Tolerances and Grind Stock

Grind Stock Allowances:

With the exception of centerless ground rod blanks, all blanks produced by Carbide Technologies will have a suitable amount of grind stock left on all dimensions which must be removed by the customer during the tool fabrication process.

  • Rod Cut to length, 12in and 14in OAL

    • Diameter stock – The amount of stock on the outside diameter (OD) of rod, is based on the OAL (overall length) of the blank. Grind stock will be added to the finished diameter of a blank as shown in the following chart:

      Blank OAL Min. OD stock Max. OD stock
       3.000” or shorter  +.016”  +.024”
       3.001” – 11.999”  +.020” +.028”
       12.000” or longer  +.024” +.032”

      Length stock – Because slight variations in shrinkage are amplified with the overall length of a part, grind stock allowed increases with the OAL of a part. Grind stock will be added to the finished length of a blank as shown in the following chart:

      Blank OAL Min. OD stock Max. OD stock
      Length up to 2.000” +.010” +.030”
      2.001” – 3.000” +.010” +.040”
      3.001” – 4.000” +.010” +.050”
      4.001” – 5.000” +.010” +.060”
      5.001” – 6.000” +.010” +.070”
      6.001” – 8.000” +.010” +.080”
      8.001” – 10.000” +.010” +.090”
      10.001” – 11.999” +.010” +.100”
      12.000” – 14.000” +.010” +.400”

      Warpage allowance – All rod is checked 100% for warpage. Rod warpage is measured on a flat plate with a feeler gauge. Maximum warpage allowed is based on the OAL/OD grind stock as shown in the following chart:

      Blank OAL Max. warpage
       3.000” or shorter  .005”
       3.001” – 11.999”  .006”
       12.000” or longer   .008”

      Note: Allowable warpage may be adjusted based on the actual rough blank diameter. To do so: first subtract the finish diameter from the actual rough blank diameter to determine the amount        of grind stock. Divide the actual grind stock by 3 and round this figure down to 3 decimal places. Please remember that .008 is the maximum allowable warpage regardless of the amount of grind stock.

       

  • Extruded tubing

    • Diameter stock – The amount of stock on the outside diameter (OD) of tubing 3/64 OD and smaller is shown in the following chart:

      Diameter  Min. OD stock Max. OD stock
      1/64” +.010” +.018”
      1/32” +.012” +.020”
      3/64” +.014” +.022”

      Diameter stock – The amount of stock on the diameter of tubing larger than 3/64 OD is based on the OAL and is shown in the following chart:

      Tube OAL Min. OD stock Max. OD stock
      3.000” or shorter +.016” +.024”
      3.001” – 11.999” +.020” +.028”
      12.000” or longer +.024” +.032”

      ID tolerance – is based on the hole size as shown in the following chart:

      Hole diameter Tolerance (+/-)
      .039” and smaller .002”
      .040” – .079” .003”
      .080” – .149” .004”
      .150” and larger .005″

      Length stock – Due to the shrinkage variation the amount of stock on the length of a tube increases as the OAL of the tube increases. Grind stock will be added to the finished length of a tube as shown in the following chart:

      Blank OAL Min. length stock Max. length stock
      Length up to 6.000” +.010” +.070”
      6.001” and longer +.010” +.200”

      Warpage allowance – All tubing is checked 100% for warpage. Tubing warpage is measured on a flat plate with a feeler gauge. Maximum warpage allowed is based on the OAL/OD grind stock as shown in the following chart:

      Blank OAL Max. warpage
      6.000” and shorter .006”
      6.001” and longer .008”
  • BCR, BSR, BEM, FCBE & FCOE

    • Diameter stock – The amount of stock on the outside diameter (OD) of female center blanks is based on the OAL (over all length) of the blank. Grind stock will be added to the finished diameter of a blank as shown in the following chart:

      Blank OAL Min. OD stock  Max. OD stock
       11.999” or shorter  +.021”  +.029”
       12.000” or longer  +.024”  +.032”

      Length stock – Due to the shrinkage variation, the amount of stock on the length of a blank increases as the OAL of the blank increases. Grind stock will be added to the finished length of a blank as shown in the following chart:

