Base Jacks, Acros, Trench Struts and Other Ironmongery

The Old Ruminator

Well-known member
For us at Vurley we have found the items above of great help in our dig. I don't want to start a war of words on the ethics or aesthetics regarding such things. Apart from Templeton  ironmongery in cave digs on Mendip is rarely seen in quantity though Willie Stanton used the odd bit of railway line in Reservoir Hole whilst his usual method was dry stone walling. Of course that is very time consuming and a lot harder to get right than you might think. Of course its worth bearing in mind that most things artificial in a cave will have a limited life span.

Base Jacks.

These are designed to hold vertical scaffold poles where the ground is uneven. The have a vertical load capacity of 4 to 6 tonnes. We are using them as climbing stemples fitted to a bit of pole and sitting on galvanised pins at either end. They can be used in place of trench struts or acro props with longer sections of pole.They are relatively cheap at about ?4 each

Peter Glanvill fitting Base jack climbing stemples.



Long term the weakness will be in the welding on the footplate so the central hole is used to sit on the pin.



Climbing stemples in place. In a restricted area the space behind them can be used to infill with boulders. Another good point is that pins can be used both ends and the pole does not have to be an exact fit.


 

The Old Ruminator

Well-known member
Trench Struts.

Like acro props but they come in shorter lengths and are designed to hold trench boards apart when fitted horizontally. The foot plate has upturned corners to grip the board. Like base jacks and acros the weakness will be in the weld holding the footplate to the strut. The weld gave way on an acro on the Reservoir Hole Ascension platform and the platform had to be rebuilt . The foot plate should sit flat on the wall on a central pin. If the foot plate is not flat it will stress the weld.

A trench strut used to support a temporary boulder store.



Acro Props.

The smallest size is 0 extending from about 1 metre to 1.8m. We tend to use them as temporary supports whilst other work is done. Sometimes they are built in and left.

Peter Glanvill fitting a temporary acro prop in Vurley terminal boulder choke.



A temporary arrangement in the boulder choke whilst we decide what course to take.


 

Ian Ball

Well-known member
Makes the efforts I go to of arriving and wandering through spaces constructed by others seem a little lazy.
 

Maj

Active member
I like the idea of the base jacks.
I sometime fabricate adjustable stemples from suitable walled and diameter tubing or scaffold pole.
I cut 4 triangular fillets out of the end of the tube, tap the remaining 4 points in and then weld together to create a solid point on the end of the tube.
A suitable diameter short length of studding ground to a point.
2 flats ground to take a spanner.
Pockets can be drilled or chiseled into the wall (if there isn't already a suitable depression) to locate the 2 ends of the stemple.
Pair of stilsons on the tube and spanner on the studding to tighten into place.

Oops! managed to post the photo twice.

Maj.

 

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SamT

Moderator
Love the look of them Maj,  I can think of numerous digs in the past where I would have liked a few of them!!
 

Rhys

Moderator
The base jacks have protruding handles. These look liable to being released by a careless welly or falling boulder. Is there a way of locking them?

The rescue team in south Wales had piles of stemples of a similar design to Maj's - I've never seen them in a dig though! Good work!

Rhys
 

Maj

Active member
Rhys said:
The base jacks have protruding handles. These look liable to being released by a careless welly or falling boulder. Is there a way of locking them?
Rhys

Bear in mind that when they fit base jacks they are pegged into the wall, so even if kicked loose, they are unlikely to drop out.
I suppose if a risk of getting kicked, the handles could be cut off or reduced. Could be done on the surface and stilsons used to tighten up.
The price of them sounds very reasonable.

Maj.
 

The Old Ruminator

Well-known member
Thanks Dave. I like your stemples. Send some over at ?3 each please. With us it is a matter of numerous things. Firstly up until now we have had all of the scaffold poles donated. Therefore we might have gone overboard in their use. Secondly in an active dig things evolve as ideas come in to being. That often occurs in the dig so post fabrication of stuff rarely happens. The base jacks have a 4 tonne plus load so are driven up very tight to the pole. I doubt you would kick them free. I would not cut off the screw arms as I have said things in a dig evolve over time and they might be replaced with a fixed ladder or even cleared away if that section of dig becomes a main route needing a ladder or SRT. I think that a            " finished " dig like Topless Aven Dig ( now a main route ) evolves into a different sort of passage in any case as it gets tidied up and problem areas are repaired. Some say that a dig that becomes a trade route remains the responsibility of the original diggers. Certainly much should be done to make the finished route more naturalistic so stemples used to facilitate hauling may well be removed.
 

The Old Ruminator

Well-known member
Fixed ladders. Well they are useful in digs . We tend to use the cut down loft ladder type as we have a maximum size that can be transported through the cave. I get them from a local scrap yard.



