Turning Aluminum

OK guys,

I'm going to take the risk. Absolute stone newbie here...

Recently got access to a lathe. I need to turn some 6061-T6 aluminum pipe from 2.4" OD down to 2.128" OD. How deep a cut can I take in a pass? Carbide or HSS tool? Lubed or dry? Rotational speed? Feed rate?

I've practiced on a spare piece, but have had zero luck, or instruction, on the speed/feed/depth-of-cut thing. It doesn't have to win any beauty contests, but I sure wouldn't mind if it came out looking decent. I'll also need to cut some plugs to fit the ID from some solid bar. That has to come out smooth and pretty. It will have an o-ring groove, and must be removable with ease.

The only thing I've ever cut on a lathe was some graphite, and that stuff is so soft I could cut it with a butter knife. Wasn't a challenge. But this aluminum is another story.

Thanks for any and all help,

James

Reply to
James L. Marino
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I'm not exactly a pro, but:

You can take as deep a cut as your lathe can handle. If you have coolant running onto it, and it's a nice rigid lathe, and your pipe is firmly mounted then you could almost do it in one whack. But the only reason not to take light cuts is speed.

When you're almost there you'll want to take light cuts. You'll also want to use a tool with a more rounded tip and feed slowly -- this will reduce the amount that the tool marks stand out. If you use an 80-mil diameter tip and feed dead slow then you will almost have a mirror finish.

At least use oil -- I don't care about speed, so I go no more than 1/2 the "usual" recommended speed and I just use a bit of motor oil rather than fancy coolant.

It would be nice if there were shop manuals for the amateur machinist -- all the manuals and handbooks that I can find assume that you'll be in a shop with an expert there to help you, so they leave out the really essential stuff. I only get time on the lathe at night when my kids are asleep so I'm pretty much fully self-taught.

Reply to
Tim Wescott

Kerosene or WD-40 works well with aluminium

"How to run a lathe" from South Bend is well worth ten times what I paid for my desk copy - $0.25. I think Atlas also had a similar book. Gerry :-)} London, Canada

Reply to
Gerald Miller

Not only does the local used bookstore have it, but they _also_ had a

1948 ARRL handbook -- I've been looking for one of the "war years" handbooks to replace my worn-out 1945 copy, this at least gets me closer.
Reply to
Tim Wescott

"James L. Marino" wrote in news:HZRqd.26702$ snipped-for-privacy@newssvr13.news.prodigy.com:

Tooling preference:

  1. PCD (polycrystalline diamond) - if available, by and far the best choice for aluminum.
  2. Polished carbide, with ~8-12° backrake, generous clearance angles.
  3. Polished HSS, also with the backrake and clearance angles.

Speeds in order with tools above:

  1. Maximum RPM of the lathe.
  2. 60% of Max RPM
  3. 40% of Max RPM

Feeds:

  1. Up to ~0.03"/rev (depending on ridgity)
  2. Up to ~0.02"/rev (depending on ridgity)
  3. Up to ~0.01"/rev (depending on ridgity)

Depth of cut:

  1. Take all but 0.005 in one pass (provided the lathe has the horsepower, and you have a good setup and that that depth does not exceed the length of the PCD.
  2. Would probably take that in 3 rough passes, with a 4th finish pass using carbide.
  3. Same as carbide

Use coolant, plenty of it. You must remove all the heat you can from the cutting process. Diamond tooling will not build up aluminum at the cutting edge, carbide and HSS will.

Reply to
Anthony

Reply to
RoyJ

Thank you to all that responded. I appreciate the help, and hope to become a contributing member of this forum in the future.

James

Reply to
James L. Marino

We turn 6061-T6 six days a week, two shifts a day.

3.25 dia. Roughing depth of cut .150, .02 in/rev, 1800 rpm. Finish cut of .02 at 3000 rpm and feed .0025. Waterbased coolant.
Reply to
gerry

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