[HuFlungDung]

Probably calipers will work ok. If you can straddle the thread from the end, then you can kind of pinch the calipers shut over top of the wires until all three are captured, then take the reading. There is a little calculation sheet that comes with the wires that tells you how to calculate the pitch diameter from your measurement. Don't lose that sheet, in fact, laminate it to protect it

The method I recommend for threading is not to try to calculate it to extreme precision in advance. You need ball park figures to work with, and you need to know what "almost done" should look like. That is what the crest width information is all about, because you do not actually measure the crest widths with any precision, but razor sharp is a sure sign that the thread depth is overcut.

For external threading, I deliberately cushion the tool offset so that I know the thread will not be overcut in depth. PeeDee it with the wires and figure out how much further to go. Then either adjust the tool offset or the program to hit the correct size.

Same logic with the ID thread: you know the toolpoint represents a small cross section of the male thread. So the logical X endpoint for the internal thread is going to be .001 to .005 greater than the major thread diameter. So trial cut the first round of passes on the ID, stopping the tool exactly on the major OD at the last cut, and try the gauge. If it is too tight, then adjust the program endpoint or the X offset by .002 and run it again.

Be prepared to sacrifice the first sample nut that you make until you get this down pat. Don't spoil a part that has a whole lot of time put into it already.

[minardsanders]

In response to the threading question. The dia. you have given is not a american thrd. Allways remember that you can cut any thrd on any dia. ther are alot of metric thrds. out there today that are very close to american thrds. for example a 41.5 mm thrd will have a 1.6338 dia. the lead of a 1.6 mm thrd is .o6299 they are only .0004 per rev difference from a 16 thread you really need to know whichever one you have, then we can go from there. Unless you are one lucky son of a gun you will allways need a thrd. plug gage to check internal thrds for fit. You can manufacture a male thrd staying on the high side of your tolerance for said particular thrd. Use 3 wire system to measure this. Remember a male thrd is 75 percent, a female thrd is 62.5 percent this allows for clearance between the two objects. Go back to what I showed you, cosine for 30 deg is .866 = perfect thrd. The male thrd will be .75 times this = .6495 this multiplied by the lead which will be 1 divided by number of thrds will give you single depth of thrd. Internal thrd will be .866 times 62.5%, looks like this .866 times .625 will give you .54127 this multiplied by the lead will give you single depth of thrd. So if you double this and subtract it from whatever dia. of thrd you have this will give you bore dia. You really need to know this info, because we work to exacting dim. this is what sets us apart from the rest. Trying to do this by eyeball will not get it, use your micrometers. Good luck Minard

[Cartierusm]

Minard, thanks for taking the time to explain. Maybe you can go a little further. I did the calculation from your original post but the depth of the threads for the male part were deeper than is listed for normal full depth threads. If you can help me work through an example then I'll get it.

Today I have to cut a 16 TPI thread on a 1.6366" OD piece. So according to your calculations I take 1/16=.0625*.6495=.04059 but my threading program say a 16 TPI male thread depth should be .0383". So this is where I'm confused.