend
on what is being attached? I can't think of any "one size fits all"
answer to your question.
Dave
On Sat, 25 Feb 2006 02:10:29 -0500, "bent" <[email protected]> wrote:
>simialry sizes use like screwdrivers
>they come in silver, gold and black
>Gold ones snap, esp. the small ones. Don't use these.
>Black ones rust. Don't use these either.
>
Color really nothing to do with material a scew is made of. You can
get black and gold steel or black and gold aluminum and the black
steel and black aluminum will behave quite differently. You have to
check for the material they are made from. Stainless steel is less
likely to rust than galvanized steel and both are less likely to snap
than an aluminum or brass screw.
<[email protected]> wrote in message
news:[email protected]...
>
>
> Just a quick question and forgive me if it annoys you, how deep into
> the wood should a screw go? A 1/3 of the width of the wood? 2/3s?
>
> Thanks and many regards.
>
Most screw manufacturers say 1/3 of the screw in the top piece, 2/3's of the
screw in the bottom piece.