How to Remove Bolts That Are Snapped Off Flushby C.L. Rease
Seized bolts that snap off flush with a part's surface create a frustrating, time-consuming issue. The majority of bolts seize due to corrosion in the form of rust. Rust forms when fasteners from a combination of heat, moisture and age. Freeing the snapped bolt requires that you attempt to break the bond created by the rust. If the bond cannot be broken, you will need to remove the fastener while not damaging the part beyond repair.
Put on your eye protection.
Place the point of the center punch on the center of the broken bolt. Holding the center punch straight with the bolt, look down from the back end of the punch, toward the bolt. Adjust the center punch as necessary to ensure that you have the exact center of the broken bolt. When you have the bolt's center, strike the back of the punch with the hammer.
Insert the smallest left-hand drill bit you have on hand into the chuck of the drill motor.
Place the point of the drill bit onto the depression left by the center punch that you created in step two.
Run the drill bit completely through the broken bolt. Keep the speed of the drill low; excessive speed will generate heat and quickly dull your drill bit.
Exchange the small drill bit for one that is slightly larger in diameter. Re-drill the hole through the broken bolt.
Test fit an extractor into the hole you drilled through the broken bolt. Repeat step six until the point of the extractor fits within the hole.
Place the point of the extractor into your drilled hole. Hit the back of the extractor to secure it into the broken bolt. Attach the 3/8th drive ratchet to the extractor. Turn the ratchet handle to remove the bolt. If the bolt does not move, do not force the extractor, Remove the extractor and proceed to step nine.
Continue enlarging the hole in the broken bolt with the left-handed drill bits. As the hole gets larger, repeat step eight to try and remove the broken bolt. If the bolt refuses to turn with the extractor, continue drilling, increasing the size slightly each time you completely drill through the broken bolt. Inspect the hole with each pass. Look for the threads of the broken bolt to show into the drilled hole. When the threads are visible, proceed to step ten.
Secure the proper size tap into the tee-handle. Apply a liberal coat of tapping fluid to both the tap and the drilled hole in the broken bolt.
Insert the tap into the drilled hole. Turn the tee-handle clockwise to start the tap.
Remove the tap after every 1/2 revolution to clean the tap. Apply additional tapping fluid to the tap after each cleaning. Run the tap completely through the broken bolt. Continue to step thirteen if the part's threads are unusable.
Follow the directions on the threaded insert kit to replace the damaged threads.
- Many times when a left-handed drill bit binds in the broken fastener, the broken section of bolt will turn out of the part.
Things You'll Need
- Eye protection
- Center punch
- Drill motor
- Left-hand drill bit set
- Bolt extractor set
- 3/8th drive ratchet
- Tap set
- Tap tee-handle
- Tapping fluid
- Threaded insert kit