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Thread milling diameter

JJackrabbit
Advocate

Thread milling diameter

JJackrabbit
Advocate
Advocate

Hello

I'm trying to thread mill in steel. I need to make a bunch of M8 holes.

In my drawing the holes are 6.8mm. I also drilled the holes 6.8mm

But how does the threading option work?

I entered the pitch (1.25), if I enter the diameter of 6.8mm it won't cut away enough material.

Do I need to enter 8mm? or how is this being calculated. 

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Anonymous
Not applicable

"Pitch diameter offset" will make your day. In your case, 1.2mm.

 

David

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JJackrabbit
Advocate
Advocate

Thanks, that seems to work

 

Tool plunges in and cuts thread from the bottom to the top

second pass also a straight plunge

third pass it moves off center before plunging in. One flute touched the part and got damaged...luckily the tool itself is still 'alive'.

How can I prevent the tool from making horizontal movements when plunging in? 

 

 

Edit

Enabled lead to center, that should solve it.

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JJackrabbit
Advocate
Advocate

Ok that seems to work

I have thread which looks good. Only it's too small, can't insert a m8 bolt.

 

Cutting diameter of the tool is setup right.

 

Or did I made a mistake by drawing the hole 6.8mm?

Should it be 8mm in the drawing? And then setup the thread cutting for m8.

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Anonymous
Not applicable

Most thread mills have a slight corner radius on the cutting edge so it doesn't chip as easily but most CAM expect a sharp V. In all my years of thread milling I have all ways used wear comp and adjusted the tool at the machine to get it to check with a thread gage.

 

If your machine doesn't have tool comp the adjust the pitch offset till it gages correct. Also, check your lead in/out values to insure the tool doesn't make contact with the wall.

 

You modeled and set up it correctly.

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JJackrabbit
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Advocate

thanks I will check the wear comp

Bolt almost fits but it needs another pass with the thread mill to make it a little bit bigger

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Anonymous
Not applicable

On "Linking" tab, check "Lead to center" if you haven't done it already.

 

Most threading tools must be compensated about 0,06-0,08 mm.

 

David

 

Edit: I apparently didn't read all of the above. Double info.Smiley Embarassed

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