UKH

This is a good reminder to regularly check your kit: https://www.incidents.thebmc.co.uk/responses/3f776905-33c4-4a1f-8f52-6a6ea6...

I'd query the use or history of the cam, had it been in a shallow pocket and fallen on previously. The manufacturer will be interested too.

The BMC published a related article a few years ago: https://www.thebmc.co.uk/have-you-checked-your-camming-devices-recently

That's scary. No obvious way that an inspection would have flagged that up.

That looks very, very well used, judging by the wear on the lobes!

Where is the picture of the lobes?

I'm wondering if the wires were broken since new due to a manufacturing issue and that the only thing holding it together was the rubber sleeving.

Just looked at mine and that's not really possible. There's a clear gap between the hard plastic sleeving and the head of the cam so it would just fall apart if the wires are broken where they are in this case. 

Also as the sleeving is hard plastic and freely rotates around the wire stem. So the plastic and the stem are not bound in anyway and the cam would just fall apart without at least some wires being unbroken somewhere in the wire stem. 

Looking at the name on the report and the state of the lobes I'm pretty sure that will have had a lot of quite adventurous use but still!

It's not one big overload event that's done that and it certainly wasn't made like that. It's either failed through countless small head flexing cycles embrittling and breaking a strand or two at a time. Or perhaps more likely given the wear and tear option seems so incredible and it looks like stainless cable it could be corrosion cracking where damp salts can accumulate right where there may also be significant local stress in the wires from the crimp. A detailed expert examination should reveal the cause.

Either way, very worrying!

jk

Needs assessing professionally, they'll be able to tell if it's repeat flexing, over loading, corrosion etc.. they've failed in what appears a neat line across. 

When I've seen wires, or steel cable fail it's usually slowly, a single strand at a time, they stick out, unravel a bit, the next fails a bit later and on it goes. I could replicate that image with a disc cutter. Even stress and strain around a radius wouldn't produce such a neat line. 

Is that a DMM dragon cam or a Camalot?  Whilst reslinging might not be a causitive factor, it may prolong the use of damaged units, -very worrying pictures.

It’s DMM

Good robust inspection uses all of the senses, I would be very surprised if it was not possible to feel or hear something whilst flexing the wire at the obvious failure point.

Woah! Scary. Especially as my identical cams are well-used and probably 8 years old... But, they've not spent a lot of time at the seaside. Will definitely be giving them a superstitious inspection this evening!

The owner has usefully left his logbook public where he reveals he's climbed roughly 3800 trad. routes over the last 8 years or around 480 a year. Even taking into account some of these are solos it's impressive productivity and the cam has probably lead an active life.

A very helpful warning nonetheless. 

Regardless of how well used it's been I'm really hoping to see DMM step up and investigate thoroughly.

I seem to remember a similar failure a few months ago and someone posted a link to a BMC report into a stem failure a few years ago.

Please can someone post the link again. Thanks

Is the consensus for retiring gear 5 years for regular use and 10 years for storage/seldom used gear?

No one likes to retire gear though.

For some reason, the images load on my phone but not on my laptop.

When they go for reslinging they are also inspected by DMM. I've had units retired due to issues found during this inspection. 

The reslinging service is a resounding positive and not a negative here. The sling does not last as long as the rest of the unit and needs to be replaced during the normal lifespan of the rest of the cam in the vast majority of cases.  

Adding a really tatty sling to the mix does not help matters one jot. 

There's no specific date in reality, as stated in the info with a lot of gear a item can be destroyed in a single use so don't just trust that because it's not reached X date it's safe.

I asked Graeme if he'd been wanging on horizontals on the reg when he showed me this and he said he doesn't fall off much. I've climbed with him a few times and haven't had to catch him yet. 

Bit scary as it's pretty much impossible to check this part of the cam. 

It was my cam in the report, the following is a bit of more detailed info that may answer some of the questions:

Bought new late Aug 2015 form a climbing shop.

Has seen continual use since then in all environments including sea cliffs. I don't know how many routes i have used it on but i think it would be several thousand (see my logbook to see how often it could have been used). I rarely fall off or dog/aid routes however I do wonder if the amount of times it has been flexed placing and removing out of tight placements in this time compared to the amount of use other people would give a cam of the same age has contributed to the stem wires breaking. I do have to confess i haven't washed my gear after every sea cliff adventure and this may be a contributing factor but at this stage it would just speculation. Non of the other parts of the cam have got any obvious salt corrosion on them, I have had to throw away a number of DMM snap gates over the year where this has occurred so it could be a factor to investigate.

