BFW General purpose-backlash

Kerk General Purpose Lead Screw Nut BFW

The Kerk® BFW Series general purpose “free-wheeling” nut is for applications not requiring anti-backlash and wear compensation. It provides effective power transmission at minimum cost, and features long life, self-lubricating polyacetal acme lead screw nuts.  Kerkite® Composite Polymers are also available as standard options.The secure mounting and convenience of a circular flange is standard on the BFW nuts with triangular flange and thread mounting as an option. Many custom configurations are available.Acme lead screws are 303 stainless steel with extended life, custom Kerkote® TFE coating optional. Assemblies can be supplied cut-to-length or with ends machined to customer requirements.

  • Dimensional Drawings +


    BFWB SERIES: BARREL MOUNT
    Screw
    Ø
    Nut
    Ø
    Nut
    Length
    Nut
    Flats
    Dynamic
    Load
    Drag
    Torque
    A
    in.
    (mm)
    B
    in.
    (mm)
    C
    in.
    (mm)
    D
    in.
    (mm)

    lbs. (Kg)
     
    oz.-in.
    (Nm)
     
    5/64
    (2)
    .22
    (5.5)
    .32
    (8)
    .2
    (4.5)
    10
    (4.5)
    Free
    Wheeling
    BFWB SERIES: FLANGE MOUNT(Rectangle)
    Screw
    Ø
    Nut
    Ø
    Nut
    Length
    Flange
    Height
    Flange
    Width
    Flange
    Thickness
    Slot
    Width
    Bolt
    Circle Ø
    Dynamic
    Load
    Drag
    Torque
    A
    inch
    (mm)
    B
    inch
    (mm)
    C
    inch
    (mm)
    D1
    inch
    (mm)
    D
    inch
    (mm)
    E
    inch
    (mm)
    F
    inch
    (mm)
    G
    inch
    (mm)

    lbs.
    (Kg)

    oz.-in.
    (Nm)
    5/64
    (2)
    0.22
    (5.5)
    0.32
    (8)
    0.22
    (5.5)
    0.47
    (11.9)
    0.08
    (2.0)
    0.07
    (1.8)
    0.35
    (9)
    10
    (4.5)
    Free
    Wheeling
    1/8
    (3)
    .40
    (10.2)
    .50
    (13)
    .40
    (10.2)
    .75
    (19.1)
    .13
    (3.2)
    .120
    (3.05)
    .600
    (15.24)
    25
    (11)
    Free
    Wheeling
    0.132
    (3.3)
    .40
    (10.2)
    .50
    (13)
    .40
    (10.2)
    .75
    (19.1)
    .13
    (3.2)
    .120
    (3.05)
    .600
    (15.24)
    25
    (11)
    Free
    Wheeling
    9/64
    (3.6)
    .40
    (10.2)
    .50
    (13)
    .40
    (10.2)
    .75
    (19.1)
    .13
    (3.2)
    .120
    (3.05)
    .600
    (15.24)
    25
    (11)
    Free
    Wheeling
    5/32
    (4)
    .40
    (10.2)
    .50
    (13)
    .40
    (10.2)
    .75
    (19.1)
    .13
    (3.2)
    .120
    (3.05)
    .600
    (15.24)
    25
    (11)
    Free
    Wheeling
    3/16
    (5)
    .40
    (10.2)
    .50
    (13)
    .40
    (10.2)
    .75
    (19.1)
    .13
    (3.2)
    .120
    (3.05)
    .600
    (15.24)
    25
    (11)
    Free
    Wheeling
    7/32
    (5.6)
    .40
    (10.2)
    .50
    (13)
    .40
    (10.2)
    .75
    (19.1)
    .13
    (3.2)
    .120
    (3.05)
    .600
    (15.24)
    25
    (11)
    Free
    Wheeling
    BFW Flange Mount Rectangle
    BFWT SERIES: THREAD MOUNT
    Screw
    Ø
    Nut
    Ø
    Nut
    Length
    Thread Thread
    Length
    Dynamic
    Load
    A
    in.
    (mm)
    B
    in.
    (mm)
    C
    in.
    (mm)
    M
    in.
    N
    in.
    (mm)

