The renaissance in capital spending the tax cut was supposed to bring about isn’t showing up in the economic data.

The Commerce Department on Friday reported that orders for durable goods—long-lasting equipment like tractors and machinery—dropped 1.7% in April from a month earlier. That decline was driven by a drop in aircraft orders, however. Orders for nondefense capital goods excluding aircraft, which economists follow closely to gauge where capital spending is going, increased by 1% to a seasonally adjusted $67.3 billion...