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This is what you have been waiting for.
This shows the difference between the largest and one of the smallest fibre sizes. It is a lot easier to push that 72f through. The orange duct may well have the odd dent or kink in it, but if the front end of the fibre can get through, then the rest will follow. Lubricant is added to the fibre to help it slide.
If the fibre comes to a dead stop it means there is a blockage. Or the cumulative friction of 'tight spots' might slow the process down to a virtual standstill. The mass of the cable is also a factor, so it is better to blow downhill.
The simplest description of a simple case is:
Your task is to blow fibre from Chamber A to Chamber C via Chamber B.
- · Set up at Chamber A. Send air down the tube
- · Person at Chamber B says ‘got air’ (we're discussing a simple case here, sometimes he says he hasn't)
- · Send tiny sponge down tube from A to B
- · Person at Chamber B says either ‘got sponge, send fibre’ or ‘sponge a bit wet, send another’ (the simple case remember)
- · Eventually blow fibre into the duct.
- · If it reaches Chamber B, then someone stationed there will radio the people at Chamber A to stop.
- · If it gets stuck on the way to B, find it, mend it, continue until it does get to B.
- · Continue blowing the fibre from A, but spread it neatly out on the grass at B until you have a long enough length of fibre to reach to C. (A process known as fleeting.)
- · Set up the blowing apparatus at point B and try to blow the fibre to C.
- · If it sticks again, repair, continue until it does reach C.
- · Adjust things a bit so there is some spare fibre at A, B and C
- · Cut the fibre back at the fibre drum which is still back at A.
- · Lids on. Finished.
If the fibre is progressing really slowly, then sometimes they dig down and break into the 16mm duct at an intermediate point and fleet the duct out on the grass there.
The core fibre comes in different sizes from the largest 288f down to the smallest 48f. The larger sizes are much more likely to get stuck than the smaller sizes.
The Volunteers Role
The Volunteers Role
B4RN get their fibre distances from the Google Earth map, not necessarily the latest version either. We like to supply them with a complete set of the distances between each pair of chambers, sometimes even having gone over the route with a surveyor’s wheel. Also, we like to tell them exactly how to get to each chamber, what the parking is like for each, and what the landowner is like. (and intermediate landowners)
Volunteers can make the process go more smoothly. Particularly someone who was there when that section was dug in, and possibly knows where any joints were made.
A volunteer can help with:
- Knowledge of the route, and the best access for each part of it.
- Talking to any farmers or householders that turn up.
- Indicating any landowners where particular diplomacy is needed
- Knowing where the plough line actually went and remembering any events at dig time that may have caused a problem.
- Being the person who can locally source a bit of extra ducting, a ladder, some tool or other, a digger, whatever.
- Being an extra person. Things can get a bit stretched when the B4RN team are spread about over a section. There is often a task that would go better with an extra person, or someone might need a lift to a different location. (.....having spent half a day on a rocky knoll just relaying radio messages between two sets of people and never seeing anyone....)
- Generally building your friendships with the B4RN staff. (Do not under-estimate the importance of this one, there are often several villages at once vying for B4RN's time)
- Gaining general knowledge on how best to build the system.
- Being responsible for tidying up, closing gates, etc once B4RN have been. Check all the dig holes they have had to make after they have gone.
- Stopping B4RN just driving across grassy fields when it is dry. Grass is a crop here and this isn’t always the done thing.
- It can be very helpful to know where every join is the core route because they can be very useful places to break into the duct if there is a problem. It is also helpful (should you get a choice) if these joins are at places where you can get close with a car. It could even be useful to deliberately put a join in, for example on a leg where there is only one good access point about halfway.
Someone here has provided annotated maps of the exact route of the laid ducting for the fibre blowing team. They may not be needed at all, but if they are then it would save a lot of time.
Another example of helping B4RN in a similar way - we provided a set of simple diagrams for the bullet splicing team so that they could locate a set of chambers, rather than their usual wandering about method.
In Pictures
In Pictures
A brand-new drum of fibre arrives in Dent (£20,000 worth) with 4 of the B4RN staff. The fibre drum is manoeuvred to near the starting chamber. It is all simple to set up after a bit of discussion as to the overall plan to ensure this is the best chamber to start from.
This is the drive unit (about 2ft by 1ft). Two chain belts grip the fibre and push down the tube at the same time as compressed air is blown along the tube. This is powered by 1 or 2 compressors. A joystick lever unit to control the speed and that’s about it. A distance meter and a speed gauge.
The set-up. The drum feeds fibre into the 16mm orange duct inside the drive unit. As more fibre gets pushed in, friction builds up and as the machine begins to labour the machine is slowed down by the operator. If the fibre suddenly stops then there is a blockage somewhere along the line. The meter reading tells you exactly where it is. With a surveyor’s wheel you trot down the route to that point. This is where you need the guy with local knowledge to remember the line. Ideally the fibre is blown in soon after the duct is laid, so that the line is still discernible.
Left
Yellow compressor on pick-up.
Black fibre feeding through the drive machine and on into the orange 16mm.
James is controlling the speed with his left hand and trying to stabilize the machine with his right hand because it is having to turn the drum as well as push the fibre. There would normally be a person turning the drum.
Different day. Different place. Same set-up. Notice how much space you need for the operation. There is also the pick-up with the compressors on to consider.
Fibre being blown through the same machine. The yellow compressor is in the horse-box and you can just see the circular chamber on the left.
There is a subtle difference here in that there is a fleet of fibre in the picture, but the fibre drum is also in view.
