US3005294A - Honing devices - Google Patents

Description

W. P. KUSHMUK HONING DEVICES Oct. 24, 1961 2 Sheets-Sheet 1 Filed Aug. 29, 1958 INVENTOR. ZUalier 1? lus/zmak Oct. 24, 1961 w. P. KUSHMUK 3,005,294

HONING DEVICES Filed Aug. 29, 1958 2 Sheets-Sheet 2 AWL-MEL 6 INVENTOR.

BY 1% r- -a 9- W 3,005,204 HONING DEVICES Walter P. Kushmuk, Chicago, Ill., assignor to on Tools, Inc, North Chicago, BL, a corporation of 1111- nois Filed Aug. 29, 1958, Ser. No. 758,034 11 Claims. (Ci. 51-1842) This invention relates to a honing device for cylinders and it is an object of the invention to provide an improved device of this character.

In apparatus incorporating a cylinder with a piston movable therein, it is occasionally desirable that the walls of the cylinder be polished, all as is well recognized in the ant. Such polishing may or may not be preceded by reboring of the cylinder. A common example of such apparatus is the brake cylinders of automobiles and trucks. A honing device constructed in accordance with the present invention is well adapted to polishing of brake cylinders, and, in particular, lends itself to use by common garage mechanics. Such a honing device is, for example, inexpensive, such that it may readily be the personal tool of any garage mechanic. Also it becomes a complete working tool when employed with a small, hand type electric drill. Still further, it requires no special training for its proper use.

The device automatically adapts itself to a wide range of cylinder diameters, and is readily adjustable as to the pressure with which the cylinder wall polishing elements bear against the cylinder walls. Still further, the device is collapsible to the extent that it occupies a very small space in a mechanics tool chest when not in use.

Various specific structural details of the preferred embodiment of the invention, especially the use of only two honing elements, greatly simplify its manufacture and thereby make it much less expensive to manufacture than previously known devices of the same category. In the preferred embodiment of the invention the hone carriers may be replaced after extended use Without special tools and without danger of improper assembly.

Accordingly, it is another object of the invention to provide a honing device which is collapsible to a smaller diameter than previously known devices of the same category.

It is still another object of the invention to provide g n improved honing device which is extremely simple in its construction and is therefore economical to manufacture.

Another object of the invention is to provide an improved honing device having only two honing elements.

Still another object of the invention is to provide an improved honing device having a novel construction for connecting the hone carriers to the supporting arms which permits ready replacement of worn bones without special tools or danger of improper assembly.

it is a further object of the invention to provide an improved honing device having various of the characteristics specified above while being of rugged design and efiicient in use.

This invention, together with further objects and advantages thereof, will best be understood by reference to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the drawings, in which like parts are designated by like reference numerals:

FIGURE 1 is an elevational view of a honing device illustrating the preferred embodiment of the invention;

FIG. 2 is an end view of the same device;

FIG. 3 is a view similar to FIG. 1 but partially broken away and showing the honing device in a different position of adjustment;

3,005,294 Patented Oct. 24, 1961 ice FIG. 4 is a side elevation of an arm member included in the apparatus of FIGS. 1-3;

FIG. 5 is a bottom view of the arm of FIG. 4;

FIG. 6 is a left end view of the arms of FIGS. 4 and 5;

FIG. 7 is a cross-sectional view of a honing unit 1ncluded in the apparatus of FIGS. l3;

FIG. 8 is an enlarged partial view showing cooperation between the honing unit of FIG. 7 and the arm of FIGS. 4-6.

FIG. 9 is a perspective view showing a second form of honing unit; and

FIG. 10 is a reduced, fragmentary, sectional view showing the unit of FIG. 9 in place on the end of an aim.

