Tapping Indexed thread on Brother

[Fal Grunt]

I have a small job (~36 pcs) that has a thread that is indexed to some other features. I always thread mill features like this, but thought maybe this would be a good learning opportunity, as for once, it is a standard thread I can buy a tap for.

Does anyone with a Brother tap something timed? How do you go about that?

 

[angelw]

It will be the same for a Brother or other makes of machine. To get consistent results, you would have to be able to rigid tap and to some degree, it would be by practical trial and error to dial in on your required result. Assuming that you can't afford to have any of your actual workpieces tapped with the incorrect index:

1. prepare a test piece of material by facing it off at the same Z height as your actual workpiece and drill and tap it using the data used in your actual part program.
2. mark the start of the thread on the face of the test piece and measure how many degrees its out by.
3. divide 360 by the result of point 2, then divide the pitch of the thread by the result.
4. move the Z Start plane (the R Plane of the Tapping Cycle) by an amount equal to the result of point 3.

Regards,

Bill

 

[Fal Grunt]

I was thinking using spindle orient to get a consistent start, and easily change the thread start.

 

[Ox]

I was thinking using spindle orient to get a consistent start, and easily change the thread start.

It already does that behind the scenes anyhow.
You can go back in the same hole umpteen times and not cross a thread.


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Think Snow Eh!
Ox

 

[gustafson]

I remember seeing some vapor polished acrylic parts years ago[before i owned a CNC] that every tapped hole ended at exactly the same point. I know my heidenhain has a setting that you can turn that off for speed I guess

 

[Vancbiker]

It already does that behind the scenes anyhow.
You can go back in the same hole umpteen times and not cross a thread.


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Think Snow Eh!
Ox

Not always on some controls. Mitsu can orient or not before rigid tapping selectable by parameter. If you are not needing oriented threads, peck tapping, or don’t plan to re-tap you can turn orientation off to save a bit of time.

 

[Orange Vise]

4. move the Z Start plane (the R Plane of the Tapping Cycle) by an amount equal to the result of point 3.

Yup, this should do the trick.

I think trial and error by changing the start plane is really the only way to do it. I'm not aware of any machine that has the ability to clock the thread helix, and even if it did, the tap itself can't be relied on, i.e. the helix on the tap isn't clocked to the square on the shank. So you pretty much have to go through the same process every time you swap a tool.

 

[BROTHERFRANK]

I was thinking using spindle orient to get a consistent start, and easily change the thread start.

yes. M19 with an R value. As Eric at Orange stated, if you change tools (new tap) you will need to check where the new thread starts. If you have more than one hole to tap per cycle, use M19 Rxxx before each tapped hole and they will all start the same. I would take some scrap material and experiment with my start point before making the final pieces.