How to execute raw queries with Laravel 5.1?

So I have this tiny query to run on my DB and it works fine in MySQL Workbench.
Basically, a SELECT with LEFT JOIN and UNION with LEFT JOIN again.

SELECT
cards.id_card,
cards.hash_card,
cards.`table`,
users.name,
0 as total,
cards.card_status,
cards.created_at
FROM cards
LEFT JOIN users
ON users.id_user = cards.id_user
WHERE hash_card NOT IN ( SELECT orders.hash_card FROM orders )
UNION
SELECT
cards.id_card,
orders.hash_card,
cards.`table`,
users.name,
sum(orders.quantity*orders.product_price) as total,
cards.card_status,
max(orders.created_at)
FROM menu.orders
LEFT JOIN cards
ON cards.hash_card = orders.hash_card
LEFT JOIN users
ON users.id_user = cards.id_user
GROUP BY hash_card
ORDER BY id_card ASC

In tried to translate it to Laravel, with no success.

$cards = Card::selectRaw('cards.id_card, cards.hash_card ,cards.table, users.name, 0 as total, cards.card_status, cards.created_at as last_update')
->leftJoin('users','users.id_user','=','cards.id_user')
->whereNotIn( 'hash_card', Order::select('orders.hash_card')->get() )
->union(
Order::selectRaw('cards.id_card, orders.hash_card, cards.table, users.name, sum(orders.quantity*orders.product_price) as total, cards.card_status, max(orders.created_at) as last_update')
->leftJoin('cards','cards.hash_card','=','orders.hash_card')
->leftJoin('users','users.id_user','=','cards.id_user')
)
->groupBy('hash_card')
->orderBy('cards.id_card','asc')
->get();

I'm getting the error

> ErrorException in Builder.php line 1249: Undefined property:
> Illuminate\Database\Eloquent\Builder::$bindings

How could I execute a completely raw query in Laravel or write the query in the right manner in Laravel?