Fusion 360-CAM -Ridged Tapping- Metric Tap programming into tool library, need help.

[Sean3073]

In Fusion 360 CAM, you can program a 1/4 - 20 pitch at .05. But if you look at the example tools for metric, example M4 0.7, it lists the thread pitch at 0.7 and the actual tap diameter at 4mm. Another example is 10-32. 10 is wire gauge, 32 is per inch,, 1/32. You enter the pitch at 0.03125. Metric as I can tell this does not hold true. I'm snapping metric taps, and not ANSI. Thank you in advance for helping if you can. Show me the math
Respectfully,
Sean

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[joeavaerage]

Hi,
you are facing the problem of 'thread engagement'.

You might imagine that if you want to form a 6mm threaded hole, that is 1mm pitch, that you would drill the hole so that 100% of the thread is formed,
that is 6-0.866=5.13mm. That would be a mistake, you'll break the tap.

Its normal to make the hole larger, commonly for 50% thread engagement. For high strength applications like head studs on a car or seatbelt bolts
the 60%-65% is common. But that is about as much as you can do with a tap, any more engagement and you'll break it.

Very high strength aircraft threads often have 85% engagement or more, but those threads are milled or rolled, expecting to tap then is unrealistic.

This speed/feed calculator has a very useful thread database:

https://hsmadvisor.com/

The bottom line is if you get greedy and try to achieve high engagements you will break taps.....I've broken plenty trying to do just exactly that.

Craig

[Sean3073]

Craig,
Thank you for taking the time. I total get what you are saying. Although I think I have more than likely phrased my question poorly. See attached pics.. If you notice, the programming to the ANSI tap, (1/4-20) to get the correct response from the rigid tapping, you divide 1 by 20 threads per inch and place that in your CAM. When doing metric, "according to Fusions examples" you just put the metric listing, M4 0.7 you put 0.7mm in the pitch. Why is it that when you enter ANSI you don't just put 20 like metric. I know for a fact that the 0.05 in the pitch settings work well. In short, why a direct entry of 0.7mm? Hope this clears up my question. Thank you again for taking the time.

[Superman]

Unless there is a check to say this is a metric tool

... it could be a post error

You are placing a metric value into an inch setting
0.7" pitch is huge, it needs to be converted to an imperial pitch

ie try these pitches.. turn the metric tool into imperial
M4x0.7p = 0.0276" pitch
M5x0.8p = 0.0315" pitch
M6x1.0p = 0.0394" pitch

inch pitch = metric pitch ÷ 25.4

[precisionmetal]

Or don't convert it (if you're in inch) and just enter ........ 0.7mm ........ as the input value. Fusion will convert.

As Superman says: If you're running your machine in inch mode, you might have to enter your M4 tap data like this: (this is how my M4 tap is set up in the tool library)





I just did a quick test in the tool library and added another metric tap (10mm x 1.25). I just left everything at inches, except entered: "10mm" as the diameter, and "1.25mm" as the pitch. The value was instantly converted to inches when I tabbed away from that field.


PM