Planer knife adjustment jig

A jig is provided for aligning the cutting depth of knife blades on a cylindrical rotary cutter head of a rotary planar machine. The jig has a tripod support adapted for spacing the jig radially over the cutter head. An indexing member circumferentially positions the jig with two radially adjustable knife adjustment members aligned longitudinally and radially over a knife blade. In use, the jig can be calibrated over a knife blade so that the knife blade can be removed and a replacement knife blade installed with the same radial projection along the longitudinal extend of the cutter head. Alternatively, or in addition, each of a plurality of knife blades of a cutter head can be set to the same longitudinal radial projection.

FIELD OF THE INVENTION

This invention relates to jigs and adjustment tools for setting cutting edges at a uniform cutting depth on cylindrically shaped rotary cutter heads. More particularly, this invention is related to an apparatus for aligning knife blades on woodworking rotary planers.

BACKGROUND

In the wood working industry and the like, it is a common practice to align the cutting edges of knives on planers to the knife cutter head. The cutter heads, cylindrical in shape are of various diameters, dependent on the manufacturer. Each cutter head has multiple knife blades, each knife blade aligned to the same cutting depth from the surface of the cutter head. A misaligned knife blade, one that is of a shallower cutting depth from the surface of the cutter head may do all the cutting (because its cutting edge is higher than the other cutting edges) and one that is of a deeper cutting depth from the surface may not do any cutting at all (because its cutting edge does not contact with the surface to be planed). In either event, there results in poor quality planed surfaces and uneven knife wear necessitating more frequent replacement of the cutting knives.

Further, as the cutter heads rotate at high revolutions per minute, any shift in the balance of the cylindrical cutter head may pose a danger to an operator. Correctly positioned knives provide better balance and do not create unnecessary and dangerous conditions for an operator. The smooth rotation of the cylindrical cutter head also ensures a smooth planed surface and uniform knife wear.

The cutting knives are also removed periodically for maintenance, including sharpening, and for replacement of worn cutting knives. The reinstallation of the cutting knives after maintenance or replacement is time intensive in that it is important to correctly align all cutting knives to the same cutting depth. The physical shape of the cutter head, being cylindrical, make such procedures difficult and time consuming.

U.S. Pat. No. 5,020,228 to Hessenthaler (Jun. 4, 1991) teaches a jig for aligning cutter blades to a cutter head comprising a magnetic bar adjustably suspended over a knife blade, set by screws, supported by a pair of arcuate members at substantially opposing ends of the magnetic bar. The arcuate members are pivotally supported by substantially parallel base bars that rest on the rotors. The Hessenthaler jig can be used with a variety of rotors of varying diameters due to the pivotally supported arcuate members. However, there is no mechanism to align the jig with the knife blade consistently and the base support bars do not allow for height adjustability of the jig itself.

U.S. Pat. No. 1,653,048 to Kelly (Oct. 1, 1925) teaches an arcuate jig gauge that rests on top of a rotor. It has an adjustable element that aligns on top of a knife blade and is height adjustable. However, '048 to Kelly does not teach the height adjustability to aid in positioning the jig over a knife blade, but rather to avoid debris that may be on the surface of the rotor. Further, this technology is not accommodating of varying diameters of a rotor.

U.S. Pat. No. 4,519,142 to Parker (May 28, 1985) discloses a blade height calibration device. It comprises a base member, a vertical support member and an arcuate head having an adjustable set screw. A cutter head is placed within the device, and a portion of the arcuate head rests on the cutter head, forming a space to accommodate a knife blade. This technology teaches a point of contact with the rotor by way of the vertical support member and a portion of the arcuate head. Disadvantageously, '142 to Parker cannot accommodate rotors or varying diameters, as the vertical member is in a fixed position and of a fixed size.

U.S. Pat. No. 2,496,800 to Larkins (Nov. 5, 1947) discloses a pair of apparatus that are placed at each opposing ends of a cutter head. Each apparatus disclosed is individually manipulated and supported independently on the cutter head by a member, having a cavity therein to accommodate the knife blade. The height of the member is not adjustable, and the position of the apparatus cannot be consistently aligned respecting the position of the knife blade.

Therefore, there is a need for a jig or adjustment tool that allows for quick, easy, and simple alignment of cutting knives on a planar cutting head that is height adjustable. Further the jig would permit reproducible alignment of the knife blades position relative to the rotary cutter head.