In Feb 2022 I sent this cam and 2 others bought at the same time off to have their trigger wires and slings replaced. As can be seen in one of the photos the sling has a batch number to say it was replaced on 21-MARCH-2022 see https://dmmwales.com/pages/dmm-product-markings-and-packaging. I have no idea what level of inspection was carried out when this was done but DMM state that "We offer servicing and re-slinging for DMM Cams and Torque Nuts if they pass a quality inspection." so it should have been inspected in some way but this may not have identified an issues with the cam assuming there was anything to see at that time. see page for further detail: https://dmmwales.com/pages/warranty-returns-servicing-repairs#servicing-rep...

The catastrophic breakage occurred with no warning when I pulled back the trigger to place the cam. Luckily I was on a route with other gear options and with grades in hand but with an incoming tide I continued up the route. Prior to this I did not notice any extra flexibility in the stem or any other indications it was about to fail. In fact following a post on the Climbers Club Facebook on 1st April 2023 group about someone having a similar failure but on much older WC friends I inspecting all my cams for broken wires and could not see any so either the failure has occurred since then to all the wire or i failed to spot any early warning signs.

I am happy for DMM or the BMC to investigate the cam further perhaps also the ones bought at the same time to see if any conclusions can be drawn to avoid this happening to anyone else. The previous day the cam was used for belaying off (in addition to another item of gear) but more worrying my climbing partner used it as the main piece of gear to do a run out above (no fall was taken) and on many others occasions this could have been a crucial runner so the outcome could have been a lot worse. 

hope this all makes sense and fire up any further questions

graeme

It would be interesting to see if it was corrosion, it would be equally hard for sea water to access there, as a rinsing would be to remove it or dilute it. Wonder if the rubber/plastic sleeve is actually a disadvantage in that respect, plus as you say making inspecting it impossible. The swage held as there's cable still in there. 8 years seems quite a concerning short life span. 

Edit. I've taken the liberty of sending DMM a link to this thread. I'd expect them to be as curious as many of us are. 

It looks like it's part of DMM's standard inspection routine they expect users to follow (~1:50). It seems like the damage might have been seen from carrying out that part of the process (though hard to say from pics)

Edit: although looking again maybe the breakages were too low down to be obvious.

youtube.com/watch?v=kgg3oMLZp54&

I am happy to raise it with Dan Middleton to see how we normally handle equipment failures like this, I am not sure if tech Committee still have access to the microscope used in previous failure investigations as this would enable an inspection of the crystallographic structure to give more information about the failure modes involved (IIRC it lives in Dan's desk).

DMM may want a look at it to determine if it's a failure mode likely to occur on other units and if a recall is required, or if there is something specific to that unit (amount of usage or one-off manufacturing fault).

Cheers

Spenser Gray

Tech Committee Chair

Thanks Spenser.

since submitting the report I have had an email this morning from incident reports to say the photos have been passed on to Dan Middleton.

No worries, he has two emails about this now then (sorry Dan!).

Hi Graeme, Hi UKC,

We’d really like to get the unit back for a thorough inspection and investigation to understand what has happened with the Dragon Cam.

Graeme – If you could email cs@dmmwales.com we’ll arrange return and get the process underway.

All the best,
DMM

I'm not suggesting anything untoward in this case, but would it not be better for the failed device to go to a neutral third party for study (most obviously for us in the UK, the BMC Technical Committee) first, before it is returned to the manufacturer?

From looking at the BMC article from 10 years ago, this sounds like it's a "normal" (!!!) failure mode for flexible cams. The manufacturers are of course aware of this but presumably every failure they see might give them information on how to alter the design to reduce the likelihood of this failure mode occurring - stick with rigid stem cams 😁

Please can you post a link to the article  thanks

Is the 3rd post in the thread

https://www.thebmc.co.uk/have-you-checked-your-camming-devices-recently

Thanks for the quick response have sent you an email.

This looks to me to be a rare but known failure mode for stems with a single short piece of cable. It's caused by the crimp at either end of the cable preventing movement within the cable and gradually over time creating a fatigue point at the crimp site. It will have little to do with corrosion, although of course that would make it worse if there is corrosion. If this indeed the case, this failure is about lots of use, which is what the owner has indicated. I would be surprised if the guys at DMM would be surprised by this failure, its something I've seen before. And transition from cable to a fixed node will be a site for fatigue with time, for example silver soldered wires in microwires, hence needing to inspect your gear. Not sure how this got last the inspection and that's not my place to speculate on.

