The direct answer

A lapidary saw’s blade diameter is not its cutting capacity. Start with the exact model’s manual, then check exposed blade height, the manufacturer’s material limit and the clearance required to hold the specimen. A rock that fits beside the blade may still exceed the operating limit.

Separate blade size, exposed height and the working limit

Blade diameter describes the complete circle, including the part hidden below the table. Exposed height describes what is above the table. A recommended material limit adds another restriction. These numbers answer different questions, so a shopping comparison should give each its own column instead of presenting them interchangeably.

Hi-Tech's current 4/5-inch product page calls the 1-inch and 1.5-inch exposed blade heights its maximum cutting heights. The current manual uses those same exposed heights but separately says material should not exceed two-thirds of the visible cutting area. Because those descriptions do not resolve to one number, this site uses the stricter manual wording for preliminary planning: about 0.67 inch with the 4-inch blade and 1 inch with the 5-inch blade. Confirm the manual supplied with the exact machine and obtain written manufacturer clarification when the difference affects a purchase.

The 6-inch manual documents 1.75 inches of exposed blade and the same two-thirds rule, producing an approximately 1.17-inch planning screen. The 10-inch manual documents 3.75 inches and the same rule, producing about 2.5 inches. Every fractional value here is editorial arithmetic from the manual wording—not a separately rated capacity, permission for irregular rough or a replacement for a workholding check.

  • 4-inch blade: 1 inch exposed; approximately 0.67 inch after the manual's two-thirds screen.
  • 5-inch blade: 1.5 inches exposed; approximately 1 inch after the manual's two-thirds screen.
  • 6-inch blade: 1.75 inches exposed; approximately 1.17 inches after the manual's two-thirds screen.
  • 10-inch blade: 3.75 inches exposed; approximately 2.5 inches after the manual's two-thirds screen.

Measure the intended cut orientation

Photograph the specimen with a ruler and mark the face you want to reveal. Record its height, width and length in that orientation. The height entered in the Saw Finder is the greatest outside dimension the blade must clear along the proposed cut—not the diameter printed on the saw, the desired slice thickness or the hollow space inside a geode. For an irregular nodule, include the highest protrusion along the proposed cut; a measurement through a convenient narrow end can give a misleading result.

Create a second sketch for the support or vise. Ask where the jaws contact the rock, how far the carriage must travel and whether the entire cut can remain supported. When a dimension or arrangement is uncertain, send the sketch to the manufacturer. A photograph communicates awkward shapes better than a description such as “fist-sized.”

Build a useful comparison worksheet

For each candidate, record the model number, approved blade diameter, exposed height, manual wording, vise option and date checked. Leave unavailable measurements blank and request them. The aim is to remove uncertainty before ordering, rather than turn missing data into an optimistic estimate.

For example, suppose your usual blanks measure one inch high, but a single prized specimen measures four inches. Those are two different purchasing requirements. Compare the annual cost of having the exceptional specimen cut elsewhere against buying a machine around that one job. Our Saw Finder helps organize the recurring requirement first.

One relevant starting point

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Do not invent extra capacity

Do not assume rotating a too-large stone halfway through converts an undersized saw into a larger one. Our recommendations do not depend on that workaround. Similarly, a bigger replacement blade is not a capacity upgrade unless the machine manufacturer explicitly approves it.

Higher RPM does not create more blade exposure or workholding clearance. Speed compatibility belongs in the RPM guide and Blade Checker; stock height and fixture geometry remain separate gates. Capacity also does not describe every aspect of convenience. A machine can meet the dimensional requirement yet be an awkward purchase for your workflow.

Make the final purchase decision

Sort your planned work into three groups: comfortably within documented guidance, uncertain because of shape or support, and outside guidance. Buy for the first group, obtain written clarification for the second, and arrange a larger appropriate saw for the third. This prevents a favorable average size from hiding the difficult pieces.

Keep your measurements with the purchase record. If your interests later change from cabochon blanks to large display slices, repeat the worksheet before adding accessories. For setup and operation, use the current manual supplied with the exact machine; this comparison is a buying aid rather than an operating procedure.

Common questions about lapidary saw cutting capacity

Can a 10-inch lapidary saw cut a 10-inch rock?

No. The diameter includes the part below the table. Check the model’s documented material limit and workholding clearance.

Is exposed blade height the maximum recommended rock size?

Not necessarily. Some manuals specify a smaller working limit. Use the stricter instruction and ask the manufacturer to resolve conflicting specifications.

What should I measure before using the Saw Finder?

Measure the specimen in its intended cutting orientation and note how it will be held. Include irregular protrusions and the space needed by the support.

Why does the 4/5-inch saw page show more height than the conservative screen?

The current product page calls 1 and 1.5 inches maximum height, while the manual applies a two-thirds limit to those visible heights. This guide keeps both statements visible and uses the stricter manual-derived values for preliminary planning until the manufacturer resolves the wording for the exact unit.

Sources and documentation

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