lead pointer; lead sharpener
A small tool used to sharpen the lead of a clutch pencil (also called a lead holder). It typically has a hole where you insert the pencil and rotate to grind the lead to a fine point.
A lead pointer is essential for drafting mechanical pencils.
After sharpening the lead with a lead pointer, I draw fine lines.
Compound of 芯 (しん, 'lead, core') and 削り (けずり, 'sharpening, shaving'), from the verb 削る (けずる, 'to sharpen, to shave').