Do you think this type of fault/failure point should be obvious before it happens if you inspect your gear? Would it be one broken strand? Do they break one at a time at a point that is visible?

Thanks

I've not seen a partially broken one so I can't say for sure. They seem to go inside the termination so not sure how wobbly it is before it goes completely. It seems to be less of a problem when it's a long loop of cable like BD or WC. But there is a patent which prevented DMM going down that road and why WC helium cams had a thinner section of cable spliced to a thicker piece with a copper ferrule. Tied hands and all that. There is a patent owned by DMM which I reckon would cure this but I suspect its too expensive a option to make it commercially viable? But that's speculation on my part...

He/she had clearly just fallen out with their husband/wife ….

That's a wildly unhelpful and unfunny comment...

Scary stuff.  Some of the cams I first bought are 20 years old and the ones I inherited are at least 10 years older than that.  Might have to inspect them all!

If you haven't inspected your gear in the last 20 years it may be time to consider giving it a quick once over.

I would expect that with all of the stresses on the outside of the bend, single broken wires would lift out of the ferrule slightly so you could see relative movement between strands. I also suspect that some noise would be generated if quite a few were broken as you bent them in the opposite direction (i.e. compressing groups of broken strands against each other, endwise on. Probably creating a 'crunchy' noise). It would be great to find some partially broken ones if people can check under the plastic covering as they bend the cam -  as shown in the assessment video. 

I wonder if soldering the joint might move the failure point out into a more visible position?

I don't believe it will because you are just moving the problem and soldering causes other issues. You are still mechanically fixing the ends of the wires and you are also heating the wire although I'm not sure if that would have an effect as the cables are either 304 or 316 stainless. They do hold patent no. EP 2 853 296 A1 which I *think* would sort the problem, but it's probably an expensive solution for them as it requires 2 silver soldered cables and an extra Aluminium piece. It's a shame its not used as its just a better solution than the pigs nostrils... IMHO of course... https://drive.google.com/file/d/1UzqEQxuJfRICIDk3kdUwFmzR3FYe03ZK/view?usp=...

I have a good look at them whenever I give them a wash but this only really after sea cliff climbing, winter climbing or climbing somewhere really grotty.   You are right though, I should probably take a look more often than that.  A job for the weekend.

Sorry, realised I copied my Google drive location rather than a publicly viewable document...

https://patents.google.com/patent/EP2954937B1/en?inventor=Mcmaster+Darren&a...

I'm struggling to get my head around what that patent is suggesting in terms of securing the stem to the head? Is it just a loop with the wire ends being secured at the thumb loop end? From what I remember the BD Ultralight Camalots have a Dyneema stem, but I presume that is secured at the head, not at the thumb loop?

As far as I can tell they detail several other developments implemented in the current generation of dragon cams in the same patent such as the machined lobes etc?

I've not seen the problem on cams but I have seen similar problems with control cables on machinery and you can both hear and feel the broken strands "rubbing" together.

You get the same effect with hydraulic hoses where the wires are totally encased within the walls of the hose.

Just was browsing the patents and I see you have filed for this:

https://patents.google.com/patent/GB2615745A/en?inventor=Mcmaster+Darren

You should be aware that Metolius have been doing something like this for years without protection, so your claim may be invalid... sorry to be the bearer of bad news...

It describes two independent wires terminated with a silver soldered lug which is seated in the aluminium thumbloop piece. The ends are then passed through the plastic stem tube and both are hydraulically crimped into place in the termination at the lobe end. This means the wires move independently of one another. We looked at something similar for WC but they had already patented this so as it was already claimed we had to stop.

Does that not retain the stress raisers associated with having them crimped into place at the lobe end which has likely contributed to this failure (albeit only after very heavy use).

I'm surprised that any of that is considered unique enough to secure a patent, it appears to be a collection of fairly standard methods for securing cables?

It's the method of forming the thumbloop which is patented, not the way you affix the lugs to the end of the cable. And in patent law possession is 9/10s of the law...

Yes it does but it is specifically the other end also being captive which is the issue. If the stainless lug is loose in the aluminium housing, it means that you're allowing the lug to move in a few different planes which should IMO reduce the issue.

