WEAPON OF CHOICE

With its roots in forestry and agriculture, paintball has evolved from a means to mark trees and cattle to an organized team sport played by millions of people in more than 60 countries worldwide. Players now compete in paintball tournaments where $10K-plus purses are common. As the sport has evolved, so too has the equipment. Manufacturers now specialize in the production of aftermarket parts for high-performance paintball guns ¡V called "markers" by those who play the game.

One such equipment manufacturer is Mesa Custom Machining Corporation, which is better known as Custom Products or CP to paintball aficionados. Mesa Custom Machining owner Dale Carpenter has always had his own products to sell, along with machine time. Under the Custom Products banner, Carpenter has enjoyed great success with performance go-cart parts and high-tech yo-yos. In the last decade, Custom Products has become a "big gun" in the world of paintball, employing 30 people at its 15,000 sq ft facility.

CP uses a Sunnen SV-1000 Series vertical honing machine to create a competitive advantage on and off the paintball playing field, producing one and two-piece marker barrels made to precise specifications for pro-level paintball players.

The surface finish and diameter of a paintball marker barrel are key components in its performance, as are the barrel's straightness and roundness, according to Carpenter. Shooters want the paintball to fit as perfectly as possible down the entire length of the bore. However, paintballs are non-uniform due to their composition – essentially a large, round "gel capsule" filled with paint.

"Paintballs are somewhat 'squishy' and their dimensions can vary based on atmospheric conditions, such as temperature and humidity," says Carpenter. "This, in turn, affects how the ball travels through the barrel, so tournament players compensate by having multiple barrels, each with a few thousandths of an inch difference in diameter."

Tournament-level players may have 8 to 10 different barrels to accommodate inconsistencies in the dimensions of their ammunition. That's where the SV-1000 honing system has earned a reputation as the weapon of choice for quick production of single pieces or lots of hundreds. CP manufactures one-piece and two-piece barrels in five diameters – 0.682 in, 0.685 in, 0.689 in, 0.693 in and 0.696 in – to fit the various makes of paintball markers.

While one-piece and two-piece barrels are almost equal in performance, the advantage of a two-piece barrel is that the ball is only in contact with the barrel for the first 5.5 in, known as the control bore, resulting in less total friction and less use of valuable compressed air. Sometimes the difference in winning and losing a tournament is the last 20 or so shots. Less air per shot equals more shots and a greater chance for victory.

"With the different bore sizes and barrel lengths for the various makes of markers, we have more than 1000 different part numbers for barrels available from our inventory," notes Carpenter. While CP typically produces lots of several hundred barrels, the CNC hone gives it the flexibility to provide quick turnaround and meet customer needs.

"Quick shipping is a big issue for us," adds Carpenter. "The CNC honing system lets us knock out a special barrel in minutes if we have to. We save a program for every part by name, length, and bore size. If we get an order for a part that we don't have on the shelf and we need right away, we can drop an un-honed part into the machine and in a couple of minutes I've got one ready to go. I can have it polished, sent out for overnight anodizing and out the door the next day."

The success of CP in manufacturing precision aftermarket paintball marker barrels did not happen overnight. "We started with only 12 in barrels, and they go to 16 in," explains Carpenter. "Initially, we struggled to get the bore size and finish produced on a consistent basis. I never realized how much science is in this."

CP uses a Citizen screw machine to manufacture blank barrels, starting with precision tubing at 1 in OD. The tubing is extruded using dies Carpenter had made to order. The Citizen does all the outside work from porting to cut off. It goes from there to the hone. "The bore is already true, concentric, round to the OD," states Carpenter. "It's just not dead accurate dimensionally and the hone brings it out to size in one shot."

Prior to the CNC hone, CP had four employees on dayshift and two on nightshift running manual hones. Now there is one operator on the CNC hone and one employee doing hand polishing, and the two produce more parts per day in a single shift than six did before – approximately 250 barrels.

Initially, Carpenter looked into broaching and drilling options to produce final bore size, before settling on honing. "I spent thousands with engineers who said they could drill this part," recalls Carpenter. "We would drill a 16 in barrel on an HMC, and get a good one, but the next one would not be concentric with the OD. We also tried working with just one size of tubing using broaching, but we just could not get the dead-on accuracy we wanted." Honing was determined to be the best option to consistently produce precision bore size, but productivity and flexibility were issues.

Carpenter went to Sunnen with his requirements for cycle time, production volume and part accuracy and charged it with developing a solution. "We told them we wanted as many parts as possible processed in one loading cycle," says Carpenter. They came back with an idea for a five-position rotary table, and together with CP developed the best way to fixture the part without distorting it.

The operator loads five parts per cycle via a clip-in-place arrangement suggested by Carpenter and developed by Sunnen. 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 cause distortion of the aluminum tube during honing. The table rotates under CNC control, five parts cycle under the spindle, they get honed and then the operator reloads.

Carpenter says he uses only a fraction of the SV-1000's accuracy potential, requiring only plus or minus 0.001 in accuracy in his parts, but gets the advantages of exceptional consistency, flexibility and productivity from the CNC machine. "This machine will produce parts all day that are accurate to plus or minus 0.000010 in, but this becomes moot when you have a hand polishing step after honing," he explains. "We hone our parts undersize by 0.0005 in to allow for some slight bit of metal removal in the polishing step. The metal-bond diamond MMT tool we use essentially does not wear on aluminum, so we rarely offset the tool. More important from a cost and productivity standpoint, this single MMT tool is capable of sizing the entire range of bore diameters we produce."

The added capacity of the CNC machine enables CP to supply barrels to paintball marker OEM's, retailers, and its own retail operation. In addition, the company has a traveling staff that attends paintball tournaments with a 53 ft Volvo tractor trailer conducting on-site sales of their barrels, regulators and other marker accessories. CP also sponsors several pro paintball teams, which helps increase brand awareness with the target market.

"We have very limited job shop work now," says Carpenter. "Our own product line takes most of our capacity. We have doubled our sales since 1996, with only a small percent of it now as job shop work." From selling high-tech yo-yos, to speed parts for go-carts to paintball marker barrels, Carpenter is always on the lookout for the next niche to fill . . . and his next big idea.

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Mesa Custom Machining Corporation, 1640 W Sunrise Boulevard, Gilbert, AZ 85233, 480-497-8882, www.mesacustom.com.

Sunnen Products Company, 7910 Manchester Avenue, St. Louis, MO 63143, 314-781-2110, www.sunnen.com.