According to PencilThings.com, the mechanical pencil was invented in 1822. The mechanical pencil offers advantages over traditional pencils because it never needs to be sharpened. Some mechanical pencils come with lead and eraser refills so you can get more life out of one writing utensil than you might normally get with a traditional wood pencil. If you need to know how to refill a mechanical pencil, you may have to try a few techniques before you find the one that is appropriate to the style of mechanical pencil that you own.
Remove the eraser from the top of the pencil. If there is a chamber leading into the inside of the pencil, this is likely the location to fill with more lead. Insert one piece of lead into this chamber to test it out, and replace the eraser. Click down on the eraser to advance the lead; if lead emerges from the pencil after a few clicks then you have refilled your mechanical pencil. If not, remove the lead and try again.
Unscrew the mechanical pencil so that you separate it into two pieces. To find the point of detachment, look for a horizontal line drawn around the barrel of the mechanical pencil. Sometimes this line is in the very centre of the pencil while other times it will be nearer to one end. Look for the lead chamber and insert one lead stick. Reattach the two halves of the pencil and push the eraser or cap to advance the lead; if lead appears, you have achieved success. If not, remove the lead and try once more.
Hold the mechanical pencil with the eraser end down and balanced on a table top. Push the pencil down onto the table to hold the eraser in the engaged position. Pinch a piece of lead with your other hand and gently poke it into the tip of the mechanical pencil. If it slides in easily, continue to push it through until only approximately 1/4 inch remains outside of the tip. Your mechanical pencil has now been reloaded and is ready to use.
Check the lead size on the mechanical pencil to be sure the lead you use for a refill matches the original lead size and weight.
Hold the lead gently or you may end up breaking it as you try to refill the mechanical pencil.