Homemade Prototype Nuts


Original Post
Joe Lange · · Unknown Hometown · Joined Aug 2015 · Points: 0

Hi All,

I am looking to make some climbing gear. Not to climb on but to make just for fun and to do some destructive failure testing. Because I am a mechanical engineer, I have full access to CNC machining, heat treating, anodizing. Basically a full production ability to do it right. I will be doing a full FEA analysis of these parts to validate things before I test them on the material testing machine.

The things that I would really appreciate from this community:

1. Where can I buy some wire for the nuts? I was planning on swaging the nuts for one of the prototypes.

2. I was planning on making offsets and and regular nuts. Any thoughts on this?

Also, I realize that I have earned the obligatory "yer gonna die" I would appreciate some leads (ha puns) on this.

Thanks

Kristoffer · · North Bend, Wa · Joined Feb 2006 · Points: 50

google aircraft cable.

Nick Penatzer · · Pittsburgh, PA · Joined May 2013 · Points: 35

As a fellow engineer, I think this is a really cool idea! For your second point, I have not used offset nuts before, but I have friends that swear by them, to the point that they have at times climbed exclusively with them over standard nuts. Interested in hearing how your project goes. Keep me posted!

Gunks Jesse · · Shawangunk Township, NY · Joined May 2014 · Points: 233

Also a mechanical engineer here - I've made my own gear and climbed on it. If you do full fea (instead of my hand calculations) and destructive test it (instead of intentionally falling on it with a couple backups), then why not use it? I suppose because your gonna die... you should be able to find the cable at Fastenal or McMaster. Check the spec sheets for swayed connections, but you already knew that.

Make it more interesting and get on a Bridgeport like I did - skip the CNC. You'll have more fun.

Allen Sanderson · · Oootah · Joined Jul 2007 · Points: 1,135

A couple of suggestions check out the specs for UIAA and CE requirements. You will learn a lot. Also try to look at something that not been previously studied (I would look at ribbed thinned walled cams lobes). For instance, BITD my senior thesis was on environment affects on ropes.

Chris Sheridan · · Boulder, CO · Joined Jan 2006 · Points: 1,625

Here's a good place to start of the cable: https://www.mcmaster.com/#standard-wire-rope/=15vgppx

I'm looking forward to hearing how it goes.

Alex Zucca · · University Heights · Joined Oct 2013 · Points: 285

Another mechanical engineer here. I've made a #7 BD hex and a #3 BD cam on a prototrak mill. I didn't do any FEA, just hand calculations. PM me if you want more info.

Andy Rasmussen · · MA · Joined Jan 2016 · Points: 45
Gunks Jesse wrote:Also a mechanical engineer here - I've made my own gear and climbed on it. If you do full fea (instead of my hand calculations) and destructive test it (instead of intentionally falling on it with a couple backups), then why not use it? I suppose because your gonna die... you should be able to find the cable at Fastenal or McMaster. Check the spec sheets for swayed connections, but you already knew that. Make it more interesting and get on a Bridgeport like I did - skip the CNC. You'll have more fun.
Can you post some pics of the gear you made? I'm curious.
Tev · · Hickory · Joined May 2012 · Points: 25

Andy,
Nice profile pic. Big fan of My Bloody Valentine!

Politically Correct Ball · · From WA to AZ · Joined Dec 2016 · Points: 5

...but new-school climbers already shun the nuts I have on my rack as it is.

What you should really do is make a better tricam, like small sizes which can take bigger whips and are easier to remove.

adeadhead · · Baltimore, Maryland · Joined Mar 2015 · Points: 25
Politically Correct Ball wrote:...but new-school climbers already shun the nuts I have on my rack as it is. What you should really do is make a better tricam, like small sizes which can take bigger whips and are easier to remove.
Show me a 5kn drop test and take my money.
Gunkiemike · · Unknown Hometown · Joined Jul 2009 · Points: 2,755

Everything else being equal, an offset nut is going to be more challenging to test b/c you'll need a test fixture that's equally offset.

You probably know this, but cabled nuts fail when the cable fails. Direct most of your attention there rather than the solid Al body of the piece.

Question - are your nuts going to be any different that what's on the market now? I'll PM you an idea for something novel.

Joe Lange · · Unknown Hometown · Joined Aug 2015 · Points: 0

Thanks for the replies and ideas guys! Really cool so many have you have made your own gear.

I have full confidence in any of the aluminum nuts that I can make but I wanted to destructive test to make sure my wires and swaged connections are good before using them since I do know they are the weak spot. If I can validate them, I would have no problem using them. As for the FEA it would mainly be for weight reduction but I would start with hand calculations.

I have been looking at the UIAA and respective EN specs that lay out the requirements. From what I can tell it seems like a medium and large sized nuts needs to hold a 10kN and 14kN falls respectively at minimum so that is a starting point for calculations at least. I would love to see any pictures of the gear you guys have made.

amarius · · Nowhere, OK · Joined Feb 2012 · Points: 20

FYI - you can swage cables at WesternMarine stores.

