Re: CNC Lathe Threading - Alternative method

--- In CAD_CAM_EDM_DRO@yahoogroups.com, erich10983@a... wrote:

>
>
> In a message dated 3/13/2005 5:58:22 AM Eastern Standard Time,
> CAD_CAM_EDM_DRO@yahoogroups.com writes:
> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>
> I would like to come up with a alternitive method of threading
> with a cnc lathe,,,,, not using a feedback system with conjuntion

of

> the G33 code, but would it be possible to cordinate the spindle
> speed with the feedrate of the z axis to do threading? I think

it

> could be done, has anyone tried this, or have a theory on how it
> could be done????

Threads usually require that you make more than one pass to complete
the part satisfactorily. In order to take more than one pass, you
need to know the rotation angle as it applies to the tool tip
motion. This permits you to recut a thread at exactly the same
point as the last pass ( within the accuracy of the control system
and the sensor)

Three methods to cut threads that do not require spindle
synchronization are:

1) Tapping
2) Chasing
3) Thread milling.

A fourth method is to utilize the thread cutting gearbox that is on
many lathes. This does mechanically synchronize the tool to the
spindle and eliminates the need for a spindle rotational sensor. You
would stilll need a "start" sensor on the screw "starts" dial to
insure that you were using the correct start point on a multiple
start thread. I expect that in order to make it work, you would
also have to use the Z axis motor to drive the spindle rotation.

Fred Smith - IMService
The source for low cost Cad-Cam and Desktop CNC
http://www.cadcamcadcam.com/hobby