turns of thread gauge formula

One revolution advances .0373"

A desired depth of .307"

.307/.0373 ≈ 8-1/4 revolutions.

What am I missing? There must be more to this somewhere.

you are not missing anything. I just took over inspection at my company, and I simply couldn't remember the correct math for it. I like to be able to tell the guys on the floor how many turns it takes to make sure its right, since they are not all that great at reading calipers...lol

thanks

Is it a gun tap, or a bottoming tap?

He tells us thread checker; I assume the hole is tapped and he is verifying torque to depth. However, if that is it... no, there HAS to be more we are not yet aware of.

I wonder if OP is friends with galla.

Maybe he's the instructor?

He needs a copy of Machinery's Handbook.

Turning a threaded fastener a specified number of turns will never assure that the fastener is properly torqued.

Turn it till it's tight.

I am only looking for a depth and a way to explain it to a machine operator.

You should use a GO-NOGO gage. On pipe threads it is a single gage that has one notch that has to go and one that should not go.

The number of turns method is problematic on many levels and is very subject to your best guess when the first turn actually starts. It is good for +/- 1/8" only.

we use go-nogo's. but we are a small shop with button pushing stoners, so instead of trusting them to do the math, its much easier to tell them "you need 8 turns of the thread gauge to know its good." once I know the depth, and most of what we do are min. depths, I always add a turn and a half to the count.

Yikes! I'm hitting the button. Good luck.

A "small shop with button pushing stoners" should not take jobs requiring those, "button pushing stoners" to thread blind holes.

Put a stop collar on the taps, that actuates a reversing mechanism.

Doorman, Hope you don't mind. Wait for me!!!!!!!!!!

You can try....Oh never mind, stoners can't.... goodbye.

Refer to the Machinery's Handbook, Formulas are listed under pipe threads

Thanks for this post.

I had my own formula that I'd forgotten, and was emboldened by your post.