Brian Matusiewicz · · Bridgewater · Joined Dec 2015 · Points: 35

Would definitely love to see some pictures of anything any of you guys have made!

Allen Sanderson · · Oootah · Joined Jul 2007 · Points: 1,135
Gunkiemike wrote:Everything else being equal, an offset nut is going to be more challenging to test b/c you'll need a test fixture that's equally offset.
When Chris Harmston was doing QA at BD he got a big chuckle after he found our reports in the archives. Especially when he realized he knew me as we were both living in SLC. Still sitting in my basement were the jigs we made to test stoppers hexs (after 10 years and several moves). I gave them to BD as Chouinard had donated gear to us. Chris actually used them for some of their testing.

Gunkiemike wrote: You probably know this, but cabled nuts fail when the cable fails. Direct most of your attention there rather than the solid Al body of the piece.
Very true for solid and thicker walled nuts/hexs. But for the thin walled hexs we found that we could pull the perlon through the wall but then the rough edge would cut the perlon and then it too would break. That was for a slow pull rather then a more dynamic fall. Which is actually one of issues with most testing - it is static not dynamic.
Joe Lange · · Unknown Hometown · Joined Aug 2015 · Points: 0
Allen Sanderson wrote: Very true for solid and thicker walled nuts/hexs. But for the thin walled hexs we found that we could pull the perlon through the wall but then the rough edge would cut the perlon and then it too would break.
Interesting and makes sense that you would get that type of failure. Do you know what the thickness of the wall would need to be to produce this failure mode?

Allen Sanderson wrote:That was for a slow pull rather then a more dynamic fall. Which is actually one of issues with most testing - it is static not dynamic.
Wouldn't a correction factor for the fact this is static testing be built into the standards? You don't hear about many instances of gear in good condition failing because of loading.
Jim Titt · · Germany · Joined Nov 2009 · Points: 490
Joe Lange wrote:Thanks for the replies and ideas guys! Really cool so many have you have made your own gear. I have full confidence in any of the aluminum nuts that I can make but I wanted to destructive test to make sure my wires and swaged connections are good before using them since I do know they are the weak spot. If I can validate them, I would have no problem using them. As for the FEA it would mainly be for weight reduction but I would start with hand calculations. I have been looking at the UIAA and respective EN specs that lay out the requirements. From what I can tell it seems like a medium and large sized nuts needs to hold a 10kN and 14kN falls respectively at minimum so that is a starting point for calculations at least. I would love to see any pictures of the gear you guys have made.
It´s 2kN minimum strength (below is progression only) and after that the manufacturer has to identify on the piece their guaranteed minimum.
Kristoffer · · North Bend, Wa · Joined Feb 2006 · Points: 50

If your swager is calibrated correctly and all swages pass with a go nogo gauge, you really dont need to test till destruction. these cable connections have already been engineered for load bearing purposes.

I should also note that you should not be using aluminum swages on stainless steel cable, nor would I suggest that you use SS cable for the aluminum nuts due to galvanic corrosion. on a positive note, galvanized aircraft cable is stronger than SS aircraft cable.

have you considered using spiced dyneema rather than cable?

Joe Lange · · Unknown Hometown · Joined Aug 2015 · Points: 0
Kristoffer wrote:If your swager is calibrated correctly and all swages pass with a go nogo gauge, you really dont need to test till destruction. these cable connections have already been engineered for load bearing purposes. I should also note that you should not be using aluminum swages on stainless steel cable, nor would I suggest that you use SS cable for the aluminum nuts due to galvanic corrosion. on a positive note, galvanized aircraft cable is stronger than SS aircraft cable. have you considered using spiced dyneema rather than cable?
This is some really great feedback. I really appreciate it. I realize that these have been engineered to handle the loads but I want to compare to some big name OEM nuts for peace of mind.

Also, the thought of Dyneema had not even entered my mind. Looks like the benefits are ~80% weight reduction, ~same strength compared to the same diameter of equivalent wire with the added bonus of no kinking. What are the downsides of it? Durability on rocks? I cant seem to find any other than that.
Gunkiemike · · Unknown Hometown · Joined Jul 2009 · Points: 2,755
Joe Lange wrote: This is some really great feedback. I really appreciate it. I realize that these have been engineered to handle the loads but I want to compare to some big name OEM nuts for peace of mind. Also, the thought of Dyneema had not even entered my mind. Looks like the benefits are ~80% weight reduction, ~same strength compared to the same diameter of equivalent wire with the added bonus of no kinking. What are the downsides of it? Durability on rocks? I cant seem to find any other than that.
Dyneema pros - lighter

Dyneema cons - doesn't last as long, is floppy - can't place nuts overhead, harder to remove the piece, snags on snaggy things, too fat for small nuts, can melt, requires specialized sewing to form loop, bulky - can't rack 6-8 nuts on one biner, more expensive.
Guideline #1: Don't be a jerk.

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