Replacement Petzl Stop Nut?

tdobson

tdobson

Member
Like a clever person, I replaced a worn bobbin on this Stop and thought "ahhh, many more years of usage out of this!"

But like a twerp, I didn't locktite the nut....

And so I've lost it.

I'm quite eager to locate a suitable nut (I have the locktite now!) because it's literally the only thing between me and a working Stop

Anyone got any suggestions of where I might locate one? Have to spend money or send beer money or cave rescue donations to anyone able to bridge the gap!

-Tim
 

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T

topcat

Active member
I doubt it would have to be Stop specific: any stainless steel half nut of the appropriate thread pitch and size should do.
I replaced the nuts on a Kong simple this way and haven't died.  Yet. :)
 
W

Wolfo

Member
It's a M8 (metric thread M8x1,25mm) nut, detailed information:
DIN 439/DIN-EN-ISO 4035, rustless steel A4, raw, type B
 
Wayland Smith

Wayland Smith

Active member
It will be 8mm or 10mm standard metric thread.
Loads on E-pay.
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=stainless+half+nuts&_sacat=0&LH_TitleDesc=0&LH_PrefLoc=1&_osacat=0&_odkw=316+stainless+half+nuts&rt=nc
(Watch that you are not ordering from China, long delivery times.)
 
wellyjen

wellyjen

Well-known member
It is a Stop specific nut, not a standard metric half nut. There is a built in flange underneath, so when it is tightened on to the top bobbin it leaves a gap to allow the top plate to slide in and be captured under the hexagonal bit. Someone with a lathe could modify a standard full nut in minutes, but if you can't do this, then the proper Petzl part is a much better idea than a bodge, what with it being safety critical and all.
Jen
Edited to add a picture.
 

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B

Benfool

Member
As Jen said, the nut has a flange on it so it leaves the correct gap and can be tightened against the bobbin. I personally wouldn't use a standard nut.

However I'm pretty certain its the same nut as the simple, so there should be spares available. Have a chat to Tony, he might be able to get you one from Petzl.

B
 
I

iwebb

New member
I have just measured the nut on my stop at 14mm across the flats
Most off the shelf nuts are 13mm across the flats so modifying a standard nut is not an option

As said before the easiest option is buy one from Tony if available

I could make you one if all other possibilities fail from A4 Stainless steel depending on availability of material

PM me for further details
 
Badlad

Badlad

Administrator
Staff member
Someone is bound to have some old stops lying around with perfectly good bolts.  A year or so ago I threw out six old stops which I had accumulated over the years.  I'm sure they would have done you.  Try rope access people perhaps.
 
cavemanmike

cavemanmike

Well-known member
It might be worth having a look at army surplus outlets, I bought a bunch of stops from one in Denbigh for no money at all. Good luck
 
wellyjen

wellyjen

Well-known member
Some in situ measurements from my Stop, in case the secondhand route doesn't work out and you want to get one made instead. 14mm AF hexagonal bar stock is available in a number of grades. The first search link was around ?6 for a 250mm long length of 303 grade stainless, so not too bad, if someone can turn one up for you.
Overall height 7mm. Height of flanged section 3.5mm. Diameter of flanged section 10mm. The top plate is 3mm thick and has a notch 12mm wide, which fits under the 14mm AF hex nut head. I've not taken it apart to confirm that it is a standard course M8 pitch bolt it goes on as I don't have any thread lock compound and don't want to risk losing it!  ;)
Jen
 
tdobson

tdobson

Member
al said:
PM sent.
Click to expand...

I just wanted to thank everyone in this thread, and across the Caving Community for all their support and nice words - the response has been much more positive than I expected. Y'all are wonderful! ;)

 
I

Ian Ball

Well-known member
I should thank you too Mr D, I replaced the bobbins on my Stop over lockdown but thought the addition of loctite was a bit of scaremongering. I've changed my mind and gunged the threads up with the stuff now.  (y)
 
tdobson

tdobson

Member
Yeah - I think I thought the same. I'm still expecting the nut to turn up and taunt me the moment I sort it.

I don't think I even lost it in a cave!
 
F

Fjell

Well-known member
For the avoidance of doubt. Handily it also gives you the setting for your torque wrench to avoid under or over tightening it. Wouldn?t be cool to crack the alloy.
This level of maintenance has now been removed as an option from the new Stop. Fewer grieving widows/widowers suing people. And if you are paying ?50-100 an hour for a maintainer, modular replacement is it - opening the box of a new one is quite enough.
 

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Ian P

Ian P

Administrator
Staff member
Whilst personally the thought of ?messing? with life critical items is uncomfortable.
A small stack of suitable SS washers then a nut of your choice ???

Pressume you got sorted, just adding to the information for future when we are all trying to keep the old stops going  :eek:
 
PeteHall

PeteHall

Moderator
Ian P said:
Whilst personally the thought of ?messing? with life critical items is uncomfortable.
A small stack of suitable SS washers then a nut of your choice ??
Click to expand...

Definitely not!  :eek:

The proper nut is threaded right the way down. By adding a stack of washers, you'd end up with about two turns of thread doing all the work. Not a wise move.
 
C

Chocolate fireguard

Active member
Rather than buy another descender I would be happy to buy a longer screw and adopt Ian P's suggestion, perhaps using 2 half nuts locked together.

Also I think that torque figure is for when the screw is tightened to hold the bobbin onto the back plate, not for the nut.

In use there is little or no outward force on the top plate, which is held by the flanged pillar at the top and the pivot in the middle, so cannot release the rope. If the nut were to fall off part way down a pitch it would grab some attention, but nothing dramatic would happen.

 
pwhole

pwhole

Well-known member
I abseiled down Murmuring Churn in Maskhill with a central nut unscrewing, unbeknownst to me at the time, as it's not something I really check for - though this was a Kong Banana, not a Stop. But the descender didn't come apart, and it was only when I unhitched it from the rope that the nut fell off in my hand. Not having the correct spanner I just had to nip it up with my fingers. If I'd dropped and lost the damn thing I would still have had to do the rest of the down pitches, though I'm glad I didn't have to test it any further.

I may have an old Stop in a bag somewhere.
 
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