Need Help!- How do I make threads on my Sieg C4?

[siegsc4]

An old thread but what am I doing wrong ?

I have set up the compund to 29 degrees by turning it clockwise.
I have the 60 degree threading tool set using a setting guage to the work piece, the shank is a right angles to the chuck.

I'm using the cross slide to back off a turn for the reverse then winding it back a turn to cut.

I'm using the compund to cut deeper on each forward pass by 0.05mm

The half nut lever is left engaged at all times.

I must be missing something here - surely winding in the compound when it is set at 29 degrees will move it deeper and towards the chuck hence the odd shaped thread ?

[Geof]

It looks to me like you have the 29 degrees the wrong way. The appearance of the thread suggest your compound is at 29 degrees to the centerline of the spindle but it should be 29 degrees to the cross slide travel.

[siegsc4]

Originally Posted by Geof It looks to me like you have the 29 degrees the wrong way. The appearance of the thread suggest your compound is at 29 degrees to the centerline of the spindle but it should be 29 degrees to the cross slide travel.

Yes you are correct, and obviously I have the wrong setup !
Had to remove the compound and refit at 90 degrees to the spindle as the rotation only goes -45 to +45 degrees.

Also had to put a 0 degree mark for the compound at that angle as there is only one when the compound is located in line with the spindle ?

Any how, this is with the compound now at 29 degrees to the cross slide....

My other question would be thread depth, can you use the compound scale when it is set at 29 degrees, if so what is the calculation for thread depth ?
In this instance I need to run a standard spark plug thread - 14mm x 1.25mm pitch

Or do you just use a thread guage ?


Thanks !

[Geof]

To be really technical you look up the specifications and measure using wires of a known diameter in the thread and a micrometer.

Or you use a nut or tap a piece of material as a gauge. Or get a thread guage.

Or take the cylinder head off and use it as a gauge.
(This suggestion is not entirely serious but for a small single cylinder engine it is feasible.)