Left Hand Thread (Lathe)

[Jack K]

Hey guys can anyone help me out. I need to program a left hand thread (Lathe) and I just do not see it. You must be able to do it.

 

Jack

[gcode]

You need a left hand threading tool (or an upside down rigth hand tool if you have room)

Run the spindle clockwise (G04) and use your regular G76 canned cycle.

[Jack K]

hey thanks gcode! man that was fast! so simple it could have smacked me in the head!

[Keith Graydon]

internal or external?

[Philcott]

Jack,

 

I got this from the help menu.

 

quote:

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5. Enter toolpath parameters such as the start position, end position, thread orientation, and taper angle value.

 

Note: When creating a left-hand thread, the start position is the back of the thread, and the end position is the start of the thread.

 

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Personally, I don't like this method as quite often the thread relief at the back of a thread is not long enough to get the feed up to the correct rate (start distance to the thread should be approximatly 1.5 times the pitch of the thread) before contacting the material. I use a left hand tool holder that allows the insert to be held with the cutting edge facing up and change the code from spindle forware to spindle reverse and this works well for us.

 

Good luck,

 

Phil

[PE @ IHS]

All you have to do is change the thread direction (Z position) to cut toward the positive direction. Nothing else needs to be done

 

Spindle direction and tooling are unchanged

 

Phil is absolutely right about acceleration problems if your start position is up against a shoulder, in which case the left hand holder and spindle reversal may be a better way to go

[crazy^millman]

I Always started on the outside of the part when cutting left hand threads for that very reason. Try doing it from the should with a class 3 thread will not pass the go-no gauge if you do. Been there done that and sucks killing 12 hours of work because of that.

[Jack K]

gcode it is a external thread.

 

Great stuff guys this will help me out big time.

 

Thanks,

Jack