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Neil Box

Version A Version B
Version A Version B

Overview


Version A
(#640)

Front View Front View: Alternate Rigging
Front View Front View: Alternate Rigging
 
Top View Bottom (Alt. Top) View
Top View Bottom (Alt. Top) View
 
Side View Open for Rigging
Side View Open for Rigging

Technical Details

I acquired this Neil Box from Speleoshoppe in 1979.

The box consists of a frame, two rollers, an axle, two side plates, and miscellaneous parts. The frame is made from a T-shaped aluminum extrusion, cut to 63.7 mm. length. The crossbar on the T is 76.2 mm. wide and the stem is 62.2 mm. long; each is 6.4 mm. thick. The cross piece of the T forms the back of the box, and rests against the climber's chest. The back has a 51 mm. tall, 5 mm. wide slot milled in each side to accept a chest harness. The top of the stem is cut off at a bout a 45° angle for about 45 mm. The bottom is rounded on a 32 mm. radius circular arc centered on the axle centerline. This arc is not tangent to the bottom of the box.

The axle is a 71 mm. long, 3/8" (9.7 mm.) hex-head bolt. The bolt passes from the climber's left to right through a flat washer, the left side plate, left roller/bushing, frame, right roller/bushing, right side plate, another flat washer, and finally a nylon lock nut. Each roller is made from hard gray plastic. The rollers are 17.9 mm. wide and have a major diameter of 32.2 mm. Each roller has a centered 14.2 mm. U-shaped groove turned in it to a depth that gives a 19.4 mm. minor diameter. The rollers ride on a steel bushing that is about 20.5 mm. long and 19.2 mm. in diameter. Since the rollers fit the bushing tightly and are centered, they do not rub against the side plates or frame.

Each side plate is made from an irregular piece of 2.8 mm. aluminum. The top half of a side plate is a 25.4 mm. circular arc, the lower front is cut at 45° angle, and the lower rear has a flat base and an extension that is curved inward to fit just forward of the frame.

There are no markings on the device except for "C," "l," and "R" on the bolt head

Comments

The Neil Box is a simple British box. The rope channels can be opened independently by simply pivoting the side plates. There are no catches to hold the plates closed.

On April 22, 2008, I received a nice email from Ivan Young, who informed me that my picture was upside down (I've since revised all the photos on this page). Ivan wrote the following:

"I used a Neil Box - Version A (1977 vintage) - and still have it. I've also a Version B in my collection (1978) that used to belong to one of my friends. Your front view photograph of them is upside down. If you tried using them in that orientation the side plates swing open and would rub on the rope all the time. The other way up their weight holds them against the back plate and (mostly) away from the rope. That also puts the 'top' slot in Version B at the bottom. I guess that is to rig a safety line down to the sit harness but I can't remember my friend ever using it. So you need to turn your photos round and rewrite the description."

The photo that he referred to was similar to the alternate view shown above. "Obviously" he was right, which I readily admitted (After all, this is how I mounted them in the 1995, 2000, and 2007 NSS Convention displays), but then he wrote back:

It's not just the photos that are upside down. So is the explanation of use.

That got me thinking that I couldn't have been completely crazy when I first wrote this page - there had to be something more. There was. Ivan is quite likely right about the way the Neil box was designed to be used, but what I had found long ago was another way to use the Neil Box which, for my rig, works better for me (your mileage may vary). Most of my original description stands, but I'll include some of Ivan's comments in blue, with my replies in green.

The climber has two ways to use the side plates when the box is inverted (alternate arrangement), as follows:

Only if you are wearing the box upside down!!! Right way up there is hardly more than the groove in the pulley to keep the rope from popping out. I think this would be far too exciting a method for me and as I wrote in my previous message I have never heard of this method ever being used. Your website is the only place I've read of it.

Perhaps I invented this way of using the box upside down.

Warning:
This method allows the rope to easily and accidentally come out of the box.

This isn't a common problem but it can happen, so be sure that your climbing system can handle this. One nice feature of this method is that one can remove a loaded rope from the box, a nice feature for Mitchell System climbers when they reach the lip, when the main line is under tension.

