Single-Point RH Threading - Reversed Direction

[jesse.lamphere]

Hello all!

I am trying to cut a right-hand thread while turning the spindle backward and feeding left-to-right. I have to have the part oriented this way to do live-tool milling on the main spindle.

Front QuarterRear Quarter

The trouble is that while Fusion allows me to flip the tool ("Clockwise spindle rotation" is unchecked in the tool's Setup tab) and it even generates a toolpath in the correct direction, it moves the tool as if the tool tip is read from the left-most edge of the insert. It simulates this same (wrong) movement, mas well as outputting the wrong code. It's as though one part of Fusion doesn't notice the flipped tool, and generates the required movements based off the left-most edge of the insert, but then it outputs movement coordinates that are based off the right-most edge of the insert.

Tool Setup Tab. "Clockwise Spindle Rotation" is unchecked.Toolpath. It seems like Fusion is using the left-most edge to calculate the toolpath, when it should be the right-most edge.Crash!

Here's the snippet of output code, for reference:

(Thread2)

M1

T202

G99

G50 S3000

G97

S500 M4

G55

/ M8

G18

G0 Z0.1734

X1.55

G92 X0.3345 Z0.6084 F0.0625

G0 Z0.1776

G92 X0.3197 Z0.6126 F0.0625

G0 Z0.1808

G92 X0.3083 Z0.6158 F0.0625

G0 Z0.1835

G92 X0.2987 Z0.6185 F0.0625

G0 Z0.1859

G92 X0.2903 Z0.6209 F0.0625

M9

G53 G0 X0.

G53 Z-8.

M5

What the heck am I doing wrong???

[seth.madore · Accepted solution]

You need to adjust your Confinement to this value (thereabouts, anyways):

 

[jesse.lamphere]

@seth.madore, thanks for the really fast response! I don't yet understand how you got those numbers, other than possibly looking at the code output and adjusting for the difference; I'll play with it a little more.

What confounded me was that I just did something similar with a 35DEG turning tool, and it worked as it should. It's odd that this seems to be a threading-specific issue.

Thanks again!

[seth.madore]

The numbers were honestly just a guess, I didn't spend much time looking at the code. I shifted it one way and then the other until I got something that was visually correct.

To clarify; you are using a RH tool that's been flipped over in the turret, correct?

[seth.madore]

And yes, there are known issues with how Threading is defined and works in Fusion 😞

[jesse.lamphere]

Correct! It reverses the spindle rotation, and the tool is physically flipped appropriately. We've done this pretty often in the past, but we're still learning how to use CAM on a twin-spindle, live tool lathe. We used to hard-code every line, which was great for optimizing certain things, but had a few too many nasty surprises.