Thread milling 1/4-18 NPT on side with Doosan Puma TT1800SY ???

[gcodeguy]

Anyone thread milling a 1/4-18 NPT side port on a lathe? Thread gage that checks top and bottom of thread is good. 6-step gage that checks the I.D. diameter is too deep and has play. Part done on vertical mill has no play with the 6-step gage and gage doesn't go in as deep. Lathe part has a larger I.D. I.D also has scallops around the circumference. Sides of the threads look like they have a line at each arc endpoint that is in a straight line down the length of the thread. Side of thread looks wavy at these points.

Back story. Been programming lathes a long time. We recently started getting some lathes with Y-axis. Job before this one required two 1/8-27 NPT side ports. I've never thread milled in my life. Two people from Doosan weren't able to help. One sent me a print and the program that (supposedly) ran three 1/4-18 NPT side ports when I was trying to figure out how to program the 1/8-27 NPT side ports. I tried to run their program, but it wouldn't run. Alarmed out. AFAIC the sample program never ran a part.

Our mill guy said he swings 12 arcs for running on the vertical mills. So I tried that. We have MasterCam, but no live tooling posts for our lathes. I laid out what I hoped would work and analyzed the construction to find my arc endpoints. Yes.....trig would work, but it is so much easier using MasterCam. LOL The 1/8-27 NPT didn't look quite as nice as the ones from a mill (had those minor scallops on the I.D.), but was good enough to get through inspection.

I haven't visited a machining forum in several years, but I know there used to be several very knowledgeable guys on here. Hopefully a couple are still around and can help. Thanks.

 

[gregormarwick]

You should be able to get starting point code out of mastercam with a Fanuc mill post, and making a threadmilled hole in the Y-Z (G19) plane.

Then you'd just need to convert all the X to diameters.

 

[gcodeguy]

Can't use G19. Alarms. Confuses me because according to how I read it G19 should be the correct plane.

EDIT: Need M-code to let you work close to spindle. Need M-code to let you work a turret on the other spindle. Need M-code to index at some positions. Never had a Y-axis lathe before. Etc. Etc. Etc. Yet the company won't send me to a free class. Have to figure everything out on my own...with a few phone calls to Doosan that may or may not help.

 

[gregormarwick]

Can't use G19. Alarms. Confuses me because according to how I read it G19 should be the correct plane.

EDIT: Need M-code to let you work close to spindle. Need M-code to let you work a turret on the other spindle. Need M-code to index at some positions. Never had a Y-axis lathe before. Etc. Etc. Etc. Yet the company won't send me to a free class. Have to figure everything out on my own...with a few phone calls to Doosan that may or may not help.

My Doosan (Y axis, but not the same model as yours) is fine with G19. Are you sure that it's definitely the G19 that is throwing the alarm? Are you specifying the arc centres with J and K?

Maybe post your code that alarms.

 

[gcodeguy]

Using R. Can't remember if I tried G19 with my program. Will give it a shot. Doosan program used G19. It alarmed on it. Didn't with G18 so I've been using G18.

EDIT: Okay. Put G19 first block in my thread mill subprogram so I would immediately know if G19 was the problem. It ran. Now thread gage is a little short and 6-step doesn't go as deep as it does from the vertical mills. Hallelujah! That I can fix. Still has the lines on the thread and scallops on the I.D. Am going to rerun the thread mill subprogram to see if a spring pass smooths things out. Kind of doubt it.

EDIT2: Spring pass no work.

EDIT3: Pilot error. Thread looks good now. Thanks for the help.

 

[gregormarwick]

Post up your code.

 

[Ox]

Take a "finish" pass, not spring.


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