Turning aluminum

Signed-In Members Don't See This Ad
sbarton22

sbarton22

Member
Joined
Sep 7, 2011
Messages
268
Location
Kansas City
Does anyone have any tips for turning aluminum? For the project I have planned, I was not going to turn it, just use it in its extruded form. Now, after all of the great response I had in another thread, I just have to try a pen out of stock.

Any particular alloy I should buy?

What are the pitfalls when turning?

I assume I can use my regular gouges/scrapers.

When I drill the blank, say, for a slimline, do I even need the 7mm tube?

If I use the tube, will the brass and aluminum corrode?

Any other helpful hints are greatly appreciated.
 
Signed-In Members Don't See This Ad
sbarton22 said:
Does anyone have any tips for turning aluminum? For the project I have planned, I was not going to turn it, just use it in its extruded form. Now, after all of the great response I had in another thread, I just have to try a pen out of stock.

Any particular alloy I should buy?

6061-T6 is considered the usual. That's what I use. Depending on the pen you're planning to do diameter-wise I find 5/8" (.625) rod is the handiest size.

What are the pitfalls when turning?

Keep your tools sharp. Dull tools will chatter a lot more and you'll get a very wavy/crappy surface. Also, it will get hot.

I assume I can use my regular gouges/scrapers.

Yes, you can use them but one of the carbide insert tipped tools would work better.

When I drill the blank, say, for a slimline, do I even need the 7mm tube?

You can do it either way. If you glue in the tube then when you're done you can press in the parts just like normal. But when turning the outside you have to be careful about the blank heating up and breaking down your glue or epoxy.

If you don't use the tube and want to glue in your parts, you'll want to drill a slightly smaller hole so the parts don't fit too sloppy.

The 3rd possibilty is to drill then ream the hole to a precise size so that you press fit your parts right into the aluminum.

In either of the cases where you don't use the tube you'll need to have custom bushings, whether regular or between centers type, to fit the holes.

If I use the tube, will the brass and aluminum corrode?

I'm not sure how you came up with the question but I have aluminum pens, both with tubes and without, that are 10 years old. They're fine.

Any other helpful hints are greatly appreciated.
Click to expand...

Take a piece, chuck it up, and play with it to get a feel for it before you do a pen. Also, you might want to consider buying pre-made blanks from Johnny CNC. I've not used them but I've heard nothing but good things about them.
 
As bluwolf quite rightly said.. chuck it up and have a play with it.

It depends on what you are planning on doing, though i also use 6061-T6 as its a good all rounder, though even when i have ordered 6061 from two different suppliers, the metals were different. I notice these differences more than the average turner as i anodise, and with the parts dipped in caustic, sometimes pitting occurs which creates alot of work sanding the finish back down smooth.. as a rule i just dont buy from them again lol. :)

wath out when drilling your stock too.. it needs coolant (WD40 works well with aluminium and does actually give a good finish when facing or turning). Drill out with a smaller diameter and work upwards rather than diving straight in with a 14mm bit. drill a little, and back it out to break and clear the swarf

Dont grab hold of your work after drilling it.... you will be left with shiny fingerprintless fingers :)

Watch out for swarf... long and stringy is lethal.. especially when it catches in the chuck. never be tempted to clear metal swarf with fingers or gloves etc... remember safety first. it is very much like razor wire and a recipe for losing a finger or worse when it snags.
 
The other thing that I read and used was Mineral Spirits as a sanding lubricant. It works like water but doesn't cause any staining or darkening of the byproducts.

Seemed to work good.....
 
+1 on not messing with the swarf with bare fingers, especially after it has just been drilled. Hot and razor sharp are not finger friendly.

I step up drill (Smaller to larger bit) because I have seen some warping that a machinist next door to our shop said was because I went right to the bigger bit with not enough coolant. He said that to insure the perfect hole step up and use a lot of coolant. I need to find a way to contain the coolant that drips off. that stuff is a bear to clean when it is full of metal shavings.
 
Whoa! Great advice! I didn't even think about some of those things.

Couple more questions.

1) What glue works best if I decide to glue a tube? CA? Epoxy?

2) Is there a chart out there that gives the inner dimension for the various tubes? I can measure, but I'm not sure I know if that dimension translates to a V bit or mm or some whacky fraction. I feel like most of those bits are dancing on the head of a pin, but I assume they do so for a reason....and I don't want to do it incorrectly for just that reason.

Great tips!! Thanks
 
Haynie said:
+1 on not messing with the swarf with bare fingers, especially after it has just been drilled. Hot and razor sharp are not finger friendly.

I step up drill (Smaller to larger bit) because I have seen some warping that a machinist next door to our shop said was because I went right to the bigger bit with not enough coolant. He said that to insure the perfect hole step up and use a lot of coolant. I need to find a way to contain the coolant that drips off. that stuff is a bear to clean when it is full of metal shavings.
Click to expand...

could you not make a seive to install in your drop tray to filter it out of the swarf?
 