There is also a need for an adjustment jig that is capable of reproducing a consistent alignment for each knife blade on a rotary cutter head and for reproducing a consistent alignment of all the knife blades on a rotary cutter head.

There is also a need for a jig or adjustment tool that is universal for use on most available rotary cutter heads.

SUMMARY OF THE INVENTION

Embodiments of the invention provide a universal adjustment jig for aligning the cutting depth of knife blades on a cylindrical rotary cutter head. The jig is adapted to fit cutter heads of various diameters and allows for the height adjustment of the knife blades in relation to the cutter head and consistent adjustment relative to each knife blade on the same cutter head. Adjustable indexing members provide for consistent lateral alignment respecting the position of the knife blades.

A tripod jig for the adjustment of knife blades on a rotary cutter head, comprises two adjustable clearance members for alignment of the cutting depth of the knife blades.

In a broad aspect of the invention, a jig for setting the radial projection of a knife blade extending radially from a rotary cutter head of a rotary planer, the rotary cutter head having a longitudinal axis, the jig comprises an elongate body having a longitudinal axis, three clearance members extending from below the body and adapted for engaging the cutter head to provide a stable tripod support spaced radially, indexing members extending from below the body and adapted for engaging the rotary cutter head at two points of contact substantially spaced apart, for orienting the axis of the body along the longitudinal axis of the cutter head and two knife elevation adjustment members spaced along the axis of the body and radially adjustable below the body wherein the indexing members orients the two knife elevation adjustment members radially over the knife blade and the two knife elevation adjustment members are radially adjusted so as to engage the knife blades for setting the radial projection of the knife blades.

In another broad aspect, the jig enables a method for providing consistent and repetitive adjustment of knife blades comprising positioning the jig with the clearance members engaging the rotary cutter head, adjusting the jig such that the at least one indexing member abuts against the knife assembly, and adjusting the knife elevations adjustment members to engage the knife blade.

Once the jig is calibrated for alignment of a cutting knife for a particular planar cutting head, the jig can accurately and consistently reproduce the alignment for every other knife blade on that particular rotary cutter head. Further, the jig is also accurate in consistently reproducing the same alignment after each repeated use of the particular rotary cutter head.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference toFIGS. 1 and 2, a typical prior art rotary planer, as shown in U.S. Pat. No. 7,100,649 to Liu, comprises a cutter head50arranged to project through a table101for planing materials such as wood. The cutter head50comprises a cylindrical rotor body102having a longitudinal axis103and one or more knife assemblies100, spaced circumferentially about the rotor body102. A typical knife assembly100comprises a knife blade51secured within the rotor body102for fixing the knife blade51with a specified radial projection longitudinally along the rotor body102. Biasing and jamming bolts58and plates57are provided to adjust and lock the knife blade's radial projection along the longitudinal axis103of the rotor body102.

As can be seen inFIG. 2, for knife blades51having a linear profile (a straight cutting edge), the radial projection of the knife blade51at a first longitudinal end104of the rotor body102can be more, the same, or less than the radial projection at a second longitudinal end105. If the longitudinal axis103of the cutter head50is parallel to the table101, then the rotary planer will plane material parallel to the table101. Further, if the knife blade or blades are not parallel to the table, or of one knife blade of two or more blades is adjusted differently than another, then operability is compromised.

Accordingly, with reference toFIGS. 3 and 4, in one embodiment of the invention, a planar knife adjustment jig10is provided for enabling consistent adjustment and setting of the radial projection of one or more of the knife blades51of the cutting-head50. One knife blade51can be set to a particular radial projection relative to the table101and two or more knife blades51,51. . . can be set to a consistent radial projection relative to each other.

More specifically, each knife assembly100of one or more knife assemblies comprises a cutting blade housed within an elongated, longitudinally extending knife well54, supported against and substantially parallel to a longitudinally extending retaining wall54b. Each knife blade51is biased substantially radially outwardly by springs52located in an elongated spring well53along the bottom of the knife well54. The knife blade51is circumferentially and positionally sandwiched against the retaining wall54bby a front face55of a knife locking bar57.

The knife locking bar57is forced into a knife locking position by jamming or knife locking screws58in the knife well54and acting between a back side56of the knife locking bar and the rotary body102. The knife locking bar57and knife locking screw58are located within the knife well54.

