Lashing Repair of Plastic Stuff

I have a plastic scoop shovel that I use for shoveling snow.  A couple of years ago, it developed a fatal crack.  From past experience with attempts to glue plastic used in tools, cars, and electronic housings, I knew that gluing wouldn't work.

I decided to try lashing.  This repair is an unqualified success.  It has held up well for two years and shows no signs of deterioration.

I used 100% nylon upholstery thread.  Virtually any abrasion resistant heavy thread or cord that will not deteriorate under the environmental conditions it will be subjected to will work just fine.

Step 1 Stress Relieve the Crack

Drill a hole at the very end of the crack. If the crack is within a surface and doesn't break an edge, drill a hole at both ends of the crack.  This will prevent the crack from "running" further.

The sharp point at the end of the crack focuses stress astronomically.  If the crack is pulled apart, all the force is concentrated at a very tiny point.  One pound of stress can concentrate to hundreds or thousands of pounds per square inch.

By drilling a hole, the stress is now distributed around the circumference of the hole and the psi is vastly reduced.

Comments

[l8nite]

I agree this is a great idea for repairing some plastic items, thank you for posting

[rimar2000]

Good work!

I repaired some plastic things (a tools box, a water valve, etc) using the tin solder and plastic bottle strips. It is very easy, and the results are satisfactory. I wolud make an instructable of that.

Your method is better for heavy duty tools.

[NachoMahma]

. Great idea. The pictures could be a bit more in focus, but seem to show enough detail.

[augur45]

Focus, yeah.... Auto-focus camera. The original 7meg bit photo looked good, but when I reduced it in size to reduce upload bytes, it blurred a bit. Maybe more light would have helped the camera get better focus. Or maybe it was a jpeg problem, jpeg being lossy and all.

Like you said, photos seemed good enough to illustrate the point, so I went with it.

Thanks for your comment.

[CaseyCase]

Nice! I do exactly the same thing to my broken plastic laundry baskets. I dab all the laces with an oil-based polyurethane for extra durability.