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Therrin This member has been banned. See the banlist for more information.
Location: North of Chicago, IL Gender: Male Total Likes: 279 likes
*Therrin puts on the penguin-suit
| | | | Re: Post your gear < Reply # 24 on 8/10/2012 7:28 AM > | Reply with Quote
| | | For all of the vertical access world : static rope For climbing where you expect to take falls, or rope swings : dynamic rope That makes it pretty easy. Technically, when doing vertical access (rappelling / ascending) you should always be *statically* connected to the rope and never put yourself in a situation where you can "fall" and create dynamic load forces anyway. If you're going to ascend a dynamic rope that is 100' long, and it's elongation is rated at 29%, then you will end up ascending 129' as your weight pulls the stretch out of the rope as you ascend up it. Conversely, static rope is closer to 3% - 5%, by standards. (roughly, I don't recall the exact standards) If you haven't read the book yet, this means that a "static" rope will only stretch a very small amount (roughly 3 to 5 feet at 2.70kN (600 pounds of force), per 100' of rope (so 6 to 10 feet for a 200' length). Dynamic rope runs (I think) somewhere around 24% to 30%. This stretching of the rope takes up the dynamic *force* generated when an object connected to the rope has slack, then falls and quickly takes up all that slack and loads the rope "dynamically" (multiplication of forces). Think of it this way. Static load = weight hanging from rope, not moving (relatively) Dynamic load = weight being dropped and the rope "catching" that weight = multiplication of forces Static rope is *supposed* to have some stretch to it. That 3% to 5% is important, and it is a good thing. As you rappel or ascend, you tend to put minute load forces on the rope when you stop, bounce, tug, or vary your speed. Each time you do that you're creating small dynamic forces which would otherwise be transferred straight into your anchor point, which would cause undue stress on it. That small amount of stretch in a static rope alows the rope itself to dampen and absorb those forces, protecting both you and your anchor point from taking the beating instead. Read the book though, it explains it better.
[last edit 8/10/2012 7:29 AM by Therrin - edited 1 times]
| Give a person a match and they'll be warm for a minute, but light them on fire and they'll be warm for the rest of their life. =) |
| Therrin This member has been banned. See the banlist for more information.
Location: North of Chicago, IL Gender: Male Total Likes: 279 likes
*Therrin puts on the penguin-suit
| | | | Re: Post your gear < Reply # 26 on 8/11/2012 5:26 AM > | Reply with Quote
| | | That 300' anthill shaft I descended out in Joshua Tree, at the Lorman Mine & Mill site was not the same, but it had 3 wicked overhangs. Each one you have to fight on the way up. And the whole time you're very aware that your rope is rubbing on them and you wish you'd brought along some extra protectors for it. You kinda have to ascend till your upper handled ascender is right up under where the rope hits the rock, then cram yourself up underneath it. Then either lunge upwards and try to scoot your ascender above the lip; or try to get a foot up high enough to push off of it. It's pretty crappy. The incline at the Union Mine near Atollia is the same. I took my new boss and his g/f (before he was my boss) out there for her first time descending & ascending. Dropped 2 ropes side-by-side, and went down it next to her to guide and instruct. Hit the overhang that I didn't know was there and she did a great job going over it and getting down. Going back up sucked cuz it pushed us into eachother. I had to get a few feet above her so we weren't fighting eachother for space. She managed it though. Helluva first ascent =P I've been working A LOT lately at my new job. (which, incidentally, is largely on fire right now, work cancelled till Monday at least). I'm trying to convince my boss to go on the trip. If he goes, I can definitely go
| Give a person a match and they'll be warm for a minute, but light them on fire and they'll be warm for the rest of their life. =) |
| Abby Normal
Location: Las Vegas Gender: Female Total Likes: 845 likes
| | | | Re: Post your gear < Reply # 30 on 9/12/2012 7:47 PM > | Reply with Quote
| | | Holy cow Batman, home made gear? Ummmm...Robin...all our gear is home made. Now shut up and get back to waxing the Batmobile. terapr0, nice work on the descenders. After carrying around a few steel mallions in my rigging bag, I'm not sure I would want to carry around a steel descender. I'm sure it's not a problems for you young guys. Heck, I wouldn't hesitate to lift my truck with one of those. Just a quick thought, powder coating will negate any friction surface you create by sanding. It would be fun to do a side-by-side test of one with powder coat and one with zinc coating to see the difference. I'm guessing the powder coat would be a bit faster. Wheeee Are the rigging plates the steel blocks in the upper portion of the photo or are those used on the machines you use? I'm trying to figure out how the carabiners would fit though that. I'm looking forward to seeing photos as you go and hearing about your "product testing". Abby Normal
| "Government is not a solution to our problem, government is the problem." Ronald Reagan |
| terapr0
Location: Sauga City Gender: Male Total Likes: 341 likes
www . tohellandback . net
| | | | Re: Post your gear < Reply # 31 on 9/14/2012 2:51 AM > | Reply with Quote
| | | thanks for the comments everyone. funny how I've had access to laser cutters, water jets, cnc mills & lathes, brake presses and all sorts of other industrial goodies for almost 7yrs at my current job, yet its only as I'm 2 weeks from leaving that I've had a flurry of ideas and motivation to follow through with them. doh! Abby: the blocks in the background are machined surface blocks used for positioning parts on a CMM machine (a really, really, really accurate measurement device)...I havent gotten around to cutting the rigging plates yet. Dont want to max out my favors with the laser department so soon. And yea I think the powdercoating would slightly decrease the friction over raw or zinc plated steel, but probably not by much, especially if I sandblast it first. The powdercoat wont fill or gloss over the pits and valleys created from blasting - the end product will be somewhat matte and have a similar finish to the substrate. Update on the rescue 8s - I got them back from the CNC mill today which machined all the edges round. On my lunch break I used a die grinder and belt sander to smooth at least one of them out and get it semi-polished. Unfortunately I also realized just how quickly they're going to rust. So instead of using mild steel for the final pieces, I asked to get 2 more cut from 3/8" 316L stainless steel. They should be cutting tonight. Machine dept. is pretty swamped, so I might just round the edges by hand with a die grinder. It'll take longer, but the end result will be about the same. good enough for me here are some pictures of the nearly-finished mild steel ones. One is more complete than the other, neither are 100% finished. A few coworkers were concerned about them being "strong enough", so I ran some calculations and determined they should be able to hold at least a 10,000lb static load. Good enough for me
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