[Newbie] What specification aluminium is the easiest to machine?

[mctle]

Hi guys,

this is my first post so please be gentle!

I have needed to make some 60mm diameter pulleys which i have already successfully done out of a piece of material I had about the workshop. I have managed to part off in the lathe quite successfully with this material but now its all used up, but I need to make some more!

My problem is other pieces of material I have tried to part off, chatter like hell and I just cant machine them very well.

Question is, what would the specification of the first piece of aluminium be for it to turn so easily? I have had it for years and no idea where it came from or its specification...

If anyone can recommend a suitable alloy I could purchase I would be very grateful. The part I am making is of low stress, low wear, and surface finish is not an issue.

Thanks in advance

 

[Bill Gruby]

That's an easy one. 6061 is quite friendly. 2024 is also good. Go to 7075 and machining properties change, it is harded that the other two. For pulleys 6061 is fine.

"Billy G" )

 

[12bolts]

Tony,
Can we have a bit more info please.
In the pic above is that of the old piece or the one you are having trouble with now? How long ago did you last make these pulleys?
I would be looking more at your tooling and setup first. Tool height, angle and sharpness. Spindle and feed speeds. Lathe wear and adjustment since you last did this. Maybe as simple as gib looseness. Are you new to machining? A hobbyist? Been doing this for years?
Its going to be hard identifying some piece of unknowinam from a written description :thinking:

Cheers Phil

 

[n3480h]

6061 or 2024, with 6061 getting my vote because its generally less expensive. Is the chatter occuring as the cut gets deep, or all the time? Using any coolant/lubrication? If the part is low stress/low wear . . . have you considered Delrin (acetal), or nylon?

Tom

 

[mctle]

Tony,
Can we have a bit more info please.
In the pic above is that of the old piece or the one you are having trouble with now? How long ago did you last make these pulleys?
I would be looking more at your tooling and setup first. Tool height, angle and sharpness. Spindle and feed speeds. Lathe wear and adjustment since you last did this. Maybe as simple as gib looseness. Are you new to machining? A hobbyist? Been doing this for years?
Its going to be hard identifying some piece of unknowinam from a written description :thinking:

Cheers Phil

hi Phil,

That was the material that was easy to machine... I only did it last week so the only thing I have changed is the material. I have been machining for years but at a very basic level....

 

[DMS]

Maybe you had a piece of cast alum?

For machining pulleys, I would say 6061, as it is very common (easy to get). The trick with it is that it is pretty "sticky". It likes to weld to dry, uncoated tools, and then things get ugly. It's easy to prevent. A little cutting fluid works wonders. Things you might try are WD-40, any synthetic coolant recommended for aluminum, kerosene/mineral spirits/paraffin oil. It doesn't take much at all. Just make sure you have plenty of fresh air.

 

[Ray C]

+1 on the recommendations and lube techniques for 6061. It's the "mother's milk" of aluminum and AL is basically a joy to work on. Bill is right on, 70xx is weird stuff -but still OK to work with.

Parting the piece as you are doing is going to be a dicey proposition because of the length of the stock. It's bending (although you can't see it) and the plate next to the piece you're cutting is rattling against the blade.

Sink that stock further into the chuck (if possible) or cut it in half and work on them separately.

 

[Jon K]

+1 on the recommendations and lube techniques for 6061. It's the "mother's milk" of aluminum and AL is basically a joy to work on. Bill is right on, 70xx is weird stuff -but still OK to work with.

Parting the piece as you are doing is going to be a dicey proposition because of the length of the stock. It's bending (although you can't see it) and the plate next to the piece you're cutting is rattling against the blade.

Sink that stock further into the chuck (if possible) or cut it in half and work on them separately.

I agree that the parting procedure is having chatter do to stick out.

I had been trying to part off an inch or two out of the chuck on like 1" or 3/4" material and had mixed results. Moving the part in and cutting it off 1/8" or so from the jaws had much nicer effect.

 

[Ray C]

I know I need to address this within myself and procedures but, parting creeps-me-out. It's a last-resort operation for me. Yes, I'm aware of the procedure and have done it plenty of times but once in a while, something goes wrong for no apparent reason and the ensuing mess is more than I care to deal with.

Anyhow, always part within an inch or so of the chuck and in situations, when a center is involved... well, I take the piece out and cut it in the saw. I don't believe I've ever parted anything that didn't fit inside the spindle tube thus making it easy to cut very near the jaws.

Ray

I agree that the parting procedure is having chatter do to stick out.

I had been trying to part off an inch or two out of the chuck on like 1" or 3/4" material and had mixed results. Moving the part in and cutting it off 1/8" or so from the jaws had much nicer effect.

 

[OldMachinist]

"Question is, what would the specification of the first piece of aluminium be for it to turn so easily? I have had it for years and no idea where it came from or its specification..."

The mystery aluminum may have been 2011. 2011 vs 6061 is like 12L14 vs 1018 in steel. It turns very easy and makes short chips instead of stringy ones.