Paintball guns originated in the forestry and agriculture industries as a means of marking trees and cattle. Today, they are part of an organized team sport played by millions of people in countries worldwide.
As the paintball sport evolved, so too has the equipment and the business of manufacturing aftermarket components for highperformance paintball guns, called “markers” by those who play the game. One such component that is always in high demand is marker barrels.
Tournament paintball players often have 8 to 10 different barrels to compensate for inconsistencies in the dimensions of their ammunition and for atmospheric conditions such as temperature and humidity.
The surface finish and diameter of a marker barrel are key factors in its performance, as are its straightness and roundness.
Mesa Custom Machining, better known as Custom Products or CP (www.customproducts.us) to paintball aficionados, manufactures one and twopiece marker barrels to precise specifications for prolevel players.
The shop runs about 1,000 different part numbers for barrels available from its inventory, and quick barrel turnaround to meet customer demand is critical to the company’s success.
To meet customer demand and barrel surface finish and bore size requirements, CP relies on an SV-1000 Series vertical honing machine from Sunnen Products Co. (www.sunnen.com).
The machine lets CP knock out a special barrel in minutes if it has to. The shop saves a program for every part by name, length and bore size, and if an order comes in for a part not on the shelves, the shop loads an un-honed barrel into the SV-1000, hones it within minutes, polishes it, sends it out for anodizing, and ships it the next day.
CP manufactures blank barrels out of 1-in.-diameter precision extruded tubing on a Citizen screw machine that does all the outside work from porting to cut off. From there blanks move to the honing machine.
“The bore is already true, concentric, and round to the O.D. It’s just not dead accurate dimensionally, and the hone brings it out to size in one shot,” Dale Carpenter, owner of Mesa Custom Machining, said.
Prior to the CNC hone, four CP employees on dayshift and 2 on nightshift ran bores on manual hones. Now, one operator runs the CNC hone and one does hand polishing. Between the two, they produce more parts per day in one shift than the six employees did — approximately 250 barrels.
“We told Sunnen we wanted as many parts as possible processed in one loading cycle,” Carpenter said. Sunnen suggested a five-position CNC rotary table, and together with CP, Sunnen developed the best way to fixture parts without distorting them.
The operator loads five parts per cycle via a clip-in-place arrangement. A steel collar is threaded onto the barrel, dropped into the fixture and locked in place. Fixturing the collar prevents any tension or pressure that would distort the aluminum barrel during honing.
According to Carpenter, his shop uses only a fraction of the SV-1000’s accuracy potential, requiring only +/- 0.001-in. accuracy in his parts. But he benefits from the machine’s exceptional consistency, flexibility and productivity.
“This machine will produce parts all day that are accurate to +/- 0.000010 in., but that’s moot when you have a hand polishing step after honing. We hone our parts undersize by 0.0005 in. to allow for slight material removal in the polishing step,” Carpenter said.
He also said that Sunnen’s metal-bond diamond MMT tool he uses essentially does not wear on aluminum, so the shop rarely has to offset the tool. More importantly from a cost and productivity standpoint, one MMT tool can size the shop’s entire range of bore diameters.
