Thread cutting dilema?

[RWanke]

Ouch! Kinda hard to hide something like that when it goes bad.
Glad you saved the shaft.

-brino

LOL. Wasn't any hiding it, especially when they watched me just shut the lathe off and walk out of the shop to calm my rattled nerves. The bosses son actually came over after I walked back in and apologized because he had just been standing over my shoulder a moment before I did it and I stopped and politely asked him to not distract me as I needed to really concentrate. I told him it was definitely my screw up because he had left me alone and I just brain farted. Stuff does happen. He wasn't mad.

 

[RWanke]

My SB9A compound degree markings are very small and difficult to read, so I made a 29.5 degree jig that lets me reset to that angle for threading whenever I have moved the compound to some other angle such as cutting an R8 taper on a piece. A one time gauge is much easier for me to reset to == Jack

And isn't it great the way South Bend put the index mark on the back side of the cross slide. I run my carriage all the way to the end of the lathe where I can stand at the end and get a light shining on it to see it to get it right.

 

[Creativechipper]

At least they understood and didn't give you too much grief.

 

[Technical Ted]

Excellent info again!!

I am still gathering the devices specific to threading. Any suggestions on thread gauges and fishtails and thread mics? Are the gauges and fishtail ok to get new cheap ones or does the quality vary enough to warrant a name brand set? Are the Mics for threading good bad, where to start with equipment?

Thanks

Probably boils down to what exactly you will be doing. I guess my generic recommendation would be: if you want to save a little money you could either buy mid level quality new or top quality used. I wouldn't go out and buy the cheapest set you can find. You want a quality set, but you don't have to buy top of the line for most home use.

I do a fair amount of threading and don't own/use thread mikes. We did have them at work and they are nice if you have to hold a tolerance from a drawing. Usually I thread to fit a mating part. I do have a set of thread wires. They take a knack to use but they do a good job and are accurate. Just make sure to clean out your chip pan before using them. They turn invisible when you drop one. I just got a cheap set of these off eBay. All they are is a set of ground wires.

Ted

 

[savarin]

I guess it all depends upon how much you wish to spend. I am a notorious cheapskate so for things like that I only buy the cheap stuff.
Even my micrometers are cheap Chinese ($10 each) but when measured against my mates top of the range items we cant measure any discernible difference.
Does the work you will be doing depend upon sub micron accuracy? Unless working for NASA then probably not.
Are you working in the optical fields then probably yes.
If you want an excellent fishtail gauge then check this one out

 

[mikey]

Excellent info again!!

I am still gathering the devices specific to threading. Any suggestions on thread gauges and fishtails and thread mics? Are the gauges and fishtail ok to get new cheap ones or does the quality vary enough to warrant a name brand set? Are the Mics for threading good bad, where to start with equipment?

Thanks

All the thread pitch gauges from the major makers are fine. I prefer Starrett but have B&S, too, and it works fine. I mostly use the Starrett 472; it goes from 4 to 84 tpi. I also use a Starrett metric gauge, too. Check ebay or Amazon.

Fishtails are also pretty accurate. I use a Starrett 391 but also have one from Mitutoyo and several from PEC. All are about the same. Check Amazon for a Mit - its accurate.

Thread mics do vary in quality but not enough to warrant spending major bucks on a high quality set. I own a 0-1 and 1-2 set from Tesa - you don't even want to know what that retails for. If I were you, I would buy an import like this one: https://www.ebay.com/itm/0-1-SCREW-...895275?hash=item519992f22b:g:nDAAAMXQrvpREJLy

You couldn't even buy a single anvil from Tesa for what that Shar's set cost and I doubt you will see a difference in outcome.

You should be clear that you do not need to use thread mics for a rough and ready thread; cutting to fit will work fine for that. But when you need to cut a thread to tight tolerances or to fit an existing part and you need it to fit right the first time, that is when you pull it out. You can also use the three wire technique. I no longer do this because I absolutely hate those things, or maybe they hate me. Either way, I'm constantly dropping or bending them so I went to thread mics.

Bear in mind that when cutting threads to tighter tolerances you need to turn the blank to the right size for that class, then cut the thread to a pitch diameter range. That might be beyond the scope of this thread. If you need more details, start a thread of your own and we can go at it there.

 

[Technical Ted]

If you find you have trouble holding the fish square/level with your stock, you can pick up or make one of these (or make something like in the video savarin posted above which is a lot more work). If I remember, mrpete222 on YouTube shows how to make a holder similar to the one in this picture, which is a Starrett brand.

Ted

 

[C-Bag]

Bear in mind that when cutting threads to tighter tolerances you need to turn the blank to the right size for that class, then cut the thread to a pitch diameter range. That might be beyond the scope of this thread. If you need more details, start a thread of your own and we can go at it there.

With all due respect Mike, personally I think this is part of the scope of thread on threading. Several of you who understand threading are making things much clearer than I've been able to get on my own. I relate this to when I was trying to understand computers and was learning from guys who had been at it forever. They couldn't drop down enough because they didn't understand I had picked it up piecemeal and there were certain pieces they took for granted, but I didn't get. Putting everything in one place would help and probably it is somewhere and I've not run across it. If it is I apologize.

So where do you find the "blank size"? A lot of what keeps me from finding info is I don't even know what it's called.

 

[MrWhoopee]

Excellent info again!!

I am still gathering the devices specific to threading. Any suggestions on thread gauges and fishtails and thread mics? Are the gauges and fishtail ok to get new cheap ones or does the quality vary enough to warrant a name brand set? Are the Mics for threading good bad, where to start with equipment?

Thanks

Any will do, these are not high precision tools. As for the thread gage, you can get by using a scale and counting the number of threads in an inch. If the thread you're cutting is not that long, set up on a test piece. It's good practice for refining your technique.

 

[Creativechipper]

"A lot of what keeps me from finding info is I don't even know what it's called."

I here that C-Bag, I have to google a lot of new tool names, terms etc. Keeps it fun always learning new stuff..lol