Cracked Aluminum Shovel

Check out the Video of the repair at: http://youtu.be/mDr2ubc9j3M

This is a common failure of this type of shovel. It happens when it is overloaded many times by either prying with the tip or lifting heavy material close to the front edge.

Based on the fact that the handle has also been broken I am going to take the leap and say that this shovel has been used to do a lot of prying.

Quickly I have to mention that this shovel is only $20 bucks at Harbor Freight.

http://www.harborfreight.com/aluminum-scoop-shovel-with-d-handle-69824.html

If you are planning on putting in more than an hour or so into repairing your shovel I would recommend you just buying a new one.  I know that some people have a hard time with the idea of throw away tools, but this is a throw away tool.

Let’s talk about section modulus.

As defined at: https://www.google.com/?gws_rd=ssl#q=section+modulus+definition

Section modulus is a geometric property for a given cross-section used in the design of beams or flexural members. Other geometric properties used in design include area for tension, radius of gyration for compression, and moment of inertia for stiffness.

What this means is that the bigger the section modulus the bigger the load can be taken by the beam (in this case the shovel) before it bends or deflects.  For example; a flat sheet of aluminum has a very small section modulus because all of the material is very close to the neutral axis. To stiffen the shovel the manufacture adds bends to the plate which pushes the material away from the neutral axis and causes the section to be stiffer. In the following pictures I will try and show this concept.

Sheet of aluminum on the left and the same material bent to make the shovel shape on the right.

Let’s talk a little about how the shovel was designed to be loaded.  The shovel has a large blade that is designed to move loose, light, low density material. I think it is fair to say that this shovel was intended to move less than 20 pounds per shovel full. I say this because 20 pounds is about the most an average person could lift very many times. The center of the weight would be located over the center of the shovel blade.

The failure on this shovel indicates that is has been used to pry heavy loads with the front edge while pivoting on the heel of the blade.  A couple of things point me to this conclusion; firstly, the front edge is badly damaged by what looks like hitting hard stationary objects, and secondly, the crack is in the middle of the center support.  This crack is a result of the top of center support seeing in many tension cycles. The most likely culprit for this tension is prying.

How to fix:

Clean the metal, and drill a hole at the end of each crack. Refer to the video for more information on why you want to drill the holes. Weld repair the cracks and increase the length of the stiffeners so they end closer to the handle.  Again, refer to the video for more info. Finally recondition the front edge to a new like condition.

If this failure has happened to your shovel I would question if you are using the right tool for the job, and then I would buy a new one from Harbor Freight for $20 bucks.