    lbs.
    (Kg)
    1/8
    (3)
    .40
    (10.2)
    .50
    (13)
    3/8-24 0.187
    (4.75)
    25
    (11)
    0.132
    (3.3)
    .40
    (10.2)
    .50
    (13)
    3/8-24 0.187
    (4.75)
    25
    (11)
    9/64
    (3.6)
    .40
    (10.2)
    .50
    (13)
    3/8-24 0.187
    (4.75)
    25
    (11)
    5/32
    (4)
    .40
    (10.2)
    .50
    (13)
    3/8-24 0.187
    (4.75)
    25
    (11)
    3/16
    (5)
    .40
    (10.2)
    .50
    (13)
    3/8-24 0.187
    (4.75)
    25
    (11)
    7/32
    (5.6)
    .40
    (10.2)
    .50
    (13)
    3/8-24 0.187
    (4.75)
    25
    (11)
    1/4
    (6)
    .63
    (15.9)
    1.0
    (25.4)
    9/16-18 0.187
    (4.75)
    50
    (20)
    5/16
    (8)
    .75
    (19.1)
    1.0
    (25.4)
    5/8-18 0.250
    (6.35)
    75
    (35)
    3/8
    (10)
    .75
    (19.1)
    1.0
    (25.4)
    5/8-18 0.250
    (6.35)
    75
    (35)
    7/16
    (11)
    1.00
    (25.4)
    1.5
    (38)
    15/16-16 0.375
    (9.53)
    90
    (40)
    1/2
    (13)
    1.00
    (25.4)
    1.5
    (38)
    15/16-16 0.375
    (9.53)
    150
    (68)
    5/8
    (16)
    1.00
    (25.4)
    1.5
    (38)
    15/16-16 0.375
    (9.53)
    225
    (100)
    3/4
    (19)
    1.50
    (38.1)
    2.0
    (51)
    1 3/8-16 0.500
    (12.70)
    350
    (160)
    7/8
    (22)
    1.50
    (38.1)
    2.0
    (51)
    1 3/8-16 0.500
    (12.70)
    500
    (227)
    15/16
    (24)
    1.50
    (38.1)
    2.0
    (51)
    1 3/8-16 0.500
    (12.70)
    500
    (227)
    BFW Thread Mount
    BFWA SERIES: FLANGE MOUNT (Triangular)
    Screw
       ∅
    Nut
    Nut
    Length
    Flange
    Flange
    Length
    Mounting
    Hole ∅
    Bolt
    Circle ∅
    Dynamic
    Load
    A
    inch
    (mm)
    B
    inch
    (mm)
    C
    inch
    (mm)
    D
    inch
    (mm)
    E
    inch
    (mm)
    F
    inch
    (mm)
    G
    inch
    (mm)

    lbs.
    (kg)
    1/4
    (6)
    0.50
    (12.7)
    1.0
    (25.4)
    1.00
    (25.4)
    0.17
    (4.3)
    0.143
    (3.63)
    0.750
    (19.05)
    50
    (20)
    5/16
    (8)
    0.50
    (12.7)
    1.9
    (48.3)
    1.50
    (38.1)
    0.17
    (4.3)
    0.143
    (3.63)
    0.75
    (19.1)
    75
    (35)
    3/8
    (10)
    0.66
    (16.6)
    1.9
    (48.3)
    1.50
    (38.1)
    0.17
    (4.3)
    0.197
    (5.00)
    1.125
    (28.58)
    75
    (35)
    7/16
    (11)
    0.75
    (19.1)
    1.9
    (48.3)
    1.50
    (38.1)
    0.17
    (4.3)
    0.197
    (5.00)
    1.125
    (28.58)
    90
    (40)
    1/2
    (13)
    0.75
    (19.1)
    1.9
    (48.3)
    1.50
    (38.1)
    0.17
    (4.3)
    0.197
    (5.00)
    1.125
    (28.58)
    150
    (68)
    BFWA Flange Mount Triangular
    BFWF SERIES: FLANGE MOUNT (Round)
    Screw
       ∅
    Nut
    Nut
    Length
    Flange
    Flange
    Length
    Mounting
    Hole ∅
    Bolt
    Circle ∅
    Dynamic
    Load
    A
    inch
    (mm)
    B
    inch
    (mm)
    C
    inch
    (mm)
    D
    inch
    (mm)
    E
    inch
    (mm)
    F
    inch
    (mm)
    G
    inch
    (mm)

