A small skatepark in San Pedro Springs Park, in San Antonio, features a popular curb ledge that was looking pretty haggard. Over time the ledge had cracked and the leading edge was crumbling away after thousands and thousands of grinds. Local advocates approached the Parks Department with an easy and inexpensive idea: Refurbish the edge with a long piece of angle iron. The Parks Department approved the repair and the skaters went right to work.
This type of repair is something that almost anyone can do. The tools are common and there are special techniques required. The only tool that may not be in every garage is a hammer drill, but it’s not so uncommon that a neighbor or friend won’t have one. As a last resort it can be rented.
— 3/16″ masonry bit (for concrete)
— Black oxide, titanium, or cobalt 1/4″ bit (for steel)
— Phillips driver bit
3/16″ or 1/4″ piece of angled steel of desired length
Tapcon 1/4″ x 2-3/4″ #3 Phillips Head screws, 2 for each foot of bar length
Enamel paint (spray is easier than brush)
In this repair, rather than cutting out the old section and replacing it, a piece of steel (or angle-iron) will be fixed right over the concrete using screws. This will provide a smooth grinding surface and protect the concrete below from any additional wear and tear.
You’ll need a piece of angle iron fabricated for your needs. In this case the piece used is 3 inches on each side so that 3 inches will be on top of the ledge and 3 inches will be on the face of the ledge. No epoxy or adhesive is used in this project so it’s important that the new steel plate is long enough to prevent the screws from blowing out the concrete.
This diagram shows how the screws will be anchoring the plate to the concrete base. If the screw is set too close to the leading edge of the plate, the concrete beneath may blow out and not hold the screw securely. At least 2 inches of concrete should be around the screw.
One must use a black oxide, titanium or cobalt 1/4″ drill bit first to start the pilot hole into the steel. You can drill these holes through the steel away from the ledge. Place the steel onto the ledge and use a 3/16″ masonry bit in the hammer drill to drill the through that pre-punched pilot hole into the concrete. Have someone hold the bar firmly in place while you drill; if the bar moves the holes won’t line up when you drive your screws in.
TIP: When drilling into the concrete make a small up and down motion with the drill allow the concrete dust to come out of the hole.
Offset the location so that the screws aren’t both going in at the same area which may weaken the concrete. In other words: At 6 inches, put a screw in the top, 6 inches from there put a screw in the face, then in 6 inches put a screw in the top, and so on…so that the screws are staggered.
After the hole is drilled into the concrete. Use a 1/2″ black oxide, titanium or cobalt drill bit to counter sink the pilot hole. Be careful not to drill all the way through the steel. (If you’re not comfortable with the technique, you may want to practice on a spare piece.) You want to drill far enough into the steel where the Tapcon screw head is flush with the steel. If the screw head is sticking up too far it can catch your truck or board when sliding or grinding.
Driving the Tapcon screw can be a difficult process. If you are having trouble driving the Tapcon screw use the masonry bit in a hammer drill to bore out the hole some more. Be careful not to bore out too much or the screw will not hold. Also using a high torque cordless impact driver can make this process much easier.
Once you have everything in place and the steel is tightly fastened to the ledge. Use some rust preventing spray paint to paint the steel. This will make the steel easier to grind, and prevent water from getting underneath the screw and rusting out the counter sink holes.
One last note. Do not go to one of the large franchise home improvement stores to purchase your angle iron. Instead, visit a steel yard and purchase a 3/16″ or 1/4″ thick piece of steel. This grinds much better than the thin types you find at a home center. You can also have it fabricated in a steel shop to avoid the sharp edge you find on most angle iron.
The angle iron isn’t typical. It’s actually rolled sheet metal with a fillet edge. Most ordinary angle iron will have a square, sharp leading edge. Depending on your budget and resources, either will work but the eased fillet edge will be more comfortable for skaters.
That’s basically it! If you repair a ledge using this technique, we’d love to hear about it!