Brushing away burrs: Trade Shows & Events

Burrs on machined metal parts come in a variety of shapes and sizes but have one thing in common: They must be removed.

JR Precision & Welding LLC generates light, medium and heavy burrs when machining 4140 steel muzzle brakes. Removing the burrs is challenging, said James Mawazeb, director of operations and lead engineer at the Houston-based machine shop, which was founded in 2017.

A muzzle brake, or compensator, is a device connected to the barrel of a rifle or pistol to help control recoil and the rising of the barrel that normally occurs after firing. Muzzle brakes utilize slots, vents, holes, baffles or similar features to redirect a portion of propellant gases to counter recoil. Burrs form on the oval-shaped gas ports of parts.

Mawazeb said the shop initially took additional passes with the cutting tools that had been used to machine the parts.

“It never helped us remove any of the burrs,” he said.

JR Precision & Welding next sought whether another company could deburr the parts with aluminum-oxide sandblasting or even glass beads, but the processes proved ineffective, Mawazeb said.

A 4140 steel muzzle brake is shown before and after deburring. image courtesy of JR Precision & Welding

Manually deburring light burrs with a hook-shaped deburring tool and removing large burrs with a Dremel rotary power tool outfitted with a sander were effective but inefficient methods.

“We pumped out 500 parts within about 10 days,” Mawazeb said, “and it took us an extra six days just to deburr all those parts. Even after we got done with deburring them, I still had to make sure every part was right. A lot of people consider me a stickler for that, but if you are going to put your name on a product, you have to make sure it’s right.”

He defined a light burr as one that can be removed with a thumbnail and said large burrs can’t be. The largest burrs the shop sees are about 3.175 mm (0.125″) high.

Adding to the challenge was that the bar stock JR Precision & Welding previously machined was from a supplier that sold only heat-treated 4140 steel bars, Mawazeb said. The shop eventually switched to a supplier of annealed stock, which is easier to machine and deburr.

For a solution, JR Precision & Welding turned to Houston-based tool distributor Bass Tool & Supply Inc., which suggested testing an abrasive brush with filaments angled down. He said results were unimpressive.