Hi, I am about to build CNC router and I have to tap 5/8x8 treads, what size should I boor the holes (Root diam: .457)
Thank you

Not sure what thread form you're talking about. There is a 5/8-8 ACME thread, you'd be looking at about 0.505" tap drill size.

Hi, I would like to thank you for the response. For the Acme rod it is one that is made by Nook, 1 start tread.

If you read this forum, you should own a copy of machinery's handbook.
You don't need a new one, the older ones will serve you just as well.

If you read this forum, you should own a copy of machinery's handbook.
You don't need a new one, the older ones will serve you just as well.

Is that like “if your not wearing a tie you can’t come in this club” ? :D lol

But I agree the book would be a wise investment.

John

Sadly, there are folks who can't/won't look up specs in books/handbooks such as Machinery Handbook.

Why should they when in less time than it takes to boot up the computer, access the internet, wait for all the cookies to dump/load and for the website to load, you can post a question and wait goodness knows how long for a reply, when you could have looked up the answer in the Handbook in far less time.

Moreover, there will always be a kind, blessed soul who will answer the reply - they surely learned the spec via wrote or research. And do so instead of showing HOW and WHERE to find the reply in the future.

Thank God for the instant gratification of the internet. How/what would we ever do without it? God forbid, go to the library?????

Generally the hole size for a thread is dia - pitch. So an 5/8-8 thread would be .500 dia hole. pitch = 1 / number of threads per diameter unit.

Technically, the basic minor diameter is the minimum minor diameter of the internal thread. It is equal to the basic major diameter minus twice the basic thread height, 2 x hight.

basic thread hight = pitch / 2