Need Help!- ID helix thread

[reachraghu]

Hi all,

I have to make ID thread - 3 helix grooves (threads) having their start points 120 deg apart. Each thread does not finish full lead but stops at 90 deg ---(If extended further, it would cut into the next groove). Hope Im posting a clear picture about the component.

Can anybody help me by suggesting whether this is possible in a CNC lathe with Fanuc0iTC controller.
PS: Raw material is Aluminium. Also the cutting tool with proper entry & rake angles have been made.

Thanks.

[sinha_nsit]

Your description is not clear.
If it is a triple-start thread (which it appears to be), the three helices would never intersect upon extending.

[reachraghu]

Sinha,

You are right. It is not a triple start thread. Three threads (only quarter lead upto 90 degrees) having their respective start points at 120 deg spacing. Is it possible to do this Fanuc0iTC turning.
Thanks.

[sinha_nsit]

Threading start angle can be specified through a Q-word.

Keeping the Z-start point same, call G32 with Q0, Q120000 and Q240000 (Add retraction moves after G32, to simulate cyclic operation). If pitch (lead) is, say, 6 mm, thread length for quarter thread would be 1.5 mm. This feature is available with G92 and G76 also, but the method is not properly explained in the manual.

[reachraghu]

Thanks for the advice Sinha. I shall try this & let you know the results.