the self - threading cassette according to the illustrated preferred embodiment is indicated generally at 1 in fig1 . the cassette 1 has a housing 2 that is shown as being a rectangular prism , but which may be of other shapes such as a circular cylinder . the cassette housing 2 is provided with feed window 3 through which strip material enters into the cassette . when the cassette is to be used with light sensitive materials such as photo - composition paper films , the feed window is provided with a light seal which may be of any conventional type utilized on film cassettes and thus is not illustrated in detail . mounted within the cassette housing 2 on opposite sides of the feed window 3 are a pair of guides 4 , 5 . the guide 4 extends from below the feed inlet 3 to a point directly above a takeup reel 6 where it is provided with a downward sloping end portion 4a . guide 4 ensures that the leading edge of the strip material does not curl downward until it has been advanced over the takeup reel 6 . this guide can be formed of any suitable self - supporting material , such as metal or plastic . guide 5 is mounted above the feed window 3 , extends across the cassette and coils partially about the takeup reel 6 . the upper guide is preferably formed of spring steel configured so as to contact the roller at a point 7 , as shown in fig2 and then separate from the reel 6 and continue around the reel to a free end positioned above the takeup reel 6 and directed toward an intermediate coiled portion of the spring for reasons discussed in greater detail below . the takeup reel 6 , as best seen from fig2 and 3 , is preferably a composite structure formed by a central shaft 10 an inner roller 11 , and spaced outer rollers 12 . the shaft 10 is connected to a drive motor 13 via a slip clutch 14 and is rotatably supported within the cassette casing in notches or other suitable bearings carried by or mounted in the walls of the cassette housing 2 . the inner roller 11 is fixed upon the shaft 10 so as to rotate therewith . the inner roller 11 is formed of a material having a low coefficient of friction such as vinyl . the other rollers 12 are fixed upon the inner roller 11 so as to rotate therewith and be spaced from each other by an amount greater than the width of the upper guide 5 thereby forming a notch or recess within which the guide 5 can sit and rest upon the inner roller 11 . in contrast to the inner roller 11 which is formed of a low friction material , the outer rollers 12 are formed of a material having a high coefficient of friction such as neoprene rubber . in the illustrated embodiment , a pair of flanged side guides 15 are shown mounted upon the ends of the outer rollers 12 at a distance corresponding to the width of the strip material to be wound upon the reel 6 therebetween . these side guides 15 can be formed of aluminum , plastic , or the like , and force fit onto the ends of the outer rollers 12 , as shown , or may be carried upon exposed ends of the inner roller 11 or the shaft 10 . these side guides rotate with the takeup reel and serve to maintain lateral alignment of the strip material . while the preferred takeup reel utilizes a pair of high friction rollers carried upon a low friction inner roller so as to both reduce frictional rubbing between the guide spring 5 at the contact point 7 , prior to threading of the strip material , and ensure that a firm frictional driving contact is applied by the takeup reel 6 to the lead end of the strip material , a single solid rubber piece can be utilized without provision of a low friction recess . the operation of the cassette and loading system according to the preferred embodiment will now be described . a feed drive 16 ( of conventional construction ) is disposed relative to the feed window 3 so as to automatically direct a lead end of the strip material through window 3 , or the lead end can be manually inserted through the light shield of the inlet window and then the feed device can be actuated . the feed device 16 supplies strip material at , for example , one inch per second , and from the feed window , the lead end of the strip material is guided to the takeup reel by the guides 4 , 5 . during this period of time the takeup roll is driven by the motor 13 via the clutch 14 at a speed approximately 10 percent greater than the feed speed , for example , 1 . 1 inches per second . alternatively , the casette can be provided with a detecting switch which can actuate the drive motor upon insertion of a strip through the light seal of the feed window . when the strip material passes into the nip 7 formed between the guide 5 and roller 6 , the guide 5 is lifted out of the recess and applies sufficient force to the strip material against the rollers 12 as to ensure that a driving force is imparted . however , the lead edge of the strip material does not become secured to the roller in any manner and passes over the roller and is guided by the free end portion of the guide spring 5 around the roller back towards an intermediate portion of the guide spring upstream of the nip 7 where the following guided portions of the strip material and the arcuate form of the guide spring 5 serve to curl the leading end downward back toward the nip 7 . this process is repeated , with the rollers 12 continuously driving the inside loop , thereby gradually rolling the strip material tightly about the takeup roll 6 . in this manner , the lead end of the strip material will be tightly threaded about the takeup reel and retained without any adherent and interengaging surface characteristics having to be provided such as by adhesives and mating sprockets and holes . once the strip material has been tightly wound upon the takeup reel 6 , the slip clutch will permit equalization of the speed of the takeup reel with that of the material fed into the cassette by the feed device 16 . the 10 percent initial speed differential has been found to be particularly advantageous since it both reduces the extent of the yanking force applied upon the strip material when initially driven by the faster rotating takeup reel and reduces the amount of slip that must occur after threading has been completed , thereby avoiding damage to the strip material and limiting clutch wear , respectively . based upon tests , applicant has found that a single three quarter inch wide centrally positioned spring is sufficient to provide the necessary guiding of paper film , such as is used in photo - composition systems ( such paper being usually 6 to 7 inches wide ) to the takeup roller as well as applying sufficient force for the roller to drive the same , while being sufficiently able to flex and expand away from the roller as the paper film is wound about the roller . furthermore , in contrast to reel - less spring coiling cassettes ( which as noted above have been essentially limited to strip lengths of about 10 feet ) the present invention has satisfactorily loaded as much as 150 feet of paper film within a cassette without the prior art binding problems occurring . as noted above , a single three - quarter inch strip has been found to be satisfactory for use in accordance with the described cassette and loading system . however , it is also contemplated that a pair of such guide springs 5a could be utilized in conjunction with a pair of recesses as shown in fig3 a in connection with a modified take - up reel 6a . such plural recesses could be formed , for example , by the ends of a single , centrally positioned , outer rubber roller 12a of lesser length than the inner roller 11 and the spacing between the side guides 15 ( which then would be mounted upon the inner roller instead of the outer roller ). likewise , one of ordinary skill in the art will recognize that the present invention is not limited to the one embodiment shown and described herein , but is susceptible to numerous changes and modifications within the scope of the overall invention described herein . therefore , i do not wish to be limited to the details shown and described herein , but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims .