[pleasedontcrash]

I have a job coming up were I have an OD and ID left hand thread M6.5x.5mm. Now I cant find any info for this thread existing only a M6x1.mm in the machinist handbook. I know this thread can be produced but how do you go about finding out your thread specs? Do you just use your Major Diameter for a M6 and program the machine to turn to the .5 pitch?

[ghyman]

With very few (if any) exceptions, Left-hand threads are identical dimensionally to the same Right-hand thread.

Whatever dimensions a right-handed thread has will be the same for the left-handed thread.


==edit==
sorry, I missed the intent of the question.

M6 x .5 will follow the same rule of thumb as other threads for internal threads -
6mm(OD) - 0.5mm (pitch) = 5.5mm tap drill.

Here is a good reference.

[jeffrey001]

Is this M6.5 X .5 or M6 X .5?

Jeff

[ghyman]

Wow, I'm sorry.
Maybe I should read the question before answering!

First of all, check out the picture here for some good direction; I believe this image is also in the Machinery's Handbook.

Running through the calculations for 6.5 x 0.5, I get:

External
Major Dia = 6.446
Minor Dia = 5.905

Internal
Major Diameter = 6.500
Minor Diameter = 5.959

Sorry it took me 3 tries to get it right :/

</hangs head>

[pleasedontcrash]

Its 6.5 x .5 threads. We so a lot of machine work for the medical industry so everything is oddball.

[chunkymonkey]

ii think i have turned that thread a few years ago. I believe the print called out Major, Minor, and Pitch Ø. We were given 2 sets of thread rings from the customer for pitch, but operators didn't check the minor well enough.