The embodiment of the invention illustrated in the drawings has a shank 11 which is adapted to be readily received in the chuck of a drill or other suitable rotating device, and a drive stem 12 which is secured to the shank through a short section of conventional flexible shafting 13. Use of the latter is conventional in honing devices and accordingly it is not described in detail herein. Arranged on the drive stem 12 are a collar 14 which is freely slidable thereon, a knurled nut 15 engaging threads 16 on the drive stem, and a spring 17 which is compressible between the collar 14 and the knurled nut 15. Two arms 20 are pivot-ally secured to the drive stem 12 substantially in diametrical alignment by a pin 21, one of such arms 20* being shown in greater detail in FIGS. 4-6.

The ends of the arms 20* which are pinned to the drive stem 12 are channel shaped, each arm including channel legs or flanges 22 and a channel base or web 23. The flanges have aligned openings 24 for receiving the pin 21. As seen in FIGS. 1-3, these channel shaped portions of the two arms 20 open toward each other and the flanges thereof overlap such that the pin 21 may pass through all four openings 24 of the two pairs of flanges 22. This construction permits the arms 20 to pivot inwardly to substantially parallel positions as illustrated in FIG. 3.

As best seen in FIG. 4, the flanges 22 have inclined or bevelled inner end edges 25 such that the tips 26 of the flanges 22 extend beyond the web 23. Still further, the web 23 is cut away such that it terminates outwardly of the openings 24, that is, to the right of the openings, as viewed in FIG. 4. This abbreviation of the web 23 permits the arms 20 to pivot outwardly to a substantial angle without interference between the web and either the drive stem 12 or the edges of the flanges of the other arm.

With the arms 20 in the position shown in FIG. 3, it will be seen that if the spring 17 is under compression the collar 14 is made to bear against the tips 26 of the flanges by force of the spring 17. This urges the arms 20 to pivot outwardly toward the position of FIG. 1 with a force depending upon the position of adjustment of the nut 15. It will also be apparent that when the arms 20 reach the position of FIG. 1, the collar 14 bears against the bevelled edges 25 of the channel legs whereby further outward pivotal movement of the arms is arrested. In the preferred embodiment of the invention illustrated in the drawings the angle between the bevelled edges 25 and the general longitudinal axis of the corresponding arm is 50, as indicated in FIG. 4. This permits each arm to have a maximum angle of outward movement of 40". When the arms 20 are in their inward or substantially parallel positions, the spring 17 is at maximum compression, with a given setting of the knurled nut 15; but the torque arm, measured laterally from either-"of the tips 26 to the pin 21, is at a minimum. As the arms are permitted to pivot outwardly the spring 17 expands and thus exerts a lesser force but the above referred-to torque arm increases. These two factors tend to neutralize each other to the effect that the outward pressure at the ends of the arms 26 remains nearly constant. As may be seen in FIG. 2 the collar 14 has a sufficient outer diameter that it extends outwardly beyond the tips 26 of the arms in all operating postons of the arms.

Extending outwardly, or to the right as viewed in FIGS. 4 and 5, from the base 23 of each arm is a strip portion 23a. As is readily seen in FIG. 4, the strip portion 23:: has a double bend adjacent its juncture with the channel shaped portion such that the strip portions 23a of the two arms are offset toward each other and may come substantially into contact with each other when the arms pivot inwardly, as illustrated in FIG. 3. Such offsetting permits sufficient pivoting of the carriers,

.for self-alignment when the arms are in their inner positions throughout the range of movement of the arms. The free end of each strip portion 23a is bent outwardly as seen in FIG. 4 for a purpose hereinafter explained, and includes a pair of ears 30 extending laterally therefrom on which a honing unit is carried as hereinafter described.

' Each honing unit 31 includes a hone carrier 38 of generally channel shaped form, having a channel base or web 32 and channel legs or flanges 33. Each flange 33 has an open ended keyhole slot 34, oriented as shown in FIG. 7, the two slots of each carrier being laterally aligned. The flanges 33 of each hone carrier 33 are spaced apart a sufficient distance that the strip portion of the free end of the corresponding arm may be freely received therebetween. The ears 30 of the arms, however, are positioned to extend through enlarged portions of the slots 34- and preferably sufiiciently beyond the flanges 33 whereby the carriers may pivot on the ears 30 and are retained on the arms.

