Description
Deep cylinder porting and confined metal die deburring require extra reach unreachable by standard compact tools. The Dynabrade Inc 0.7HP 20000 RPM straight-line extension air die grinder enters long tubular channels to smooth weld seams. Precision machinists gain steady high-speed abrasive rotation, but extended spindle whip will cause violent tool chatter if burr shanks exhibit excessive runout.
The extended drive system houses an alloy steel extension shaft supported by double-shielded precision ball bearings inside an aluminum housing. The motor wet-end features four phenolic composite rotor vanes turning within a ductile iron cylinder. Case-hardened rotor journals resist torsional deflection under high side-loads. The rear exhaust deflector houses an integrated sintered bronze muffler that reduces air noise without creating high backpressure that slows motor RPM.
Field Hardware Performance Matrix
Aerospace and die-mold finishing operations require extended pneumatic grinders that deliver high rotational speed without spindle deflection. The hardware points below demonstrate the precision engineering inside this extended straight-line grinder.
- 0.7 horsepower air motor maintains high torque under sustained abrasive contact pressure
- 20000 RPM free speed finishes weld seams and deburrs deep casting pockets fast
- Extension housing provides extended reach into narrow pipe bores and structural fabrications
- Precision 1/4-inch collet assembly minimizes burr runout to prevent dangerous spindle chatter
- Phenolic composite rotor vanes maintain dynamic chamber seal with low air consumption
- Safety lockout throttle lever prevents accidental motor starts when placing the tool on steel benches
- Rear exhaust deflector vents cold expanded air away from the operator and work surface
Dyno Bench Load Telemetry
Dyno pull testing confirms 20000 RPM free speed that drops to 14200 RPM under aggressive carbide burr load. The pneumatic motor draws 34 CFM at 90 PSI dynamic under full grinding stall. Connecting through a 50-foot 3/8-inch air hose creates a 14 PSI dynamic pressure drop. Adiabatic expansion plunges rear exhaust temperatures to 25°F, causing frost formation across the muffler element. Sound levels measure 82 dBA.
Field Service Operational Directives
Side-loading an unrated, bent carbide burr at 20000 RPM will snap the extension spindle neck. Do not hook this high-demand 0.7 HP motor to small portable 120-volt air compressors. Inadequate airflow drops grinding speed and overheats the motor cylinder. Precision metal fab shops must enforce these routine maintenance directives.
- Inject four drops of ISO VG 32 air tool oil into the air inlet before every four-hour run
- Check collet tightness using matching factory wrenches to prevent high-speed burr slippage
- Clean out the sintered bronze exhaust muffler with clean solvent if oil residue builds up
Commercial Warranty Package Inventory
Dynabrade backs this industrial extension grinder with a 1-Year limited warranty against flaws in materials and assembly workmanship. The unboxing package contains the 0.7 HP extension die grinder, a 1/4-inch precision collet, dual collet wrenches, and a detailed operational guide with an exploded drive breakdown.