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Rate my Rack!

Is this rack worn out ?


  • Total voters
    26
  • Poll closed .

JasonC

Active member
I bought this rack some time ago (8 years?) - a hardly-used bargain on ebay.
As you can see, it's showing some signs of wear - so I wondered, how much wear can the bars take before it's no longer safe to use?
As you might deduce, I cave less than most of the users of this forum!

Opinions welcome, but please don't bother telling me you can change the bars round (done it), get replacements (no, as it's from Caving Supplies, not Petzl) or make new bars (I haven't got the kit), or start a debate about the best descenders.  And yes, I have got a stop, but I do rather like the rack.

Rack1.jpg

Rack2.jpg


Thanks
 

tamarmole

Member
Probably got a bit more life in it.  I would be tempted to dress the edges of the grooves to remove any potentially sharp edges.

I managed to put 3mm grooves in a set of aly rack bars on a single 50ft pitch, since then I have used stainless bars.  If you want to go down this route you will have to import from the US.  Try Inner Mountain Outfitters - I bought a BMS micro rack from them a couple of years ago, they are very helpful people.  The downside is shipping and import costs, I reckon this added almost 50% to the cost.
 

Pete K

Well-known member
It's end of life IMO.
If Phil at Caving Supplies can't do you some spare bars then I suggest you buy a new one.
Sure that many will say it's fine but you only have 1 life, is a replacement really that expensive?
 

Mike Hopley

New member
Pete K said:
It's end of life IMO.
If Phil at Caving Supplies can't do you some spare bars then I suggest you buy a new one.
Sure that many will say it's fine but you only have 1 life, is a replacement really that expensive?

I agree.

Sure, you could eke it out a bit longer and it would probably be fine. But given you are already questioning its safety now, how are you going to feel when it's worn some more?

Not only is a replacement quite cheap, but also think about it in terms of marginal cost. You can either retire it now or slightly later, so the effective difference in cost is very small. You cannot get another 8 years out of it.

Peace of mind is a real thing too! You don't want to have a niggling doubt in the back of your mind when you're leaning out over a big pitch...
 

robjones

New member
About ten years ago Phil Brown had a rummage in his spare parts drawers and managed to find three CS rack bars which I bought. He was pretty confident that they were the last ones he had.

Petzl bars can be a bit of a tight fit into a CS rack - you need to slightly compress the width of the frame to get them on.

If you are discarding that CS rack, I'll take the bars and the locknut for the price of a pint plus postage as they are in better condition than the bars on my rack!

I keep meaning to ask a local machine shop for a price to make a small batch of stainless bars...
 

PeteHall

Moderator
I do wonder what the mode of failiure is for a solid aluminium bar. My gut feeling is that once it is worn far enough, it will start to bend and close op on the rope, at which point you'd know it was time to replace them  ;)

I can't imagine the bars breaking before they start to bend, so unless you're planning a massive SRT trip on muddy rope, you're probably ok to continue using it for quite a while longer. However if it was me I'd be thinking about replacing the bars pretty soon.

It would be an interesting experiment to test one to destruction though. Perhaps the BCA Equipment and Techniques Committee might oblige if we all donate our retired rack bars  (y)

 

JasonC

Active member
PeteHall said:
I do wonder what the mode of failiure is for a solid aluminium bar. My gut feeling is that once it is worn far enough, it will start to bend and close up on the rope...

That was what I was curious about really - it's hard to imagine it failing suddenly or catastrophically, although Tamarole's point about ensuring no sharp edges is a good one.

I did take it to my local metalworking shop and asked if they could machine some new bars, but they declined as they didn't want to responsible for critical kit.  Elfn Safety gorn mad, innit?
 

owd git

Active member
zomjon said:
Have you asked Phil, because I've got a caving supplies rack, and he did put a petzl bar on it.

No he didn't. he sold me petzl replacement bars, i did the rest.  (y) :sneaky:
 

PeteHall

Moderator
JasonC said:
I did take it to my local metalworking shop and asked if they could machine some new bars, but they declined as they didn't want to responsible for critical kit.  Elfn Safety gorn mad, innit?
When I was at uni, I got some new bars made in the engineering workshops, they asked what it was for and I said it was a friction device for rope. "It's not PPE is it?" was the next question. I gave a big wink and said of course not, so they made them anyway and said be careful!

