Aluminum Issues

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Simplex

Member
Joined
Aug 22, 2010
Messages
155
Location
Mather, Ca
I'm taking a crack at turning aluminum and I am having some issues that I hope some IAP members can help resolve. I am working on an original design (no kits) so I bought at 5/8" 6061 T6 aluminum rod. I wanted to get the feel for turning aluminum and so I did my setup as follows:

  • Mount rod into 5/8" PSI collet/chuck
  • lathe speed: ~650
  • tool: Woodchuck pen pro
  • Tool position: centered to middle of rod

The problem is that I am getting chatter marks and small flakes of aluminum all over the place. I can't seem to get a consistent ribbon for the life of me. here is what I have tried to rectify the issue:

  • Increase lathe speed up to 3000 (and everything in between)
  • light pressure with tool
  • heavy pressure with tool
  • lubricants (e.g. water, oil, etc.)
  • adjust lathe height up and/or down

Nothing seems be working and turning this seems to be way harder than I anticipated. Talk about frustrating.

Anyway, what am I doing wrong? Any advice is appreciated. Thanks everyone.
 
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How long is the rod, ie how far does it stick out of the collet?

Are you supporting the end with a live centre in the tailstock?

I think you are experiencing flex in the rod caused by the forces exerted by the carbide tool.
 
I've adjusted the rod length so that only a small portion is sticking out (maybe 1.5" to 2") but the element I am missing is the live center support. I'll need to try that.
 
If that doesn't work you might try to use HSS. From the previous post it sounds as if you're using carbide. Aluminum will cut better with HSS. Sounds unbelievable, but it's true. Carbide does not have a sharp edege. Imagine if you filled a laundry basket with softballs. then filled the laundry basket with marbles. That would be a quick easy analogy of the difference between the two. Alu needs a sharp edge. Get a sharp tool use a stone to hone a .003-.005 edge and give it a whirl.
good luck.
 
Hello! Well everyone has their own way of doing things.I have turned over 50 aluminum pens.I turn on center using a "Rotondo" carbide tip.I do get a little flakeing when I first get started but after that I get some ribbon but not like an acrylic blank.
You should have some support from the tailstock but just keep working with it.You will get it after a little time.
JIM
 
Studioso Im with you the best I can figure the Marbles are more cutting edges than the softballs...like molecules I guess...I may be waaaay off here.
 
Acornelius said:
Imagine if you filled a laundry basket with softballs. then filled the laundry basket with marbles. That would be a quick easy analogy of the difference between the two.
Click to expand...

:mad: Now I have marbles all over the floor of my imaginary room because they fell through the holes in the laundry basket! :biggrin: Seriously, what does this mean ? :confused:
 
studioso said:
Call me stupid, but for the life of me I am not sure what the marbles in the laundry basket analogy is all about...
Click to expand...


Sorry. Was in a hurry when I typed it out. the difference is the grain structure between carbide and HSS. Carbide is very hard, but will not get sharp like HSS.
 
Gary,
Gouges, skews and scrapers all work well on aluminum, as I don't have a Woodchuck (yet). Keep 'em sharp and you should have no problems. Ribbons are a bit sharp when comming off the piece, so be careful (been there, got the hat-they were out of t-shirts). Heed Freds advice and use the tail stock if possible.
 
Simplex said:
I've adjusted the rod length so that only a small portion is sticking out (maybe 1.5" to 2") but the element I am missing is the live center support. I'll need to try that.
Click to expand...

You are at the limit of practical unsupported overhang. A good rule of thumb for metal turning is that you need support when the piece extends more than 2x to 3x of its diameter.

Having the cutter level with the edge on center is where you want it, but also consider your cutter edge geometry relative to the piece. Metalworking lathe cutters are point tools. On say a mini metal lathe when taking a depth of cut of 0.010", and cutting from left to right, the cutting takes place on the 0.010" portion of the edge to the right of the point. If you are presenting a larger amount of cutting edge to the metal, you are increasing the torque, which decreases the allowable unsupported overhang. Most people I see using these carbide tools, present the entire front edge of the carbide insert to the piece being turned.
 
If your design will allow TBC, that does me a better job on metals than chucking it up in the Beall. If you must use the collet chuck, substantial tailstock pressure will get you past the "chatter cuts" with the Woodchuck.

ONE WORD OF CAUTION: Wear long leather gloves and face protection. When the Woodchuck gets the "bite" it sends out 6-10 inch metal ribbons that are hot and sharp. Be mindful to stop the lathe and clear the ribbons before they bind to the tool rest.

I always cut aluminum at 4,000 RPMs and I dip the tool in cool tool lubricant or WD 40.
 
I use a multi-cut file to get the shape i want and move to a finer file before sanding,Skiprat once posted a comment about useing a file instead on stainless steel and i have been doing that with aluminum and some of the brittle acrylics that like to chip easy.Hope that helps!
 
600 is proper speed. Tailstock support should be used whenever possible. Chisel position a hair below center. Drop of oil on tool end to prevent metal chips sticking to tool. U won't get shavings as good as plastic...esp using hand tools. Gloves are a safety issue..never use them. The metal will get warm only...if its too hot ur spinning too fast and aggressive damaging properties of the metal. You end up forming instead of cutting...ie pushing metal to 1 side making it oor
 
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Gloves are a personal preference...I myself do not wear them except applying CA. There is no way you can get out of gloves if caught up in the machine. By the same tokin you should not get caught in a machine with gloves on. I like to be able to feel everything and yes cuts and burns come with the territory. Take your pick.
 
I was standing next to my lathe one day not that long ago, wearing a nice large heavy flannel shirt being winter and all, and my shirt was not tucked in. I was drinking coffee while the cutter worked it's way across the machine and all of a sudden I got a nice tug on the body...and I looked down to see my shirt was wrapping up in the screw. First instinct was to grab and pull on my shirt..but there was no way it could ever be pulled free..and luckily quick thinking told me to pull the engaging lever and stopped the screw. It's a slow moving screw thank goodness..but I still had to hand crank the machine back about 12 times to get my shirt out. No harm done other than ruining the shirt..lesson learned by me.
 
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