How do you check your threads when threading on lathe ?

[754]

I dont use wires before trying the nut, why would I ? When you get to sharp vee, or just before.. try the nut.
if you use a die what number do you end with if you have multiples to cut ?.. no need to run the die after 1st one is done..

[Doozer]

Sharp vee was obsolete in 1908 or something like that.
You are aiming for a truncated vee.
But I agree, I do the same thing.
Eyeball it to get it close,
Then try the nut.
It should only take 2 or 3 more passes
to get the perfect fit from there.

-Doozer

[Doozer]

Same here. Nice thing about threading on the lathe is you can get any fit you want.

JL...........

That is the way I look at it as well.

-D

[JRouche]

I have a set of wires. Learned how to use them. I worked better with them on the bench then the lathe.

I never cut any inside or out threads, single point to where I thought wires would improve the thread engagement. And thats what it comes down to. Thread engagement.

I cut just as many internal theards and would like to make a tool to make that easy with wires

And yes, as crazy as it sounds. I love to single point threads on my lathe. Just the way it is...JR

[eKretz]

You can't cut ID threads with wires... You can make your own thread gage with wires to fit and gage your I.D. threads. You can also buy I.D. gages that use an indicator that work sort of like a thread micrometer.

You guys can fit nuts for threading all you want in the home shop, but that doesn't always fly for paying industrial customers. They want to be able to grab another nut from anywhere and have it fit. We're comparing apples and oranges in a lot of cases here.

In a home shop situation fitting to a nut should be fine.

[nickel-city-fab]

They want to be able to grab another nut from anywhere and have it fit.

That's actually why I do it that way. I grab a random hardware store nut out of the pile and try it. If it fits like a generic 2A/2B hardware item, then it's good to go. Only time I use the mics etc. is when I have to for a close fit.

[Doozer]

You can't cut ID threads with wires... You can make your own thread gage with wires to fit and gage your I.D. threads. You can also buy I.D. gages that use an indicator that work sort of like a thread micrometer.

You guys can fit nuts for threading all you want in the home shop, but that doesn't always fly for paying industrial customers. They want to be able to grab another nut from anywhere and have it fit. We're comparing apples and oranges in a lot of cases here.

In a home shop situation fitting to a nut should be fine.

Agree. At work we have thread plug gauges and thread ring gauges.
For home shop things, I have often made a male plug by measuring
the pitch diameter over wires, and used it to gauge an ID thread that
I was cutting. First time I did this was years ago, when I was 25 years
old, and had a 10" Atlas. I made a plug that was 1-1/2" -8 for checking
a chuck backing plate I was making for it on the big lathe at work.
Man, I do love threads. The sense of accomplishment when they fit
just right is awesome. I try to block out of my memory the times that
I opened the half nuts too soon and buggered it all ! LOL Ha ! ! ! ! !

-Doozer

[JoeLee]

That's actually why I do it that way. I grab a random hardware store nut out of the pile and try it. If it fits like a generic 2A/2B hardware item, then it's good to go. Only time I use the mics etc. is when I have to for a close fit.

Yeah, and how many times have you ever had to do that??? I have a few thread mics too, think I used them once for comparison purposes for some sensitive adjustment screws I had to make. The mating nut has always served as a go - no-go gauge.

JL..............

[nickel-city-fab]

Yeah, and how many times have you ever had to do that??? I have a few thread mics too, think I used them once for comparison purposes for some sensitive adjustment screws I had to make. The mating nut has always served as a go - no-go gauge.

JL..............

probably half a dozen times in the last several years...
I would say once or twice a year I have to use the mics.
It sure is nice to have them, tho.

[J Tiers]

Grabbing ONE random nut means you don't know where in the tolerance band it is. If you have a selection from different sources and lots, you have a better chance if you try them all, but ultimately, a measurement is what gets it done.

For many things, fitting to the mating part is OK. it's when you do not have a mating part that you need to do everything to the numbers, or to a gauge that is known.

At least with running a die for the last bit, I know the fit is correct for the class of fit I need........................... Either way, the die is faster and the fit is always right on.

You don't have very many adjustable dies then?

Europeans seem to like fixed dies, but just about all the dies in the shop here are adjustable. They need to be set up for whatever class fit is intended. And then they need to be locked, or else it has to be done every time.

In the US, fixed size dies tend to be cheap imports (not always, of course), and it is anybody's guess what class thread fit those make.

[nickel-city-fab]

Since all of my nuts come from Ace hardware, and Ace has only 2A/2B then its safe to say its a 2A/2B fit. Exactly *where* it may be in the tolerance band is irrelevant IMHO as long as it is within its class of fit. And for 90% of the stuff "out there" it's plenty good enough.

Measuring the threads doesn't come into play until you are working to something much closer than that. Say con rod bolts for example. Those get measured.

[J Tiers]

Since all of my nuts come from Ace hardware, and Ace has only 2A/2B then its safe to say its a 2A/2B fit. Exactly *where* it may be in the tolerance band is irrelevant IMHO as long as it is within its class of fit. And for 90% of the stuff "out there" it's plenty good enough.
............................

Agree is is likely "good enough".

But, by using a nut and roughly assessing the slop, you are employing a "one sided tolerance range". What you know is that the thread is small enough that the nut goes over it. It may be under size, all you know is that it probably is not over size.

That is why there are Go/NoGo gauges. And no you do not need them for every thread, agreed without a fight. More of a pedantic point, but engineering and machining are full of pedantic points.

[Doozer]

I grab one random nut all the time...........
Sometimes two....


--D

[eKretz]

Yeah, it's pretty application specific when you get a job. For instance, something like a bearing locknut you need to be right on the money or you may add runout to the assembly when the nut is tightened. For garden variety fasteners on something like a hose clamp or what have you, you can do whatever you want...

What the customer doesn't want is to have one of their millwrights butcher that bearing locknut taking it off and then they buy a new one and it's a tight fit and it won't go on... Leading to more butchery by the millwright, etc.

Or say a nut is in a tight place and the wrench can only turn ⅛ turn at a time. They will curse you every ⅛ turn if it's too tight and they can't turn it on all the way without a wrench until the last torque-up. It doesn't take much grime or grit to cause that either.

[DR]

Using a nut as a gage can be problematic. If your cut thread doesn't have the correct crest flat or radius you can go way undersize until a nut will screw on.