threadmilling

[ROB]

i just f#&*%up a part doing some threadmilling

on a part went o/size i don/t know how much it is a 1x11.5 npt thread using a single point threading tool,this is what i did.I went to my machinest book puled the major dia 1.315

pitch .0869 taper 1.7833 based on the angle

opened up a hole 1.14 using c/comp g42 based on conventional cutting top to bottom

cut it and oops don't know it went o/s.

don't have much experience on this operation

using mill9.

i fixed later luckly,any help will be apreciated

thanks!

did i read the major dia wrong may be?

machinery's handbook 25

page 1774

 

->forgot this is an internal thread

 

[ 08-28-2002, 03:49 PM: Message edited by: Dave Thomson ]

[Surface]

The foolproof method I use to machine pipe threads is to create a tapered spiral using the "thelix" c-hook.

I use the tap-drill size as the smallest arc diameter. I offset the geometry (spiral) by half the tool dia and add a lead/in/out arc. Turn cutter comp off in computer.

Perhaps not the most efficient method, but why take chances. A bad thread can spoil your day

[ROB]

it's there a formula to figure out npt

thread's? like...

min dia=

major dia=

length of thread=

and thanks for the reply!

[Jack Mitchell]

Rob,

 

Thank You for this question.

 

I already typed a 1/2hr response two days ago and lost it when my computer hung.

 

Tell me more about the cutting tool; I want the specifics so that I can buy the exact tool that you are using. – Single point rules for this type of thread. Please do not disappoint me with a G94 solution.

 

I have programmed these threads before using comp & quadrants (which required four lines of code and vectors based upon 1Deg 47min for the half angle for each 360).

Let’s do it the hard & the easy way – what say you?

 

Here’s the catch, rapid to the bottom, pickup comp, interpolate from the bottom to the top.

 

This is in reverse of the method that you used in Mastercam - were going to punch this one out once & then were going to punch out another four different ones – this is fun! Truly an honest education.

 

A lesson learned the hard way is truly owned – personally, any lesson that I learned the hard way becomes imbedded, impassioned. I truly despise screwing up a workpiece – for this I truly burn – for this I truly own the knowledge.

 

The very first thread I had to face on the shop floor was a ½-14 Npt; this was not fun, this was very difficult; Bottom line here is I did it on an Nc lathe using G32. (Guildemiester with the ever adorable GE 550T) – GOD I despised that control, and, I am so glad to have suffered the abuse of it all.

 

Let’s have some fun with this, Regards, Jack

[ROB]

hello jack.

thanks for the response.

well,unfortunally i'm not at work right now

to give you the specs for the tool, the only thing

that i can remember at this moment is,that the cutter is .557 dia and want to cut a 1x11.5 npt

id thread using c/comp on g42 based on conv/cutting top to bottom.Honestly i will like to learn the procedure if any like a formula

or the way to do it you may want to call it

the "old school way" i love machining especially

mills so if you can give me a "hint" on this i will really apreciate it.

it seems to be that a lot of people don't know about threadmill, since i only had 2 responses

on this topic in 3 or 4 days that i had this question on the forum.

i wont be home tomorrow and won't get back to work until tuesday, sorry! its "labor day weekend"

[Jack Mitchell]

Rob,

 

There are no hints or secrets here.

I also seek the knowledge as well - that’s why I am going to buy the exact same tool that you are using.

Patience is required, so is tenacity.

Let’s work the math & logic and actually write the program using the conventional Fanuc compatible method (I will upload a drawing and the hand written program).

Then, let’s write the program using Mastercam to its fullest potential.

 

The method of rapiding into the hole, then picking up comp, then helixing out – is the preferred method from my take on this.

 

I agree with you, I’m surprised as well that there has been such a low response to the question. The bottom line is we are going to know this the hard way and the easy way.

 

Regards & always learning, Jack

[ROB]

hello jack i'm back at work!

sorry, the dia of the cutter is .564

not .557, so just let me know when you put the file or drawing on the ftp.

[McRae]

Labour is spelt with a "U" - the Queen's english you know. See advent threadmilling for some technical information on programming. Bottom to top so there are places for the chips to go and feed heavy to reduce chatter. Also when using the quadrant method, the form isn't quite true and there are some leakage paths from the "Arc" fitting that goes on. Start with a tapered hole as well if you "Single Point"

 

I will do what I can to help,

[Scott Bond]

Hi all

quote:

---

The foolproof method I use to machine pipe threads is to create a tapered spiral using the "thelix" c-hook.

I use the tap-drill size as the smallest arc diameter. I offset the geometry (spiral) by half the tool dia and add a lead/in/out arc. Turn cutter comp off in computer.

Perhaps not the most efficient method, but why take chances.

---

I have been useing this method myself since day one.I have been reading this thread and I to would like to know if there is some new sure footed feature.

[Jack Mitchell]

Rob,

 

The make, model, insert etc!, of the cutting tool.

I need all of this, in order to duplicate and appreciate exacting results from both our ends.

 

This will be great fun; this will also be professional & scientific now that MfgEng has shown an interest.

 

The remark on the tapered hole is correct but not always achievable for the smaller of the Npt holes; perhaps, for the 3/4" and larger should be considered for tapered holes.

 

C-drill, tap drill, G84 pipe tap = smaller npt thread forms.

C-drill, tap drill, form tool slotdrill, G84 pipe tap = medium npt thread forms.

 

Sorry, (slotdrill is a slang term and is the common method of referring to a center cutting two flute or four flute endmill) – in Canada, – think it was borrowed from England.

 

Regards, Jack

[Jack Mitchell]

Andrew,

 

I missed you at Flowserve.

I realize that your busy with your sister plants, IMTS, Etc!

 

Please spend up to $250.00 US as per our email discussion regarding some lunches, what is not spent on lunches will be spent on Emuge taps. There is a cheque at Flowserve for you at reception.

 

I am sorry to resort to leaving this message on the forum – but hey, I know how much of a Mastercam junky we have all become as of late. Although you’re unavailable until Sept. 10th and that I’m also unavailable until Sept. 28th I just know that you will peruse the forum – hence, the best place for contact.

 

Regards, Jack

[ROB]

ok Jack!

i'll see if i can get the info later today.

[ROB]

THIS ARE THE SPECS FOR THE CUTTER AND THE INSERT

 

KENNAMETAL-K067TM1RW062-STN16N

INSERT N0. STN16