    lbs.
    (kg)
    1/4
    (6)
    0.50
    (12.7)
    1.0
    (25.4)
    1.00
    (25.4)
    0.19
    (4.8)
    0.140
    (3.56)
    0.750
    (19.05)
    50
    (20)
    5/16
    (8)
    0.63
    (15.9)
    1.0
    (25.4)
    1.13
    (28.7)
    0.19
    (4.8)
    0.140
    (3.56)
    0.875
    (22.23)
    75
    (35)
    3/8
    (10)
    0.63
    (15.9)
    1.0
    (25.4)
    1.13
    (28.7)
    0.19
    (4.8)
    0.140
    (3.56)
    0.875
    (22.23)
    75
    (35)
    7/16
    (11)
    0.75
    (19.1)
    1.5
    (38)
    1.50
    (38.1)
    0.19
    (4.8)
    0.203
    (5.16)
    1.125
    (28.58)
    90
    (40)
    1/2
    (13)
    0.75
    (19.1)
    1.5
    (38)
    1.50
    (38.1)
    0.19
    (4.8)
    0.203
    (5.16)
    1.125
    (28.58)
    150
    (68)
    5/8
    (16)
    0.88
    (22.2)
    1.5
    (38)
    1.50
    (38.1)
    0.19
    (4.8)
    0.203
    (5.16)
    1.188
    (30.18)
    225
    (100)
    3/4
    (19)
    1.12
    (28.4)
    2.0
    (51)
    1.75
    (44.4)
    0.25
    (6.4)
    0.203
    (5.16)
    1.438
    (36.53)
    350
    (160)
    7/8
    (22)
    1.50
    (38.1)
    2.0
    (51)
    2.25
    (57.1)
    0.25
    (6.4)
    0.203
    (5.16)
    1.875
    (47.63)
    500
    (227)
    15/16
    (24)
    1.50
    (38.1)
    2.0
    (51)
    2.25
    (57.1)
    0.25
    (6.4)
    0.203
    (5.16)
    1.875
    (47.63)
    500
    (227)
    BFW Flange Mount Round
  • Diameter and Lead Options +


