Locking carousel with locating features

An indexer for use with a microbial detection and/or enumeration system comprising a carousel configured to hold one or more cassettes and including an carousel-side positioning element configured to assist the indexer in rotating the carousel into predefined positions, the indexer comprising:

• an indexer body housing a motor;
• an indexer-side plate configured to be rotated by the motor;
• and
• a spindle configured to receive the carousel-side positioning element, the spindle comprising one or more grooves configured to position the carousel with respect to the indexer as the carousel-side plate is lowered onto the spindle.

A carousel for use with a microbial detection and/or enumeration system comprising an indexer configured to rotate the carousel into predefined positions, the carousel comprising:

• one or more cassette columns;
• a carousel base supporting the one or more cassette columns;
• and
• a carousel-side positioning element configured to position the carousel with respect to the indexer, the carousel-side positioning element comprising an opening configured to receive a spindle of the indexer, the opening including one or more protrusions corresponding to grooves in the spindle.

A method of manufacturing a system for positioning a carousel with respect to an indexer configured to rotate the carousel into predefined positions, the method comprising:

• forming an indexer spindle on an indexer-side plate, the indexer spindle extending from a proximal end closest to the indexer-side plate to a distal end and tapering from a relatively large diameter at the proximal end to a relatively small diameter at the distal end;
• forming one or more grooves in the indexer spindle;
• accessing a carousel-side plate;
• and
• forming an opening in the carousel-side plate, the forming comprising shaping one or more protrusions in the opening to correspond to the one or more grooves of the indexer spindle.

A method of using a system for positioning a carousel with respect to an indexer configured to rotate the carousel into predefined positions, the method comprising:

• attaching a carousel-side positioning element to the carousel, the carousel-side positioning element comprising an opening;
• attaching an indexer-side positioning element to the indexer, the indexer-side positioning element comprising a spindle configured to be received in the opening of the carousel-side positioning element;
• and
• dropping the carousel-side positioning element onto the indexer-side positioning element, wherein dropping the carousel-side positioning element causes one or more protrusions in the opening of the carousel-side positioning element to be received in one or more corresponding grooves on the spindle to automatically align the carousel with the indexer.