A suitable stone 36 or other suitable abrasive element is secured to the outer surface of the web 32 of each carrier 38 as by a suitable adhesive.

In assembling the honing units 31 on the arms 20, the ears 36 are slid through the narrow portions of the keyhole slots 34 and into the enlarged or circular portion thereof. A tip 35 defining one side of the narrow portion of the keyhole slot 34- is then deformed such that the slot is substantially closed as illustrated in FIG. 8. The material of the hone carrier and the dimensions thereof are preferably such that the tip 35 may be thus distorted by use of ordinary pliers or merely by pressure of a screw driver thereagainst. In the preferred embodiment the hone carrier is formed of sheet metal and is proportioned as shown in FIG. 7, which is twice actual size. With this construction, the tips 35 are readily bent down to close the slots. The circular portions of the keyhole slots 34 must be of such size as to receive freely the corresponding ears 30, after the keyhole slots have been closed, in order that the carrier may pivot freely on the arm.

Pivotal movement of the units 31 on the arms 20 in one direction (counterclockwise as viewed in FIG. 1) is limited by engagement of the channel portions 32 thereof with the arms 20. Accordingly, it is desirable that the length of the planar portion of the arm extending outwardly of the offset therein be of sufficient length that the inner ends of the hone carriers are engageable only with the inwardly offset portions of the arm, as shown in FIG. 3. With this arrangement the arms 20 do not interfere with the pivotal movement of the hone carriers, and the latter may assume parallel positions when the device is reduced to its smallest possible diameter.

Pivotal movement of the hone carriers in the opposite direction with respect to the arms 20 (clockwise, as viewed in FIG. 1) is limited by engagement of the tip of each arm with a tab 37 which is punched inwardly from the base 32 of the corresponding carrier 38, as best seen in FIG. 8. The tip of each arm is preferably bent outwardly as shown in FIG. 4 for this purpose and serves to bolt the units in poistions generally parallel to the axis of the drive stem 12. These parts are so dimensioned as to avoid interference with proper alignment of the honing units at the most widespread position, illustrated in FIG. 1. The purpose of limiting pivotal movement in this other direction is to permit ease of insertion of the honing units in a cylinder and to prevent them from assuming such positions that the operator might insert the honing device into a cylinder with the abrasive elements facing inwardly.

The honing units 31 must be assembled in proper endto-end relationship with the corresponding arms 20 in order that the tabs 37 be properly positioned for engagement with the tips of the arms. Analysis of FIGS. 3 and 8 reveals, however, that the ears 30 of an arm 20 cannot be inserted into the keyhole slots of a hone carrier if the latter is improperly turned end-for-end. Accordingly, improper assembly is prevented.

Because of the fact that the inner or channel-shaped ends of the arms Ztl are necessarily staggered by virtue of the overlapping of the channel legs thereof, there tends to the off-center positioning of the honing units 31 with respect to the drive stem 12. This is preferably compensated for by the configuration of the arms 20. As may be seen best in FIGS. 2 and 5, the outer or strip portions of the arms 20 are formed such that the axes thereof are offset in a direction opposite the above referred-to offset of the channel-shaped ends. Accordingly, the honing units 31 are centrally positioned with respect to the drive stem 12.