    5/64" (2 mm) Diameter Lead Screw. Diameter Code 008
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %
    in mm In mm in mm
    0.012 0.3 0012 0.079 2.01 0.068 1.73 24**
    0.016 0.4 0016 0.075 1.91 0.058 1.47 30**
    0.02 0.5 0020 0.077 1.96 0.057 1.45 36**
    0.039 1 0039 0.079 2.01 0.059 1.5 52**
    0.079 2 0079 0.077 1.96 0.057 1.45 66**
    ** Listed efficiency for Micro screws are theoretical values based on non-coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.
    1/8" (3.2 mm) Diameter Lead Screw. Diameter Code 012
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm in mm in mm
    0.024 0.61 0024 0.129 3.28 0.093 2.36 44
    0.039 1 0039 0.129 3.28 0.094 2.39 57
    0.048 1.22 0048 0.129 3.28 0.093 2.36 61
    0.075 1.91 0075 0.129 3.28 0.093 2.36 70
    0.096 2.44 0096 0.129 3.28 0.093 2.36 75
    0.125 3.18 0125 LH Only 0.125 3.18 0.078 1.98 80
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.
    0.132" (3.3 mm)) Diameter Lead Screw. Diameter Code 013
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm In mm in mm
    0.02 0.5 0020 0.132 3.35 0.104 2.64 42
    0.039 1 0039 0.132 3.35 0.08 2.03 61
    0.079 2.00. 0079 0.132 3.35 0.08 2.03 75
    0.157 4 0157 0.132 3.35 0.08 2.03 84
    0.315 8 0315 0.132 3.35 0.08 2.03 87
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.
    9/64" (3.6 mm) Diameter Lead Screw. Diameter Code 014
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm in mm in mm
    0.012 0.3 0012 0.14 3.56 0.123 3.12 26
    0.024 0.61 0024 0.14 3.56 0.105 2.67 43
    0.048 1.22 0048 0.14 3.56 0.081 2.06 62
    0.096 2.44 0096 0.14 3.56 0.081 2.06 75
    0.394 10 0394 0.14 3.56 0.102 2.59 86
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.
    5/32" (4 mm) Diameter Lead Screw. Diameter Code 016
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm
    in mm in mm
    0.033 0.84 0033 0.156 3.96 0.116 2.95 45
    0.05 1.27 0050 LH Only 0.156 3.96 0.096 2.44 59
    0.094 2.39 0094 0.164 4.17 0.128 3.25 67
    0.125 3.18 0125 0.168 4.27 0.13 3.3 74
    0.25 6.35 0250 0.156 3.96 0.13 3.3 83
    0.375 9.53 0375 0.156 3.96 0.13 3.3 85
    0.5 12.7 0500 0.156 3.96 0.13 3.3 86
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.
    3/16" (5 mm) Diameter Lead Screw. Diameter Code 018
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm
    in mm in mm
    0.02 0.5 0020 0.188 4.78 0.163 4.14 30
    0.025 0.64 0025 0.188 4.78 0.15 3.81 39
    0.039 1 0039 0.188 4.78 0.144 3.66 47
    0.05 1.27 0050 0.188 4.78 0.124 3.15 58
    0.1 2.54 0100 0.188 4.78 0.136 3.45 69
    0.1875 4.76 0188 0.188 4.78 0.167 4.24 78
    0.2 5.08 0200 0.188 4.78 0.124 3.15 82
    0.375 9.53 0375 0.188 4.78 0.161 4.09 84
    0.4 10.16 0400 0.188 4.78 0.124 3.15 84
    0.427 10.85 0427 0.188 4.78 0.162 4.11 85
    0.5 12.7 0500 0.188 4.78 0.142 3.61 86
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.
    7/32" (5.6 mm) Diameter Lead Screw. Diameter Code 021
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm
    in mm in mm
    0.024 0.61 0024 0.218 5.54 0.181 4.6 31
    0.03125 0.79 0031 0.204 5.18 0.16 4.06 39
    0.048 1.22 0048 0.216 5.49 0.156 3.96 50
    0.05 1.27 0050 0.2 5.08 0.135 3.43 52
    0.0625 1.59 0063 0.218 5.54 0.142 3.61 60
    0.096 2.44 0096 0.218 5.54 0.156 3.96 66
    0.192 4.88 0192 0.218 5.54 0.156 3.96 78
    0.25 6.35 0250 0.204 5.18 0.14 3.56 81
    0.384 9.75 0384 0.218 5.54 0.159 4.04 86
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.
    1/4" (6 mm) Diameter Lead Screw. Diameter Code 025
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm
    in mm in mm
    0.024 0.61 0024 0.25 6.35 0.218 5.54 28
    0.025 0.64 0025 0.25 6.35 0.214 5.44 30
    0.03125 0.79 0031 0.25 6.35 0.208 5.28 34
    0.039 1 0039 0.25 6.35 0.19 4.83 40
    0.048 1.22 0048 0.25 6.35 0.19 4.83 45
    0.05 1.27 0050 0.25 6.35 0.191 4.85 46
