Summary

GibbsCAM uses fixed decimal limits for applicable numeric values. A document set to Millimeters supports up to three decimal places. A document set to Inches supports up to four or five decimal places, depending on the applicable field. These limits cannot be changed by a preference or user setting.

Material-hardness values shown in GibbsCAM use the Brinell hardness scale. Treat a hardness value as Brinell unless the applicable documentation explicitly states otherwise. If source data is supplied in Rockwell, Vickers, or another scale, convert it with an approved reference before using it as GibbsCAM material data.


Table of Contents


Before You Begin

  • Confirm whether the active GibbsCAM document is set to Inches or Millimeters.

  • Identify the exact numeric field being reviewed; an inch field may allow four or five decimal places.

  • Retain the original engineering value before entering or importing data that contains more precision than GibbsCAM displays.

  • Confirm the required dimensional tolerance with the print, model, customer specification, and shop standard.

  • Identify the hardness scale used by the material certificate, supplier data, or cutting-tool recommendation.

  • Verify posted NC output separately because post formatting and control resolution are not changed by GibbsCAM's input-field display limit.

Important: Do not assume that a value labeled only as hardness is Rockwell. GibbsCAM hardness values use Brinell, and values from different hardness scales are not interchangeable.


Quick Reference

Topic

GibbsCAM Value

Interpretation

Decimal limit - Millimeters

Up to 3 decimal places

Fixed; the limit cannot be changed.

Decimal limit - Inches

Up to 4 or 5 decimal places

The applicable field determines whether four or five places are available; the limit cannot be changed.

Material hardness

Brinell hardness scale

Convert values from Rockwell, Vickers, or another scale before using them as GibbsCAM hardness data.


Decimal Limits

The active document units determine the maximum decimal precision available in applicable GibbsCAM numeric fields. In Millimeters, enter values to no more than three decimal places. In Inches, use no more than four or five decimal places as allowed by the specific field. There is no setting that increases these limits.

For example, 12.345 uses the maximum three decimal places available in a millimeter document. In an inch document, 0.1234 uses four decimal places, while some fields can accept a fifth place such as 0.12345. If additional source precision is important, document it outside the limited field and confirm that the resulting GibbsCAM value still meets the engineering requirement.

Note: The field limit does not establish the number of decimal places written by every post processor. Inspect the posted NC program and confirm the CNC control's resolution before releasing a job.


Hardness Scale

GibbsCAM material-hardness values are represented on the Brinell hardness scale. A displayed value such as 250 should therefore be read as a Brinell value, not as Rockwell C, Rockwell B, Vickers, or another hardness system.

When a material certificate or tooling recommendation uses another hardness scale, use an approved conversion source appropriate to the alloy and condition. Hardness conversions can be approximate, so retain the original scale and source value in the job documentation and use the converted Brinell value only when that conversion is technically acceptable.


Procedure

Step 1 - Confirm the Document Units

  1. Open the GibbsCAM document and identify whether it is set to Inches or Millimeters.

  2. Confirm that the document units match the print, model, stock, tools, and intended post output.

  3. Do not change units solely to obtain another decimal place; unit changes affect the interpretation of dimensional values throughout the document.


Step 2 - Enter and Verify Decimal Values

  1. For Millimeters, enter no more than three digits after the decimal point.

  2. For Inches, enter no more than four or five digits after the decimal point, according to the applicable field.

  3. After entry, reopen or reselect the field and confirm the value retained by GibbsCAM.

  4. Compare the retained value with the print tolerance and determine whether the available precision is acceptable.

  5. If the requirement cannot be represented adequately, stop and coordinate an approved alternative instead of assuming the limit can be changed.


Step 3 - Interpret Material Hardness

  1. Read the GibbsCAM hardness value as Brinell.

  2. Check the material certificate or supplier data for the original hardness scale and value.

  3. If the source is not Brinell, convert it with an approved material-specific reference before using it in GibbsCAM.

  4. Record the original value, original scale, conversion source, and resulting Brinell value in the job documentation.


Step 4 - Verify Downstream Results

  1. Regenerate affected operations after changing dimensions, tolerances, units, material, or hardness data.

  2. Review feeds, speeds, depths, allowances, and other values that depend on the edited data.

  3. Post the applicable operations and inspect the actual coordinate precision, units, feeds, and speeds in the NC output.

