Ground Bar Tolerances


Our steel bar can be centreless ground to your exact sizes and tolerances.

Precision ground steel bar is suited for applications which require a tighter tolerance than standard commercial bright drawn, bright turned or bright peeled bar. Precision ground steel bars can be supplied to a defined tight tolerance on diameter, providing good roundness, straightness and a fine surface finish. The roundness and straightness of a ground steel bar ensures its suitability for machining in environments which require minimum vibration as the bars rotate at high speeds. Precision ground steel bars are well suited for a wide range of applications such.

Below we list the standard ISO tolerances for precision ground, bright drawn, smooth turned and polished round steel bar (diameters).
Metric Diameters

Dia – mmISO h6ISO h7ISO h8ISO h9ISO h10ISO h11
1 < 30.0060.0100.0140.0250.0400.060
3 < 60.0080.0120.0180.0300.0480.075
6 < 100.0090.0150.0220.0360.0580.090
10 < 180.0110.0180.0270.0430.0700.110
18 < 300.0130.0210.0330.0520.0840.130
30 < 500.0160.0250.0390.0620.1000.160
50 < 800.0190.0300.0460.0740.1200.190
80 < 1200.0220.0350.0540.0870.1400.220
120 < 1800.0630.1000.1600.250
180 < 2500.0720.1150.1850.290
250 < 2750.0810.1300.2100.320

 

Imperial Diameters

Dia – inchesISO h6ISO h7ISO h8ISO h9ISO h10ISO h11
0.039 < 0.1180.000250.00040.00060.00100.00160.0024
0.118 < 0.2360.00030.00050.00070.00120.00190.0030
0.236 < 0.3930.00040.00060.00090.00140.00230.0035
0.393 < 0.7070.00040.00070.00100.00160.00280.0043
0.707 < 1.1810.00050.00080.00120.00200.00350.0051
1.181 < 1.9690.00060.00100.00160.00250.00400.0063
1.969 < 3.1500.00070.00120.00180.00300.00460.0075
3.150 < 4.7240.00090.00140.00220.00350.00550.0087
4.724 < 7.0870.00250.00390.00630.0098
7.087 < 9.8430.00280.00450.00730.0114
9.843 <10.8270.00310.00510.00830.0126

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Form of Supply

Precision ground steel bar is available in our full range of special steel specifications and can be produced to your required sizes in the following steel types; tool steel, high speed steel, carbon steel, alloy steel, high tensile steel and stainless steel ground bar. Dependent on your required sizes, quantities and specifications precision ground bar can be produced in approximately 2 to 3 weeks.


When enquiring on precision ground steel bar grades please provide the following information to our sales team:-

  • Size & quantity – details of the diameter of the round bar, length and quantity.
  • Tolerance – please detail the exact size and tolerance allowance.
  • Steel specification – full details of the steel grade.

All our precision ground bar supplies are available with a cast and analysis certificate or a certificate of conformity. Please request when placing any orders.


Precision ground bars are supplied in accordance with our ISO 9001 : 2008 registration. Our aim to satisfy the quality and delivery needs of our customers and we measure our performance by meeting customers’ requirements. We work to continually improve the service that we provide. In order to achieve this, it is our policy to maintain an efficient and effective Quality Management System based upon the requirements of BS EN ISO 9001:2008. Our staff are appropriately trained in order to effectively implement the Quality Management System. The achievement of quality and continuous improvement is fundamental to all the steel products and services provided by us and are practiced by all employees as an integral part of their work.