"stainless lug is loose in the aluminium housing" - won't that introduce other wear issues?

Ultimately, any piece of kit that includes a mechanism is likely to wear out sooner than a solid piece of kit - 50 year old hexentrics - no problemo.

A cable isn't a solid piece of kit though as shown by this failure. Ultimately no one knows until you put one in the field for 10 years... and your example of a hex is a bit spurious. It's a lump of aluminium. Not much to go wrong. Anyway, it's all a moot point. If they were going to release it they'd have done it by now, the patents getting on for 10years old now...

No he hadn't. And however much he may irritate me at times, I prefer my husband alive rather than dead

With other companies/industries I'd agree. But first and foremost DMM are climbers themselves. They know their customers' (and perhaps their own) lives depend on the reliability of their kit. The testing they've previously published shows how seriously they look into any failure, or aging gear. I've never met any of them, but will continue to trust in their honesty and expertise.

Same thing happened to a friend of ours. Went to place it and the wire snapped. No prior falls.

I have checked ones I have and due to the plastic sleeve it is hard to see if damage has occured other than listening or checking how it flexes.

Respect to you for creating a profile just to come and clear that up ! Hang on, I feel a tin hat moment coming on. 

Just double checked and you've been on here for ages - sorry ! Tin hats stand down !

I just found it weird that all the strands failed spontaneously which, to my mind cries foul play. 

I'll be checking my flexible friends post haste.

There's your problem.. Assuming they all failed at once. Almost certainly didn't fail that way.

In fact individual strands are almost certainly failing sequentially from the outside in, and as each failed, the rest of the load is then passed onto the outermost again. 

Yesterday at an informal club workshop, we subjected two sacrificial cams (old Wild Country flexible friends) to repeated flex testing to see what we could learn.

This was not a controlled test, just an exercise in curiosity.

Cam A was subjected to repeated aggressive back and forth flexing of the stem by hand.

Cam B was secured in a vice and repeatedly loaded to flex the stem.

Cam A, showed signs of reduced elasticity after 15 back and forth manual flexes. At first the stem seemed to resist bending to the same degree through most of the bend angle. After 15 flexes, it felt less resistant at the start of the bend, and did not fully recover to straight, but remained a bit bent. It took another 80 flexes before we could hear wires breaking and then another 20 to cause the complete failure.

Cam B, in the vice, suffered 17.5 full flexes top to bottom, and then the head fell off when removing it from the vice.

And you conclusion is... it was worse or better than you hoped?

Good experiment

Can you expand on how cam B was repeatedly loaded?

The obvious conclusion is that flexing alone of this sort of cam is enough to degrade the strength over time. Not really a surprise, since I have often used flexing to snap individual wires.

I don't bring any materials science or engineering knowledge to this, so my expectations were purely based on experience with replacing cam triggers or breaking domestic wire.

I was hoping to get an early indicator of risk of impending failure.

Cam A surprised me because it showed a loss of springiness or elastic recovery earlier than I expected, but took many more bends than I expected before wires started breaking. I'd guessed around 20 aggressive bends would snap the wires, and hadn't expected a prior loss of elasticity.

I think gently flexing your cams and checking that they spring back fully in the opposite direction is a useful test. If they stay bent, or don't spring back fully, then some of the wires are likely degraded. Store and transport them so they are protected from flexing.

I think it was body weight. I'll find out the details - I didn't see these tests, just the results.

The reason this happens is because the material has reached its yield strength, the point at which non elastic deformation occurs. With more flexing, greater deformation will take place until it breaks. Wires will thin etc until they can't take it anymore.

Has there been any known similar failings in Camalots? Asking for entirely selfish reasons.

Looking through my cams, I can that the plastic sleeve that covers the top section of stem appears to increase flexion in the wires where the plastic ends because it’s fairly stiff. In other words, it creates a bit of a pressure point there.

Whether that’s a factor or not I have no idea. Camelots and Dragons share the same sleeve feature.

I had a WC flexi friend fail in this way about 20 yrs ago. The cam was 5 or 10 yrs old. WC gave me a new one and asked me lots about its history. Thankfully I noticed nearly all strands had snapped while lubing it.

Out of curiosity, how old were the cams you tested to destruction, and had they previously seen plenty of hammer?