The jig10is adapted to be radially spaced and supported by the rotor body102for enabling adjustment of the knife blades51relative thereto. The jig10is fit with various means of adjustment which enables adjustment of the jig body11radially relative to the rotor body102and circumferentially relative to the knife blade51.

With reference also toFIGS. 4,5A and5B, the jig10comprises an elongated body11having a longitudinal axis A for alignment substantially parallel to the rotor body axis103. The jig's elongated body11has a leading edge12and a trailing edge13, with two lateral opposing ends14,15corresponding generally with the first and second longitudinal ends104,105of the rotor body102. A circumferentially protruding member16extends from the trailing edge13at an intermediate point between the opposing ends14,15such as a point equidistant therebetween.

Best seen inFIG. 3, one embodiment of the jig further comprises three radial clearance members20a,20b,20c, two circumferential indexing members30a,30b, and two knife radial adjustment screws40a,40b. The three clearance members20a,20b,20cextend substantially radially from the body11and provide three points of contact between the jig body11and the cutter head50. The first and second radial clearance points20a,20bare spaced from each other and substantially along axis A for longitudinal radial adjustment of the jig body11form the rotor body102. As shown inFIGS. 5A and 5B, the third clearance member20cis offset circumferentially and positioned intermediate therebetween. The first and second radial clearance member20a,20bcan be located in the opposing ends14,15of the body11respectively. The third clearance member20ccan be located in the protruding member16.

The three clearance member create a stable tripod support base for engaging the cutter head50and providing radial clearance between the jig10and the rotor body102.

The first and second clearance member20a,20bare adjustable for generally setting the jig's radial clearance at each of the first and second longitudinal ends104,105. Each clearance member20a,20bis individually adjustable relative to the jig body11, such as being threaded through the jig body11, accessible from a top surface17and extending through the body11to a bottom surface18. The clearance members20a,20bcan have comparable length which is sufficient to be accessible from the top surface17and extend below and beyond the bottom surface18of the jig10for engagement with the rotary cutter head50. Each clearance member20a,20bcan be graduated to allow the user to accurately adjust each member20a,20bso that the pins20a,20bmay provide radial height adjustment of the body11relative to the cutter head50. The clearance members20a,20bcan be similarly graduated to permit the radial clearance of the jig's body11at each of the ends104,105to be identical.

The third clearance member20cis not necessarily adjustable and therefore need not extend through to the top surface17of the jig but does extend sufficiently below the bottom surface18to provide a point contact with the rotor body50. The third clearance member is spaced sufficiently form the first and second clearance members to engage rotor body102circumferentially either side of the knife assembly100.

With reference toFIG. 6, an alternative embodiment shows the jig body with multiple placement locations30c,30c,30c,30c, for the indexing members. The multiple placement locations30c. . . allow the operator to change the placement of the indexing members30a,30bto adjust for the differences in the distance between the knife blade51and back side56of the knife locking bar57from various manufacturers.

The knife elevation adjustment screws40a,40bare spaced longitudinally and located adjacent the opposing lateral ends14,15and spaced circumferentially sufficiently from the clearance members20a,20bso that the clearance members can engage the rotor body102and the knife elevation adjustment screws40a,40bare positioned generally above the knife blade51.

In an alternative embodiment, the knife elevation adjustment screws40a,40b, may be magnetized to engage the knife blades51for use on rotary cutter heads that do not have springs52to radially outwardly bias the knife blade51.

At least one indexing member engages the rotary cutter head at two points of contact. In an embodiment, and, as shown inFIGS. 3,5A,5B, and6, two indexing members30a,30bare also positioned at about the opposing lateral ends14,15and spaced adjacent the trailing edge13of the body11spaced circumferentially sufficiently from the clearance members20a,20bto circumferentially straddle the knife elevation adjustment screws40a,40b. Each indexing member30a,30bis individually adjustable, such as being threaded through the jig body11, extending out of the top surface17and through the bottom surface18to engage a portion of the knife assembly100relative to the knife blade51. The indexing members30a,30bcontact the knife assembly100so that the knife elevation adjustment screws40a,40bare positioned radially over the knife blade51. The indexing members provide two circumferential points of reference, or points of contact, relative to the cutter head50.

In one embodiment shown inFIG. 3, the indexing members30a,30babut against the back side56of the knife locking bar57of the knife assembly100, providing two consistent lateral points of contact for alignment during radial height adjustment of the knife blade51.

