Felt bobs can be used with an appropriate polishing or diamond compound on tool steel and hardened steel after the surface has been properly pre-finished. Felt should not be expected to remove deep machining or grinding damage efficiently. Keep the bob moving to control local heat and preserve geometry.
Felt can carry compounds for many metals, but the compound, density and pressure may differ. Do not reuse a contaminated bob across metals or compound grades where finish quality matters. Softer metals are especially vulnerable to embedded particles and unwanted scratches.
Felt and diamond-compound finishing may be part of a high-polish process, but an SPI-level result depends on the complete preparation sequence, steel quality, polishing environment and inspection method. Vardhman should publish such claims only when the exact tools and a validated polishing process support them.
No. Felt bobs are soft carriers designed for fine polishing, not heavy stock removal. Coarse cutter marks, chatter lines and deep scratches must be removed first using abrasive stones, emery papers or lap sticks before transitioning to felt polishing.
Felt bobs alone cannot cut through hard, brittle EDM recast layers. The heat-affected recast layer must first be stoned or abraded away with hard ceramic stones or diamond files before polishing with felt and diamond compound.
Conical or tapered felt bobs are ideal for reaching into draft angles, tapered cavities, bevelled edges, countersinks and narrow angled recesses in mould tools.
Cylindrical bobs are versatile tools used for polishing flat surfaces, outer radii, wide channels, large bore interiors and straight sidewalls.
Pointed or bullet-shaped bobs allow precise polishing in tight internal corners, small radii, intricate engraving, ribs and complex detail areas without rounding adjacent land faces.
A felt wheel provides a wider contact face for fast, uniform polishing on large flat plates, straight outer diameters or accessible contours, whereas a felt bob is designed for localized or recessed detail areas.
Hard, high-density felt maintains shape under pressure and provides crisp cutting action for pre-polishing. Soft, lower-density felt conforms easily to complex contours and yields a high-gloss finish during final polishing passes.
Use hard felt bobs with medium-to-coarse diamond compounds during initial polishing stages to maintain crisp geometry, flat edges and prevent rounding over sharp parting line corners.
Use softer felt bobs with fine micron diamond compounds for final high-luster or mirror polishing, where compliance and smooth blending over curved surfaces are required.
Operate felt bobs at moderate speeds (typically 5,000 to 15,000 RPM depending on head diameter). Excessive speeds generate heat, sling compound off the felt, and accelerate felt charring.
Over-speeding creates friction heat that breaks down diamond compound carriers, burns or glazes the felt surface, and can cause local thermal distortion or soft spots on critical mould surfaces.
Yes. Felt bobs act as a carrier substrate for abrasive particles. Using a dry felt bob without compound yields negligible cutting action and can burn the felt or scuff the workpiece surface.
Yes. Diamond compound (oil- or water-soluble) is the industry standard pairing with felt bobs for polishing hardened tool steels, carbide, stainless steel and precision mould inserts.
Besides diamond paste, felt bobs can be charged with aluminum oxide paste, silicon carbide compound, rouge, or chromium oxide bars depending on the metal substrate and desired finish.
Yes. Always assign a dedicated felt bob to a single grit size. Reusing a bob across different grit sizes carries coarse abrasive particles over to fine polishing steps, causing scratch marks.
Progress sequentially from coarse to fine micron grades (e.g., 15 micron → 9 micron → 6 micron → 3 micron → 1 micron). Clean the workpiece thoroughly between every grade change.
Apply light to moderate, uniform contact pressure. Let the abrasive compound perform the cutting action. Excessive pressure squashes the felt, generates heat, and wears out the bob prematurely.
Keep rotational speeds moderate, apply suitable lapping fluid or lubricant extender, maintain light pressure, and keep the felt bob moving continuously across the surface.
Dwelling in one spot creates localized hollows, dips, orange-peel texture or heat damage. Continuous figure-eight or overlapping passes ensure an even, uniform surface finish.
Yes. Lapping fluid or lubricant fluid dilutes the diamond paste evenly, improves cutting efficiency, prevents felt clogging, and dissipates frictional heat.
Wipe the surface completely clean using solvent (like alcohol or degreaser) and a lint-free wipe to eliminate all residual coarse abrasive grains before switching to a finer felt bob.
Glazed or dirty felt bobs can be lightly dressed or cleaned with a clean stone, card, or solvent wipe to remove excess dried paste and expose fresh felt fibers.
Store felt bobs in clean, sealed plastic bags or labeled drawer compartments sorted by grit grade to shield them from airborne dust, shop grit and moisture contamination.
Always wear safety glasses or a face shield to guard against flying compound or debris, use dust extraction or mask protection, and ensure handpiece collets are fully tightened.
Verify that the shank overhang is minimal, the collet fits snugly, the felt is firmly bonded to the shank, the tool speed is set correctly, and the workpiece is securely clamped.
