September 28, 2006

Polished Finishes on Stainless Steel

The most popular finish in stainless steel fabrication is the No 4 finish--the easiest to maintain and one with a nice surface appearance. A No 4 surface is produced by cutting the surface with coated abrasive belts to remove a very small amount of metal without affecting its thickness. Because it is directional, it allows for easy matching of surfaces. The "official" definition of a No 4 finish is "a linearly textured finish that is produced with mechanical polishing. The average surface roughness (Ra) may generally be up to 25 micro-inches (0.64 micrometeres)."

The Specialty Steel Industry of North America has set guidelines for polished finishes on stainless:

No 3: An intermediate polished surface obtained by finishing with a 100 grit abrasive. Generally used where a semi finished polished surface is required. A No 3 usually receives additional polishing during fabrication.

No 4: A polished surface obtained by finishing with a 120-150 grit abrasive, following initial grinding with coarser abrasives. This is a general purpose bright finish with a visible "grain" which prevents mirror reflection.

With the introduction in recent years of non-woven abrasives, many fabricators are also using a medium non-woven belt to achieve the No 4 finish. If you have other questions regarding finishing stainless, please feel free to call Abrasive Resource at 800-814-7358, or visit us online at:

September 14, 2006

Sanding Backing Pad

A quality disc sander back-up pad should have:

1. A specially designed, environmentally friendly, molded polyurethane foam, that dampens vibration to prevent your tool from bouncing, yet is flexible and tough enough to withstand the rigorous operation of dual-action random orbit sanders. A permanent bond between the polyurethane and other components of the pad eliminates separation problems.

2. A rugged thermoset fiberglass epoxy backing, that withstands the abuse of heat, flexing and impact, to keep the pad running flat and true for a long time. Aluminum backings bend from impact and lose their flatness, while heat and flexing cause molded plastic backings to warp, distorting the face of the pad. A pad that is not flat causes vibration--which fatigues the user and compromises your finish.

3. Full 1/2" diameter vacuum holes that match the industry standard in sanding discs and allow maximum performance of your tool's vacuum system.

4. A durable welded and plated stud assembly. Welding assures a permanent alignment between the pad and the tool. Plating assures easy pad removal by preventing corrosion.

5. A stud assembly that is rigidly attached to the backing with four rivets. Stud assemblies that are molded in place can loosen and strip causing poor performance and difficulties when removing the pad from the tool. A large, flat, raised steel washer with a four rivet attachment forms an ideal distributor of stress. This assures perfect alignment with all tools, and allows the pad to remain in service for a long time.

6. An embossed vinyl facing or hook facing that is intimately molded with the polyurethane to create a permanent durable and flat surface. Embossed vinyl facings offer maximum adhesion with PSA style paper while operating the tool, yet allow quick and easy replacement. Quality hook facings also offer secure adhesion yet quick and easy removal.

7. Strict tolerance on weight, balance, roundness, and flatness. A pad that is not the correct weight, out of round, out of balance, or not flat causes vibrations which fatigue the user and prevent creating a professional finish. Strict tolerances assure you that each pad performs consistently for a long time.

Abrasive Resource carries back-up pads in stock for same day shipping in both the embossed vinyl facing for PSA or the hook facing for hook-n-loop discs. Check out our website at:

Basic Sanders

The basic styles of portable sanders haven’t changed very much over the years. We have some old advertising posters from the Rockwell Manuf...