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| How do I prevent stringers when cutting aluminum on the lathe? |
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| ibuildstuff4u:
Hey guys, I have been cutting a lot of 6061 aluminum on the lathe lately and have been having trouble with long stringers that wrap around the chuck dangerously and want to know if there is any way to prevent this. I tried changing the spindle speed as well as the cutting angle of the insert and still have this problem. I'm using some good inserts that are made for aluminum and are suppose to help break up the chips but they don't seem to work. Here are the inserts that I'm using http://www.grizzly.com/products/Carbide-Inserts-TNMG-for-Aluminum-pk-of-10/H8330 and I'm running the spindle at 620 RPM but I also have tried 1100 RPM with out any change. Thanks for the help! Dale P. |
| bigmini:
The simple way I've found to achieve this is to interrupt the feed every so often. That may leave a slight ring at each stop, but you can run a continuous finishing cut to get rid if those, and the swarf is so fine then it is less of a problem. Another way is theoretically to grind a chip breaker into the tool. This is a groove just behind the cutting edge that forces the chip through such a tight radius that it breaks off. Not sure if it makes any difference with aluminium. Some carbide inserts I've seen have this built in, but I haven't used them in years and never on aluminium. |
| ibuildstuff4u:
The parts I'm making are only 3.5 inches long and even with interrupting the cut I still get long enough stringers that they can wrap around the part and make a mess. Here is a picture of the inserts that I'm using to show the chip breaking profile that they have but they don't seem to work. I tried using some inserts made for cast iron and steel and I get the same results. |
| Jonny:
Pretty confident they are not proper inserts for working aluminium just general purpose. An uncoated, tips with radius work best but do have tendency to like Iscar, Ceratizit and certain Kennametal tools and tips. Chip breaker will only work with certain aluminium grades that are brittle or free machining. As above keep backing off, it will break up the stringer. Final pass for a finish. If you intend to remove metal like 5" plus diameter with a recess going in 1/2" i usually do tis in two maybe three passes. If you get the feel for whats going on you can get the continuous string to wrap around itself and bunch up. Taken on previous lathe about 12 yr ago an action shot at 1000rpm 5" dia aluminium blank in small chuck, one pass on power feed facing off 1/2", no wrap around just a bit of swarf in tray at back. http://pic20.picturetrail.com/VOL15/728921/1252422/14582043.jpg Its very rare it ever wraps around the chuck perhaps 1 in 70 jobs, just make sure the swarf dont knock tools off head stock. Verniers gone a few times. |
| ibuildstuff4u:
I bought these inserts from Grizzly and I was told they were made for aluminum, but your may be right about being general purpose as they work just fine on steel and cast iron. Thanks for the help, Dale P. |
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