What aluminum grade do you use?

I'm just beginning to play with machining aluminum.

In order to practice on my new little lathe (MicroMark 7x14) I need to order some aluminum rod stock.

Chief Wiggum suggested using 7075 aluminum because of better machinability. Other lathes sites suggest 6061.

So, lathe-masters... what is your prefered aluminum stock, and why?

Thanks in advance.

Well, I have no experience yet, so,, dont listen to me.

But, I just ordered $150 in Al 6061 stock last night.
I here its fine for our needs, I will soon know. /ubbthreads/images/graemlins/smile.gif

Good luck with your new lathe Alan, glad to see theres another member diving into the lathe world with me. /ubbthreads/images/graemlins/wink.gif

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alanz said:
In order to practice on my new little lathe (MicroMark 7x14)

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Would that be this?



Nice. /ubbthreads/images/graemlins/popcorn.gif

Velcro,

Yes, that's the lathe... here are two photos of it in my little shop.

6061 in T6 temper is probably the most common wrought alloy out there. It offers decent strength, corrosion resistance, and weldability. 7075 T6 is a lot stronger- 73,000psi yield strength vs 40,000 for 6061 T6. Ultimate strength is even better at 83ksi for 7075 vs 45ksi for 6061. Elongation to break suffers a little- from 17% for 6061 to 11% for 7075. (Hardly brittle.) In my own experience, it machines a lot nicer- less gummy and I can use less cutting fluid. Oh, it's a little harder to get and costs more.

Larry

tvodrd,

So given the two materials, what would be your preference for making flashlights?

alanz,

I've been using the 7075 lately. My local metal yard doesn't even stock it, and they are a pretty big outfit. I've been buying the precision ground stuff from McMaster. (Grab ur wallet! /ubbthreads/images/graemlins/rant.gif )

Larry

I looked at the McMaster product sheets.

Why have you been buying the precision ground? What sizes do you find yourself using?

Thanks so much for your input.

What Larry said. /ubbthreads/images/graemlins/grin.gif I use 6061 T6 because it's readily available and inexpensive compared to the 7075. The 6061 T6 machines fine but I would probably prefer the 7075; never tried it. I don't know how the 7075 responds to typical hard anodize, Larry? The 6061 T6 will do great with black and natural HAIII. I sent some parts made from 2024 in with a batch of heads that were all to be black HA and the 2024 came back battleship gray. /ubbthreads/images/graemlins/grin.gif Oops!

alanz,
I use the prec ground because it fits/repeats better in lathe collets. Size depends on the battery /ubbthreads/images/graemlins/grin.gif .

Don,
I don't have a lot of experience with "HA." 6061 typically comes out dark grey. The first 123 lights I did came out a much lighter gray, which turned greenish gray after exposure to skin oils/temperature/time. I found I could accelerate this with the aplication of some light spindle oil. I suspect it will take black dye fine, though I haven't tried it. (Just don't ever ask for dark green! /ubbthreads/images/graemlins/rant.gif ) 2024 is copper-bearing, (the increase in thermal conductivity is negligable) unweldable, and naturally ages from the T0 cond. if you buy it that way. Good for rivets! (Keep 'em refrigerated until use. Set them, and let them sit at room temp for a week or so and voila full strength.

Larry

Velcro,

Where did you buy your MicroMark?

I don't have a lathe.

icarus, I believe the only place you can get that particular lathe is directly from micromark. They are more expensive than similar machines, but have dials that are .050 inch per turn instead .040 (actually .0397 because of the metric conversion) per turn of the cross or compound slide. It also is 14 inch between centers, where most others are 10 or 12, and lastly has a Digital read out for RPM. It is a very nice machine. I bought a 7x12 from homier as it is basically made by the same manufacturer (a company called sieg) but is only $300 compared to $575 for the micromark. If you are interested in these machines a great review site is mini-lathe.com reviews

Thanks a lot for the info unnerv. Especially for the link to mini-lathe.com, very useful to me because i am new to metalworking lathes and want to buy one in the near future.

Any recommendations when buying a lathe?

I also have the Micro-Mark 7x14 and have been happy with it. I would recommend making a Carriage Gear Chip Guard as described by this mini-lathe.com page on modifications. One of my better investments was a set of tools that take carbide and high-speed steel (HSS)indexable inserts as available at littlemachineshop.com. You will likely need a grinder whether or not you use indexable insert tools.

I use 6061 because it's easy to find, inexpensive, and works fine, though don't doubt that other grades might be easier to machine and stronger.

Over the past half year, I've probably spent two to three times the amount on tooling and accessories as I originally did on the lathe. Let the metal fly!

yeah, the tooling and accessories are what get you. Littlemachineshop.com has seen more of my $$$ than homier did form my lathe. I was talking to my dad, who is a machinist by trade, and he recommends that for the kind of work we do, buy high speed steel tools when you can. They will take a sharper end so require less pressure to cut (although they wear faster...not a big issue with aluminum tho) and they don't tear up your grinder like carbide does.

As far as recommendations when buying a lathe, I think for flashlights any of the mini lathes will do about the same job. The harbor frieght, and homier seem to have about the same fit and finish. The micromark from what I understand seems to be a bit better quality, and has the nice DRO for RPM as well as the longer carriage and the .050 dials.

The tooling is really important or you won't be doing any cutting (would recomend several blanks if you want to grind your own or pick up pre ground ones), as well as getting a larger chuck, as the thru hole of the stock on is only about 5/8, not even big enough for a mini mag to fit through. The 4 inch 4 jaw is nice, and you can manually center the work also if you need to. You will also need to get a chuck and live center for the tail stock of the lathe. You will need a grinder, and probably a good set of calipers. Eventually you will probably want to get a full set of Numbered and 64th drills, as well as a boring bar. Whew, I need to start taking more breaths and adding more punctuation /ubbthreads/images/graemlins/smile.gif

Good luck on your purchase.

I use 6061 the most because it's readily available and the cheapest between the 2000, 5000, and 7000 series of alloy available. Given the other series have their advantages like corrosion resistance (as a result, you may not need to annodize) and strength.

Get yourself on the Enco mailing list and you will see Aluminum and Brass on sale regularly. Buy a full 6' length in and assortment of sizes that you will expect to work with and scan e-Bay once in a while for the odd pieces you may need for that special reflector you want to spin.

Goodluck! /ubbthreads/images/graemlins/thumbsup.gif

Re: anodizing the various grades as mentioned by Don and Larry - the 6061 anodizes the best. It is reasonably consistent and takes dye well. The 7075 needs special handling, and may not take the dyes as well.

7075 is lots stronger, as Larry noted, but unless you are making your flashlight walls REALLY thin (see Firefly), the 6061 is plenty strong enough. Keep your tools nice and sharp, and you can machine it well, too.

Especially for beginners, I would suggest the 6061T6, as it is common, inexpensive (relatively speaking) and works well for flashlight parts. It's what I use in all my flashlight parts except for the Firefly, which needs the strength of the 7075.

YMMV. /ubbthreads/images/graemlins/wink.gif

I dont know if this is a dumb question, but what KIND of aluminum stock is used? I see there are solid rods, and tubes or pipes. Depends on what is being built? Also what would be really interesting to see is the lathe processing steps of the build of some of these lights. Some of these custom built lights make me want to run out and by a lathe! ("Honey, what is this piece of equipment on our dining room table??!! -Oh just something they threw in when I bought you these diamond earrings")

Thanks

Arden