Also a general question to the thread - how often would this sort of extreme flexing, especially under load, happen in day-to-day climbing scenarios? If a cam was in a horizontal break and you took a fall on it I could see it stressing the stem, for example, but other than that nothing really sinister immediately comes to mind.

Not sure why you are getting dislikes for that. Very likely correct, I'd say.

If it's jammed in place it might get some fairly firm treatment to help free it, otherwise probably not many other causes of stem flexion.

Sometimes a second falling off can really wang a cam if it is at all off to the side. I've had partners turbo-dogging routes and the bending of a cam make me wince in sympathy for it. 

A very interesting thread. So summing up, the failures seem to be at the point at which the wire leaves the protective plastic sleeve and enters the swage (or whatever the correct technical term is).

Hence any flexing is concentrated in the tiny bit of wire here. It also seems that we don't need high shock loadings to cause a problem - just repeated flexure will do it. 

I would suspect (no evidence to prove) that the problem will be worse on smaller cams inserted in shallow horizontal breaks. Which is one of the key types of placements that we use such cams for. If the outside edge of the break happens to coincide with the end of the swage that will worsen the problem by making any bend more pronounced. High placements at belays on multipitch routes will be an issue, because the cam will be loaded in exactly this way. 

Paul

The cams are pretty old - about 20 years. However they had relatively little use as they were bought for me before I gained trad experience and I replaced them with a set of dragons.

My assumption was that someone risking their life on some gear they have had for years would check said gear. Would you go on a track day in a car, crash, then go - ooo look who would have thought my tyres were bald ! 

Don't worry bro. My ego remains intact.

You need to flex more.

That would lead to inelastic deformation and a catastrophic cable failure if I do it too much.

The entire point is that the damage occurs where you can't check.

I can bring some materials science to the party. Metals normally have their atoms arranged in the form of 'crystals' separated by 'dislocations' - look at a galvanised item to see the very large crystal structure in the zinc coating. Dislocations are where the atoms aren't packed neatly - two adjoining crystals have their atoms packed in different planes.

When you flex a bit of metal a little bit you stretch the bonds between the atoms and then they ping back to their original shape (this is what your car suspension springs do)  The metal is in it's 'elastic deformation zone'.

  When you flex it harder you will eventually exceed the atomic bond strength (probably at a dislocation zone) and the dislocation will move through the item as the atoms re-bond themselves in a different arrangement.  This movement will continue until the dislocation has nowhere to go, or the energy required to rearrange the bonds is higher than that you put in.  This rearrangement of atoms results in permanent deformation, and the force required to make this deformation is known as the 'yield stress'.  Think of this as opening out a paperclip - the metal is permanently deformed.

  Because it's harder to deform a crystal than it is to move a dislocation, and the dislocations left in the item require more energy to move them, the deformed metal is stiffer than the original metal.  When you try to flex it again it will invariably flex in a new place where the metal hasn't been flexed before.  This is why metal things get 'wobbly' when you try to straighten them, you're unable to straighten the original deformed section in preference to the rest of it.  Repeated flexing results in more dislocations moving each time and the part getting stiffer and stiffer.  This is called 'work hardening'.  It's why parts of engines are shot-peened - the action of the shot hitting the surface moves around the dislocations and stiffens the surface layer, making it harder. Cold forging (e.g. stamping of car body panels) and cold drawing (of wires/tubes) are similar - the resultant piece is stiffer and harder.  Eventually, with repeated flexing all the dislocations have been moved as far as they can and the only thing left to do is break atomic bonds in the resultant 'single crystal' structure... and the item breaks.   Go get a paperclip and start bending it

You would theoretically see an increase in stiffness due to the work hardening. As to how much stiffer the wires will be before breakage will depend on the shape of the stress-strain curve of the metal. If the breakage force ('tensile strength') isn't much higher than the yield stress you're going to get relatively little warning.  If there isn't a huge amount of deformation that can take place you won't get much warning.  I strongly suspect the wires will have been drawn during manufacture to improve their strength to weight ratio, thus a lot of the plastic deformation will have already occurred.  Beardy Mike might be able to add more from a manufacturer/designer point of view.

