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The helical grooves make this look different, but it is essentially a vertical spool with close ties to the Sky Genie and Frost Rope-rider II.
The central portion of the Miller Descender is a forged shank with helical and longitudinal rope grooves. The grooves are just under 10 mm. deep, so using 9 mm. rope is indicated. Each end has an attachment point, and a horn at the bottom end provides a convenient fixture for tying off. The cover is made from sheet steel. An Allen bolt with a knurled knob secures the cover at the top, and a push pin secures it at the bottom.
The
Miller Descent Device is NOT reversible. If used upside
down, the cover may come off, leaving the rope free to uncoil.
The rope is rigged by removing the cover, wrapping the rope around the helical groove the proper number of times, and then running it out the longitudinal groove. The cover is then replaced. Instructions are clearly printed on the device, and give the following recommendations for the number of wraps:
| Slow Descent | 3-1/2 turns for 150-200 lbs (70-90 kg) | Add 1/2 turn for each additional 75 lbs (34 kg) |
| Medium Descent | 3 turns for 150-200 lbs (70-90 kg) | Add 1/2 turn for each additional 75 lbs (34 kg) |
Acquiring this device was amusing. I tried to order one in time for the 1991 NSS Convention so I could have it on display with the rest of my collection. They wouldn't sell it without selling me their own rope (I never learned whether the lawyer or accountant decided this), but they loaned me this demo unit for display. I returned it after convention, and a few weeks later the Large one arrived (along with 15 feet of rope - I didn't have to order much!). When I asked, I was told that the small one was no longer in production (the "bigger is better" crowd had forced them to redesign the device), and I could have it for free. Everything worked out in the end!
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This is the larger, more recent version of the Miller Descent Device. The device is simply a larger version of the original. The grooves are now about 17 mm. deep, allowing one to use huge 15 mm. or 5/8" ropes. Naturally, using such immense ropes will add more friction, so the instructions were revised as follows:
| Slow Descent | 3 turns for 150-200 lbs (70-90 kg) | Add 1/2 turn for each additional 75 lbs (34 kg) |
| Medium Descent | 2-1/2 turns for 150-200 lbs (70-90 kg) | Add 1/2 turn for each additional 75 lbs (34 kg) |
The
Miller Descent Device is NOT reversible. If used upside
down, the cover may come off, leaving the rope free to uncoil.
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©2007, Gary D. Storrick