Some threading help

Can anyone help me out with some coding? I have to single point a 1 1/4-11 1/2 NPT, male thread, and I can not for the life of me remember how to calculate the turning points for the taper and threads. Also doesn't help my Handbook has turned up missing.

If someone could post the code for it, rather than a math lesson, that'd help even more. I can reteach myself how to come up with the right numbers later.

Edit: Having just seen the sticky post for threading help, I'll include the following:

2008 Haas SL-20, standard Haas control. Threading is done with G92. I can convert the numbers into a program, I'm just blanking mentally on how to get them.

DarkEdge said:

Can anyone help me out with some coding? I have to single point a 1 1/4-11 1/2 NPT, male thread, and I can not for the life of me remember how to calculate the turning points for the taper and threads. Also doesn't help my Handbook has turned up missing.

If someone could post the code for it, rather than a math lesson, that'd help even more. I can reteach myself how to come up with the right numbers later.

Edit: Having just seen the sticky post for threading help, I'll include the following:

2008 Haas SL-20, standard Haas control. Threading is done with G92. I can convert the numbers into a program, I'm just blanking mentally on how to get them.

Click to expand...

Hello DarkEdge,
The numbers used in the G92 cycle when cutting a tapered thread, are the same as those for cutting a parallel thread, but with the addition of an I address to specify the taper.

1. The X value for an External Thread will be the target X for each Threading Pass, the last pass will have an X value of the Minor Diameter of the Thread.

2. The Taper is specified by an I address in terms of radius. The taper of the thread you're cutting is 1:16 (diameter), 0.5:16 (radius). The Taper length is measured from the Start Point in Z of the Threading Tool to the Z End point specified in the Threading Cycle.

I know you didn't want a math lesson, but as you have not stated whether you will write the program in Metric, or Imperial, its best you calculate the taper amount.

The approx length of the thread is 25.4mm. You need to Start a distance from the end of the Thread in Z to circumvent Lead Error in the first couple of threads due to acceleration. This distance is directly related to the Lead of the Thread and the RPM used in the Threading Op (Slide Velocity). The minimum distance can be calculated (based on Lead and RPM), but generally a distance of 5 - 10mm will suffice.

Lets say the you have a Z Start of 10.0mm from the end of the Thread and the Z End Point of the Thread is Z-25.4. The Total Z distance traveled is 35.4 and given a taper of 0.5:16 (radius value), the I value used in the G92 Cycle will be:

35.4 / 16 x 0.5
= 1.106

Therefore, the I value will be I-1.106 in the Threading Cycle for the total Z Travel of 35.4mm

Regards,

Bill