Tips & Techniques for Removing Roll Pinsby G.K. Bayne
Roll pins are typically used in place of bolts to hold two pieces of metal together. The roll pin is generally a solid piece of metal that fits tightly into a machined hole. At times these pins will have to be removed to repair machinery. The pin can be difficult to extract because of various circumstances.
A Simple Drift Pin Punch
In the easiest of all extractions there will be two ends of the roll pin exposed. In these cases, a small diameter drift pin punch can be employed. The diameter of the drift punch must be smaller than the hole in which the roll pin is placed. Caution must be exercised so as not to flatten the end of the roll pins as it is extracted. By using a small, ball-peen hammer and striking with short strokes, most roll pins can be pushed from the placement using a drift pin punch.
Drill and Tap
Small roll pins may be wedged tightly into place or there is no access from the backside of the hole. In such cases, the center of the roll pin may have to be drilled out with a carbide drill bit. Apply plenty of penetrating oil while you drill to act as a coolant. The center hole of the pin is then tapped so a bolt can be inserted. The bolt is then used to pull the pin from the hole.
If the pin is too hard to tap, use a hardened, self-tapping screw. Drive the screw into place with a screwdriver. A slide hammer may have to be used to "knock" the bolt and pin assembly from the precision hole. You may have to modify the end of the slide hammer to accommodate the size of bolt or screw that was threaded into the center of the roll pin. Allow some time for the oil to soak through the sides of the roll pin and into the hole. The lubricant may help loosen the stuck roll pin before extraction with the slide hammer.
Some roll pins may be so tight or rusted inside the hole that the only alternative is to completely remove the pin by drilling it out with a carbide bit. Caution must be exercised as the drill bit may attempt to wander off the center of the pin. This can cause a mis-centered or an oblong hole. Once the pin is removed, the hole can be re-drilled with a slightly larger bit. A larger roll pin must be inserted after the repairs are made.