    0.059 1.5 0059 0.25 6.35 0.172 4.37 52
    0.0625 1.59 0063 0.25 6.35 0.17 4.32 52
    0.079 2 0079 0.25 6.35 0.17 4.32 59
    0.096 2.44 0096 0.25 6.35 0.19 4.83 61
    0.1 2.54 0100 0.25 6.35 0.19 4.83 62
    0.118 3 0118 0.25 6.35 0.175 4.45 68
    0.125 3.18 0125 0.25 6.35 0.19 4.83 67
    0.197 5 0197 0.25 6.35 0.172 4.37 72
    0.2 5.08 0200 0.25 6.35 0.17 4.32 65
    0.25 6.35 0250 0.25 6.35 0.168 4.27 79
    0.3125 7.94 0313 0.25 6.35 0.184 4.67 81
    0.333 8.46 0333 0.25 6.35 0.17 4.32 82
    0.394 10 0394 0.25 6.35 0.17 4.32 78
    0.4 10.16 0400 0.25 6.35 0.17 4.32 84
    0.5 12.7 0500 0.25 6.35 0.169 4.29 85
    0.75 19.05 0750 0.25 6.35 0.17 4.32 86
    1 25.4 1000 0.25 6.35 0.17 4.32 84
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.
    5/16" (8 mm) Diameter Lead Screw. Diameter Code 031
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm
    in mm in mm
    0.057 1.44 0057 0.315 8 0.243 6.71 43
    0.0741 1.88 0074 0.312 7.92 0.211 5.36 51
    0.111 2.82 0111 0.312 7.92 232 5.89 60
    0.167 4.24 0167 0.312 7.92 0.211 5.36 69
    0.25 6.35 0250 0.312 7.92 0.234 5.94 76
    0.5 12.7 0500 0.312 7.92 0.232 5.89 83
    0.8 20.32 0800 0.306 7.77 0.243 6.17 86
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 
    3/8" (10 mm) Diameter Lead Screw. Diameter Code 037
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm
    in mm in mm
    0.025 0.64 0025 0.375 9.53 0.337 8.56 21
    0.039 1 0039 0.394 10.01 0.35 8.89 28
    0.04167 1.06 0042 0.375 9.53 0.32 8.13 34
    0.05 1.27 0050 0.375 9.53 0.301 7.65 36
    0.055 1.4 0055 0.375 9.53 0.303 7.7 38
    0.059 1.5 0059 0.389 9.88 0.313 7.95 38
    0.0625 1.59 0063 0.375 9.53 0.295 7.49 41
    0.068 1.73 0068 0.388 9.86 0.295 7.49 42
    0.079 2 0079 0.375 9.53 0.264 6.71 47
    0.0833 2.12 0083 0.375 9.53 0.293 7.44 48
    0.1 2.54 0100 0.375 9.53 0.266 6.76 53
    0.125 3.18 0125 0.375 9.53 0.295 7.49 59
    0.157 4 0157 0.375 9.53 0.274 6.96 65
    0.1667 4.23 0167 0.371 9.42 0.261 6.63 61
    0.197 5 0197 0.375 9.53 0.266 6.76 69
    0.2 5.08 0200 0.375 9.53 0.266 6.76 69
    0.25 6.35 0250 0.375 9.53 0.268 6.81 70
    0.3 7.62 0300 0.375 9.53 0.255 6.48 76
    0.333 8.46 0333 0.375 9.53 0.245 6.22 78
    0.363 9.22 0363 0.375 9.53 0.26 6.6 79
    0.375 9.53 0375 0.375 9.53 0.265 6.73 79
    0.394 10 0394 0.375 9.53 0.26 6.6 79
    0.4 10.16 0400 0.375 9.53 0.293 7.44 79
    0.472 12 0472 0.388 9.86 0.287 7.29 82
    0.5 12.7 0500 0.388 9.86 0.265 6.73 81
    0.667 16.94 0667 0.375 9.53 0.273 6.93 83
    0.75 19.05 0750 0.388 9.86 0.273 6.93 84
    0.984 25 0984 0.375 9.53 0.262 6.65 84
    1 25.4 1000 0.383 9.73 0.254 6.45 84
    1.2 30.48 1200 0.383 9.73 0.254 6.45 84
    1.25 31.75 1250 0.375 9.53 0.278 7.06 84
    1.5 38.1 1500 0.375 9.53 0.264 6.71 83
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 
    7/16" (11 mm) Diameter Lead Screw. Diameter Code 043
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm
    in mm in mm
    0.05 1.27 0050 0.437 11.1 0.362 9.19 30
    0.0625 1.59 0063 0.436 11.07 0.358 9.09 38
    0.079 2 0079 0.472 11.99 0.374 9.5 42
    0.111 2.82 0111 0.437 11.1 0.327 8.31 52
    0.118 3 0118 0.438 11.13 0.363 9.22 52
    0.125 3.18 0125 0.438 11.13 0.357 9.07 54
    0.197 5 0197 0.438 11.13 0.315 8 65
    0.263 6 0236 0.433 11 0.313 7.95 70
    0.25 6.35 0250 0.442 11.23 0.325 8.26 70
    0.307 7.8 0307 0.445 11.3 0.343 8.71 73
    0.325 8.26 0325 0.444 11.28 0.342 8.69 74
    0.394 10 0394 0.446 11.33 0.331 8.41 78
    0.472 12 0472 0.438 11.13 0.318 8.08 80
    0.5 12.7 0500 0.452 11.48 0.327 8.31 80
    0.615 15.62 0615 0.475 12.07 0.376 9.55 82
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 
    1/2" (13 mm) Diameter Lead Screw. Diameter Code 050
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm
    in mm in mm
    0.05 1.27 0050 0.495 12.57 0.433 11 29
    0.079 2 0079 0.473 12.01 0.355 9.02 41