For our 7m entrance pipe we fitted an extending aluminium ladder donated by my Sister in Law. We have a removable top section of 1.5m to deter break ins. The removable top section clips into the slots at the top of the fixed ladder and then clips to the top of the concrete pipe.



Reservoir Hole was a bit of a conundrum. Fixed ladders or not ? The two in The Frozen Deep were placed there for conservation reasons as both short climbs are close to formations. A third ladder ( from Skyfall ) was left at WISh You Were Here. Its an awkward short climb near the top of the pitch. I suppose it could be removed. There is a fixed aluminium ladder above the platform on Ascension on the vertical wall there . Mainly for safety reasons . The platform was erected to keep climbers away from the loose boulders in the rift at that point. At some future date we hope to replace the wooden plank deck with plastic scaffold boards but as yet we have not researched the product thoroughly. Has anyone yet used non rot plastic scaffold boards in a cave.

For those interested here is a product description -

Plastic Scaffold Board (Supadeck)

    Description Delivery Details

Generation Supadeck is a unique lightweight decking system that is h3 and durable.  With its textured non-slip grip it is easier, safer and cleaner to use than steel and traditional timber scaffold boards.  The boards come in a range of lengths and are all 45mm deep x 225mm wide.

Generation Supadeck for tubular scaffolding: 45mm x 225mm clear spans of at least 1.5m.  Weight @ 3.9m ? 16kg

Generation Supadek for batten applications: 63mm x 225mm clear spans of at least 2.4m.  Weight @ 2.4m ? 11.5kg

Other additional benefits of the Generation Supadeck are:

    Stronger and lighter than traditional timber boards
    Long working life offers an excellent return on investment
    Environmentally friendly
    Can also be used with Genstage and Genlok System Scaffolding



 

The Old Ruminator

Well-known member
Base of our pipe fixed ladder and fixed ladder below in the top of the dig.



Fixing the entrance pipe ladder.



Single fixed pole in the top area of the dig. The cement should reveal and subsequent movement.





 

The Old Ruminator

Well-known member
Gabion baskets and cages.

More often seen along eroded river banks but can be useful in a vertical dig like the well named " Egg Timer ".

Gabion cage in The Egg Timer. This is not structural as there is another layer of supporting scaffolding behind. This method is used to create space for boulder dumping.



Securing The Egg Timer before the gabion cages were added.







Originally The Egg Timer shaft was dug several metres down only to find that the whole lot was sat on a cracked boulder below which was a large void. A " controlled" collapse of the whole shaft occurred and we had to start again.

Now diminished scaffold pole store in La La Land. The maximum length we can get there is 2.25 m.



Cutting poles in situ. With generator electricity this can be simple using a mains angle grinder. Its last use involved the operator leaping about the chamber with the switch jammed on getting successive electric shots. A battery angle grinder is safer.



 

The Old Ruminator

Well-known member
Boulders from The Egg Timer being stacked behind pinned scaffold tubes.



Later view.



Generator electric supply going down The Egg Timer.



Drilling rocks for Hilti capping.



With the powered drill we can get up to 50 caps use per session.



 

JasonC

Well-known member
Blimey, that's not digging, that's engineering!  You'll be getting headhunted by Cross Rail  :clap:
 

The Old Ruminator

Well-known member
Gabion cage ( right ) in The Egg Timer .



Temporary dig ladder in Skyfall.



With acro retained platform.





Ladder in Magic Smoke Dig. The Frozen Deep.



Installing the fixed ladder at upper Ascension.









Lower Ascension ladder or SRT pitch from the platform away from the loose boulders in the rift.

 

The Old Ruminator

Well-known member
Engineering is much more fun than mud sloshing. :LOL:

Thousands of botryoidal stalagmites on the wall below Ascension platform. Note the non slip decking.



Working on pitch platform into The Frozen Deep. Again built to avoid dangerous boulders.



The ladder drop now avoids that horrible boulder seen below.





Constructing the Ascension platform to avoid the boulders in the rift.







Scaffolding and Ali Moody at the breakthrough point below Great Expectations, Reservoir Hole.



 

The Old Ruminator

Well-known member
Capn Chris is quite correct and he knows I value his opinions. Willie spent 30 years building walls in Reservoir Hole . Sadly most of our digging team are of an age that we would be lucky to be caving in 5 years time let alone 30. Some of our ironmongery has been built into cemented walls and looks very naturalistic. However the current project at Vurley would require many tons of cement to do the job that scaffolding does. We are apparently now inside The South West Overthrust series of faults and distorted strata. That means quite a lot of boulders. I agree that dry stone walling and cementcrete ( the liquid cement that dries like flowstone Willie used in Reservoir) will always be preferable to scaffolding. A bit more from me later perhaps.
 
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