In operation, the shank 11 is inserted in the chuck of an electric drill, for example a conventional handheld drill, and the chuck is tightened. The knurled nut 15 is adjusted to produce the desired pressure of the homes against the cylinder walls. As is well understood in the art, a higher pressure tends to produce a grinding effect whereas a lighter pressure produces more of a polishing effect. The operator may bring the arms 24 and the honing units 31 toward each other sufliciently to permit their insertion into the cylinder to be honed simply by manual squeezing together of the inner or channel-shaped portions of the arms 20. When the hone carriers have been inserted into the cylinder to be honed he may release the arms, and the spring 17 and collar 14 will bring the honing elements 36 into engagement with the cylinder walls. As indicated above, there is no possibility that the honing units 31 will pivot about the ears 30 to such an extent that the honing elements 36 will face inwardly rather than outwardly, since pivotal movement of the honing units 31 is limited with respect to the arms 2.1) in both directions. The electric drill may then be started and the honing elements 36 will be driven around the cylinder walls while bearing against the walls with selected pressure. The drill may be moved axially with respect to the cylinder such that any desired length of the cylinder may be honed. The abrasive elements 36 may reach the extreme depth of the cylinder (limited only by the length of the drive stem 12, flexible shaft 13, and shank 11), and may hone the extreme outer portion of the cylinder since the ends of the honing elements 36 extending toward the drive stem 12 may be permitted to extend slightly beyond the lip of the cylinder without undesired effect.

A second form of honing unit is illustrated in FIG. 9 to which reference now is made. The unit 50 includes a carrier 51 of generally channel-shaped form having a web 52 with flanges 5'3 and 54 extending perpendicularly therefrom in spaced relation. The flanges 53 and 54 are provided with aligned circular openings 55 at the longitudinal midpoints thereof for receiving the ears 30 of the carrying arm 20 (such as shown in FIGS. 1 to 6).

One of the flanges, for example, the flange 54, is provided with spaced notches 56, 56 on either side of the opening 55 which extend preferably substantially throughout the depth of the flange and which define a tongue 57. The tongue thus can be bent readily out of the plane of the remainder of the flange 54 without bending the remaining portions of the flange, which, as seen in FIG. 9 are located on opposite sides of the tongue 57. The carrier 51 is provided with a tab 59 formed and arranged in a manner similarly to the tab 37 above described and for the same purpose.

An abrasive element such as a stone 58 is suitably secured, as by an adhesive to the outer face of the web 52, as seen in FIG. 9.

The carrier 51 preferably is formed with the tongue 57 in the plane of the remainder of the flange 54 and the tongue 57 is then bent outwardly from such plane, as indicated in broken lines in FIG. 10.

The honing unit 59 is attached to the corresponding arm 20 by inserting the appropriate ear 30 of the arm 20 in the opening 55 formed in the unnotched flange 53. The arm is then positioned to place the other ear 30 in alignment with the opening 55 in the tongue 57 which is at that time bent out as indicated in broken lines in FIG. 10. The tongue 57 is then bent inwardly, as by the use of an appropriate tool, such as a pair of pliers, into the plane of the remainder of the flange 54, which action causes the opening 55 in the tongue 57 to receive the car 30. This results in the flanges 53 and the tongue 57 being brought into parallelism so that the ears 30 are received in the openings 55 and the unit 50 thus securedly attached to the end of the arm 25 Preferably the unit is so oriented with respect'to the arm 2'9 that the unnotched flange 53 is in the leading or pressure side of the arm. Thus, the pressure which might tend to bend the flange outwardly and thus possibly dislodge the unit from the arm is applied to the stiff flange 53 and the possibility of dislodgement is minimized.

A honing device has now been disclosed which serves the purposes of devices of this general character while employing only two honing units. The use of only two honing units combined with the channel-shaped inner ends of the arms makes it possible for the device to be used for honing a very small cylinder. More particularly, the device may hone a cylinder which will encompass the two relativel flat hone carriers. As oppose to this, any honing device employing three honing units, as is common in the art, cannot be employed to hone as small a cylinder since the three honing units must, at minimum size, form a triangle. The minimum size of cylinder which can encompass three honing elements arranged in a triangle is necessarily substantially larger than the minimum size of cylinder which can encompass two of the same honing units arranged back to back. Furthermore, all other portions of the device are of such dimensions that the device may be stored in a very small space when the knurled nut is turned in such a direction as to release the spring 17.

In the honing device described above, the arms and hence the honing units are driven positively by the shaft through pin 21. This is opposed to various previously known honing devices in which the arms are arranged in slots which, of necessity, receive the arms quite loosely. Further-more, there is little friction involved in the pivotal movement of the arms and of the hone carriers in the device described above whereas in many prior art devices substantial friction accompanies these pivotal movements.