      Blank OAL  Min. length stock Max. length stock
       Length up to 3.000”  +.000”  +.030”
       3.001” – 4.000”  +.000”  +.040”
       4.001” – 5.000”  +.000” +.050”
       5.001” – 6.000”  +.000”  +.060”
       6.001” – 8.000”  +.000”  +.080”
       8.001” – 10.000”  +.000” +.100”
       10.001” – 11.999”  +.000” +.120”
       12.000” – 14.000”  +.000”  +.400”

      Female center size – Use the following chart to determine female center size and type (round off all fractional dimensions to 3 decimal places):

      Blank diameter Center #  Top opening diameter       Tolerance
       .125” – .187”  0  .050”  +/- .006”
          .188” – .250”  0  .060”  +/- .006”
       .251” – .312”  0  .080”  +/- .006”
       .313” – .375”  1 .080”  +/- .006”
       .376” – .437”  1  .100”  +/- .006”
       .438” – .562”  1  .110”  +/- .006”
       .563” – .687”  2  .130”  +/- .006”
       .688” – .812”  2  .150”  +/- .006”
      .813” or larger  3  .180”  +/- .006”

      Warpage allowance – All female center blanks are checked 100% for warpage. Blank warpage is measured on a flat plate with a feeler gauge.  Maximum warpage allowed is based on the OAL/OD grind stock as shown in the following chart:

      Blank OAL  Max. warpage
       3.000” or shorter  .005”
       3.001” or shorter  .006”
  • STB blanks

    • Width and Thickness stock – The amount of grind stock on the width and thickness of STB blanks is based on those sizes. Grind stock will be added to the finished dimensions of the blank as shown in the following chart:

      Finished size                                 Min. stock  Max. stock
       1/16” and smaller  +.010”  +.018”
       5/64” – 3/16”  +.015” +.023”
       13/64” – 31/64”  +.015” +.027”
       1/2” – 39/64”  +.015” +.028”
       5/8” – 63/64”  +.015”  +.030”
       1” or larger  +.015”  +.035”

      Length stock – Due to the shrinkage variation, the amount of stock on the length of a blank increases as the OAL of the blank increases. Grind stock will be added to the finished length of a blank as shown in the following chart:

      Blank OAL                      Min. length stock       Max. length stock
       Length up to 2.000”  +.010”  +.030”
       2.001” – 3.000”  +.010” +.040”
       3.001” – 4.000”  +.010” +.050”
       4.001” – 5.000”  +.010”  +.060”
       5.001” – 6.000”  +.010” +.070”
       6.001” – 8.000”  +.010” +.080”
       8.001” – 10.000”  +.010” +.090”
       10.001” – 11.999”  +.010” +.100”
       12.000” – 14.000”  +.050”  +.250”

      Warpage allowance – All STB blanks are checked 100% for warpage. STB warpage is measured on a flat plate with a feeler gauge.  Maximum warpage allowed is based on the actual grind stock. Actual grind stock is determined by subtracting the finished dimension from the actual rough blank dimension. The result is the amount of actual grind stock. Use the following chart to determine maximum acceptable warpage:

       Actual grind stock          Max. warpage
       010” – .014”  .004”
       .015” – .017”  .005”
      .018” – .020”  .006”
      .021” – .023”  .007”
       .024” or more  .008″
  • Non-fluted preform blanks (coolant and non-coolant fed)

    • Diameter stock – The amount of stock on all diameters (major dia. and step dia(s).) of non-fluted blanks are based on the OAL (over all length) of the blank. Grind stock will be added to all finished diameters of a blank as shown in the following chart:

      Blank OAL                             Min. OD stock Max. OD stock
       3.000” or shorter +.018” +.026”
       3.001” – 11.999”  +.021”  +.029”
       12.000” or longer  +.024” +.032”

      OAL stock – Due to the shrinkage variation, the amount of stock on the length of a blank increases as the OAL of the blank increases. Grind stock will be added to the finished length of a blank as shown in the following chart:

       Blank OAL                      Min. length stock      Max. length stock
       Length up to 2.000”  +.010”  +.030”
       2.001” – 3.000”  +.010”  +.040”
       3.001” – 4.000”  +.010”  +.050”
       4.001” – 5.000”  +.010” +.060”
       5.001” – 6.000”  +.010”  +.070”
       6.001” – 8.000”  +.010”  +.080”
       8.001” – 10.000”  +.010” +.090”
       10.001” – 11.999”  +.010” +.100”
       12.000” – 14.000”              +.200” +.400”

      Major diameter length stock – All grind stock will be added to the length of the major diameter in accordance to the blank OAL (see chart above).

