Metal Polishing for Bluing: Files, Foredom & Belt Sander Techniques | OTGS Ep. 28

Most gunsmiths ruin a finish before they ever touch the bluing tank — bad polish, wrong direction, rounded edges. Watch Master Gunsmith Ken Brooks break down exactly how he preps metal for bluing using files, sandpaper, a Foredom tool, and a 1-inch belt sander, and why each one gets used in the right situation. In this episode of Over the Gunsmith's Shoulder, Master Gunsmith Ken Brooks walks through his complete metal polishing workflow — the same process he uses daily in the shop. ✅ Using a flat file as a rigid backing for sandpaper to maintain flat surfaces ✅ Grit progression for metal prep: 80, 100, 120, 320, 400 grit ✅ Why sanding direction matters and how crosshatching doubles your work ✅ Keeping edges crisp and sharp — not rounded over ✅ Identifying low spots, hammer marks, and rust pits during polish ✅ Using the Foredom rotary tool with sandpaper for curved and contoured surfaces ✅ Adjusting sandpaper radius on the Foredom to match the contour of trigger guards ✅ Avoiding the washboard effect when using a rotary tool on metal ✅ Using the 1-inch belt sander for floor plates and large flat surfaces ✅ Why a hard backing cuts flat when rubber backing just follows the waves ✅ Polishing the inside of trigger guards (Winchester 94, Mauser, Savage 99) ✅ Spinning a barrel on the belt or a lathe for polishing magazine tubes ✅ Knowing when power tools are appropriate vs. hand polishing only This is the kind of practical, real-world gunsmithing you only learn by watching a pro do it. No fluff — just hands-on skill. 🔧 Want to learn real gunsmithing from certified professionals? 👉 https://americangunsmithinginstitute.... Whether you're a hobbyist, a gun owner, or ready to train as a certified professional gunsmith, AGI has the courses to get you there. 🔔 Like and Subscribe so you never miss an episode of Over the Gunsmith's Shoulder. Common Questions Answered in This Episode Q: How do you polish metal for bluing without rounding off the edges? A: Ken uses a flat file as a rigid backing under the sandpaper — not rubber, not wood. Because the file is stiff, it bridges low spots and keeps the surface flat while leaving edges crisp and sharp. Rubber backing follows the contours of the metal and rounds everything over. Q: What grit sandpaper do you use for metal prep before bluing? A: Ken works through grits progressively: starting with a file to remove heavy material, then 80, 100, 120 grit to cut down the surface, stepping to 320, 400, and 500 depending on the final finish required. Each grit needs to remove the scratches from the previous one before you move on. Q: Why does sanding direction matter so much in metal prep? A: If you sand in two different directions, you create a crosshatch pattern that must be completely removed before moving to a finer grit — essentially doubling your work. Ken sands in one consistent direction, in line with the barrel or part length, and doesn't change direction partway through a grit. Q: How do you polish trigger guards and curved gun parts? A: Ken uses the Foredom rotary tool with sandpaper wrapped around the shaft. You can add or remove sandpaper to change the radius so it matches the contour you're polishing. Keep the tool moving constantly — stopping in one spot creates a groove. Control your speed to prevent the washboard effect. Q: How do you get a floor plate perfectly flat for bluing? A: Floor plates are almost always warped — stamped, dropped, bent. Ken uses the 1-inch belt sander with a firm, flat backing plate. The rigid surface cuts across the high spots uniformly and flattens the whole plate to one facet. Rubber-backed sanding would just follow the waves and leave you with the same unevenness. #Gunsmithing #MetalPolishing #GunBluing #AGI #AmericanGunsmithingInstitute #OverTheGunsmithsShoulder #GunRepair #FirearmsTraining #MasterGunsmith #MetalPrep #ForedomTool #BeltSander #GunFinishing #KenBrooks #GunsmithingTips #BluingPrep #TriggerGuard #FloorPlate #SandpaperTechniques #GunMaintenance Chapters 00:00 — Cold Open: Polishing the Trigger Guard Area 00:45 — Gene Kelly Intro 01:20 — Ken at the Vise: Tools Overview 01:51 — File as a Sandpaper Backing: Why It Works 02:31 — Demonstrating the File-Backed Sandpaper Method 03:51 — Grit Progression: 80, 100, 120, 320 Grit 04:00 — Avoiding Crosshatch Sanding Marks 05:00 — Maintaining Flat, Crisp Edges 05:54 — Identifying Low Spots and Hammer Marks 06:40 — Moving to the Foredom Tool for Curved Surfaces 07:36 — Foredom + Sandpaper for Trigger Guards 08:26 — Adjusting Sandpaper Radius to Match Contour 09:52 — Polishing Inside Curved Recesses 11:04 — When to Use Power vs. Hand Polish 11:56 — 1-Inch Belt Sander for Floor Plates 12:47 — Why Rigid Backing Beats Rubber Backing 14:47 — Demonstrating the Belt Sander on a Mauser Floor Plate 15:18 — Reading the Surface After Belt Sanding 16:41 — Polishing Barrels on a Lathe 17:36 — Anecdote: The Bluer Who Sent It Back Wrong 18:27 — Wrap-Up and Techniques Summary