COMPRESSION SPRING TENSIONER FOR THE BLADE OF PORTABLE ELECTRIC BAND SAW

• US 3,829,970 A
• Filed: 09/20/1973
• Issued: 08/20/1974
• Est. Priority Date: 09/20/1973
• Status: Expired due to Term

• Current Assignee: Martin P. Anderson
• Original Assignee: Martin P. Anderson
• Inventors: Anderson, Martin P.
• Primary Examiner(s): Smith, Al Lawrence
• Assistant Examiner(s): Ramsey, K. J.
• Application Number:
  US05/399,264
• Time in Patent Office: 334 Days
• Field of Search: 30/380,274 83/818
• US Class Current: 30/380
• CPC Class Codes: B23D 55/10 of devices for tensioning strap saw blades B23D55/06 takes precedence; incorporated in the strap B23D61/12

Abstract

A compression spring tensioner for the blade of a portable electric band saw has a rotatable blade release lever which upon rotation causes a release shaft with an eccentric crank pin bearing to move a blade tension bar which acting through compression spring means and a spring anchor bar causes the front pulley guard and the front idler pulley to slide. As this unit is slid forward, the blade becomes fully tight and the guard and pulley cannot move further forward. However further rotation of the blade release shaft forces the blade tension bar to compress the compression spring means to apply an accurate predetermined tension to the band saw blade. Furthermore, the eccentric crank pin bearing operates in an overcenter relationship to the blade tension bar to provide a positive means of holding the rotatable blade release lever against a fixed stop to assure that the accurate preload on the band saw blade is maintained under all conditions during usage of the saw.

Claims

1. A compression spring tensioner for the blade of a portable band saw comprising:

a. a main housing;

b. a unit consisting of a front idler pulley and pulley guard slidably mounted with respect to said main housing;

c. a blade tensioning member slidably movable relative to said unit, said member having a bearing slot;

d. an anchor member secured to said unit;

e. compression spring means reacting between said blade tensioning member and said anchor member; and

f. an eccenTric means for moving said blade tensioning member, said means having a rotatable shaft with an eccentric crank slidable in said slot.

2. A compression spring tensioner for the blade of a portable band saw as defined in claim 1 wherein:

a. said main housing includes a forward extension; and

b. said unit is slidably mounted on said extension.

3. A compression spring tensioner for the blade of a portable band saw as defined in claim 2 wherein:

a. said rotatable shaft is mounted in said forward extension; and

b. there is blade release lever on the upper end of said rotatable shaft outside said forward extension.