A novel form of connection between the honing units and the corresponding arms has also been disclosed. This connection permits free pivotal movement of the hone carriers with respect to the associated arms while involving very simple construction and permitting convenient assembly and disassembly without the use of special tools.

Finally, it will be apparent that a honing device constructed in accordance with the present invention is in its entirety of very simple construction and therefore inexpensive to manufacture while having various other advantages over prior art devices.

It will be apparent that the invention may be varied in its physical embodiment without departing from the spirit of the invention, and it is desired, therefore, that the invention be limited only by the scope of the appended claims.

The invention having thus been described, what is clairned and desired to be secured by Letters Patent is:

1. A honing device comprising a drive stem, a collar slidably supported on said stem, and having an end face perpendicular to said stem a nut threadedly engaging said stem, a spring compressed between said nut and said collar, a pair of hone carriers, a pair of arms each pivotally supporting adjacent one end thereof one of said carriers and being pivotally connected adjacent the other end thereof to said stem, said arms each having a channel portion adjacent said other end and being arranged with said channel portions opening toward each other and with the flanges of said channel portions overlapping, said flanges having beveled ends extending beyond the web of said channel portions, a pin extending through overlapping portions of said flanges and through said stem adjacent one end thereof, whereby said arms may pivot from substantially parallel positions outward to spread positions, said collar bearing at said end face against the beveled ends of said flanges through action of said spring and thereby urging said arms toward spread position.

2. A honing device comprising a drive stem, a collar siidably supported on said stem, and having an end face perpendicular to said stem a nut threadedly engaging said stem, a spring compressed between said nut and said collar, a pair of hone carriers, 21 pair of arms each having a substantially planar outer end pivotally supporting one of said carriers and ,a channel shaped inner end portion pivotally connected to said stem, said arms being arranged with said channel portions opening toward each other and with the flanges of said channel portions overlapping, said flanges having beveled inner ends and extending inwardly beyond the webs of said channel portions, a pin extending through overlapping portions of said channel flanges and through said stem adjacent one end thereof, whereby said arms may pivot from substantially parallel positions outward to spread positions, said collar bearing at said end face against the beveled inner ends of said channel flanges through action of said spring and thereby urging said arms toward spread position, said outer substantially planar portions of said arms being offset toward each other whereby they may move substantially into contact with each other.

3. A honing device comprising a drive stem, a collar slidably supported on said stem, and having an end face perpendicular to said stem a nut threadedly engaging said stem, a spring compressed between said nut and said collar, a pair of hone carriers, a pair of arms each having a substantially planar outer end portion pivotally supporting one of said carriers and a channel shaped inner end portion pivotally connected to said stem, said arms being arranged with said channel portions opening toward each other and with the flanges of said channel portions overlapping, said flanges having beveled inner ends and extending inwardly beyond the webs of said channel portions, a pin extending through overlapping portions of said channel flanges and through said stem adjacent one end thereof, whereby said arms may pivot from substantially parallel positions outward to spread positions, said collar bearing at said end face against the beveled inner ends of said channel flanges through action of said spring and thereby urging said arms toward spread position, said outer substantially planar portions of said arms being offset toward each other near their extremities whereby they may move substantially into contact with each other, said hone carriers being channel shaped and having channel sides spaced sufliciently to receive said outer arm portions freely therebetween, each of said outer arm portions having a pair of laterally projecting ears, each of said hone carriers having opposed, open-ended keyhole slots in opposite sides thereof for receiving said ears, said walls being readily deformable to close said slots.

