HP Required To Run 1-5/8-12 Tap @ 75% Of Full Thread

[Toolingtek]

Like the title says, I need to run this tap on a quick repair project. I have a 20 HP Vert Okuma mill...

Anyone know the answer?

 

[mrainey]

You have plenty of power.

 

[Toolingtek]

I came up with .0022 Sq In in the cross section of a 12 pitch thread, which required .242 HP @ 16 SFPM. Just seems much lower than what I had expected...

 

[EnglishMuffin]

I can tell you how much torque you will need - but since I don't have the torque spec for that machine you will have to figure out if it has enough yourself.(With tapping it's torque that counts).

Torque = K*Ct*Cm

Where K = material factor
Ct= tap condition multiplication factor
Cm = torque constant (metal removed per rev)

For 150 BHN Steel, k = 290000 in lbf/in^3
400 BHN Steel, k = 500000 in lbf/in^3

For a sharp spiral point tap, Ct = 1.0
For a dull straight flute tap, Ct = 2.5

For a 1.625-12 Tap at 75%, Cm = 0.00099 in^3/rev

So assuming some kind of steel, torque required will be anywhere between 24 ft lbf and 103 ft lbf. Your machine should be able to deliver that much torque.