Machine Design

Plastic Bushings Help Routers Take the Plunge

Woodworking tools operate in harsh environments characterized by high shock loads and heat generation. Flying chips and sawdust can clog passages and prevent smooth operation. These were problems engineers at Porter-Cable Inc., Jackson, Tenn., had to overcome when designing a new 2-hp plunge router. They solved their problems with Garlock plastic bushings.

The router bit rides on two vertical shafts that project perpendicularly from the base. The 12-A motor runs at speeds from 10,000 to 23,000 rpm. A free-turning micrometer ring lets users fine-tune the bit depth to less than 1⁄128 in. for precise cuts. With this level of precision, the slightest unexpected friction between the shafts and router hinders performance. And despite an integrated dust-collection system that lifts dust from around the bit, flying chips and sawdust can still reduce efficiency.

Garlock MA plastic bushings combine wear resistance with an integral lip seal that keeps most solid particles out of the bushing/shaft interface. The bushings provide triple the wear resistance of previous bronze units in similar service. High-impact resistance lets MA bushings withstand severe shock loads without cracking or suffering permanent deformation. Under ASTM test procedures, the bushings withstand five times greater impact loading than standard nylon bearings. Also, power losses in operation are minimal and heat generation is low because of a low friction coefficient.

Randy Cooper, senior designer at Porter-Cable, chose the bushings for their low cost, ruggedness, and the integral seal. “We use a different bushing on another tool we manufacture and have to add a separate lip seal,” says Cooper. “With the plunge router, there’s one less part to assemble and the bushing adds reliability because the tool operates in a cleaner environment.”

“The router delivers a new level of speed, precision, and ease to end-users,” says Woodworking Products Manager Mike Whitman. “It works superbly in free-hand applications as well as table-mounted projects.”

This information supplied by Garlock Bearings, Thorofare, N.J.
For more information, Circle 622.

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.