I’d like to drill 5400 holes through a 0.039 inch thick piece sheet of mild steel. The holes would be 0.118 inch in diameter. if i were drilling one then no issue i’d use a drill but i’ve 5400 to do 0.079 inches apart from one another in a tight grid. What bit/mill would i use as my spindle runs at 8000rpm as a minimum and that’s way above what a drill bit would be in a drill. Is this something i could do on my onefinity? cheers for any advice. here’s hoping not to have to manually drill 'em all.
What kind of cut quality do you need? Since your material is about the same thickness as the depth of a 3mm drill point, it’s gonna be an ugly hole. And the material will want to pull up as soon as the full diameter of the drill breaks through. Depending on how much time you have, I’d consider peck drilling with an endmill but be sure to keep it cool! Or possibly a step drill if you can find one that small.
I’m curious now…what are you making that needs 5400 holes?
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I am drilling 3mm holes 2mm apart to allow airflow through a 1mm steel panel on a high end pc build for a friend. I realise there are lots of pre drilled mesh sheets in the world but i’ve been tasked to cut these holes in a very specific part and in a very specific pattern. The issue you mention is what i was worried about. Having slept on it though i figured i’d sandwich it betweem some plywood to stop the bit pulling the sheet up and wrapping itself around the bit.
My main concern was how a drill bit will cope running at 8000rpm and wondered what experiences others had had if they have. I will go with your suggestion and use an endmill.
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BTW. I happen to have dozens and dozens of 1/8" 4 flute carbide endmills. They are used but still useable and would be perfect for what you need. Are you in the U.S.?
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I’m in Scotland! very far away. But thank you very much for the offer. I do actually buy my bits from the US. Maybe I should buy some cheap ones 1/8th fluted endmills like you mention from amazon just for this job.
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I can only imagine how wonderful it must be to say “no” to my last question. 
Best of luck with your project.
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To drill 5400 holes through a 0.039 inch thick piece of mild steel, each 0.118 inch in diameter and spaced 0.079 inches apart in a tight grid, you would use a milling process with an appropriate end mill on your Onefinity machine, given its 8000rpm spindle speed capability.