  4. Confirm that the CNC control can interpret the posted precision and that the resulting values meet the print and shop requirements.

  5. Follow the shop's approved simulation, review, and prove-out procedure before machining.


Expected Result

Millimeter documents use no more than three decimal places, while inch documents use no more than four or five decimal places as permitted by the applicable field. The limits are understood to be fixed. Material-hardness values are interpreted as Brinell, and any non-Brinell source data is converted and documented before use.


Best Practices

  • Confirm the document units before entering dimensions, tolerances, feeds, or speeds.

  • Keep source calculations at full precision and round only when entering the approved GibbsCAM value.

  • Recheck a field after entry instead of assuming every typed digit was retained.

  • Do not change the document unit system simply to gain an additional displayed decimal place.

  • Inspect posted NC output because post formatting and control resolution are separate from GibbsCAM field limits.

  • Label hardness values with their scale in job notes and setup documentation.

  • Use an approved conversion reference when source hardness is not Brinell, and preserve the original material-certificate value.

  • Regenerate and verify operations after changing units, dimensional values, material, or hardness data.


Troubleshooting

  • Problem: A millimeter field will not retain more than three decimal places.

Possible Causes

  • The active document is set to Millimeters.

  • GibbsCAM's millimeter decimal limit is three places.

  • There is no user preference that increases the limit.

Resolution

Confirm the document units and evaluate the retained three-place value against the engineering tolerance. If it is not adequate, coordinate an approved workflow change; the GibbsCAM decimal limit cannot be expanded.

  • Problem: An inch field stops at four decimal places while another accepts five.

Possible Causes

  • Inch values are limited to four or five decimal places depending on the applicable field.

  • The two fields use different built-in precision limits.

  • The extra place is not controlled by a general preference.

Resolution

Use the precision supported by each field, confirm the retained value, and compare it with the print requirement. Do not expect one setting to make every inch field accept five places.

  • Problem: An imported or calculated value appears to have less precision in GibbsCAM.

Possible Causes

  • The source contains more decimal places than the active unit system or field supports.

  • The displayed field cannot represent all source digits.

  • The source units do not match the active document units.

Resolution

Confirm the source and document units, inspect the value retained by GibbsCAM, and compare it with the allowed tolerance. Preserve the original value outside the limited field when traceability is required.

  • Problem: A GibbsCAM hardness value does not match a Rockwell value on the material certificate.

Possible Causes

  • GibbsCAM uses Brinell hardness values.

  • The certificate uses Rockwell C, Rockwell B, Vickers, or another scale.

  • Values from different hardness scales were compared directly.

Resolution

Identify both scales, then use an approved conversion reference appropriate to the material. Record the source hardness and scale and the converted Brinell value; do not relabel the original number as Brinell.

  • Problem: The posted coordinates use a different number of decimal places than the GibbsCAM field.

Possible Causes

  • The post processor applies its own numeric format.

  • The CNC control expects a specific unit or decimal convention.

  • The GibbsCAM field limit was assumed to control NC output formatting.

Resolution

Inspect the posted blocks and confirm the active post, document units, and control requirements. Have the approved post developer review any required formatting change; do not treat the GibbsCAM input-field limit as a post-format setting.


Additional Information

Scope: This article identifies GibbsCAM's decimal limits and the hardness scale used for material values. It does not define part tolerances, perform hardness conversions, change post formatting, or establish CNC control resolution.



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Keywords

GibbsCAM, Decimal Limits, Decimal Places, Numeric Precision, Millimeters, Inches, Metric, Imperial, Hardness Scale, Brinell, Brinell Hardness, Rockwell, Vickers, Material Hardness, Post Precision, Coordinate Precision