Questions on clipping internal acme on an Okuma LB4000

[hheych]

Hello,

I cut a lot of internal threads that are usually for oilfield applications; these sometimes require a blunt start thread or clipped thread. I'm looking to see if anyone has any tips on a go to method for this. Usually its trial and error with some layout fluid until we start to see a scratch, then adjustments are made to achieve the desired result (seemingly stumbling across it) which is quite time consuming.

I run an Okuma LB4000 EXII with an OSP-P300L controller
When clipping, i am using a grooving insert that is .250 wide.

This is a 8" internal 3 acme thread so quite coarse (grooving tool might not be wide enough for good results). I'm using a G71 threading cycle that has been copied over to the grooving tool, with the Z end distance adjusted, as well as the z approach distance adjusted for synching properly (adjusting the cut from the start of the partial thread, usually a multiple of the pitch).

Here is an example of the the threading line:
G0 Z.6
G71 X8.85 Z-3.3 A0. B29 H.3533 D.03 U0. F.333 M32 M75

And the clipping line:
G0 Z.4335 (adjusted to move the initial contact point of the thread)
G71 X8.85 Z-1.1665 B29 H.3533 D.08 U0 F.333 M32 M23 M75

I'm using the M23 auto chamfer pull out as well.

Shouldn't it be as easy as knowing the pullout length (which i believe is the pitch if not denoted by an L value)
Knowing the pitch/lead
Knowing where the thread starts
Adjusting Z start and finish amounts for the desired result?

I feel there should be "simple" parameters based off these values i just cant wrap my head around it haha.

If anyone has any tips or ideas that would be greatly appreciated!

Thank you,

 

[DouglasJRizzo]

Um. Define "clipping."

 

[hheych]

Um. Define "clipping."

Hello,

Clipping is just another term for blunt starting a thread to deter from cross threading. Similar to a higby just doesnt require any technical dimensions.

Removing the first feathered thread roughly up to the start of the full thread form.

Thanks!

 

[DouglasJRizzo]

Hello,

Clipping is just another term for blunt starting a thread to deter from cross threading. Similar to a higby just doesnt require any technical dimensions.

Removing the first feathered thread roughly up to the start of the full thread form.

Thanks!

Ahh. Ok. Got it.

 

[Tom]

If you have live tooling and C axis it is pretty simple to do it other than that it is some trial and error to line up to the two tools to single point it

 

[escapethewrmhole]

Usually I just copy the threading cycle, adjust the start point by half a pitch, measure how far in I want the clip to go for an end point and tweak to get it perfect from there.