Re: EMC Lathe mode.

>The feedrate for threading is the pitch of
>the thread ie. 1/4-20 would be .05000 ipr
>and yes they usually are programed to at
>least 5 decimals in inches.

I've been following this thread with great interest.

I would like to add my $.02 here.

Most lathes I've encountered with a Fanuc or Yasnac or simular
control use a feedrate command for threading using the following:

F.#### is used for threading lead accuracy to 4 decimal places.
E.###### is used for threading lead accuracy to 6 decimal places.


The Mitsubishi Meldas control will also use the following by setting
system parameters up for it:

E12. (which would be interpreted as 12 threads per inch.)
The control does the lead calculation for you.


Multiple start threads are programmed on these systems by using
multiple threading cycles and changing the starting point of the z
axis in front of the part.

For a 1/2-20 2 start thread:

The z start point could be set at say .250 in front of the part.
(This allows room for the axis acceleration to get up to speed before
the tool encounters the part.)
The thread lead would be programmed at F.1000.

To cut the second start on the thread, another thread cycle is
programmed and the start point for z would be .300 in front of the
part. The feed rate remains at F.1000. Both are timed to the same
index pulse.

The important thing here is that the machine must remain in the same
gear range and the rpm must remain constant through the whole process.

As mentioned elsewhere in this thread the manufacturer sets limits on
minimum/maximum rpm and lead.


That's my $.02.

Don