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Turning a straight shaft!

KennyBoi

Plastic
Joined
Jul 29, 2017
Okay Forum, need some unique ideas and straight honesty, haha. I need to turn a titanium shaft 1" diameter by 32" long on a lathe.
Scenario:
  1. CNC lathe
  2. 2" annealed barstock
  3. Grinding not available and no heat treating
  4. No follower rest
Diameter has a +/- .001" tolerance and must be cylindrical within .002", with a 16Ra finish:eek:. There is also a 1.5" diameter hub on one end about an inch long.

I thought of using a steady rest, flipping the part, and straightening afterward. I am not sure there is a way I can hit the straightness tolerance at all and will need post machining straightening.

Does anyone have some secret techniques to relieving stress in a barstock of this diameter and still be able to hit the size tolerance and straightness tolerance with the scenario that I have?

I respect the amazing cumulative knowledge on this forum and will appreciate any feedback.
 

Omega

Aluminum
Joined
Nov 3, 2014
Do you have a tail stock, is your thru bore on the lathe larger than 2.00 ?
 

KennyBoi

Plastic
Joined
Jul 29, 2017
"Box Tool"

Not sure if this Box tool can accommodate the size stock and finish diameter. It looks like this tool needs to allow the finished bar to traverse through it and not sure this is possible with the 1" finish diameter.
 

Bobw

Diamond
Joined
Feb 8, 2005
Location
Hatch, NM Chile capital of the WORLD
I think I'd start by taking the length(Diamter?) to 1.2" or so, and seeing what distortion I got at that time.

I'd start bigger than that.. 1.9".. WTF happened, how's it measure etc....

Learn some more.. 1.8"...

Learn some more maybe go 1.6"

etc....

Of course, throwing in test cuts.. You know.. You need 1".. So take 2 exact repeatable
cuts.. Rough to 1.06. Finish 1.03.. Adjust and then finish again with an almost identical cut
at 1".. None of this sneaking up on it shit...

Sounds like a pain in the ass. I hope it was quoted properly, or you are getting paid hourly..
By properly, I mean throw a really big # at it, then double it, and then pad it a bit.
 

Ox

Diamond
Joined
Aug 27, 2002
Location
West Unity, Ohio
Okay Forum, need some unique ideas and straight honesty, haha. I need to turn a titanium shaft 1" diameter by 32" long on a lathe.
Scenario:
  1. CNC lathe
  2. 2" annealed barstock
  3. Grinding not available and no heat treating
  4. No follower rest
Diameter has a +/- .001" tolerance and must be cylindrical within .002", with a 16Ra finish:eek:. There is also a 1.5" diameter hub on one end about an inch long.

I thought of using a steady rest, flipping the part, and straightening afterward. I am not sure there is a way I can hit the straightness tolerance at all and will need post machining straightening.

Does anyone have some secret techniques to relieving stress in a barstock of this diameter and still be able to hit the size tolerance and straightness tolerance with the scenario that I have?

I respect the amazing cumulative knowledge on this forum and will appreciate any feedback.


Why is grinder not an option?
Concerned with impregnation from the wheels and coolant?

Turn a 1" shaft 32" long to .001 tol without a C/L grinder?
Better you'n me!


----------------------

Think Snow Eh!
Ox
 

Mechanola

Stainless
Joined
Mar 21, 2011
Location
Äsch
Thou shall find someone in California who centerless grinds the bar to a straightness under half that value. Surface can be baby-skin smooth and the price decent. Come up with an old chocolate Easter Bunny as a tip.
 








 
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