Delaney was just too slick for his Tyrone opponent as his straight lefts from the southpaw stance found the range to score.
The west Belfast man made Cummings pay for dropping his guard while his footwork also helped him evade any counters from his bigger opponent.
As this bout wore on, the Emerald southpaw grew stronger with a left in the second rocking Cummings who was unable to really get a grip on the eventual winner who advances into Thursday's final.
"It was a good wee scrap," Delaney said. "I actually boxed him four years ago and I stopped him that time. He came out tonight and gave a good account of himself.
"I was looking to feint to the body and go over the top tonight which worked. I had been out of boxing for a while so I had a good few family and friends here to give me a bit of support. Hopefully I can do the same again on Thursday night."
There were two other semi-finals down for decision last night.
Mark McLaughlin advanced into the lightweight final with a split decision win over Seamus Og Deeds. Heavyweights Damien O'Hagan and Damien Ramsay served up an interesting battle with Bishop Kelly's O'Hagan doing enough to advance.
Both men traded jabs in the first, but as the fight wore on, O'Hagan was able to bring his right into play and had built an unassailable lead going into the final round, Ligoniel's Ramsay tried to turn it around in the third, but had given himself too much to do as the Tyrone man made the final.
There was also one quarter-final last night as Gerard French advanced into tonight's middleweight semi-final with a shout-out win over Daniel Anderson.
There was only one winner in this bout and it was the west Belfast man who advanced to meet Connor Wallace in tonight's second semi-final.
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