      Minor diameter length stock (step length) – All minor diameter lengths will be held to size.

      *Please note: An exception is made for double major diameter blanks (blanks with a small diameter between larger diameters at each end). In these blanks the small diameter length is made to size, the length of each larger diameter is stocked +.010” min./+.010” per inch of the corresponding diameter’s length as a maximum. As a result the OAL of the blank is then stocked +.020” min./+ the total of both major diameters maximum stock.

      Coolant hole tolerances

      Hole diameter   +/- .005”

      Hole location    +/- .005”

      Bolt circle         +/- .005”

      Length (depth) of hole

      1. if measured from the drilled end of the blank the tolerance is the same as the OAL stock.
      2. if measured from the remaining end of the blank the tolerance is +/- .010”.

      Radius tolerances – Increases with the size of the radius.

      .250” or less                +/- .005”

      .251” – .500”               +/- .010”

      .501” – 1.000”             +/- .020”

      1.001” or larger           +/- .025”

      Tang tolerances

      Thickness                    +/- .005”

      Length                         +/- .005”

      Angle tolerance     +/- 2 degrees

      Female center size – Use the major blank dia. and the following chart to determine female center size and type (round off all fractional dimensions to 3 decimal places):

      Blank diameter  Center #                 Top opening diameter           Tolerance
       .125” – .187” 0  .050”  +/- .006”
      .188” – .250” 0  .060”  +/- .006”
       .251” – .312” 0  .080”  +/- .006”
      .313” – .375” 1  .080”  +/- .006”
       .376” – .437” 1  .100”  +/- .006”
       .438” – .562” 1  .110”  +/- .006”
       .563” – .687”  2  .130”  +/- .006”
      .688” – .812”  2  .150”  +/- .006”
       .813” or larger  3  .180”  +/- .006”

      Extended nib for false female centers – The diameter and length of an extended nib changes in accordance with the major diameter of the blank. Use the following chart to determine nib diameter and length if not given. Nib diameter and length are made to size.

      Blank diameter Nib diameter x nib length
       .188” – .250”  .125” x .125”
       .251” – .375”  .188” x .188”
       .376” – .687”  .250” x .250”
       .688” or larger  .313” x .313”

      Male nib centers – Male nib centers are considered to be 90 degree included unless otherwise stated. The diameter of a male nib changes in accordance with the major diameter of the blank. Use the following chart to determine nib diameter if not given. Nib diameter and length are made to size.

      Blank diameter Nib diameter x nib length
       .188” – .312”  .125”
       .313” – .562” .188”
       .563” or larger .250”

      OD chamfers – Corner chamfers are considered to be 45 degree unless otherwise stated. The length of a chamfer changes in accordance with the major diameter of the blank. Use the following chart to determine the  length if not given. Chamfers are made to size.

      Blank diameter Chamfer length
       .312” or less  .030”
      .313” – .437” .040”
      .438” – .812” .050”
      .813” or larger .060”

      Warpage allowance – All non fluted blanks are checked 100% for warpage. Blank warpage is measured in one of two methods:

      1. Blanks with a single OD. – Blanks are checked on a flat plate with a feeler gauge. Maximum warpage allowed is based on the OAL/OD grind stock as shown in the following chart:
      Blank OAL     Max. warpage
       3.000” or shorter  .006”
       3.001” – 11.999” .007”
       12.000” or longer  .008”

      Note: Allowable warpage may be adjusted based on the actual rough blank diameter. To do so: first subtract the finish diameter from the actual rough blank diameter to determine the amount      of grind stock. Divide the actual grind stock by 3 and round this figure down to 3 decimal places. Please remember that .008 is the maximum allowable warpage regardless of the amount of grind stock.

