Combination square

When it earns a place in your kit

Useful from the first layout through the dry fit. A square references an edge; it cannot correct a crooked edge or bowed panel.

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What to check before choosing

• Choose a readable rule and a head that locks firmly without wobble.
• A compact square fits inside a case; a longer rule reaches farther across a panel.

A practical setup sequence

1. 1

   Choose and label a straight reference edge on the part. Remove chips from the square head.

2. 2

   Seat the head against that edge, set the rule to the needed offset and lock it. Mark from the same face on mating parts.

3. 3

   Use a separate straightedge for long lines; check the joint from both faces during the dry fit.

A common mistake to avoid

Measuring matching holes from opposite faces can reverse the layout even when both marks look square.

Use it with