threading lathe

[Thoob]

Hi guys, I have a part I need to thread. The guy wants 3.4 MD with an 8 pitch. I have in my parameters whats shown in picture. Can I compare with what you guys would have in the settings? Also can you explain the parameter "amount of last cut"? These threading parameters still mess me up a little. I'm using X5 MU1

[CADCAM3D5AXIS]

Thoob

the amount of last cut is your finish pass cut control, i believe this will be your last pass and it moves the amount i believe if you add or change the number of spring passes.

HTH

[Mr. Wizzard]

standard 60 thread or acme or other? Plain steel or aluminum or other? If aluminum or plain carbon steel, i would say you're fine. My only concern would be harder material with a standard (sharp point) 60 degree threading insert. You may want some light cuts in that case to avoid blowing off the insert tip. just guessing here...

[Sbarner]

Thoob,

 

FWIW depending on the material, those look good to me. Where I have the most trouble is the depth of the thread. Using the software's tables or standard values for threads gets me results ranging from perfect with no cutter comp to having to comp up to .018. An 8 pitch 60 degree? I think I'd be going with about .081 depth on that. I realize that's not what you were asking, but that's my 2 cents.

[Thoob]

Thoob,

 

FWIW depending on the material, those look good to me. Where I have the most trouble is the depth of the thread. Using the software's tables or standard values for threads gets me results ranging from perfect with no cutter comp to having to comp up to .018. An 8 pitch 60 degree? I think I'd be going with about .081 depth on that. I realize that's not what you were asking, but that's my 2 cents.

 

Ya its just plain 1018 steel. I am using a threader with a .004 radius on it. I do as well have trouble with my depths. They are always under what I put in Mastercam. Example if I want it to be .081 per side (8 pitch), my cycle always ends up putting it to say .065-.07. It varies on pitch. I remember someone once telling me that the "amount of last cut" is not actually that. It adds or minus' to the thread calculation giving different amount of passes. Just seems to me Mastercam has not even figured it out properly cause they can't give me a reason why it threads like that, lol. Maybe its my controller who knows. What my main beef is when I watch the verify, it shows the cutter to do about 20 passes, but then when its ran on the lathe, it cuts to more than double that amount. In this case it would end up taking 40+ passes. So i struggle with making Mastercam verify show about 10 passes, so that it will only cut approx 20 passes on the lathe. See my dilemma?

[Mr. Wizzard]

I see you have it set for canned cycle. Does it output the correct parameters for the canned cycle? Another thing, sometimes there are settings in the control that adjust how the canned cycles are interpreted. The passes may be starting .03 bigger than the part diameter or more, cutting air basically, because of a setting in the control.

[Sbarner]

As far as your depths go, Thoob, I think there is another factor at work there. Do you have something in the "allowances" fields on the parameters? What if you post the code longhand instead of canned? Do you still get the .065-.07 instead of what your depth value is? As far as the number of passes, what does it do in backplot? Does it take the 20 you want or the 40 that your code gives you? I'd check the control definition (if you feel comfortable) and see if there is something in there that could be doing it. It could be a post thing too.