That is one of the reasons I grew to hate my chest box! I couldn't easily remove it from the main rope so non-free-hangs were a pain in the chest.

This method works better for me than the original method does, although I admit that the curved sides sometimes "catch" on the slings. I use a Cuddington 3-phase climbing system, and this means that I expect to"come out of the box" at least once on every climb. That is quite easy using this method and quite difficult, by comparison, using the method described in the next bullet. You can place the curved section behind the rope or sling (from below), although it will drag slightly as the rope/sling moves downward. Mitchell climbers might like doing this with the ascender sling rope, since one rarely removes this one from the box - and when one has to. lifting the foot provides all the necessary slack. Perhaps the best option of all is to replace the rope-side plate with a custom plate that lacks the bend, and then use the box right-side up.

As far as I am concerned this is the only method for both rope and foot sling. It is a pain having to haul up enough slack on the main rope to free it from the box, but (unless the nut drops off!) it just cannot disengage from the box by itself.

I cannot argue against someone else's preference, but I have shown that there is an alternative. My rig has a safety strap (as it should), so box failure isn't something that I worry about.

Ivan, Thank You for your comments!

Overall, I think that the Neil Box is a clever design. Each of the cutouts and curves has a specific function, and they work together nicely. On the other hand, I prefer somewhat more security against the main line accidentally opening my box. I also like a wider box, since I'm willing to trade some bulk and weight for improved harness efficiency.


Version B
(#823, 2600)

Front View Bottom View
Front View Bottom View
 
Side View Bottom View: Open for Rigging
Side View: Closed Bottom View: Open for Rigging

Technical Details

I acquired this box from Brian Trevelyan on eBay in 2005. I acquired another in 2017 as part of Bob Thrun's collection.

The description is similar to Version A's, so I'll note the differences in red:

The box consists of a frame, two rollers, an axle, two side plates, and miscellaneous parts. The frame is made from a T-shaped aluminum extrusion, cut to 76.2 mm. length. The crossbar on the T is 76.2 mm. wide and the stem is 52.1 mm. long; each is 6.4 mm. thick. The cross piece of the T forms the back of the box, and rests against the climber's chest. The back has a 52 mm. tall, 7 mm. wide slot milled at a 45° angle (front to back) in each side and a centered 26.5 mm. wide, 7 mm. high top slot to accept a chest harness. The top of the stem is cut off at a bout a 45° angle starting just below the top slot. The bottom is rounded on a 19.3 mm. radius circular arc centered on the axle centerline. This arc is tangent to the bottom of the box.

The axle is a 71 mm. long, 5/16" (8 mm.) steel rod threaded on both ends. The bolt passes from the climber's left to right through a hex nut, flat washer, the left side plate, left roller/bushing, frame, right roller/bushing, right side plate, another flat washer, and finally another hex nut. The ends of the rod are crudely chiseled and punched to keep the nuts in place. Each roller is made from hard gray plastic. The rollers are 16.2 mm. wide and have a major diameter of 25.8 mm. Each roller has a centered 11 mm. U-shaped groove turned in it to a depth that gives a 21.6 mm. minor diameter. I don't see a ny roller bushings, and the rollers do rub against the side plates and frame.

Each side plate is made from an irregular piece of 2.8 mm. aluminum. The top half of a side plate is a 25.4 mm. circular arc, the lower front is cut at 45° angle, and the lower rear has a flat base and an extension that is curved inward to fit just forward of the frame.

There are no markings on the device.

Comments

Although essentially unused, this is much older than the 2005 acquisition date suggests. I recall seeing a virtually identical Neil Box at the NSS Vertical Section meeting at our 1978 convention - even the color is the same. I am fairly certain that that box was the one that I later acquired as part of Bob Thrun's collection.

Aside from the finish and dimensional differences, this box has two features missing on Version A: the horizontal slot and angled side slots. Neither is essential. I don't need the slot with my harness, but I like the angled side slots since it makes it easier to adjust the lateral position of the box on my harness.