Saturday, 11 July 2015

Repairing An M5 Thread On A Capacitor

I salvaged four capacitors from the Red Light Camera i did a teardown on a while ago. I found when i removed them that one capacitor had one thread completely gone. It looks like it might have just been over tightened at the factory.

The damaged thread.

I opted to try and Helicoil it, i have used them before to repair larger threads like M12, the capacitor uses two M5 which are much smaller but i thought i would give it a try.

The procedure involves buying a kit which contains the coils, drill, tap and a couple of insertion tools.

The first step is to drill out the old thread with the included drill bit then you tap and then insert the coil. The coil becomes the new thread at the original size.

In this instance there is a small issue in that these are not really designed to be inserted into shallow blind holes, you need enough depth to get the drill in and the tap has to work to a minimum depth to cut the thread.

So first off i ground the tip off the drill and the tap so i can work with a shallow hole.

Drill and Tap with ground ends.

After drilling out the old thread.

Cutting the new thread with the supplied tap.

The new intermediate thread for the coil.

The coil on the insertion tool. The coil will become the new M5 thread.

Inserting the coil. It simply screws in.

The end result, a new M5 thread that will actually be stronger than it was originally.