Graston Tools CNC Machine: How to Make Them in 6 Steps

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  Key takeaways
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  What a Graston Tools CNC Machine Actually Has to Cut
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  Blank, Alloy, and Setup Choices That Decide the Result
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  Machining the Edge: Toolpaths, Tolerances, and Chatter Control
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  Polishing, Passivation, and Marking Without Rounding the Edge
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  Step by Step: From Drawing to Finished Instrument
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  Choosing Alloy, Machine, and Finish for IASTM Tools

Graston Technique is a patented form of instrument-assisted soft tissue mobilization. The instruments are stainless or titanium hand tools with a polished edge that a clinician drags across skin and muscle. The patent covers the method and the branded tool set, so most shops that ask how to make graston tools on a cnc machine are building a generic IASTM instrument for their own brand, not a licensed copy. That distinction matters for your drawing: you are free to design your own contour, but you should not copy a protected profile.

Every IASTM tool is two features and a lot of air. The handle carries grip and mechanical advantage, usually 12–20 mm thick with a rounded cross-section between 15 and 25 mm wide. The treatment edge is the working feature: a long, shallow curve that sweeps across the face of the tool and then rolls into a controlled radius. The middle of the tool is mostly clearance geometry. That means most of your machining time goes into two small regions, and most of your scrap risk lives in one of them.

The edge is where the money is. It is not a sharp corner and it is not a chamfer. It is a blended form: a generous sweep that lets the clinician load the tissue, followed by a radius that stays smooth in every direction of travel. If that radius varies along its length, the tool will grab in one spot and glide in another. Clinicians notice within one stroke.

So the real question behind how to make graston tools with a cnc machine is not how to remove metal. It is how to hold a continuous, repeatable blend on a compound curve. Everything below serves that goal.

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  Two critical zonesHandle ergonomics and the treatment edge blend. Everything else is clearance.
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  One protected zoneDo not copy a patented profile; design your own sweep and radius.
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  One process riskEdge radius consistency along the full sweep length.

Start with the alloy. Grade 5 titanium (TC4, Ti-6Al-4V) is the common pick for premium instruments: about 4.4 g/cm³, so a 200 mm tool stays light in the hand, and it resists chloride-based disinfectants. 316L stainless is the value option. It is denser and therefore heavier, but it machines more predictably, polishes to a mirror more easily, and costs less per blank. Both are stocked in our material list, along with 17-4PH if you need higher hardness.

For most IASTM instruments we recommend 316L for the first article and titanium once the geometry is frozen. The reason is iteration speed. Stainless cuts cleanly at higher feed rates, so a design change costs you hours, not days. Once the contour is signed off, move the same program to titanium and expect to reduce feed by roughly 30–40% and increase coolant pressure.

Leave 0.3–0.5 mm of stock on the treatment edge for finishing. If you machine the edge to final size in the roughing pass, the finishing cutter will have nothing to blend and you will chase the radius with a polisher. That never ends well. On a 4,000 mm machine envelope you can nest several tools per blank, but keep the edge direction consistent across the nest so your toolpath stays predictable.

Fixturing is the quiet failure point. These parts are long, thin, and easy to spring. A vise on the handle end with a support under the edge zone keeps deflection under control. If you hear the cutter change pitch as it passes the middle of the sweep, the part is moving. Stop and re-fixture.

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  316L firstFaster to iterate; switch to TC4 once the contour is frozen.
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  Stock allowanceLeave 0.3–0.5 mm on the edge for the finishing pass.
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  Support the sweepAny audible pitch change mid-pass means deflection, not a dull cutter.

The treatment edge is a compound curve. A 3-axis machine can reach it only by tilting the part several times, and each re-setup leaves a witness line exactly where the clinician's hand feels it. On a 5-axis machine the cutter stays normal to the surface through the whole sweep, so the blend is one continuous motion. This is the single strongest argument for putting these parts on a graston tools cnc machine with simultaneous 5-axis capability rather than a 3-axis mill.

Rough the profile with a Ø6–10 mm carbide end mill, leaving the 0.3–0.5 mm allowance. Then finish the edge with a Ø4–6 mm ball nose, stepover 0.05–0.1 mm, spindle 8,000–12,000 rpm in titanium and 12,000–16,000 rpm in 316L. Feed per tooth stays modest: 0.03–0.05 mm in titanium, 0.05–0.08 mm in stainless. You are not chasing cycle time here. You are chasing a surface that needs almost no hand work.

Tolerances on the edge zone should be ±0.025 mm or tighter. The rest of the tool can live at ±0.05 mm without anyone noticing. Write the print that way. Tightening the whole part to ±0.005 mm adds cost and buys nothing on the handle. We hold ±0.005 mm where it matters and inspect the edge zone specifically for radius consistency, not just for nominal size.

Chatter is the enemy. If the tool sings, the edge picks up a ripple you cannot polish out without changing the radius. Slow the spindle slightly, shorten the tool overhang, and check that the part is supported directly under the cut. A stable 5-axis pass at moderate speed beats a fast pass you have to rework.

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  Ball nose finishØ4–6 mm, stepover 0.05–0.1 mm, cutter normal to the surface.
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  Edge tolerance±0.025 mm on the edge zone; ±0.05 mm elsewhere is fine.
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  Chatter checkShorten overhang and support under the cut before touching speeds.

Machining leaves a surface around Ra 0.8–1.6 μm. That is a good starting point but not a finished instrument. The treatment edge should end up between Ra 0.2 and 0.8 μm: smooth enough to glide, not so polished that it loses the controlled bite that makes the tool work. Over-polishing is a real failure mode. It rounds the radius, and the tool stops doing its job.

Sequence matters. Deburr first with a fine abrasive, then polish the edge zone by hand or on a lapping fixture, keeping the motion along the sweep rather than across it. Crossing the sweep direction flattens the radius. Check under magnification as you go, not at the end. If you wait until the whole tool is bright, you have usually already taken too much off one section.

For stainless parts, passivate after polishing to restore the chromium oxide layer, especially if you used any iron-bearing abrasive. Titanium needs a separate finishing line and dedicated media to avoid cross-contamination. Bead blasting is fine on the handle for grip; keep it off the treatment edge.

Laser marking handles branding and traceability. Minimum character height is 1.5 mm, so plan the layout before you cut the pocket. Put the mark on the handle, away from the edge, and confirm the marking depth does not create a stress riser on a thin section. Anodizing and plating are available for color coding, but hardcoat on the working edge changes the geometry by a few micrometres. Account for it or mask it.

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  Stop at Ra 0.2–0.8 μmBeyond that the radius rounds and the tool loses bite.
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  Polish along the sweepCross-direction polishing flattens the radius.
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  Passivate stainlessRestore the oxide layer after any iron-bearing abrasive.
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  Mark on the handle1.5 mm minimum character height, away from the edge zone.