    0.098 2.5 0098 0.5 12.7 0.383 9.73 46
    0.1 2.54 0100 0.49 12.45 0.364 9.25 46
    0.125 3.18 0125 0.5 12.7 0.374 9.5 51
    0.157 4 0157 0.5 12.7 0.384 9.75 58
    0.16 4.06 0160 0.5 12.7 0.388 9.86 67
    0.1667 4.23 0167 0.5 12.7 0.384 9.75 58
    0.197 5 0197 0.5 12.7 0.365 9.27 62
    0.2 5.08 0200 0.492 12.5 0.366 9.3 63
    0.25 6.35 0250 0.5 12.7 0.382 9.7 67
    0.333 8.46 0333 0.497 12.62 0.362 9.19 73
    0.394 10 0394 0.497 12.62 0.362 9.19 76
    0.4 10.16 0400 0.497 12.62 0.364 9.25 76
    0.5 12.7 0500 0.488 12.4 0.352 8.94 79
    0.63 16 0630 0.5 12.7 0.374 9.5 80
    0.75 19.05 0750 0.525 13.34 0.399 10.13 83
    0.8 20.32 0800 0.5 12.7 0.37 9.4 83
    0.984 25 0984 0.5 12.7 0.369 9.37 84
    1 25.4 1000 0.49 12.45 0.372 9.45 84
    1.5 38.1 1500 0.49 12.45 0.374 9.5 85
    2 50.8 2000 0.488 12.4 0.378 9.6 87
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 
    5/8" (16 mm) Diameter Lead Screw. Diameter Code 062
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm
    in mm in mm
    0.1 2.54 0100 0.615 15.62 0.498 12.65 40
    0.125 3.18 0125 0.625 15.88 0.47 11.94 45
    0.2 5.08 0200 0.625 15.88 0.495 12.57 53
    0.25 6.35 0250 0.625 15.88 0.469 11.91 63
    0.315 8 0315 0.627 15.93 0.493 12.52 68
    0.41 10.41 0410 0.625 15.88 0.481 12.22 72
    0.5 12.7 0500 0.625 15.88 0.478 12.14 76
    0.63 16 0630 0.625 15.88 0.491 12.47 78
    1 25.4 1000 0.625 15.88 0.481 12.22 83
    1.5 38.1 1500 0.625 15.88 0.499 12.67 85
    1.575 40.01 1575 0.625 15.88 0.499 12.67 86
    2 50.8 2000 0.625 15.88 0.499 12.67 86
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 
    3/4" (19 mm) Diameter Lead Screw. Diameter Code 075
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm
    in mm in mm
    0.0625 1.59 0063 0.75 19.05 0.671 17.04 25
    0.098 2.5 0098 0.742 18.85 0.626 15.9 35
    0.1 2.54 0100 0.746 18.95 0.624 15.85 35
    0.1667 4.23 0167 0.727 18.47 0.645 16.38 47
    0.197 5 0197 0.745 18.92 0.624 15.85 51
    0.2 5.08 0200 0.741 18.82 0.632 16.05 52
    0.25 6.35 0250 0.731 18.57 0.639 16.23 57
    0.276 7 0276 0.75 19.05 0.624 15.85 59
    0.333 8.46 0333 0.75 19.05 0.624 15.85 64
    0.5 12.7 0500 0.744 18.9 0.623 15.82 73
    0.551 14 0551 0.75 19.05 0.624 15.85 73
    0.591 15 0591 0.749 19.02 0.623 15.82 74
    0.709 18 0709 0.78 19.81 0.65 16.51 77
    0.748 19 0748 0.672 17.07 0.547 13.89 80
    0.787 20 0787 0.78 19.81 0.648 16.46 78
    0.8 20.32 0800 0.75 19.05 0.618 15.7 79
    0.945 24 0945 0.734 18.64 0.633 16.08 80
    1 25.4 1000 0.743 18.87 0.619 15.72 81
    1.5 38.1 1500 0.712 18.08 0.59 14.99 84
    1.969 50 1969 0.751 19.08 0.62 15.75 84
    2 50.8 2000 0.742 18.85 0.611 15.52 84
    2.4 60.96 2400 0.75 19.05 0.62 15.75 84
    3.622 92 3622 0.75 19.05 0.634 16.1 87
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 
    7/8" (22 mm) Diameter Lead Screw. Diameter Code 087
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm
    in mm in mm
    0.2 5.08 0200 0.87 22.1 0.742 18.85 48
    0.236 6 0236 0.848 21.54 0.773 19.63 52
    0.25 6.35 0250 0.875 22.23 0.749 19.02 53
    0.394 10 0394 0.875 22.23 0.741 18.82 65
    0.5 12.7 0500 0.862 21.89 0.744 18.9 69
    0.667 16.94 0667 0.871 22.12 0.745 18.92 74
    0.787 20 0787 0.875 22.23 0.741 18.82 78
    0.945 24 0945 0.875 22.23 0.741 18.82 79
    1 25.4 1000 0.871 22.12 0.742 18.85 80
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 
    15/16" (24 mm) Diameter Lead Screw. Diameter Code 093
    Lead Lead Code Left Hand Avail. Outside Diameter (For Reference) Root Diameter (For Reference) Efficiency %*
    in mm
    in mm in mm
    0.05 1.27 0050 LH Only 0.938 23.83 0.874 22.2 17
    2 50.8 2000 0.927 23.55 0.815 20.7 85
    3 76.2 3000 0.939 23.85 0.803 20.4 86
    *Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
    Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 
  • Lubrication Options +


