Many casinos use "ferris wheel automatic shufflers" nowadays. Can this model both return the same deck and completely reverse a deck?

I know these two "shuffles" are extremely rare theoretically, but in principle, I'd like to play in a game where all shuffles are equally possible.

I believe this machine has 38 slots, so the algorithm seems equivalent to placing cards one at a time into 38 bins (given by a random sequence of bin numbers) and then taking the top card from a particular bin (given by a second random sequence of bin numbers). But, it seems I would need 52 slots to get the two extreme shuffles in my question above...can someone explain if any shuffles are impossible on these machines?

  • I have seen this machine in the pit, but never in a poker room.
    – Jon
    Feb 20, 2020 at 8:01
  • Are you acquainted with the dovetail shuffle? Apr 6, 2020 at 8:18
  • Every shuffle can return the original deck after enough shuffles. That's basic group theory. Nov 16, 2020 at 6:37
  • @Acccumulation I'm asking about one run through the machine (since dealers only do one).
    – bobuhito
    Nov 17, 2020 at 4:42

1 Answer 1


While you could use that machine to shuffle for a poker game, I wouldn't think it would be very common. One of its features is that it has a large capacity to hold multiple decks simultaneously and continuously shuffle them together. This is workable for blackjack, but not useful for poker. It also usually holds some cards in the shoe. Unless you take the time to pull everything out before feeding the deck, you would know the first card out on the next hand wasn't one that you saw on the board of the previous hand. That's a lot of information in poker.

You are correct that given a single pass of a single deck input, it doesn't seem to be possible for the machine pictured to produce a completely reversed output, since after 39 cards are placed in the machine, there must be two cards in the same bin, those cards will have the same order that they had in the original deck, and they will be served in that order. There's no physical limitation from it returning the original deck order though, since you could imagine it placing a couple of cards in each bin in sequence, and then the bins dealt in the same sequence. The cards would not be shuffled at all, but returned in order.

There are other shufflers that are more suited to single deck games, giving the dealer a full deck at once, ready to cut. It is possible that they use different mechanisms and algorithms and would be capable of returning any shuffle.

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