Because you don't wish to cut the fibre unnecessarily, they have blown the fibre in one direction successfully and have taken another long length off the drum - enough to reach the next chamber in the other direction. They then cut it and feed this end into the machine. With good measurement that just reaches the next chamber leaving say 20 metres spare to be coiled up in this chamber without a joint.
If all goes well
If all goes well
Frank sending the fibre, waiting for good news
Bruce ready to report that the fibre has landed
James doing the final adjustment. He has fibre, but is doing the final juggle to get the right amount of spare duct at his chamber and the other chambers down the line.
If the fibre comes to a dead stop
If the fibre comes to a dead stop
Then it means there is a blockage. The blowing machine has a reading on it showing exactly how many metres of fibre have been put in, so you have to walk the line of the ducting to get to where you think the problem is.
At this point the volunteer with knowledge of the route, and preferably a person that was there when it was put in, can be really useful. A problem will usually be the fibre sticking at a joint, or the duct being crushed by rocks. Sometimes the volunteer can say "200 metres?, I bet that's where we had trouble with that gateway" or "there's a joint about there" and they can go straight there.
Or they use a measuring wheel and trace back over the duct route for the 200 metres, Again if the right volunteer is there they can at least help with the route finding which may not be at all obvious after the months since the duct was laid. When they get to the point where they think the duct has got to, this may jog the volunteer's memory as to a likely cause.
So they have arrived at the problem point.
They may have been given the inside knowledge and be able to dig down almost straight away to the problem point. Or they look around to see if there is a likely cause, like some rocks sticking up, a stream crossing, a gateway, or a hump in the ground.
They dig down to the duct. If you expose a foot or two of duct and tap it or shake it, then you can tell if the fibre has reached that point.
If the fibre is not there you go back 10 metres and dig down again to see if you have duct with fibre in, or keep tracing the line back until you find a point where you have.
So you have found a point with fibre. Cut the orange duct, without damaging the fibre, and pull out the black fibre. There should only be about 10 metres of it at most. Lay this out along the duct route and that will give you an accurate location for your blockage. Dig at this point to find the problem. Replace the section of damaged duct. Re-assemble
This is the blockage point. The on-hand volunteer remembers that just about here a spur went off up to that house and the main line was joined here as well. Digging down finds the join. The join itself was a bit higher than the moleploughing either side of it, creating an up and down bend, and it was here the fibre was caught. Straighten the joint out, go back to the blowing machine and it starts moving along again.
Digging down again. I think this was a house fibre actually, where we had a join on a bend, but the same principles apply. Volunteer was again on hand to narrow down the search.
If the fibre is going slower and slower
If the fibre is going slower and slower
Then it means the total friction along the duct is getting too much for the blowing machine and the fibre is unlikely to get to the end. You have your meter reading so you know roughly how well you are doing.
So there comes a time when you decide to stop. You go to where the fibre has got to. Dig down (tap the duct to make sure the fibre is there, otherwise dig further back until you find some). Cut the orange duct. Pull the fibre out. Blow all the necessary fibre to this point in a neat figure-eight shape. (A 'fleet'). This point needs to be a point with vehicle access so there may not be many places to choose for an intermediate fleet
When all the required fibre has been fleeted, move all the blowing equipment to this point and blow again towards your destination.
An intermediate fleet because the fibre was going too slow on an uphill section. Fleeting on a hillside is a bit tricky, the fibre is slightly greasy and very much wants to slide away.
Fleeting into a muddy field. There was a problem with access here, the fleet had to be made a lot further back. The fibre had nearly reached those houses,
Reblowing from this muddy point. The fibre now has to be cleaned and dried as it enters the machine.
It is unusual to have to fleet house fibre.
It is a desperate measure. (It wouldn't work at all if it was raining, wet fibre does not flow well)
If you had a very long spur and the fibre is just not going to get there, you can go through the same procedure as with core fibre and fleet out house fibre. It is flimsier and care is needed.
Fleeting at a Chamber
Fleeting at a Chamber
A chamber should be located with the possibility of fleeting in mind. You would like a nice flat area where it is safe. A fleet may not be necessary at every chamber, and if there is a fibre count change at a chamber then there certainly won't be. It is helpful to the B4RN fleeters if you can at least tell them before they come which chambers have good vehicle access (including all-day parking) and which would be okay for fleeting because that affects the blowing plan.
A perfect place for a fleet
A complete fleet at a chamber in a field with no stock, left overnight for the blowing operation to begin from here the next day.
Fleeting onto a plastic sheet stops it catching on vegetation, but on a slope it all wants to slide off.
People have to be kept from treading on it and in fact the plastic sheet is aiding here, on grass they would be more unaware.
This works well in terms of being foolproof, but cannot be done at speed and will start to get difficult with very long lengths of fibre.
Videos of the operation
Videos of the operation
This is shown at quarter speed so you get a chance to see what's going on. A useful way volunteers can help is to turn the fibre drum and maybe to guide or clean the fibre as it feeds into the blowing machine
Good pictures of the blowing process
Chipping 2018
If it's going well it looks like that. They are in radio contact with someone at the next chamber. (Communication is sometimes difficult because of the noise) It looks like they have just heard that fibre has reached the other end as James appears to shut down the machine at the end of the clip.
Note the good chamber location with a very suitable parking area.
This is Paul letting a fleet of core fibre feed in to a chamber. If the fleet is well made then Paul doesn't have to pay much attention but if the ends of the loops are in a bit of a muddle, he has to scoot around or turn the blower off smartish.
The fibre has arrived through one of the 16mm tubes at the chamber and is fed down the other. (Ignore the offcut of 16 on the grass)
Loading blowing machine
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