Maintenance and care of the combo square set

Storage
	When purchasing a set of combo squares, you may find that it comes in a box or case that you can store it in when not in use.
Accuracy check
	Over time it is possible that the set of combined squares will become inaccurate.
	This can happen if there is a problem with the heads or the rule.
	You can check if the square head and ruler combination is inaccurate by attaching the square head to the ruler and drawing a line from the straight edge.
	Flip the tool over and check if the ruler lines up with the line you just drew. When drawing the second line, it should be parallel to the first.
	If it doesn't, then your rule or square head is most likely inaccurate.
	Inside the head, you can find two small "pin" segments that the ruler usually stays flush with. If there is wear on the inside of the heads, the rule may sit at an angle.
Repair
	You can use a file to get the ruler back on track, securing the edges of the file with tape to avoid filing the sides of the head. However, doing this may not be very accurate, and some advise buying a new tool.
	Some manufacturers may simply replace a defective tool, provided it is still under warranty and has not been mishandled.
	What else can cause a set of combined squares to fail? A combination square set can also fail if there is debris or damage on the work surface.