    Haydon Kerk Motion Solutions™ offers multiple options for lubrication. All Kerk® lead screw nuts feature self-lubricating polymers. When maximum performance is required, Kerkote® and Black Ice™ TFE coatings provide unmatched results in the most demanding applications. 

    Kerkote® TFE Coating 

    Kerkote TFE is a soft coating, a long-term dry lubricant that is optimized for softer plastics like acetals and nylons, with or without mechanical reinforcement. Lubrication to the nut / lead screw interface occurs by the nut picking up Kerkote TFE particles from the coating as well as from the migration of the internal lubricant within the plastic nut. The lubricant, although solid, also has some “spreading” ability as in fluid lubricants. Kerkote TFE coated screws provide the maximum level of self-lubrication and should not be additionally lubricated or used in environments where oils or other lubricant contamination is possible. 

    Black Ice™ TFE Coating 


    Black Ice TFE coating shares many of the benefits of Kerkote TFE but, in contrast, is a hard coating that offers exceptional durability in all types of environments, with virtually any type of polymer lead screw nut. Rather than acting as a dry lubricant, Black Ice TFE is an anti-friction coating whose surface properties displace the metal to which it is applied. Though it is not intended for use with metal or glass fiber reinforced nuts, Black Ice TFE is bonded securely to the surface of the lead screw and can withstand abrasion from contamination, rigid polymer systems, fluid impingement and wash down applications. 

    Available Greases 

    TFE coatings are intended to be used without additional lubricants. There are certain applications where external lubrication may be desired. These include the use of nut materials such as glass reinforced plastic or metal. Haydon Kerk Motion Solutions does offer a selection of greases developed specifically for these applications. Please contact a sales engineer for assistance selecting the best lubricant for your requirements.
  • Part Number Guide +


    Part Number guide

    EXAMPLES

    WDGABR-037-0125-XXXX = Assembly: WDG Series Nut, triangular flanged mount, Black Ice™ TFE coating, right hand thread, 3/8-in nominal screw diameter, 0.125 thread lead, without an assigned unique identifier.

    ZBXTKR-043-0250-XXXX = Assembly: ZBX Series Nut, thread mounting, Kerkote® TFE coating, right hand thread, 7/16-in nominal screw diameter, 0.250 thread lead, without an assigned unique identifier.

    For applications assistance or order entry, call your the Haydon Kerk Motion Solutions Leadscrew Assemblies technical advisors at 603.465.7227.
    NOTE:
    Not all thread leads are available in all screw diameters.
    New nuts and leads are continually being added. Contact Haydon Kerk Motion Solutions for latest availability.
  • Mechanical Properties +


    Screw Inertia
    Screw Size Screw Inertia
    inch mm (oz-inch sec2/inch)
    5/64 (2) 3.4 x 10 –8
    1/8 (3.2) 1.8 x 10 –7
    3/16 (4.76) 1.1 x 10 –6
    1/4 (6) 3 x 10 –5
    5/16 (8) 5 x 10 –5
    3/8 (10) 1.5 x 10 –5
    7/16 (11) 3.5 x 10 –5
    1/2 (13) 5.2 x 10 –5
    5/8 (16) 14.2 x 10 –5
    3/4 (19) 30.5 x 10 –5
    7/8 (22) 58.0 x 10 –5
    15/16 (24) 73.0 x 10 –5

    Anti-Backlash Life
    Series Without Kerkote® TFE Coating With Kerkote® TFE Coating
    BFW N/A, Typical Backlash (inches) N/A, Typical Backlash (inches)
    .003 to .010 (.076 to .25) (cm) .003 to .010 (.076 to .25)(cm)

    MP
  • Design and Engineering Data +


    Screw Accuracy
    Haydon Kerk Motion Solutions, Inc uses a unique precision rolling process for screw manufacturing. Standard lead accuracy for Kerk screws is .0006 in./in. (mm/mm). Lead accuracies are available up to .0001 in./in. (mm/mm). Please consult the factory for higher lead accuracies. Assemblies have an extremely high bi-directional repeatability of 50 micro-inches (1.25 micron).
     