No drop tray. I don't know what they were thinking but it is one of the easy modifications I plan on making, as long as I can figure out a way to safely lift the lathe after unbolting it from the bench.

A couple of drilled 1 inch solid chunks of steal as spacers, a sheet pan, framed screen and the job is done.

After giving it some thought, I would forgo the traditional wood lathe tools and only use the carbon ones.
 
sbarton22 said:
Whoa! Great advice! I didn't even think about some of those things.

Couple more questions.

1) What glue works best if I decide to glue a tube? CA? Epoxy?

2) Is there a chart out there that gives the inner dimension for the various tubes? I can measure, but I'm not sure I know if that dimension translates to a V bit or mm or some whacky fraction. I feel like most of those bits are dancing on the head of a pin, but I assume they do so for a reason....and I don't want to do it incorrectly for just that reason.

Great tips!! Thanks
Click to expand...

There is a pen chart in the library that lists most of the dimensions for a lot of the different pen kits. There is also a conversion pdf with the different drill sizes you can use to match them to.

I recomend epoxie over superglue when woking with metal. It will withstand heat build up slightly better than C/A
 
If you plan on turning it on a wood lathe, make sure you take light cuts, otherwise you get a rough finish and possibly a bent mandrel. Hold your tool tight to the toolrest otherwise it can jump and give you an uneven finish. BradG is very right about the swarf by the way, definitely stay clear, even if the lathe is off. The swarf is often rather hot also, so that doesn't help the situation, more reason to stay away from it.
 
Ok. I picked up some stock today. 5/8" rod is really the perfect size and cost effective as well.

Lesson of the day...drilling the hole.

My 7mm bit has a brad point. Brad point bits do not like smaller holes. Chuck 2 blanks out the window to learn that lesson. Pulled out the old school standard bits. 4 step drilling process. Mix in a little A6 and beautifully drilled holes.

I think I need to invest in a good set of metric bits.

I epoxied the tubes in. Tomorrow we try the first turning!
 
When sanding aluminum or titanium, wet or dry sandpaper, around 320 grit works great wet with WD-40. I can go straight to polish from there.

Also, CA and some other chemicals will oxidize aluminum, so be aware of that. There's not really a great way to keep it shiny. It's going to scratch pretty easily. One train of thought is to keep it a brushed finish, which is easy to maintain if it gets scratched.
 
Transmission fluid is an excellent lubricant. Before getting a carbide tool, I found that the point of a parting tool was the easiest to control when getting close to the finished size.
 
OK...lesson #2....chatter.

I turned the two halves of a slimline (not sure I can sell a slimline for the amount of effort it took to turn it).

First lesson...take more time to find the center when drilling. Getting the blank back to round seems to be the hardest part. It took forever with a constantly sharpened round nose scraper. chip, chip, chip away.

Next lesson...just be patient. Damn, it took forever to shape the thing. I could get any good cutting action with any other of my tools so I stuck with the scraper. Some areas I could get real smooth cuts, while others kept with the chatter.

finally...interesting way to use the skew. I finally got the skew to make good cuts. shaping was easier, but not great. Riding the bevel on the skew helped. Then, with perfect timing, I drug the skew across the piece in the opposite direction of the point. I found (accidentally) that it was a great way to smooth the cut. That helped to clean it up REALLY well.

Sanding revealed that I still had a bit of a golf ball, but not bad.

Tomorrow, I will give 'er hell polishing it up

If the rest of assembly and polishing is simply mediocre, this will be my best pen to date. The Silver Surfer would be proud.
 
Last edited:
Congratulations, it sounds like your first shot at aluminum was about par for the course. Good for you.

The one thing that I would add at this point is that I usually don't polish the aluminum. At least not when it's the bulk of the pen.I prefer a brushed finish. I think it looks better but it also hides scuffs and scratches better. Aluminum is pretty soft. Don't expect a polished pen to stay like that for long.
 
bluwolf said:
Congratulations, it sounds like your first shot at aluminum was about par for the course. Good for you.

The one thing that I would add at this point is that I usually don't polish the aluminum. At least not when it's the bulk of the pen.I prefer a brushed finish. I think it looks better but it also hides scuffs and scratches better. Aluminum is pretty soft. Don't expect a polished pen to stay like that for long.
Click to expand...

Let me run this by you...I prefer the brushed finish in a lot of cases. So much so, that my wedding ring is gold in a brushed finish. But, the opposite of what you saying happened. The normal wear and tear actually polished the ring and there are no signs that it was ever brushed.

I'm going to try one polished and then try brushed. I want to figure out the polishing for another project and I like the look of brushed. So I think there is a lot of room for experimentation.
 
I use scotch brite pads to get the brushed look. Nice and even, but you need to get it all the way to polish first. Sounds counter intuitive but sanding marks show up well.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom