This is day four of waterwheel building. We've seven buckets in place and the last row of holes to drill on the seventh bucket. The location holes for the bottom edge of the buckets are already laser cut but the holes through the shrouds need to be drilled.
Stainless steel work hardens very quickly and burnt out drills are a likely outcome if they are not drilled at the right feed rate and speed. In practice high-speed steel cobalt drills with a drop of lubricant do the job very well indeed provided the speed is slow and the pressure fairly high.
Hopefully, not a shroud to be buried in rather the name given to the stainless plates that form the inside of the waterwheel and make the bottom of the buckets. These stack one above each other and are bolted in place with stainless steel bolts.
The buckets are held onto the cast iron wheels and drilled and bolted into place on the shrouds.
Here we are with the magic complete. We set a day aside to get the gearbox in place on the end of the drive-shaft. It was a bit daunting on the face of it because it weighs in at 600kg and is a big lump of a thing. Thinking time was important here because the downside was going to be painful financially and the potential danger to body parts was significant.
The gearbox had arrived some months previously and was bolted into a big steel crate which we moved about on a pallet truck. It had to go down nine inches into the gearbox pit and be mounted onto the drive shaft. We constructed a pair of wooden ramps with a brick under the center of each plank. We fitted two bent scaffold posts on top of these ramps and slid the gearbox down them half an inch at a time with the aid of a big stick. The bent scaffold poles couldn't roll off the ramp and they made it possible to get the big stick between the gearbox and the ramp to slide it incrementally into place. The brick in the middle of the ramp meant that we could pivot the ramp to lift the gearbox into place.
The gearbox has a hollow shaft that fits onto the drive shaft and is jacked into place by a 22mm drawbolt.
The whole thing was done and finished and we were drinking the first morning cuppa by ten thirty.
Here is the method by which the wheel assembly was lifted. The idea is to pick the oak beam up and place an engineering brick under it. The key point here is that the jack at the extreme right of the photo has to lift the oak plank which in turn lifts the strap that lifts the beam upon which the waterwheel stands. This is merely a quarter of the total weight of the assembly so about two tons.
The brick was just the right size and certainly strong enough. The short plank of oak took the strain albeit with a bit of a bend.
In order to clear the old, worn out plain bearing located in the wall we needed to raise the waterwheel assembly a bit. In practice the width of a pencil. The tip of the marking gauge has moved from the top of the pencil to the bottom as the assembly was lifted clear of the old bearing. At this point, the waterwheel was loaded onto two new roller bearings for the first time.
When this was complete the six-ton waterwheel could be moved easily simply by hand pressure. It also became clear that the whole assembly was almost perfectly balanced.
The main bearing shown here replaces the worn out plain bearing mounted in the wall behind the pit-wheel. This is a modern rolling element bearing that is capable of high speeds and very significant loads. The manufacturers think it will never need replacing as it is doing "trivial" duty.
The bearing is fixed to the shaft by an expanding collet and it sits upon a huge oak beam that will be lifted onto engineering bricks at each end with a void below to give a bit of vibration isolation. It is shown here standing on a block of oak.
The outside main-bearing was a plain bronze bearing that was in a sorry state of repair having very little to offer. Notwithstanding that we made up a sleave to repair the damage to the end of the shaft that would support a new "posh" roller bearing. This sleeve was to be glued in place with an epoxy resin-based compound called belzona.
Here the drive flange is in place prior to final adjustments and a few bolt changes.
It was particularly rewarding to discover that the drive-shaft was only three-thousandths of an inch out of alignment when the pit-wheel was rotated. A remarkable result considering the pit-wheel is 88" in diameter and sits on the end of a11.5" shaft that was made over a hundred and fifty years ago.
This looks like a very small item from a watch or clock mechanism; in practicethis is a four-man lift.
Here we are with the mag-drill. Cast iron pit-wheels don't have much magnetism so we had to rig up a steel plate in the right place that was clamped onto the flange so we could drill the holes for the drive flange. These holes are 26mm diameter and about 65 mm deep - not a black and decker activity.
This is the main coupling to the gearbox. The Flange is in itself a two-man lift.
The drive flange is incomplete at this stage but it was necessary to "find" the holes in the pit-wheel so we could drill them in the right place. The flange then goes to have the drive-shaft welded in place and the whole assembly is fitted at a later date.
Here's a view of the old main bearing sitting in the wall of the mill. This is a bronze plain bearing with no cap that has been open to the elements for a long time. There was precious evidence of lubrication and the journal is in a chronic condition. The plan is to leave it in place but lift the wheel a few millimeters and support it on new rolling element bearings at either end.
We can then brick up the wall to seal the building from the elements.
Here are Don and David fitting the new sluice gate. Don has designed a rack and pinion system to control the water flow. He has followed traditional practice carving the engineer's name (that's Don) and the year into the front panel. The water is held back by the stop boards further back since the dagger-boards for the new sluice gate haven't been installed yet. Even with low flow rates the fine sheet of water is evident as it flows over the tray it resembles a sheet of black plastic.
Bedfordshire drainage board finished dredging the river last week and we were keen to try the new sluice tray. Shifting thirty years of accumulated silt is challenging. As we lifted the stop boards we were rewarded by a beautiful clean flat sheet of water flowing over the new sluice tray.
The water is running properly again after a very long time resting. We continue to excavate the tail race by hand and hope to render the waterwheel "dry" ie running with clearance below the buckets rather than flooded which loses efficiency.
The new sluice is made of of Accoya. The tray curves very slightly to direct water into the waterwheel buckets.
Accoya is a remarkably stable material used extensively in the waterways of the Netherlands. It is is guaranteed to last 25 years submersed in water and 75 years as a cladding material.
Finding the right bolts to hold the new buckets onto the waterwheel has taken some time and a sample or two along the way. Here we have a stainless steel bolt combined with a tapered SG-iron washer that matches the geometry of the grey cast iron waterwheel flanges the washer ensures that the fixings operate properly.
We've closed the mill gates to stop the flow of water over the waterwheel. Now that the wheel has dried out, we can remove the rusting buckets and start to renovate the wheel, ready for new buckets to be installed. Once the buckets have been removed, we'll be able to inspect the wall behind and remove whatever had stopped the wheel from turning. When the frame has been renovated, we'll install new buckets and then look at renovating the mill gates and mill tray.