Removing broken studs: getting rid of debris without damaging the thread

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If you are a motorist with experience, then you must have come across the fact that after several years of operation it is not so easy to unwind a bolted connection. It often happens that a bolt or stud breaks off. There are many ways to wring out broken pieces from the movement case. This includes welding nuts to them, and then power twisting, and inserting special screws. All of these methods have one disadvantage: applying excessive force can damage the case, which is expensive. Yes, and the welding machine may not be at hand. We offer you a chemical method to remove the rest of the stud from the body. Although it takes two days, it gives an excellent result.

Content:

Work materials

Materials for work

To remove a broken stud, you will need:

drill;
set of drills;
lemon acid;
heating element with a power of 1 kW;
infusion system for dropper and syringe;
machine oil;
PID (proportional-integral differentiating) thermostat REX C100;
tap.

Step 1. Remove the remains of the hairpin as much as possible

We drill out the remains of the stud from the body, starting with a thin drill and gradually increasing it to the maximum possible.

Drilling the rest of the stud out of the body

Drill carefully without damaging the threads in the housing.

Step 2. Etching the remnants of the hairpin

We make a concentrated solution of citric acid and use a dropper to feed it into the hole with a broken hairpin.

To speed up the reaction, we heat the engine block with a heating element, attaching it to the body from the side of the broken stud.

We connect the heating element through a thermostat and set the temperature to 80 degrees Celsius. We wrap the back of the engine to keep warm.

We install the thermocouple from the sensor in one of the holes for the stud, which we first fill with engine oil.

A violent reaction began in the acid hole.

To prevent erosion of the inner surface of the cylinders, lubricate them with machine oil and cover with oiled paper.

With a dropper, we regulate the flow of the acid solution at the level of its evaporation from the hole.

We leave everything for about 36 hours, until the reaction is completed. Periodically remove the liquid from the hole with a syringe and fill it with a new one.

Step 3. We drive the thread with a tap

After the specified time, we notice that the reaction has practically stopped.

We turn off the heating element, the acid supply system and remove the remains of the solution from the hole in the body and the plaque that has formed on it.

We drive the thread with a tap.