4. A honing device comprising a drive stern, a collar slidably supported on said stem, and having an end face perpendicular to said stem a nut threadedly engaging said stem, a spring compressed between said nut and said collar, a pair of hone carriers, a pair of arms each having a substantially planar outer end portion pivotally supporting one of said carriers and a channel shaped inner end portion pivotally connected to said stem, said arms being arranged with said channel portions opening toward each other and with the flanges of said channel portions overlapping, said channel portions having beveled inner ends and extending inwardly beyond the webs of said channel portions, a pin extending through overlapping portions of said channel flanges and through said stem adjacent one end thereof, whereby said arms may pivot from substantially parallel positions outward to spread positions, said collar bearing at said end face against the beveled inner ends of said channel flanges through action of said spring and thereby urging said arms toward spread position, said outer substantially planar portions of said arms being offset toward each other near their extremities whereby they may move substantially into contact with each other, said hone carriers being channel shaped and having channel sides spaced sufficiently to receive said outer arm portions freely therebetween, means pivotally supporting said hone carriers on said outer arm portions of said arms respectively pivotal movement of said hone carriers with respect to said arms being limited in one direction by engagement of the bases of said carriers with the corresponding arms, the base portion of each of said channel shaped hone carriers including a tab engageable with the portion of the corresponding arm outwardly beyond said piovtal means to limit pivotal movement in the other direction when said arm is substantially normal to the honing surface of the homes carried by said honing carriers.

5. A honing device comprising a drive stem, a collar slidably supported on said stem, and having having an end face perpendicular to said stem a nut threadedly engaging said stem, a spring compressed between said nut and said collar, a pair of hone carriers, a pair of arms each pivotally supporting adjacent one end thereof one of said can riers and being pivotally connected adjacent the other end thereof to said stem, said arms each having a channel portion adjacent said other end and being arranged with said channel portions opening toward each other and with the flanges of said channel portions overlapping, said channel portions having beveled ends and extending inwardly beyond the webs of said channel portions, a pin extending through overlapping portions of said channel legs and through said stem adjacent one end thereof, whereby said arms may pivot from substantially parallel positions outward to pread positions, said collar bearing at said end face against the beveled inner ends of said channel flanges through action of said spring and thereby urging said arms toward spread position, said hone carriers each being channel shaped and having channel sides spaced sufliciently to receive said one end of one arm freely therebetween, each of said arms having adjacent said one end a pair of laterally projecting ears, each of said hone carriers having opposed, open-ended keyhole slots in opposite sides thereof for receiving said ears, said walls being permanently deformable to close said slots.

6. A honing device comprising a drive stem, a collar slidably supported on said stem, and having an end face perpendicular to said stem a nut threadedly engaging said stern, a spring compressed between said nut and said collar, a pair of hone carriers, a pair of arms each pivotally supporting adjacent one end thereof one of said carriers and being pivotally connected adjacent the other end thereof to said stem, said arms each having a channel portion adjacent said other end and being arranged with said channel portions opening toward each other and with the flanges of said channel portions overlapping, said channel portions having beveled ends and extending inwardly beyond the webs of said channel portions, a pin extending through overlapping portions of said channel legs and through said stem adjacent one end thereof, whereby said arms may pivot from substantially parallel positions outward to spread positions, said collar bearing at said end face against the beveled inner ends of said channel flanges through action of said spring and thereby urging said arms toward spread position, said hone carriers each being channel shaped and having channel sides spaced sufliciently to receive said one end of one arm freely therebetween, each of said arms having adjacent said one end a pair of laterally projecting ears, each of said hone carriers having opposed, open-ended keyhole slots in opposite sides thereof for receiving said ears, said walls being permanently deformable to close said slots, pivotal movement of said hone carriers with respect to said arms being limited in one direction by engagement of the base of said carriers with the corresponding arms, the base portion of each of said channel shaped hone carriers including a tab engageable with the outer portion of the corresponding arm outwardly beyond said pivotal means to limit pivotal movement in the other direction.

7. A honing device comprising a drive stem, a collar slidably supported in said stem, and having an end face perpendicular to said stem a nut threadedly engaging said stem, a spring compressed between said nut and said collar, a pair of hone carriers, a pair of arms each pivotally supporting adjacent one end thereof one of said carriers and being pivotally connected adjacent the other end thereof to said stem, each of said arms having two generally parallel, spaced apart walls adjacent said other end and overlapping the walls of the other arm, a pin extending through overlapping portions of said walls and through said stem adjacent one end thereof, whereby said arms may pivot from substantially parallel positions outward to spread positions, said walls having bevelled ends against which said end face of said collar may bear through action of said spring and thereby urge said arms toward spread position.

