Threading upside down

Parlo said:
That will cut a left hand thread.
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You're not understanding what the OP wants to do. He wants to thread a right hand thread going away from the chuck. That requires running the spindle in reverse, and leaving the threading direction gears in the normal forward position. When you run the spindle in reverse, it will cut a right hand thread if you use a tool with the insert upside down. He can use a left hand tool upside down like Joe Pie does to get close to the shoulder, or he can use the tool I referenced that was designed to do exactly that.
 
This is the video he is talking about where Joe explains it.

 
Ischgl99 said:
You're not understanding what the OP wants to do. He wants to thread a right hand thread going away from the chuck. That requires running the spindle in reverse, and leaving the threading direction gears in the normal forward position. When you run the spindle in reverse, it will cut a right hand thread if you use a tool with the insert upside down. He can use a left hand tool upside down like Joe Pie does to get close to the shoulder, or he can use the tool I referenced that was designed to do exactly that.
Click to expand...
Your tool looks like a standard right hand tool. When it is inverted the cutting tip is then on the right of the tool body. Therefore instead of the cutting tip being able to go up to a shoulder, the holder body will hit the shoulder. This is the issue the OP is about.
 
This is the tool I linked to, it's not a standard right hand tool, this is how you put the tool in the toolholder with the insert upside down.

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@Parlo that toolholder uses an on-edge insert, so that might be what was causing the misunderstanding.
 
All of the below will cut a right hand thread away from the chuck. If leadscrew and spindle turn same direction, you get RH thread, if they turn opposite you get a left hand thread. Notice the first 2 have a spacer with the socket head capscrew, to allow adjustment to get the cutting tip on center. I use the top Shars 99.9% of the time.

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xr650rRider said:
All of the below will cut a right hand thread away from the chuck. If leadscrew and spindle turn same direction, you get RH thread, if they turn opposite you get a left hand thread. Notice the first 2 have a spacer with the socket head capscrew, to allow adjustment to get the cutting tip on center. I use the top Shars 99.9% of the time.

View attachment 457926

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Don't forget that a standard internal threading insert in a round toolholder with the insert uppermost will cut a right handed external thread with the spindle in reverse away from the chuck at the back side of the part; from a shoulder.
Here is an example - cutting bias on the leading edge advancing the tool 1/2 the cutting depth on the compound slide. No need for moving the compound to 29 degrees to acheive the same result.


Or at the nearside of the part with the tool inverted, which luckily remains at the ideal tool height.
 
That method doesn't work to well when you need to use a center for support.
 
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