There have been several Versions of the C.M.I. 5000 series ascender, but the differences appear to be fairly minor so I did not acquire each Version when it was available. As a result, I am missing the "5001".The "5001" was apparently never given a new number, instead there were two Versions of the 5000. Ian Ellis read me a press release indicating the "5001" was scheduled to have a stronger cam spring, a cam change to accommodate the new spring, a repositioned safety, and radiused versus chamfered tie-in holes. The 5002 has all these features except the repositioned safety, and my 5000 does not have chamfered tie-in holes. If someone wants to trade a pair of "5001" ascenders for a new pair, I may be interested in accommodating you. Similarly, I'm looking for a pair of C.M.I. Shorti IIs.
Ian Ellis of Speleoshoppe kindly went through his old purchase
records to find the approximate time frame for each of the C.M.I.
5000 series ascenders. Apparently the 5000 was introduced in mid
1979, the "5001" in early 1980, the 5002 in late 1980,
the 5003 in mid 1984, and the 5004 in mid 1986.
[ Top | 5002 | 5003 | 5004 | Return to H.E.C. Ascenders ]
I acquired this pair of ascenders from Speleoshoppe in 1979.
C.M.I. ascender frames are made by milling an aircraft alloy extrusion. The extrusion direction is oriented parallel to the vertical axis of the ascender. The frame contains two opposing channels. One channel is rounded and becomes the rope channel., the other is square and holds the cam. Starting with a length of extrusion, everything that doesn't look like ascender frame is machined away. In particular, the rope channel is shortened, the handle hole is cut, two 15.6 mm. sling attachment holes are drilled at the bottom and a third is drilled at the top, the unused lower portion of the cam channel is cut back, and all the sharp corners are rounded. My ascenders have a red anodized finish. This was a custom color made specially for Speleoshoppe, the standard color is dark gray.
The cam is identical to the C.M.I. Shorti cam. The cam is a skeletonized casting with a (2)(5.4)^4(3.4)^2(3.2)^2 conical tooth count. According to an undated C.M.I. brochure acquired with the ascender, the cam material is 17-4ph stainless steel. The inner cam face radius reduces from top to bottom of the cam in order to match different diameter ropes. "CMI" is cast on the side of the cam. The cam pivot is a solid 6.4 mm. round head pin held by an external retaining ring. The cam safety is an elbow shaped nylon(?) lever mounted on a roll pin in the cam. A single spring serves as cam spring and safety spring. Normally this spring holds the safety where it protrudes from both the top and bottom of the cam. The bottom protrusion interferes with the shell's cam channel and prevents opening the cam. When the top of the lever is pushed towards the cam teeth, the lower protrusion rotates into a recess in the cam, thus allowing the cam to open.
The shell on this ascender is very strong, but a competitor pointed out that this C.M.I. cam was weaker than some of the competition's. Personally I feel the C.M.I. cam strength is more than adequate for my purposes. Since the cam channel is extended to form a handle, the frame is well reinforced against lateral bending, so the pit lip scenario described for the Clog should not destroy the ascender (but it is still very bad technique!). The ascender can be opened with one hand, but the safety is awkward, particularly when used in the "wrong" hand. The extra bulk of the handle makes it slightly easier to open than the C.M.I. Shorti. The cam pin is excellent, and allows one to easily replace a worn cam at home. The cam spring is too weak, so the ascender occasionally fails to grip the rope. I have heard reports of 11 mm. rope becoming wedged in the channel below the cam (i.e., the "handle" part of the frame) but have not observed this problem myself. The handle is not as comfortable as most, but is certainly adequate. Like the Clog, the C.M.I. 5000 is not an easy ascender to grip from above.
[ Top | 5000 | 5003 | 5004 | Return to H.E.C. Ascenders ]
I acquired two left-handed C.M.I. 5002 ascenders from Speleoshoppe in October, 1989. I acquired a used pair from Barry Kooda in March, 2004, so I now have a complete pair.
There are several changes between the 5000 and 5002. The cam was redesigned with somewhat more reinforcing than the 5000 cam. The spring channel in the cam has been enlarged to accommodate a stronger cam spring. The cam pin has a smaller head, and the safety pivot diameter was increased. The 5002 cam is also plated, while the 5000 cam was unfinished.