8. A honing device comprising a drive stem, pivot means projecting diametrically from said stem adjacent an end thereof, a pair of arms, each including a channel portion having a flat strip extending from one end of the web and flange extensions extending beyond the web at the other end, said flange extensions being mutually overlapping in straddling relation to said stem and receiving said pivot means therethroug-h, a longitudinally adjustable abutment on said stem, a collar slidably carried on said stem between said abutment and said pivot means and having a planar end wall perpendicular to the axis of said stem and positioned to bear against the end edges of said flange extensions, a spring compressed between said abutment and said collar, each pair of flange extensions having their inner end edges inclined in opposite directions to cause the outer ends of said arms to be urged outwardly apart by said spring, and an abrasive honing unit pivotally carried at the outer ends of each of said web extensions.

9. A honing device comprising a drive stem, pivot means projecting diametrically from said stem adjacent an end thereof, a pair of arms, each including a channel portion having a web extension at one end and flange extensions at the other end, said flange extensions being mutually overlapping and receiving said pivot means therethrough, a longitudinally adjustable abutment on said stem, a collar slidably carried on said stem between said abutment and said pivot means and having a planar end wall perpendiculr to the axis of said stem and positioned to bear against the end edges of said flange extensions, a spring compressed between said abutment and said collar, the extensions of each pair of flanges having their end edges inclined oppositely and in a direction to make an acute angle with the free side edge of the flange thereby to cause the outer ends of said arms to be urged outwardly apart by said spring, and an abrasive honing unit pivotally carried at the outer ends of each of said web extensions.

10. A honing device comprising a drive stem, a pair of arms each having a channel portion with the flanges extending beyond the web in one direction and having inclined end edges and a resilient elongate strip portion extending from the web of said channel portion in the opposite direction, hone carriers pivotally carried on the outer ends of said arms, means projecting diametrically from said stem and through the extending portions of said flanges for pivotally supporting said arms on said stem with said channel portions in opposed relation and each straddling said stem and extending on both sides of the axis of said stem, a collar slidable on said stem and having an end face perpendicular to the axis of said drive stem and positioned to engage the end edges of said flanges which extend beyond said web, an abutment adjustable longitudinally on said stem and a spring compressed between said abutment and said collar for yieldably urging said collar in a direction to swing said arms outwardly.

11. A honing device comprising a drive stem, a pair of arms each having a channel portion with the flanges extending beyond the web in one direction and having end edges inclined at an acute angle to the tree side edge of the flanges, and a resilient elongate strip portion extending from the web of said channel portion in the opposite direction, hone carriers pivotally carried on the outer ends of said arm, means projecting diametrically from said stem and through the extending portions of said flanges for pivotally supporting said arms on said stem with said channel portions in opposed relation and each straddling said stem and exciting on both sides of the axis of said stem, a collar slidable on said stern and having an end face perpendicular to the axis of said drive stem and positioned to engage the end edges of said flanges which extend beyond said web, an abutment adjustable longitudinally on said stern and a spring compressed between said abutment and said collar for yieldably urging said collar in a direction to swing said arms outwardly.

References Cited in the file of this patent UNITED STATES PATENTS 723,818 Brewington Mar. 31, 1903 1,474,649 Storm Nov. 20, 1923 2,056,777 Evans Oct. 6, 1936 2,128,822 Horne Aug. 30, 1938 2,196,542 Zaiger Apr. 9, 1940 2,404,523 Nesson July 23, 1946 2,736,146 Brooks Feb. 28, 1956 2,778,168 Clark Jan. 22, 1957 2,782,572 Clark Feb. 26, 1957 2,805,528 Barrett Sept. 10, 1957

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