ACME thread

[SAISAY]

How do I explain an ACME thread count?
My lead screw is 0.5" 8tpi 2 start.
Is that the correct way or do I divide by 2 to get 0.5" 4tpi 2 start?
TIA :U

[.RC.]

So the pitch is 1/8" but the lead is 1/4"?

[MasterSpoon]

My understanding is you describe it as the total threads per inch x how many starts
So while a 8tpi 2 start thread is really 2 x 4tpi threads side by side, they are cut using a 8tpi thread form / depth and the total thread count would be 8tpi

I may of course be incorrect as this is only my understanding of it.