      2. Blanks with Multiple ODs. – Blanks are checked on a center fixture or roller plate with an indicator.  Maximum warpage (TIR) allowed is based on the OAL/OD grind stock as shown in the following chart

       Blank OAL Max. TIR
       3.000” or shorter  .012”
       3.001” – 11.999”  .014”
       12.000” or longer  .016″

      Note: Allowable TIR may be adjusted based on the actual rough blank diameter. To do so: first subtract the finish diameter from the actual rough blank diameter to determine the amount of grind stock. Divide the actual grind stock by 3 and round this figure down to 3 decimal places then multiply by 2.  The result is the maximum allowable TIR. Please remember that .016in is the maximum allowable warpage regardless of the amount of grind stock.

  • Bushings

    • Diameter stock – The amount of stock on the outside diameter (OD) of a bushing is based on the OAL (over all length) of the blank. Grind stock will be added to the finished diameter of a blank as shown in the following chart:

      Blank OAL                              Min. OD stock Max. OD stock
       3.000” or shorter  +.018”  +.026”
       3.001” – 11.999” +.021”  +.029”
       12.000” or longer  +.024”  +.032”

      Note: For stepped OD’s all diameters will be stocked according to the OAL of the blank.

      Length stock – Due to the shrinkage variation, the amount of stock on the length of a blank increases as the OAL of the blank increases. Grind stock will be added to the finished length of a blank as shown in the following chart:

      Blank OAL                         Min. length stock Max. length stock
       Length up to 2.000”  +.010”  +.030”
      2.001” – 3.000”  +.010”  +.040”
       3.001” – 4.000”  +.010”  +.050”
       4.001” – 5.000”  +.010”  +.060”
       5.001” – 6.000”  +.010”  +.070”
       6.001” – 8.000”  +.010”  +.080”
       8.001” – 10.000″  +.010”  +.090”
       10.001” – 11.999”  +.010”  +.100”
       12.000” – 14.000”  +.200”  +.400”

      Inside diameter (ID) – The grind stock on the inside diameter (ID) increases as the OAL of the blank increases. Grind stock will be added to the ID as shown in the following chart:

       Blank OAL                          Min. ID stock Max. ID stock
       3.000” or shorter  -.018”  -.026”
       3.001” – 11.999”   -.021”  -.029”
       12.000” or longer   -.024”  -.032”

      Note: For stepped ID’s all OD’s will be stocked according to the OAL of the blank.

      Warpage allowance – All bushings are checked 100% for warpage. Warpage is measured in one of two methods:

      1. Blanks with a single OD. – Blanks are checked on a flat plate with a feeler gauge. Maximum warpage allowed is based on the OAL/OD grind stock as shown in the following chart:
      Blank OAL                         Max. warpage
       3.000” or shorter     .006”
       3.001” – 11.999”  .007”
       12.000” or longer    .008”

      Note: Allowable warpage may be adjusted based on the actual rough blank diameter. To do so: first subtract the finish diameter from the actual rough blank diameter to determine the amount       of grind stock. Divide the actual grind stock by 3 and round this figure down to 3 decimal places. Please remember that .008in is the maximum allowable warpage regardless of the amount of grind stock.

      2. Blanks with multiple ODs. – Blanks are checked on a center fixture or roller plate with an indicator. Maximum warpage (TIR) allowed is based on the OAL/OD grind stock as shown in the following chart:

       Blank OAL  Max. TIR
       3.000” or shorter  .012”
       3.001” – 11.999” .014”
       12.000” or longer  .016”

      Note: Allowable TIR may be adjusted based on the actual rough blank diameter. To do so: first subtract the finish diameter from the actual rough blank diameter to determine the amount of grind stock. Divide the actual grind stock by 3 and round this figure down to 3 decimal places then multiply by 2.  The result is the maximum allowable TIR. Please remember that .016” is the maximum  allowable warpage regardless of the amount of grind stock.