1. #1
    I thought this looked interesting so I pointed a camera at it..

    Pic 1: Same program, two different metals. HE20 cuts nicely, pure aluminium creates an enormous burr. Proving the cutter can handle a bit of extrusion.

    Pic 2: HE20 aluminium, 6mm HSS cutter, 1250 rpm, 0.1mm off final size, feed 2.5 mm/s, 2mm DOC, good flow of suds.

    It enters the picture top right and you can see it already in trouble because it is only cutting on the leading edge. It has picked up metal on it's flutes, it's bending in to the cut and has gone past depth.

    It slows up at the corner and things get worse, it is now barely cutting. It passes a hole and veers towards it, it is now bent in two directions, it tries to recover but everything gets too much for it.

    I haven't got a clue why it suddenly decided to pick up metal, I dropped the DOC to 1.5mm and finished the job without losing another. A bit of a fudge, I hate not understanding.

    Unrelated but I popped three 6mm cutters one ofter the other last week. Didn't make it an inch in to the slot. Problem was a new draw bar which bottomed out on it's thread. The collet chuck felt firm but it obviously wasn't. That had me scratching my head until I thought, what has changed?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  2. #2
    Is HE20 just 6061? I've only once cut 6061 but the finish was amazing...

    I notice you're not using carbide cutters, is this due to lack of spindle speed making it not worthwhile or some other reason?
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  3. #3
    No idea what 6061 is, HE20 is the best seller for extrusions.

    I heard that HSS takes a better edge than carbide, could be a myth.

    I think my spindle speed is about right. Increasing the rpm means increasing the feed rate, which increases the power going through the tool which increases the bending. As soom as I drop below 8mm tooling I find bending to be a factor.

    I just measured an outline on this part, the drawing says 28.25mm, Mitutoyo calipers say 28.26mm. The error is 0.0004", could be the mill, could be the calipers, works for me

  4. #4
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 5 Hours Ago Has been a member for 9-10 years. Has a total post count of 1,832. Received thanks 192 times, giving thanks to others 5 times.
    HE20 is pretty much 6061, just that certain industries can't quite drag themselves to use international standards.

  5. Quote Originally Posted by m_c View Post
    HE20 is pretty much 6061, just that certain industries can't quite drag themselves to use international standards.
    Yep,
    NOTE : All Dimensions are in mm except weight
    Sr.
    No.
    Standard
    Composition
    Remarks
    USA
    IS
    UK
    DIN
    Cu
    Mg
    Si
    Fe
    Mn
    Zn
    Ti
    Cr
    1
    1050
    19500
    E 1B
    Al 99.5
    0.05
    -
    0.3
    0.4
    0.05
    -
    -
    -
    Aluminum 99.5% Min.
    2
    1100
    19000
    E 1C
    Al 99.0
    0.1
    -
    0.5
    0.6
    0.1
    -
    -
    -
    Aluminum
    99% Min.
    3
    3003
    31000
    NE 3
    AlMn
    0.1
    0.1
    0.6
    0.7
    0.8 - 1.5
    0.2
    0.2
    0.2
    -
    4
    3103
    -
    -
    AlMn1
    0.10
    0.30
    0.5 - 0
    0.7
    0.9 - 1.05
    0.20
    0.10
    0.10
    -
    5
    5051A
    -
    -
    AlMg1.8
    0.05
    1.4 - 2.1
    0.3 - 0
    0.45
    0.50 - 1.1
    0.20
    0.10
    0.30
    -
    6
    5052
    52000
    NE 4
    AlMg2
    0.1
    1.7 - 2.6
    0.6
    0.5
    0.5
    0.2
    0.2
    0.25
    -
    7
    6005A
    -
    -
    AlMg Si 0.7
    0.30
    0.40 - 0.70
    0.50 - 0.90
    0.35
    0.50
    0.20
    0.10
    0.30
    -
    8
    6061
    65032
    HE -20
    AlMg SiCu
    0.15-0.4
    0.7 - 1.2
    0.4 - 0.8
    0.7
    0.2 - 0.8
    0.2
    0.2
    0.15
    -
    9
    6063
    63400
    HE-9
    AlMg Si 0.5
    0.1
    0.4 - 0.9
    0.3 - 0.7
    0.6
    0.3
    0.2
    0.2
    0.1max
    -
    10
    6351
    64430
    HE -30
    AlMg Si 1
    0.1
    0.4 - 1.2
    0.6 - 1.3
    0.6
    0.4 - 1.0
    0.1
    0.2
    0.25max
    -
    From: Chemical Composition of Aluminium Alloy

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