Pitch in Auto Circle

[Mike Boero]

How do you use the pitch option for say 1/4-20 thread. What number would go in the pitch box and would you need more that 0 start and 360 end. Thanks for any help.

[Wes Cisco]

Pitch is the number of threads per inch, so for a 1/4-20 it would 1 divided by 20 = .05. I have always just used 0 and 360, but I almost always use a cylinder to measure a thread, not a circle. Someone posted recently that you should go more than 360, and I intend to try that sometime soon. With a cylinder, 360 gives good results. HTH

[#2#]

As was suggested in a previous thread going more than 360º can only improve your measurement. To use the feature just enter the pitch (1/threads per inch(1/20=.5 for 1/4-20)) of the thread. Also, I enter the minor diameter of the threads as the hole nominal diameter. Of course you want to make sure it is progressing the correct direction. I don't trust it yet so I enter a large pitch (.1), execute the hole and visually check that it moves in the correct direction. Then I F9 the circle and edit the pitch to the correct one.

Apparently Wes thinks and/or types faster than I do.

[Mike Boero]

pitch in auto circle

Thanks for the help. If it were metric pitch like 1.75 would it still be1 by 1.75?

[Matthew D. Hoedeman]

Also, if you are in metric, use a metric value, if in inch, use an inch value.

[Wes Cisco]

As was suggested in a previous thread going more than 360º can only improve your measurement. To use the feature just enter the pitch (1/threads per inch(1/20=.5 for 1/4-20)) of the thread. Also, I enter the minor diameter of the threads as the hole nominal diameter. Of course you want to make sure it is progressing the correct direction. I don't trust it yet so I enter a large pitch (.1), execute the hole and visually check that it moves in the correct direction. Then I F9 the circle and edit the pitch to the correct one.

Apparently Wes thinks and/or types faster than I do.

And I check myself with a calculator for even simple math. After I milled a hole in the wrong position because in my brain I said, "90 degrees - 40 degrees = 60 degrees", I learned that the second it takes to punch it up is well worth not making the potential boneheaded error.

[#2#]

Metric threads are different. For example a M20X1.5 would have the pitch of 1.5 you do not divide 1 by 1.5. Now, since most of my programs are in inches and I have some threads that are metric I usally convert the metric pitch to inches and carry as many digits as possible.

[Paul Sarrach]

If you use pitch, it should not matter how the tapped hole is lined up. In theory it will be hitting the same surface all the way around, to which will give you the center?