I think people just need to cover themselves, so just don't tell them what it's for and you might have better luck.  (y)
 

Antwan

New member
PeteHall said:
I do wonder what the mode of failiure is for a solid aluminium bar. My gut feeling is that once it is worn far enough, it will start to bend and close op on the rope, at which point you'd know it was time to replace them  ;)

I can't imagine the bars breaking before they start to bend, so unless you're planning a massive SRT trip on muddy rope, you're probably ok to continue using it for quite a while longer. However if it was me I'd be thinking about replacing the bars pretty soon.

It would be an interesting experiment to test one to destruction though. Perhaps the BCA Equipment and Techniques Committee might oblige if we all donate our retired rack bars  (y)

Unless the rack frame is made of spaghetti I would not expect the ends of the bars to move closer to each other, as would have to happen if they were going to bend and trap the rope once the bar is worn more than half way, instead I would expect it to ping open in a rather undramatic event
 

Kenilworth

New member
PeteHall said:
I do wonder what the mode of failiure is for a solid aluminium bar. My gut feeling is that once it is worn far enough, it will start to bend and close op on the rope, at which point you'd know it was time to replace them  ;)

I can't imagine the bars breaking before they start to bend, so unless you're planning a massive SRT trip on muddy rope, you're probably ok to continue using it for quite a while longer. However if it was me I'd be thinking about replacing the bars pretty soon.

It would be an interesting experiment to test one to destruction though. Perhaps the BCA Equipment and Techniques Committee might oblige if we all donate our retired rack bars  (y)

The failure mode is not bending or breaking, but increasing loss of braking ability due to decreased angle of bend around the bars. This point cannot be reached by any reasonable person, since they will have to be worn (depending on the rack, some offset bars more than others) almost through before they become dangerously fast. They have been tested to death, and remain useable far beyond most user's psychological tolerance. 
 

JasonC

Active member
Kenilworth said:
The failure mode is not bending or breaking, but increasing loss of braking ability due to decreased angle of bend around the bars. This point cannot be reached by any reasonable person, ...

Interesting.  That would make sense, and I have found myself using the 5th bar somewhat more recently, although it's obviously rope-dependent.
In the spirit of scientific enquiry (and Yorkshire reluctance to disturb my wallet unnecessarily), I'll carry on using it until it scares me, then post updated pics back here :)
 

John S

Member
I used my rack until the wear was to a point that the bars closed up to create a lock. The only way to finish the pitches off was to add a crab between the next two bars  and use the fifth bar which I didn't need normally. This was made worse by using a small diameter rope. This made it jam even more. It sound counter-intuitive, but that's what seems to happen.
No bending of the bars.
I also use a bit of copper tube to force a larger space between the top top bars to make the wear more even across the bars.

 

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Kenilworth

New member
Very interesting John, I've never heard of bar wear creating a pinch point. I have seen examples of bars worn even more than yours, and they rode so fast that a braking carabiner was added to the top of the rack. This was all with 11mm, so maybe that's the difference.

I'm not surprised that they didn't bend though. I have a 4-bar micro-rack frame that I have fitted with all manner of homemade bars; wood of different diameters, bone, plastic, etc. It seems that there is surprisingly little lateral force on the bars, and that friction, heat dissipation, and durability, not strength, are the factors driving bar manufacture.
 

pwhole

Well-known member
Doesn't the deposit of aluminium onto the rope become a problem though? I recently had to change the bottom bobbin of my Banana from ally to stainless, as the rate of wear was disturbing me, but the grey streaks I was leaving all over the rope disturbed me more. And frankly I find the smell of working aluminium repellent - having that alongside my nose was really spoiling my trips. So I swapped it out, and haven't had a problem other than it's a bit heavier - and my nostrils are happy too.

I can imagine stainless bars on a rack might be quick, but presumably they could be jammed tighter together, possibly even with elastic band stoppers?
 
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