Author Topic: Threading on a 1A616 STANKO lathe  (Read 4692 times)

Offline ksor

  • Sr. Member
  • ****
  • Posts: 316
  • Turn off the TV - life ain't replayed !
    • Keld's hjemmeside
Threading on a 1A616 STANKO lathe
« on: September 18, 2013, 02:30:42 PM »
I'm preparing for my first threading cut on my old STANKO lathe (the 4. Picture from the top):

http://kelds.weebly.com/mine-maskiner.html

I've seen some vidoes on Youtube on "how to" BUT ...

I wonder why the compound should be set to 29° (sometimes 29.5°) - I know it should be THE HALF of the thread's degrees - but I plan for 60° - why then 29° (29.5°) ?

Tubalcain says "Look in the books for the explanation - but I can't find any explanation - do you know why ?

 :scratch: :scratch: :scratch: :scratch: :scratch:
Best regards
KSor, Denmark
Skype name: keldsor

Offline philf

  • Hero Member
  • *****
  • Posts: 1108
  • Country: gb
Re: Threading on a 1A616 STANKO lathe
« Reply #1 on: September 18, 2013, 02:50:02 PM »
I'm preparing for my first threading cut on my old STANKO lathe (the 4. Picture from the top):

http://kelds.weebly.com/mine-maskiner.html

I've seen some vidoes on Youtube on "how to" BUT ...

I wonder why the compound should be set to 29° (sometimes 29.5°) - I know it should be THE HALF of the thread's degrees - but I plan for 60° - why then 29° (29.5°) ?

Tubalcain says "Look in the books for the explanation - but I can't find any explanation - do you know why ?

 :scratch: :scratch: :scratch: :scratch: :scratch:

ksor,

This has been discussed very recently.

Have a look at http://madmodder.net/index.php/topic,8677.msg94089.html#msg94089

Basically - If you don't set the topslide to exactly half the angle and set it even slightly more than the half angle (e.g. 30.5 deg) you can't get the correct thread form. (Unless you take the last cuts by advancing only the cross slide.)

Personally, I never bother angling the topslide and keep it parallel with the lathe axis. I advance the top slide about half the amount I advance the cross slide every cut and for the last few passes just advance the cross slide. With insert type tools it's normal to plunge straight in with the cross slide and not to touch the top slide.
 
Cheers.

Phil.
Phil Fern
Location: Marple, Cheshire