The knife elevation adjustment screws40a,40bare located adjacent the opposing lateral ends14,15in between the clearance members20a,20band the indexing members30a,30brespectively. Each knife elevation adjustment screw40a,40bis graduated to ensure accurate cutting depth measurement by the operator. The screws40a,40bare of sufficient length to be assessable from above the top surface17of the jig10and extend below the bottom surface18. The top portion of each screw40a,40bcan be fit with a dial indicator41a,41bwhich aid in the relative indexing and individual adjustment of the screws40a,40b.

With reference again toFIG. 3, in one typical operation, an operator could set or calibrate the jig10to a selected knife blade51of one or more knife assemblies to simplify knife removal, sharpening and replacement task or to ensure consistency in the radial projection of each of a plurality of knife blades51. Both knife elevation screws40a,40bcan be backed off radially, such as until they are flush with the bottom surface18of the jig body11. The jig10is positioned over the cutter head50with clearance member20cproviding the trailing edge height adjustment. Indexing members30a,30bare adjusted as necessary to abut against the knife assembly100, such as the knife blade51itself or back side56of the knife locking bar57. The indexing members30a,30balign the longitudinal axis A of the body11along the axis103of the rotor body102. Using clearance members20a,20bthe operator adjusts the height of the leading edge12of the jig10such that the jig10is spaced from the knife50and generally parallel thereto. After height adjustment of the leading edge12, there should be three points of contact between the jig10and the rotary cutter head.

Ensuring that the spaced indexing members30a,30bare in firm and constant contact with the back side56of the knife locking bar57, the operator may adjust the knife elevation screws40a,40bsuch that the screws40a,40bare just touching the top portion of the knife blade51.

The jig is now calibrated to a selected knife blade and can be moved to each knife blade in turn to ensure consistency therebetween or for assisting with the removal and installation of replacement knife blades, in accordance to the manufacturer's instructions.

After a replacement knife blade51is installed or for another of a plurality of knife blades, the calibrated jig10is placed radially over the blade51. Ensuring that the indexing members30a,30bare firmly positioned against the back side56of the knife locking bar57, the knife blade51height within the cutter head50is manually adjusted such that the top of the knife blade51is in physical contact with the bottom of the knife adjustment screws40a,40b. This operation sets the cutting edge of the knife blade51to the same radial positioning as the earlier knife blade. If an old knife blade51, which is being replaced, was significantly worn, one may wish to set the new knife blade51with a slightly greater radial projection by adjusting both of the knife adjustment screws40a,40bradially outward a known amount from the calibrated position.

While maintaining the knife height adjustment, the operator would tighten the knife locking screw58to ensure sufficient force against the knife blade51to lock it in place and prevent it from being shifted during operation of the rotary planar.

The operation can be repeated for each replacement blade51in turn, removing and replacing a knife blade51with the calibrated jig10.

The previous operation sets the cutting edge of the replacement knife51to the same radial positioning as the old knife. If the old knife blade was significantly worn, one may wish to set the replacement knife blade51with a slightly greater radial projection by adjusting both of the knife adjustment screws40a,40ba known radial amount from the calibrated position.

Alternatively, if there was a concern about mis-aligned blades, a single calibration can be applied for a plurality of blades for a given rotor body102. Each knife blade51is thereby set to a consistent and same radial projection relative to the longitudinal position along the rotor body102.

In some rare occasions, a table101may be mis-aligned from the rotor axis103. Accordingly a blade51can be set with a varying radial projection along the rotor axis103so as to be aligned parallel to the mis-aligned table101. The jig10can then be used to set each knife blade51to a consistent and varying radial projection relative to the longitudinal position along the rotor body102.

For handling comfort by the user of the jig10, the leading edge12can be thicker at the leading edge12and becomes thinner approaching the trailing edge13, as shown inFIG. 3and with the optional profile of the body11shown inFIG. 6.

As shown inFIGS. 3 through 5B, the top surface17of the jig10has an optional concave region19which may be used as a finger rest when using the jig10.

Where the jig10is used repeatedly for the same rotary planer, the rotor body102and the knife assemblies100remain consistent and the two indexing members30aand30bwould be rarely altered once adjusted. Therefore, alternatively, the two indexing members30aand30bcould optionally comprise at least one indexing member which extends sufficiently along the jig body11to align the first and second clearance members20a,20bover the knife blade51. Such a clearance member could comprise one or more non-adjustable radial projections or a longitudinally extending bar.