Strange, I know I posted a reply before
You mentioned Shareholders, does this mean both companies are corporations?
Who owns the machinery? Which company is insuring it AND taking depreciation? The construction company could lease the equipment to the machine shop , or you could treat the money as loans if it is intended to be paid back regardless of profits.
Is the construction company taking am equity stake in the machine shop and expecting a tax return from it?
If the Assets are to be property of the machine shop then it should not be an expense of the construction company unless it is a billable expense to the machine shop. Asset are not normally expenses