At a basic level, you probably know that building materials are stronger in certain axes than others. While you could learn all about moments of inertia and beam bending, what the average DIY builder really needs is an intuitive sense of the practical ways you can configure whatever you're building with to make it stronger. Whether you're building a tank or a table, understanding the forces at work will help make it both light and strong.

Recently, I built a kitchen table for a couple in NYC using thin metal for the main support. Here are a few simple tricks for adding strength without adding much weight.

Technically, we're talking about the area moment of inertia and resistance to bending. Practically, we're talking about strength and rigidity. Since most DIY builders are more concerned with building something strong and light than with quantifying resistance to bending, we'll consider the practical approach and leave the math for another time.

Lets look at a simple example. Picture a 2x4 sitting on top of two sawhorses. (If you've never handled a 2x4 before, step away from the computer right now, head to the lumber yard, and try this.) Imagine pushing on the center of that span. Experience tells us that it will be harder to bend the 2x4 when pushing on the narrow side than when pushing on the wide side. Theory tells us that a plane passing through the 2x4 parallel to one of the "4" wide sides contains more material than a plane parallel to one of the "2" sides. At a very basic level, more material means more material to bend, which means a greater resistance to bending—what we call strength.

I used this concept twice recently in the steel column of a table I built for a customer. The column is made of 1/8" thick hot-rolled mild steel. Standing on its own, the 12" wide x 28" tall x 1/8" thick piece that forms the main part of the column would not be very rigid at all. A small amount of force—even just the weight of the tabletop—would cause it to bend and twist. Adding the 4" wide x 1/8" thick pieces on either side—essentially turning it into an I-beam—makes the column much more resistant to bending and adds very little weight compared to other ways of building such a rigid column. Even if I stopped here, the table base would have been strong enough to support the weight of the tabletop and several people standing on it.

With this design however, we went even further. In this table, the cutouts are purely for looks. In larger panels though, this style of cutout can significantly increase the local resistance to bending. The concepts at work are exactly the same as above: More material is added in a plane aligned with an otherwise easily bendable axis of the part. It is important to note that the part as a whole does not need to be made thicker to gain most of this strength - adding the material in just one or in a few places can give significant results.

This concept is found in most sheet metal parts that include large flat spans. Beads or flared holes in the sheet metal add material in planes that are aligned with an axis in which the part would otherwise be weak. That is, they essentially allow a thin part to behave like a thicker part without adding much weight. Where material is removed, as in the case of cutouts as above, or flared holes in sheet metal, weight can actually be reduced.

This concept is not specific to steel; it applies equally well to all materials. Consciously applying it to design decisions will yield significantly lighter and stronger results.

" /> Science of DIY: Make Weak Materials Strong with Simple Geometry
Monday, September 06, 2010
   
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Science of DIY: Make Weak Materials Strong with Simple Geometry

How putting holes in a mainstay can indeed have it stronger

At a elementary level, you substantially understand that office office office office office building materials have been stronger in sure axes than others. While you could discover all about moments of sluggishness as good as lamp bending, what a normal DIY builder unequivocally needs is an discerning clarity of a unsentimental ways you can configure whatever you have been office office office office office building with to have it stronger. Whether you have been office office office office office building a tank or a table, bargain a army during work will assistance have it both light as good as strong.

Recently, you built a kitchen list for a integrate in NYC regulating skinny steel for a categorical support. Here have been a couple of elementary tricks for adding strength but adding many weight.

Technically, you have been articulate about a area impulse of sluggishness as good as insurgency to bending. Practically, you have been articulate about strength as good as rigidity. Since many DIY builders have been some-more endangered with office office office office office building something clever as good as light than with quantifying insurgency to bending, you will cruise a unsentimental proceed as good as leave a math for an additional time.

Lets demeanour during a elementary example. Picture a 2x4 sitting upon tip of dual sawhorses. (If you have never rubbed a 2x4 before, step divided from a mechanism right now, conduct to a two by four yard, as good as try this.) Imagine pulling upon a core of that span. Experience tells us that it will be harder to hook a 2x4 when pulling upon a slight side than when pulling upon a far-reaching side. Theory tells us that a craft flitting by a 2x4 together to a single of a "4" far-reaching sides contains some-more element than a craft together to a single of a "2" sides. At a really elementary level, some-more element equates to some-more element to bend, that equates to a incomparable insurgency to bending—what you call strength.

I used this judgment twice not long ago in a steel mainstay of a list you built for a customer. The mainstay is done of 1/8" thick hot-rolled amiable steel. Standing upon a own, a 12" far-reaching x 28" high x 1/8" thick square that types a categorical partial of a mainstay would not be really firm during all. A tiny volume of force—even only a weight of a tabletop—would means it to hook as good as twist. Adding a 4" far-reaching x 1/8" thick pieces upon possibly side—essentially branch it in to an I-beam—makes a mainstay many some-more resistant to tortuous as good as adds really small weight compared to other ways of office office office office office building such a firm column. Even if you stopped here, a list bottom would have been clever adequate to support a weight of a tabletop as good as various people station upon it.

With this pattern however, you went even further. In this table, a cutouts have been quite for looks. In incomparable panels though, this character of cutout can significantly boost a internal insurgency to bending. The concepts during work have been accurately a same as above: More element is combined in a craft aligned with an differently simply bendable pivot of a part. It is critical to note that a partial as a entire does not need to be done thicker to benefit many of this strength - adding a element in only a single or in a couple of places can give poignant results.

This judgment is found in many piece steel tools that embody vast prosaic spans. Beads or flared holes in a piece steel supplement element in planes that have been aligned with an pivot in that a partial would differently be weak. That is, they radically concede a skinny partial to act similar to a thicker partial but adding many weight. Where element is removed, as in a box of cutouts as above, or flared holes in piece metal, weight can indeed be reduced.

This judgment is not specific to steel; it relates identically good to all materials. Consciously requesting it to pattern decisions will produce significantly lighter as good as stronger results.


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