Precision Granite Straight Edge with Weight-Reduction Bores
Long precision straightedges have a reputation problem: the longer they get, the heavier and harder to move they become. A solid granite bar the length shown here, without any material relief, quickly turns into a two-person lifting job every time it needs repositioning on a shop floor or moved between an inspection bench and a machine bed. That's the practical problem this straightedge is designed around.
The bar in front of you is a full-length black granite straight ruler, precision-ground on its working faces, with a row of five circular bores machined through the body along its length — largest near one end, tapering down to progressively smaller diameters toward the other. It isn't decorative. Those bores are strategically placed to cut dead weight out of sections of the bar that don't carry critical load, while leaving the working edge geometry and overall rigidity intact. The result is a tool that's noticeably easier to lift, position, and transport than an equivalent solid-body straightedge, without giving up the dimensional stability granite is chosen for in the first place.
The surface finish tells its own story under close inspection: a fine, even matte-black grain, consistent from end to end, with sharply defined edges along the top working face where flatness and straightness tolerances actually get measured. That consistency isn't cosmetic — uneven grain or visible mineral banding in a granite blank is often an early sign of lower-density stone that won't hold tolerance as reliably over years of use.
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Model |
Details |
Model |
Details |
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Size |
Custom |
Application |
CNC, Laser, CMM... |
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Condition |
New |
After-sales Service |
Online supports, Onsite supports |
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Origin |
Jinan City |
Material |
Black Granite |
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Color |
Black / Grade 1 |
Brand |
ZHHIMG |
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Precision |
0.001mm |
Weight |
≈3.05g/cm3 |
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Standard |
DIN/ GB/ JIS... |
Warranty |
1year |
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Packing |
Export Plywood CASE |
After Warranty Service |
Video technical support, Online support, Spare parts, Field mai |
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Payment |
T/T, L/C... |
Certificates |
Inspection Reports/ Quality Certificate |
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Keyword |
Granite Machine Base; Granite Mechanical Components; Granite Machine Parts; Precision Granite |
Certification |
CE, GS, ISO, SGS, TUV... |
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Delivery |
EXW; FOB; CIF; CFR; DDU; CPT... |
Drawings’ format |
CAD; STEP; PDF... |
• Reduced handling weight. The bored sections remove non-critical mass without compromising the working edge, making longer bars practical to move by hand or with lighter lifting equipment than a solid-body equivalent would require.
• Dimensional stability over time. Granite doesn't carry the residual internal stress that rolled or cast metal straightedges can develop, so the bar isn't prone to the slow warping that eventually throws off a metal reference over years of service.
• Corrosion-free, non-magnetic. No rust risk in humid shop environments, and no magnetic interference near sensitive measuring instruments — a factor metal straightedges can't offer.
• Consistent thermal behavior. Low thermal expansion means the bar holds its calibrated geometry across a wider range of ambient shop temperatures than most metals.
• Traceable accuracy. Flatness and straightness are verified with calibrated laser interferometry and electronic levels, with certification traceable back to a recognized metrology institute — not just a factory-issued number.
We use various techniques during this process:
● Optical measurements with autocollimators
● Laser interferometers and laser trackers
● Electronic inclination levels (precision spirit levels)
1. Documents together with products: Inspection reports + Calibration reports(measuring devices) + Quality Certificate + Invoice + Packing List + Contract + Bill of Lading(or AWB).
2. Special Export Plywood Case: Export fumigation-free wooden box.
3. Delivery:
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Ship |
Qingdao port |
Shenzhen port |
TianJin port |
Shanghai port |
... |
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Train |
XiAn Station |
Zhengzhou Station |
Qingdao |
... |
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Air |
Qingdao Airport |
Beijing Airport |
Shanghai Airport |
Guangzhou |
... |
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Express |
DHL |
TNT |
Fedex |
UPS |
... |
Do the weight-reduction bores affect flatness or straightness accuracy? No, when engineered correctly. Bore placement is calculated to remove material from low-stress regions of the bar, and the working face is finished and verified after all machining, including the bores, is complete — so the certified flatness figure already accounts for the finished geometry, not a theoretical solid-bar spec.
Can I get a custom length or a different number of bores? Yes. Length, bore count, bore diameter, and spacing are all configurable based on the intended use case and how the bar will be handled and stored.
What grade should I choose for machine tool alignment versus lab calibration? Machine tool leveling work commonly uses Grade 1 or Grade 0 tolerances, while lab reference standards and CMM verification often call for Grade 00. If you're not sure which applies to your application, it's worth confirming your required tolerance class before ordering rather than defaulting to the tightest available grade.
How is flatness verified before shipment, and is a certificate included? Flatness and straightness are measured with laser interferometry and precision electronic levels, calibrated and traceable through a recognized metrology institute. A calibration certificate ships with the bar.
How should this straightedge be stored and handled to preserve accuracy? Store it horizontally, supported at its designated support points (typically near the Airy points for long bars), away from direct sunlight and temperature swings, and avoid dragging it across abrasive surfaces. Even a stable material like granite can develop measurable wear or chipping at the edges from careless handling.
QUALITY CONTROL
If you can’t measure something, you can’t understand it!
If you can’t understand it.you cant control it!
If you can’t control it, you can’t improve it!
More information please click here: ZHONGHUI QC
ZhongHui IM, your partner of metrology, help you succeed easily.
Our Certificates & Patents:
ISO 9001, ISO45001, ISO14001, CE, AAA Integrity Certificate， AAA-level enterprise credit certificate…
Certificates and Patents are an expression of a company’s strength. It’s society’s recognition of the company.
More certificates please click here: Innovation & Technologies – ZHONGHUI INTELLIGENT MANUFACTURING (JINAN) GROUP CO., LTD (zhhimg.com)
