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As soon as I began to turn it I realized that something was wrong. It spins several foot long chips across the floor instead of producing nice rice-sized flake that I am used to. I run about 1000 rpm at 1" diameter and increase to 1200 or 1500 closer to the center. It does produce nice smooth surface but the chips look wrong. Anyone else got burned by ebay 6061 bar sellers? Did you ever get a refund for the wasted bars?
Talk to E-Bay they have a product / price guarantee .Quote:
Originally Posted by Tokarev
It might well have been 6061 but what was the heat treat condition? T6 or? Heat treat determins both machinabity and yield.
I don't think it is heat treated. Should not be.
The 6061 T6 stock I turn behaves in the fashion you mention. T0 gives smaller chips.
As you are getting a good surface, and a long chip, I do not believe you have to be concerned with having a lesser grade (5052, 6063, etc.)
material.
Sounds encouraging. I'll try to get the bar hardness tested to get at least some idea of what I got.
The source of the steel may be a problem. German sourced steel with the same designation is not always the same as domestic steel. I condemned several hundred rifle barrels because of it.
Tool geometry, speeds, feed rates,and coolant all affect the turning and chips you get. The depth of cut also affects the chip. Getting the nice chips in a 6 shape is hard to do in some materials.
I run around the same speeds as you are maybe a little faster, and a feed rate in the .010-.015 er revolution with a heavy chip breaker ground on the high speed tool. A square cut to the stock will bring the chip back on it self helping it to break an angled cut allows it to roll off in a long coil. I normally grind the bit so that it has clearance so that the shoulder is lightly under cut, not only does this aid the chips breaking but it allows the shoulder to be faced square when size is reached.
The other thing to remember is any material designation is not a dead set exact mix of ingredients but a certain range of each ingredient this makes for slight variations in each batch.
I normally grind the chip breaker with a narrow wheel parallel to the face. About .060 back and about as deep giving the face a roughly 10* angle back into it. This is fone with the very corner of the wheel. You need a well dressed wheel To do this breaker on a tool. But when done it makes the prettiest little 6s chips.
The long coils are dangerous and can cause safety issues.
I find that the chip breaker is key in that type material.
If your using "Positive Rake" geometry tooling, you'll get long stringy chips. "Negative Rake" geometry or something with a chip breaker will definitely help.
6061 is commonly available in various pre-tempered grades. The most common are below. They all machine differently.
6061-O (annealed)
For tempered grades the following ones are the most common.
6061-T4 (naturally aged to a stable state after solution heat treatment)
6061-T6 (solutionized and artificially aged)
6061-T651 (solutionized, stress-relieved stretched and artificially aged).
Virtually all common Aluminum is 6061 T6 or T651 others are available but not that common. T0 and T4 6063 etc. machine like goo.
I use pretty much all ''Carbide Insert" tooling on my Lathes. it is just simpler to use with the least amount of problems,
All the talk about chip breakers and the like are built in to this type of tooling and they work on just about any normal material.
Also and a Hot Tip: I buy all my small quantities of metal and plastic stock from Mc Master-Carr. They are the most reputable company to deal with there is !!!!!!!
Just last week I needed a weird Lock with a specific Key that I had looked for every where. Supposed to be sourced from Grainger who once again Sucked and couldn't produce. Then a little light bulb went on in my head and it said "why don't you look at McMaster Carr?" They had it and every variation of it, in stock and it came the next day. I made sure the key worked in all of the previous locks I was trying to duplicate, and it did. I had no other use for it until I get an order for the boxes so I returned it to get my money back. They even sent me a free shipping label so it cost me nothing $$$! In the 40 years I have used them, they have failed to deliver what I ordered the next day exactly one time. That was a Royal Chamfering tool that was not in stock and took Royal 3 weeks to fill the order to McCarr. Then I got it next day!
They have virtually everything known to man and you'll get it next day. Best run company in the world! In My NOT so Humble Opinion!
Randy.