    End Machining
    Haydon Kerk Motion Solutions can custom machine screws to your specifications or provide cut-to-length screws for your own machining.  

    Critical Speed
    This is the rotational speed at which a screw may experience vibration or other dynamic problems. See CRITICAL SPEED CHART to determine if application parameters result in speed approaching critical. To minimize critical speed problems: use a longer lead, choose a larger diameter or increase bearing mount support.

    Critical Speed

    Lengths
    Lengths can be specified up to 12 ft. (4M) from stock, (depending on diameter and lead). Cut to length screws are offered in 6-in increments (6-in, 12, 18,....) +1.0-in/-0-in.

    Lead
    Advancement per revolution. All screws are listed by lead, not pitch. Lead = Pitch x Number of Starts

    Pitch
    Crest-to-crest distance or one divided by threads per inch. (On a multiple start thread, the pitch equals the lead divided by the number of starts.)

    Traverse Speed
    The nut materials we use provide long wear-life over a wide variety of conditions. However, very high loads and/or speeds will accelerate nut wear. Special materials may be required for these situations. We offer the following guidelines for continuous duty linear traversing speeds for optimum life:
    Lead Traverse Speed Lead Traverse Speed
    1/10 - 1/2-in 4-in/sec. 1 - 12 mm 100 mm/sec.
    1/2 - 1-in 10-in/sec. 12 - 25 mm 250 mm/sec.
    1 - 2 1/2-in 30-in/sec. 25 - 60 mm 760 mm/sec.

    Maximum Load
    Although the Kerk® Anti-Backlash Assemblies are capable of withstanding relatively high loads without catastrophic failure, these units have been designed to operate under the loading shown in the size charts.

    Efficiency
    Efficiency is the relationship of work input to work output. It should not be confused with mechanical advantage. Listed efficiency are theoretical values based on Kerkote® TFE coated screws.

    Torque
    The required motor torque to drive a lead screw assembly is the sum of three components: the inertial torque, drag torque, and torque-to-move load. It must be noted that
    this is the torque necessary to drive the lead screw assembly alone. Additional torque associated with driving frictional bearings and motor shafts, moving components, and drag due to general assembly misalignment must also be considered.

    Inertial Torque:

    T = I α  Where I = screw inertia
     j                   α = angular acceleration

    Drag Torque:
    The Kerk Anti-Backlash Assemblies are typically supplied with drag torque of 1 to 7 oz.-in. The magnitude of the drag torque is dependent on the standard factory settings or settings specified by the customer. Generally, the higher the preset force, the better the Anti-Back- lash characteristics.

    Torque-to-Move:

    T=        LOAD x LEAD
      L    2 π EFFICIENCY

    Back Driving:
    Sometimes referred to as reversibility, back driving is the ability of a screw to be turned by a thrust load applied to the nut. Generally, back driving will not occur when the screw lead is less than 1/3 the diameter for uncoated screws or 1/4 the diameter for Kerkote® TFE coated screws. For higher leads where back driving is likely, the torque required for holding a load is:

    T  =         LOAD x LEAD x BACKDRIVE EFFICIENCY     
     b                                   2π

    Screw Straightness:
    Screw straightness is measured as Total Indicator Runout(TIR). The standard straightness for lead screws is .003-in/ft. Haydon Kerk Motion Solutions can provide tighter specifications on customer request.  

    All screws are hand straightened before shipping.



  • Customization +


    In addition to The Kerk® standard nut types, modified and complete custom configurations represent a large portion of the company’s production. Modifications may be simple changes such as different mounting hole patterns or mounting threads, small dimensional changes, or special materials. Haydon Kerk Motion Solutions can provide tremendous value by producing a multi-functional acme nut. Using custom molds and specialty machining, nuts can also include guide bushings, carriages, timing pulleys, gears, syringe components, sensor mounts and flags, encoder features, clamps and many other complimentary elements. In addition, custom designed nuts can offer quick release mounts, partial thread engagement, half nut construction or special shapes and geometries. Special materials are offered to extend the performance of our assemblies. Materials can be chosen for extreme temperature, chemical compatibility, autoclaving, agency approvals, special loadings and many other specific requirements.
  • Typical End Machining Features +


    Standard End Machine