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Unknown Racks

Version A Version B Version C Version D
Version A Version B Version C Version D

Overview


Version A
(#2403)

Front View Rear View Side View
Front View Rear View Side View

Technical Details

I acquired this rack in 2017 as part of Bob Thrun's collection.

My Unknown #1 rack is 344 mm. tall, 64 mm. wide, 21 mm. thick, and weighs 664 g. The frame is made from 9.5 mm. stainless steel bent into shape, with an internal width of 32 mm. and a 14 mm. diameter welded eye. There are seven REI brake bars, secured by a hex nut. The bars are 19 mm. in diameter and 64 mm. long. Allowing 45 mm. for the rope leaves 68 mm. for spreading the bars.

Each bar has an "REI" stamped on it.

Comments

Although seven bars are on the rack in the photo,it should be used with only six bars. For safety reasons, the bars should be filed on the unloaded side and moved to the spine of the rack.

I once wrote (Random Synapse Firings, The Nylon Highway #26, April 1988) that there might be reasons to distrust welded eye racks. I don't have concerns with high-quality commercial racks such as the SMC, but home welds are a different matter. This rack is an example of one that I don't fully trust. I do not know what type of stainless steel was used to make the frame or whether the builder followed the proper welding procedure, but a look at the weld area shows numerous hollows and signs of poor fusion.


Version B
(#2426)

Front View Side View Rear View
Front View Side View Rear View

Technical Details

I acquired this rack in 2017 as part of Bob Thrun's collection.

This rack is 385 mm. tall, 64 mm. wide, 40 mm. thick, and weighs 786 g. The frame is made from 11.1 mm steel bent into shape, with an internal width of 29 mm. and a 19 mm. diameter welded eye. There are six SMC brake bars. The bars are 19 mm. in diameter and 64 mm. long. Allowing 45 mm. for the rope leaves 112 mm. for spreading the bars.

There are no markings on this rack.

Comments

Many racks have 3/8 inch (9.5 mm.) frames, but this one is 7/16 inch (11.1 mm.). Standard brake bars will fit this rack, but it requires excessive filing to move them to pivot on the spine where they belong. I have not done that on this rack, and so I do not recommend using it as-is.

The eye on this rack is turned 90° and a dogleg in the frame centers the eye with the bars. This attempt to keep the rope running centered helps, but ultimately is doomed to failure by simple geometry - the distance from the eye to the side of the frame below the top bar is longer than the distance to the center.

At 50 mm., the threaded area for the nut is far too long. It should be no longer than the height of a lock nut. Someone filed the top 30 mm. of the threads on the inside of the frame so that the nut would only engage 20 mm., and the rope would not run over the threads. Shorter threads would have been a better approach.

The threads have one curious feature. The end of the frame below the threads is center drilled, indicating that the threads were chased on a lathe rather than cut by a threading die. Either method is perfectly acceptable.


Version C
(#2457)

Front View Side View Rear View
Front View Side View Rear View

Technical Details

I acquired this rack from CarolJo Rushin-Elron in at the 2017 NSS Convention.

Version C is 460 mm. tall, 63 mm. wide, 25 mm. thick, and weighs 790 g. The frame is made from 9.5 mm. stainless steel bent into shape, with an internal width of 33 mm. and a 25 mm. diameter welded eye. There are six brake bars. The top bar is a 25 mm. SMC aluminum bar with a pre-formed guide groove. The second bar is a 19 mm. SMC tubular stainless steel bar, and the remaining four are 19 mm. SMC aluminum bars. Each of the six bars is 63 mm. long. Allowing 45 mm. for the rope leaves 139 mm. for spreading the bars. A lock nut holds the bars in place.

There are no markings on this rack, but each of the bars is stamped with "SMC."

Comments

An unknown Georgia caver hand-made this rack for Carol Jo Rushin-Elron in 1983 after seeing how hard it was for her to feed rope on long drops. She doesn't know of his making any others.

This rack is fitted with SMC bars in the way that I received it. While I don't object to the choice of bars, I would have at least moved the five 19 mm. bars so that they swung on the back of the frame rather than the open end. This would greatly decrease the risk of the bars opening if the rack is bumped during descent.

Although I don't really object, I prefer angle-slotted bars, and the steel bar on this rack is straight-slotted. Some people feel that this prevents rigging the rack backwards, but I find that to be almost impossible for me to do  - even when I try, my hands refuse to cooperate. It is a moot point on this rack - the rack is a bit too narrow for the angle slotted bars to engage well, and they tend to flop around anyhow.

There is an 83 mm. gap between the top of the eye and the bottom of the lock nut. This opening need only be large enough to swing the rope in and out of, so there are about 60 mm. of wasted length that could have been used to either make the rack shorter, or to extend the range of bar motion. For a heavier caver, shortening the rack would be more desirable, while for lighter cavers, extending the open end of the frame would be preferred.


Version D
(#2459)

Front View Side View Rear View
Front View Side View Rear View

Technical Details

I acquired this rack from the eBay seller vtgtrends in 2017.

Version D rack is 371 mm. tall, 63 mm. wide, 20 mm. thick, and weighs 687 g. The frame is made from 11.1 mm alloy steel bent into shape, with an internal width of 33 mm. and a 14 mm. diameter eye. The rack came with the orange REI bar. I added two more REI bars and then three SMC bars (two with beveled ends, one without). All bars are 19 mm. in diameter and 63 mm. long. Allowing 45 mm. for the rope leaves 25 mm. for spreading the bars.

There are no markings on this rack, but the bars are stamped "REI" or "SMC," respectively.

Comments

The eBay listing identified this as an REI rack, but I have my doubts. I do not recall REI selling rappel racks, and certainly not allow steel racks with this older style of eye. This may be an old BlueWater rack, but I am not sure about this, as I don't have one to compare. For now, I'll just call it "Unknown."