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Best timber for stemples?

pwhole

Well-known member
I've been having this discussion with a few people recently in terms of installation of climbing aids in mines and/or caves, where timber stemples were the original method, and we're often wrestling with problems like bad wall rock or very wide pitches to span, making Y-hangs almost impractical. In most cases many would reach for some (ideally new) scaff tube or stainless cable, etc., but I'm increasingly wondering whether simply re-stempling with timber would be appropriate, and if so, which timber? The sockets are usually still in-situ, and undamaged. And the elasticity of wood compared to metal is crucial for fitting them tightly.

I appreciate there can't really be 'standards' applied to timber installations in terms of caving organisations like DCA, but timber is no weaker than metal in many cases - we had five people climbing up the Titan Streamway cascades last night on a cut-down hickory pick-axe handle with some etriers, with the added advantages that it floats and doesn't damage the rock lip of the cascades. Some mines I've been in, particularly Odin Mine in Castleton, seem to have incredibly well-preserved stemples, and I've used many as deviations and climbing-aids in the past, so either something in the shaley atmosphere is preventing bacterial growth there, or Richard Bagshawe had a really good mate in the timber industry who was giving him the best material! Though the table legs in Chippendale Rift are probably from the 1960s. I've heard larch and elm can be quite good - obviously I'm trying to think 18th century fidelity here, so not tanalised, pressure-treated etc. - just good round fence posts or similar in a very strong, mould-resistant species - any ideas?
 

Brains

Well-known member
Pitch pine would be a good choice and is the timber used for the bridges in the slate caverns.
Oak is a poor choice as hard to work with and will degrade quickly
Elm will last well in wet conditions but can be expensive due to disease
Ash is very strong but not sure of longevity underground
Square cut or rounded is another issue
 

tomferry

Active member
I have got a lot of information in books I have about this will dig it out later if I get a chance . De barking the wood makes a large difference though as your are not risking taking in diseases in the bark , Are you going to use timber straight from a tree or seasoned ? Or purchase it for example 4” 4” 6ft long fence posts ?
 

pwhole

Well-known member
I have got a lot of information in books I have about this will dig it out later if I get a chance . De barking the wood makes a large difference though as your are not risking taking in diseases in the bark , Are you going to use timber straight from a tree or seasoned ? Or purchase it for example 4” 4” 6ft long fence posts ?

No idea yet - just thinking about the options and whether the push-fit of timber gives more flexibility than drilling and resining metal fixings in. It would definitely be de-barked, and almost certainly purchased, for standard sizes, and to answer Brains' point, probably round, just for ease of rigging and climbing with less rub on sharp corners. The other advantage of timber is that it can be checked and replaced easily, unlike resined-in metalwork.
 

Rob

Well-known member
We've used wood a few times for stemples in Cussey. I've found the best wood to use is whatever stuff i've had about. Bits of old table have mostly seemed to work well so far. Whilst an interesting discussion, I think in general it's easy to over think some things...
 

Mr Mike

Active member
CATMHS have used treated round fence posts as stemples that seem to have lasted a long time. Coniston is full of them in parts. A good example is in Nenthead in Frog Shaft. The Frog Shaft ones were installed circ 1991, we went to do a reki June 2007 and the shaft through trip in Oct 2007. They were sound, used one as a backup and one as the main hang down / deviation.
 

Brains

Well-known member
To avoid the overthinking thing, timber skids (the bits of wood that support goods to allow forklift access when pallets aren't used) can be very useful and free if you know the right people. Have used them in the past to good effect
The corners of square cut can appear sharp and can be rounded off with a hatchet. I believe in the round is harder to work with, and if turned like a fence post not really any stronger. Using a de barked log however is different if you can get a tree of the right size!
 

shotlighter

Active member
If you can get hold of it, greenheart is superb underground & was the choice of mine companies for anything "permanent". It is bloody hard, so try and do the cutting somewhere comfy. I've seen it sold from reclaimed dock piles etc.
Alternatively, the good old "Kirkham" expanding stemple, as used in Oxlow to support the Armco below the first pitch.
 

legendrider

Member
If its just for clambering, I agree with Tom Ferry regarding tanalised round fence posts. In a different application, our group are currently pushing an extensive dig 'somewhere interesting' and our primary support stemples are expanding scaff tubes pocketed into diamond-core-drilled holes either side on hangingwall and footwall of the vein - luckily the span is only 2-3 feet, never more than 6ft. The expanding bit is facilitated by use of a 250mm length of M20 zinc plated allthread, plus a nut and suitable thrust washer. If you grind off the corners of a M20 nut it will slide into a scaff, thereby centring the studding inside the tube. Another method is to use an internal steel pipe sleeve, both methods we have used to good effect. I'd happily primary belay off a steel expander; wood not so much.
 

tomferry

Active member
Emails sent over . I would see speak to any local tree surgeons to try get some lengths a few feet + , Store it let it season for up coming years “ de bark “ wood is only going up in money .
 

Pitlamp

Well-known member
Isn't there an old country saying that a fence post of yew will outlast a fencepost of iron?
 

pwhole

Well-known member
Thanks for the replies all - much appreciated. And yes, I think I have heard that one before. Hickory is certainly tough, but I can imagine it being possibly expensive in larger diameters - I normally only see it as handles for hitting tools. I'm just about to oil up my 'travelling stemple' actually - its been a few years.
 

tomferry

Active member
Isn't there an old country saying that a fence post of yew will outlast a fencepost of iron?
Yew is rock solid issue is how long it takes to grow usually only found here in church yards “East Midlands “ the one in my garden has grown around 25” in 8 years
 

bograt

Active member
The reason yew is mainly seen in churchyards is that it is highly poisonous to livestock so must be kept away from grazing land, it was grown for longbow making before saltpetre for gunpowder (and guns) became readily available.
 

Steve Clark

Active member
Western Red Cedar

Light, strong, very few defects, naturally oiled and moisture resistant.

We recently demolished a shed from the late 1980s, everything was rotten, ply roof, ship lap cladding, studs, flooring. All except 6 3x2 cedar floor joists, that were soaking wet but absolutely fine.
 

Tripod

Member
One day some years ago I was walking through some woodland with my hedgelaying mentor, who told me then about different timbers used for fence posts and rails. Something which struck home but I sadly cannot remember the details of now was that some timbers rot if sawn but not if split (and some rot if split but not if sawn (?) though that sounds less believable). Another opportunity missed but worth keeping in mind and worth researching further.
 

Brains

Well-known member
Split timber doesn't cut the fine structure of xylem and phloem, so less chance for water ingress... Think it's called frown or thrown... Can last a lot longer.
My mate in the wood working industry says...

"The answer is elm the second best is one of the oaks the old miners used the whole limb of oak but reaved the trunk of elm the thin boards were used for leats & barrows pitch pine was used for rail lines as it is soft enough to bend round corners and resistance enough against rot when soaking wet but does not splinter like oak & elm which is a problem with bare footed children☹️"
 

tomferry

Active member
Their is some beautiful pitch pine still in situ “rock hard” in north wales in parc lead mine . Make sure you contact cal for access .http://www.caveaccess.co.uk/

Mind the holes !!

Good luck finding any elm since the die back also oak trees are rare that’s coming down … I no where some limbs are from lightening damage I might have a go at this myself !
 
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