How to Repair Broken Plastic - Diy Plastic Welding

A while back, a corner snapped off one of my plastic parts, leaving me with two separate pieces. Replacing it would have been the easy option, but I didn't want to throw away something that was mostly still in good shape.

So I decided to try plastic welding with a soldering iron. I made a custom tip for the iron, joined the broken pieces temporarily, and then reinforced the break with fine mesh from an old metal tea strainer, melting it into the plastic.

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1. The broken plastic part
2. Soldering iron
3. Two soldering rods to compare (one normal, one custom-made with a slightly pressed and pointed tip)
4. Nose plier
5. White tape
6. Old metal tea strainer with a very fine mesh
7. Scissors
8. Drill machine with a drill bit
9. A piece of wood board (to support the part while drilling)
10. Soft cloth
11. Screwdriver

Start by looking closely at the damage. In my case a corner of the plastic had snapped off completely, so I had two separate pieces. Checking how the break lines up gives you a clear idea of what needs to be repaired and how the pieces will fit back together.

I compared two soldering rods and picked the custom-made one, which has a slightly pressed and pointed tip. I opened the screw on the soldering iron, slid the custom rod inside, and tightened it securely so it wouldn't move during the repair.

Using a nose plier, I bent the tip of the rod into an L-shape. This made the iron easier to handle on the plastic surface during the repair.

I brought the broken piece back to its exact original position. Holding one side in place, I used the soldering iron to melt and join the plastic temporarily. Then I aligned the other side carefully and secured it the same way. Good alignment here matters, because everything afterward builds on it.

I stuck white tape on the exterior side of the part, where I hadn't used the soldering iron. Then I trimmed off the excess tape at the front so the next steps would be easier.

I used an old metal tea strainer with a very fine mesh. Since the plastic was quite thin, a fine mesh was the better fit. I cut the mesh from one side of the strainer, placed it over the broken area, and trimmed it to match the size and shape of the break.

I held the mesh in position and used the soldering iron to secure the corners and side sections first. Then I worked on the broken center and welded it back together. As I pressed the hot iron over the mesh, it sank into the plastic and became embedded, which adds strength to the repair. I kept pressing around the edges and across the center until the whole mesh was firmly fixed in the plastic. I also used the tip of a screwdriver to help press the mesh down in tight spots.

Some plastic was slightly raised on the repaired area. I carefully applied heat again with the soldering iron to smooth and level it, giving the repair an even, uniform shape.

I peeled the tape off the repaired plastic. Some adhesive stayed behind on the surface, which I left to clean up in a later step.

The mesh had covered the part's original hole. The other side of the part has the same hole, so I used it as a guide and drilled a new hole of the same size and position, with the part supported on a piece of wood. Now both sides matched again.

I used a soft cloth to carefully wipe the leftover tape adhesive off all sides of the part. After cleaning, the surface was smooth, clean, and even.

To check the strength, I held the repaired corner and hit it firmly against the table several times. I also pressed on it with force and tapped the corner with a screwdriver. The repaired section stayed firmly in place with no visible damage.