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    <title>tema Re: THREAD MILLING minor diameter problem en FeatureCAM Forum</title>
    <link>https://forums.autodesk.com/t5/featurecam-forum/thread-milling-minor-diameter-problem/m-p/6777243#M370</link>
    <description>&lt;P&gt;I don't&amp;nbsp;do much&amp;nbsp;thread milling&amp;nbsp;so it's mostly an experiment every time to get all the numbers and dimensions correct.&lt;/P&gt;&lt;P&gt;A tapered pipe thread is even more difficult to machine correctly and I would never expect the first&amp;nbsp;one to come out exactly the way you need it.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;There are multiple possibilities for an incorrect thread size: Bad&amp;nbsp;numbers in&amp;nbsp;the thread dimensions/definition&amp;nbsp;but it could also be the tool diameter or tool length.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;I don't know how FeatureCAM comes up with 23.127 or 24.577mm as a pilot hole. The chart below has 59/64 inches as a pilot hole (=23.416mm).&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;&lt;A href="http://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html" target="_blank"&gt;http://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html&lt;/A&gt;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;According to this chart you should mill 10 revolutions of thread which is about 18.14mm deep but to start&amp;nbsp;I would back-off the tool length offset&amp;nbsp;by 9.07mm (=5x&amp;nbsp;thread pitch)&amp;nbsp;and cut only 5 threads. Increase the diameter comp until the thread gage (or mating pipe) goes into&amp;nbsp;your thread 2-3 turns then you can go to full depth and do a little more "fine tuning".&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;...hope it helps but maybe someone else with more thread milling experience has a better method.&lt;/P&gt;&lt;P&gt;F.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;</description>
    <pubDate>Sat, 31 Dec 2016 23:57:47 GMT</pubDate>
    <dc:creator>Anonymous</dc:creator>
    <dc:date>2016-12-31T23:57:47Z</dc:date>
    <item>
      <title>THREAD MILLING minor diameter problem</title>
      <link>https://forums.autodesk.com/t5/featurecam-forum/thread-milling-minor-diameter-problem/m-p/6776355#M369</link>
      <description>&lt;P&gt;I was trying to make an Internal NPT 3/4 thread hole using the option of&amp;nbsp;THREAD MILLING. The program gave me 2 options to do it.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;UL&gt;&lt;LI&gt;Using the hole feature&lt;/LI&gt;&lt;LI&gt;Using the thread milling option&lt;/LI&gt;&lt;/UL&gt;&lt;P&gt;The first option takes care of the initial hole the second one you need to have the hole already.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;Using the standard values the minor diameters aren't equal. &amp;nbsp;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;UL&gt;&lt;LI&gt;Using the hole feature (24.577 mm)&lt;/LI&gt;&lt;LI&gt;Using the thread milling option ( 23.127mm)&lt;/LI&gt;&lt;/UL&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;I did mill the first option but the thread is to big (using a solid carbide 3/4-14 NPT 0.495 cutting diameter &amp;nbsp;)&amp;nbsp;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;Is this a problem of the program???&lt;/P&gt;</description>
      <pubDate>Fri, 30 Dec 2016 18:37:24 GMT</pubDate>
      <guid>https://forums.autodesk.com/t5/featurecam-forum/thread-milling-minor-diameter-problem/m-p/6776355#M369</guid>
      <dc:creator>Anonymous</dc:creator>
      <dc:date>2016-12-30T18:37:24Z</dc:date>
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    <item>
      <title>Re: THREAD MILLING minor diameter problem</title>
      <link>https://forums.autodesk.com/t5/featurecam-forum/thread-milling-minor-diameter-problem/m-p/6777243#M370</link>
      <description>&lt;P&gt;I don't&amp;nbsp;do much&amp;nbsp;thread milling&amp;nbsp;so it's mostly an experiment every time to get all the numbers and dimensions correct.&lt;/P&gt;&lt;P&gt;A tapered pipe thread is even more difficult to machine correctly and I would never expect the first&amp;nbsp;one to come out exactly the way you need it.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;There are multiple possibilities for an incorrect thread size: Bad&amp;nbsp;numbers in&amp;nbsp;the thread dimensions/definition&amp;nbsp;but it could also be the tool diameter or tool length.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;I don't know how FeatureCAM comes up with 23.127 or 24.577mm as a pilot hole. The chart below has 59/64 inches as a pilot hole (=23.416mm).&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;&lt;A href="http://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html" target="_blank"&gt;http://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html&lt;/A&gt;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;According to this chart you should mill 10 revolutions of thread which is about 18.14mm deep but to start&amp;nbsp;I would back-off the tool length offset&amp;nbsp;by 9.07mm (=5x&amp;nbsp;thread pitch)&amp;nbsp;and cut only 5 threads. Increase the diameter comp until the thread gage (or mating pipe) goes into&amp;nbsp;your thread 2-3 turns then you can go to full depth and do a little more "fine tuning".&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;...hope it helps but maybe someone else with more thread milling experience has a better method.&lt;/P&gt;&lt;P&gt;F.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;</description>
      <pubDate>Sat, 31 Dec 2016 23:57:47 GMT</pubDate>
      <guid>https://forums.autodesk.com/t5/featurecam-forum/thread-milling-minor-diameter-problem/m-p/6777243#M370</guid>
      <dc:creator>Anonymous</dc:creator>
      <dc:date>2016-12-31T23:57:47Z</dc:date>
    </item>
    <item>
      <title>Re: THREAD MILLING minor diameter problem</title>
      <link>https://forums.autodesk.com/t5/featurecam-forum/thread-milling-minor-diameter-problem/m-p/6804018#M449</link>
      <description>&lt;P&gt;We do quite a bit of thread milling here on a variety of materials. We use single form, partial form, and full form thread mills as well, but I can't say that I have used an NPT thread mill. I don't want to write the obvious, but like other features, having your tool drawn exactly to size is critical.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;I'm not following your process so I'll write what I do.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;New Feature&lt;/P&gt;&lt;P&gt;From Dimensions-Thread Milling&lt;/P&gt;&lt;P&gt;Type is ID&lt;/P&gt;&lt;P&gt;Select Standard Thread and choose 3/4-14 NPT&lt;/P&gt;&lt;P&gt;All I would adjust here is the thread depth&lt;/P&gt;&lt;P&gt;Next select the location&lt;/P&gt;&lt;P&gt;Next page I select Positive. I have found I get much better threads when I plunge to depth and climb mill. Of course this will be operation specific. I do rough and finish, and usually 1 spring pass.&lt;/P&gt;&lt;P&gt;There is no 3/4-14 so you have to draw one.&lt;/P&gt;&lt;P&gt;I got the attached dimensions using Harvey Thread Mill PN&amp;nbsp;&lt;SPAN&gt;70226&lt;/SPAN&gt;&lt;/P&gt;&lt;P&gt;Should be straight forward from there. As always if it is an expensive part I would use some positive cutter comp and work the tolerance in until I found the right numbers. As long as I draw the tool right the program has always been within .001"-.002". Hope this helps.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;</description>
      <pubDate>Fri, 13 Jan 2017 15:19:41 GMT</pubDate>
      <guid>https://forums.autodesk.com/t5/featurecam-forum/thread-milling-minor-diameter-problem/m-p/6804018#M449</guid>
      <dc:creator>Anonymous</dc:creator>
      <dc:date>2017-01-13T15:19:41Z</dc:date>
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