Looking at the actual failure at the top of the thread the logical place for flexing is halfway down the cable, and breakage at the head joint would have required the rest of the stem to be stiffer than the entry to the head.  It's almost as if the combination of cable & plastic sheath is too stiff for the user to notice before the cable fails at the weak point entering the head.  There's an additional problem that plastic deformation of the wire beyond the yield stress is being hidden by elastic deformation of the plastic sheath - the sheath is able to re-straighten the wire even though it's lost some of it's ability to absorb force.  It's as if the wire is weaker than the plastic, and it probably is in terms of fatigue cycling (repeated flexing) - the plastic will have a lower elastic modulus and be able to stretch further again and again without work-hardening.  The only logical explanation for the breakage is that it's been flexed back and forth loads of times and strands have individually broken over time, yet the plastic has hidden that by not losing it's stiffness - the stiffness of the cable is being determined by the plastic sheath, not the wire in the middle. The wire provides the strength in a 'tension situation' which the plastic wouldn't cope with, but is ultimately fairly flexy (hence the need for the plastic stiffening sheath.   Damage to an unprotected wire would have very obvious I suspect.

Would it be a good idea to remove these plastic sheaths? 

I'm with you - but like others have said - maybe we should do a test every time with flexible gear - people seem to be down with the idea that a flex could reveal anything if the down votes are anything to go by. 

I was wondering this myself. There's been a tendency, over time, to want to make all items look more sleek/smooth/refined. This can apply to everything from cars and electronics to things like tools (some of my adjustable spanners and hacksaws seem to have been made to look like they are 'aerodynamic' ) This is almost always achieved by putting a layer of plastic on the external surface.

In the case of cams it seems there is a pretty good reason not to cover the pinch points.

I really wish they would cover the swages on the trigger wires though. The first manufacturer to put some strain relief where they always always break would get my money. All my new cams get a blob of epoxy there.

Covering up the bits you need to inspect but not the bits where it would help is an odd, but apparently universal, design choice.

I wonder if the breaking of the swages isn't a 'micro-version' of what happened above.

It would be great if you as a DMM representative or graeme could eventually post an update with the results of the investigation 💚 

Hi UKC,

We’ve finished looking at the cam that Graeme returned us and have responded directly to Graeme. We have also shared the response with the BMC.  A copy of the main body of the email to Graeme outlining our findings is copied below and is shared with his agreement:

We confirm that the cam passed our inbound and outbound inspections carried out as part of the cam re-sling service we provided to you in February 2022.  The inbound inspection contains a detailed look at the stem junction where the cam has failed.  We also note that you’ve mentioned that you did a thorough inspection on your cams in April 2023.

The failure mode is consistent with the bending stress fatigue mentioned in the BMC article from 2013 Have you checked your camming devices recently? https://www.thebmc.co.uk/have-you-checked-your-camming-devices-recently rather than any issues or irregularities with materials or workmanship.

These breakages tend not to happen in one dramatic instance to the complete cross section of the stem, but rather the individual wire strands of the stem can get fatigued and snap one-by-one.  Once the initial strands start to break, it is easier for the other strands to follow.  With this in mind, catching the initial broken wires is essential.  Further guidance on inspection is found herehttps://dmmwales.com/knowledge/april-2021/cam-inspection-maintenance . Please pay particular attention when pulling back the plastic protector on the stem and make sure that there are no frayed or broken wires on the stem (you may require a magnifier for this). This will ensure any frayed/broken wires are picked up when they occur. (Cam inspection video for reference, 1:49 - Cam Inspection and Maintenance https://www.youtube.com/watch?v=kgg3oMLZp54&t=110s ). Once individual strands of wire start snapping the overall strength of the wire is reduced and it is not safe to climb on so must be retired. 

In the case of really well used cams that have seen lots of action (potentially including being part of top rope anchors, lots of falls and loading, usage for working routes, shallow/crozzly placements with sub-optimal loading) we would always recommend that a climber increases the frequency of their inspections to cater for the intensity of their usage. 

We’ve been asked to share our findings with the BMC too, so we’ll forward this to them in order that they can complete their incident reporting process which may involve issuing further guidance and advice to the climbing community. 

If you have any further questions we’ll be happy to try and answer them.

DMM

Thanks for the response. I look forward to seeing what you have sent over to the BMC (presumably Dan Middleton?)

Thanks

Spenser Gray

Tech Committee chair

Thanks for sharing your report.

Your link to dmm did not work for me so I have reposted it here: https://dmmwales.com/blogs/knowledge/cam-inspection-and-maintenance

This paragraph is consistent with the stem failure of one of our tests:

"Check that the stem has no sharp bends, or permanent deformations (some slight gentle, bending/curvature of the stem is acceptable)."