CNC Threading

[cncuser1]

Sort of a poll:
What type of threads ( internal and also external) have users here made with thier CNC Lathes, and briefly what lathes werre used?

I'm looking at small stuff in the 0-80, 1.2mm range.

[cncuser1]

OK then, question answered, not alot of fine threading done in CNC

[RotarySMP]

I am using Turbocnc on my converted 7x1 mini lathe. I have done from M6 thru 12x0.5mm metric micrometer thread to internal .938x16tpi imperial. The G77 canned cylce in TurboCNC is great.

What do you mean by 0-80 1.2mm? Do you mean thread diameters up to 1.2mm or pitches up to 1.2 mm?

[cncuser1]

I forgot a comma.

"0-80" is a very small screw. I don't know the name of the numbering system but it belongs to the same numbering system as 6-32. So "0" is the niminal diameter (approx .070" from memory) and it has 80 threads per inch.

"1.2mm" is 1.2mm nominal diameter with a pitch of about .25mm ( from memory)


somewheres around the size of screws from reading glasses.


Anyone done this on a CNC'd 7x lathe?

[HuFlungDung]

Well there is nothing stopping you from doing small diameter threading work on the cnc, if you've got the manipulation technology to handle the parts without loosing them in the chips.

The useful unsupported length of the stock is proportional to the diameter, I guess. This means for a #0-80 screw (.060 OD), that you might be able to thread a stub maybe .125" long, if you are lucky. Much longer than that, then you need a tail-center support, which is very constraining on the distances and diameters you would have to work at.

There is also the problem of how close to a shoulder do you need to run the tool? Two threads might be a reasonable stopping distance, that is .025", which is a significant amount on such a small screw.

I am awestruck at the manufacturing technology that must be used to manufacture these tiny fasteners, for pennies apiece, and right up to the head, as well. I suppose they are rolled between flat plates like most all other threaded products nowadays, but still, feeding the parts in straight, and so on, is quite an achievement.

So far as internal threads, well I've done a fair amount of #0-80 tapping, and it is quite straightforward. I don't even want to think about trying to single-point thread one with a boring bar, though

[cncuser1]

I currenly do 0-80 manually with tap and die. But I wanted to know about CNC.

Are people using a CNC 7x for 80tpi or finer?

[HuFlungDung]

CNC is not a magic answer to the problem, if that is what you are wondering. Sure, a cnc gives excellent tool control and so on, but the problems lie more with the support and stiffness of the stock while it is being worked. CNC does not really solve those problems at all.

[Konrad]

Agree with Hu
I would not even think about single point threading this small!
Konrad

[cncuser1]

I was wondering what lies within the realm of "possible"

I have made these screws already so I have an idea of what it takes to make them.

I was curious about CNC, I still am.