Steel Manufacturing Blog: Keeping it Steel

Understanding the Math Behind Steel Wedges

Posted on Wed, Dec 17, 2014 @ 02:23 PM

Steel Wedges are among the most basic and yet unique products our steel fabricating customers use.  They are used for almost everything, from separating heavy plates in the shop, to with an erector lift for extremely heavy objects, to shimming stair stringers.

For shim applications, there is usually no need to understand the lifting force the wedge can provide.  However, for lifting and/or separating purposes, the user will want to have an understanding of the weight being lifted versus the force being applied to the object.

The wedge is known in physics as a simple machine.  It is derived from the concept of an incline, and with this knowledge this is how the ancient Egyptians first built the pyramids. The theory behind the incline is that it takes less force to slide an object up an incline than it does to lift the object straight up.  It should be noted that in its original form this theory assumes there is no friction resistance, whereas friction in reality will depend on the object and the wedge being used.

To understand how utilizing a wedge works according to this physics theory, we’ve included an equation using an incline as an example.

In Fig. 1, the force required to lift 100 lbs. = 100 lbs.


Fig. 2 shows an incline of 45°. Assume side a = 100, and side b = 100. Side c would = 141.

understanding steel wedges

To calculate the force required to move the 100 lbs. up side c we would divide the distance the object will travel (c) by the height (side a).

Weight of object ÷ Force Required = side c ÷ side a.

Through this equation, Fig. 3 shows that the force required to lift 100 lbs. up a 45° incline is 70.92 lbs. Again, this assumes no resistance due to friction.


Taking this same equation one step further, we can adjust the numbers to suit more realistic steel wedge dimensions.  Fig. 4 shows a typical steel wedge, as shown as stock item - Steel Supply part no. 155-8 x 1, found here.


Following the same equation as before, in Fig. 5 the 100 lbs. requires only 12.40 lbs. of force to move it up the incline.


To the steel fabricator, this equation translates into a tremendous leverage advantage and makes steel wedges an important tool to have available.  The Steel Supply Company keeps wedges in stock in many sizes and can make wedges in almost any dimensions.

Check Out the Steel Stock Wedges Catalog!


made to order steel wedges

Tags: Wedges, Steel Wedges, Steel Wedge, Steel Shims, STEEL SUPPLY