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John Blum Boxes

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

Overview


Version A
(#635)

Front View: Closed
Front View: Closed
 
Open for Rigging
Open for Rigging
 
Top View
Top View

Technical Details

I acquired my John Blum, Version A box from Inner Mountain Outfitters at the 1988 Old Timers Reunion. I acquired another in 2017 as part of Bob Thrun's collection.

My John Blum, Version A is 77 mm. long, 127 mm. wide, 44 mm. high, and weighs 256 g. It is a double channel chest box with a cast aluminum frame. The back plate has 51 mm. tall vertical slots for attaching the box to a chest harness. The roller assembly pivots at one end, and is held by a quick-release pin at the other. The rollers are nylon, with a larger nylon bushing to keep the rope and foot sling separated.

The frame is stamped "JB1A"

Comments

One thing I don't like about the Blum box is that it opens both sides at once. There is no way to open the foot sling side without releasing the main line and vice versa. For this reason, I never used this box for regular caving.


Version B
(#1879)

Front View: Closed Open for Rigging
Front View: Closed Open for Rigging

Technical Details

I acquired my John Blum, Version B from CarolJo Rushin-Elron at the 2016 NSS Convention. I acquired another in 2017 as part of Bob Thrun's collection, and a third from Bill Liebman at the 2017 Old Timers Reunion.

Version B is 76 mm. tall, 125  mm. wide, and 44  mm. thick, and weighs 254  g. The rollers are different colors than those on Version A. The roller closest to the hinge is 19 mm. in diameter by 14 mm long, the central spacing roller is 35 mm. by 14 mm, and the outer roller 20 mm. by 19 mm.

The body on the one from C. J. is stamped "JB1A" and "9060." The one from Bill is stamped "JB1A" and "92040."

Comments

C. J. bought hers from Inner Mountain Outfitters at an unknown NSS Convention many years ago. The serial numbers indicate that this version was made in the early 1990s.


Version C
(#636)

Front View: Closed
Front View: Closed
 
Open for Rigging
Open for Rigging
 
Top View
Top View

Technical Details

I acquired my John Blum, Version C from Bob & Bob at the 1993 NSS Convention.

My John Blum, Version C is 64 mm. tall, 175 mm. wide, 43 mm. high, and weighs 327 g. It is a double channel chest box with a cast aluminum frame. There is a 42 mm. tall trapezoidal opening on each side for for attaching the box to a chest harness. The roller assembly is similar to Version A & B's but the Version C rollers are brass.

The frame is stamped "JB2-9322."

Comments

Version C has a larger frame and brass rollers. Even with the large cutout, Version C is 28% heavier than Version B. As far as operation goes, it is similar to Version B.


Version D
(#1899)

Front View: Closed
Front View: Closed
 
Open for Rigging
Open for Rigging
 
Top View
Top View

Technical Details

I acquired my John Blum, Version D in 2017 as part of Bob Thrun's collection. I acquired two more from Bill Liebman at the 2017 Old Timers Reunion.

Version D is 177 mm. tall, 66 mm. wide, and 44 mm. thick, and weighs 332 g. It is a double channel chest box with a cast and painted aluminum frame. There is a 42 mm. tall trapezoidal opening on each side for for attaching the box to a chest harness.

There are no markings on this box.

Comments

The one acquired as part of Bob Thrun's collection is painted a bright orange-red. If you've ever mislaid a piece of gear in a cave, you should appreciate the color. The two I acquired from Bill are painted a bright yellow, and the QR pins on those two do not have the black finish.

The paint in the roller channels can wear off and leave a mess on the rope. I would scrape it off prior to use.

Other than the paint, this is essentially the same as the previous version.