The 5002 ascenders in my collection have slightly different tooth patterns. In each set, one has a (2)(5.4)^4(3.4)(3.2)^3 conical tooth count, the other a (3)(5.4)^4(3.4)(3.2)^3 count. Evidence for the missing tooth on the first one is obscured by the plating. The teeth are well formed, more so than on the 5000. The teeth are still perpendicular to the cam face. "Cmi" is cast on the side of the cam.
The frame is essentially identical to the 5000 frame except for the rope channel, which has been increased in height and given a pentagonal shape. The lower and upper tie-in holes are radiused on one side only. This ascender has the typical dark gray anodizing of most early C.M.I. ascenders.
The stronger cam spring is an improvement which causes the cam to grip more reliably, although it also makes operating the cam safety and opening the cam more difficult. There are too many cam teeth. Too many teeth causes the 5002 (and similarly the 5000) to perform less satisfactorily in mud than the 5003 and 5004. The missing tooth on the one ascender can be viewed as a rather amusing statement about quality control.
The increased height for the rope channel is more than a cosmetic improvement. One strange feature of the 5000 was that the rope-cam contact point was well below the center elevation of the rope channel. The 5002 design places the contact point much closer to channel mid-elevation. This is a much cleaner design than the original and indicates at least some attention to detail; however, tool marks on the frame are very prominent. In general the workmanship on this ascender is inferior to that on my 5000s.
The radiused tie-in holes are a nice improvement, but the job was only half completed. Both sides of the holes should be radiused.
[ Top | 5000 | 5002 | 5004 | Return to H.E.C. Ascenders ]
I acquired this pair of ascenders from Bob & Bob at the 1987 N.S.S. Convention.
This ascender is very similar to the C.M.I. 5000, even though it is three Versions later. The frame extrusion has been substantially thickened in the rope channel area, and is now finished in a black epoxy(?) paint. The remainder of the frame appears to have been beefed up, but the extra thickness may only be paint. The three sling holes are now beveled. The cam and cam safety are the same as those on the C.M.I. Shorti III. The cam has been modified in several ways. A reinforcing bar now extends from the back of the cam face arc to the mid-bottom of the cam, providing better cam face support under load. The conical teeth are larger, sharper, and better made, and the tooth count has been changed to (5.4)^2(3.4)^3(3.2). The teeth are now oriented parallel to the top of the cam. The cam finish appears to be plated, but this may be just a change in alloy or heat treating. "Cmi" is cast on the side of the cam. The cam safety is now molded, and the enlarged actuating lever lies along the top of the cam rather than sticking up from the cam.The cam pivot head is flatter than on the C.M.I. 5000, and the safety pivot is larger in diameter.
The ascender is very well made. In my opinion, the extra frame thickness is superfluous since the C.M.I. 5000 frame was already very strong. The cam spring is stronger than the C.M.I. 5000 spring and functions adequately. Orienting the cam teeth axes parallel to the top of the ascender cam is an improvement. This design gives the teeth a slight downwards alignment with respect to the climbing rope. This increases their grip, reduces tooth friction while raising the ascender, and provides a small self cleaning action at the same time. The ascender can be opened with one hand, but the safety is is even more awkward than on the C.M.I. 5000. I suspect that the new design was developed to reduce the risk of accidentally opening the ascender, but I don't find this to be a problem. My safety is cracked on one ascender, and Ken Kramer reports that his safeties broke on the way to their first cave trip. Obviously a tougher plastic is needed for the cam safeties.
Since this ascender's cam is essentially identical to the 5004 cam, but the Shorti III and Shorti IV have different cams, I suspect that this ascender has a 5004 cam.
[ Top | 5000 | 5002 | 5003 | Return to H.E.C. Ascenders ]
I acquired a right handed C.M.I. 5004 ascender from Bob & Bob at the 1989 O.T.R. I acquired a left handed ascender from Speleoshoppe two weeks later.
The only discernible difference between this ascender and the 5003 is in the rope channel design. The 5004 rope channel extends farther towards the cam pivot and has a small lip inside.
In 1986 C.M.I. issued a press release noting that "under some unusual circumstances [the C.M.I.] 5003 and Shorti III ascenders can be forced off the rope." It is possible to get some thinner, soft lay ropes to pull out between the cam and the side of the rope channel if one works at it a while, but I have been completely unsuccessful in pulling 11 mm. P.M.I. out of my pair of 5003s under any reasonable circumstances. There is no doubt that the 5004 provides a great deal more rope security than the 5003, but I have no practical worries about either one of my ascenders.
[ Top | 5000 | 5002 | 5003 | 5004 ]
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©2007, Gary D. Storrick