Lathe - Taper Threading- help

[newbie70]

Hi Members

 

I need help with taper thread.

No matter what size the taper thread is?

 

What I learnt in school is 1 line format using G76 thread cycle where X is the minor diameter of long end. However, when I am using Mcam,

G76 thread cycle , X comes up as minor diameter of short end even though my setup is for minor diameter of long end.

My query is, do I need to edit this in mcam post to manual programming setting or leave it as it is?

 

Thks in Advance

Newbie

 

 

[crazy^millman]

Well seems like you learned it wrong in school if you are applying this to cutting OD threads. If you are cutting a tapered OD thread from the end of the part to the body of the part the smaller side has top be toward the end of the part and the larger side needs to be towards the body of the part. I always program off of the Major Diameter of a an OD thread never off the minor diameter when cutting OD. Since you were not specific in your thread cutting process then one could think will no you are cutting an ID thread and then you would need to make sure the Minor is at the back of the bore and bigger minor is at the front of the bore. Problem might be if you have not changed the threading cycle from OD to ID you would see a problem or vice versa.

 

People seem to complain about me asking for more information to help people yet those same people are not willing to help others as much. I took my best stab at it, but without a file or some screen shots not much more information I can offer to help you out.

[newbie70]

5th Axis

 

Of course it is OD taper thread.

I've screen shot of setup and NC file in text format

 

Newbie70

Text.txt

[Guest]

Are you by chance machining an API Thread?

[newbie70]

Trax

No it is just a metric profile, 2.5 pitch.

newbie70

[newbie70]

Hi Members

Am still waiting for inputs on how to fix lathe taper thread X value.

Newbie70

[Guest MTB Technical Services]

I have posted about this on numerous occasions.

 

This is a post bug that has been in the tapered threading in Mastercam since V9.

Your post needs to be fixed to output the 3rd X value in the NCI instead of the 2nd.

In a straight thread the 2nd X value will be correct but not for a tapered thread.

 

There is also a bug in the NCI that doesn't properly account for the run-in distance

when calculating the radial difference for the taper.

It appears you used the work around of moving the Z start point to handle that because the taper is correct.

 

I know Colin fixed this in all the new X7 posts before he moved on to eApprentice.

You need to contact your reseller to get the corrected post.

 

Happy Thanksgiving!