Waterwheel

February 13, 2018
Half the wheel now has buckets

Hot on our bucket list is finishing this job. We have folk arriving tomorrow to make a film about the machining of the drive system they want to see "real milling" rather than five axis precision CNC milling. It's just an industry thing really.

February 10, 2018
Seven buckets installed

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.

February 8, 2018
Shaping the shrouds

It's a long job, the shrouds come laser cut as complete as possible but they need fettling to make them fit properly around the wrought iron spokes that support the cast iron wheels. Here we are chomping a chunk off the edge prior to test fitting to mark out the bolt holes.

February 3, 2018
Second shroud

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.

February 2, 2018
First bucket installed

We now have control of the gearbox and that means we can move the waterwheel at will. Bucket fixing was the next task.

February 1, 2018
Gearbox installation

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.

January 16, 2018
Lifting the Waterwheel Assembly

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.

January 16, 2018
Raising the bearing

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.

January 15, 2018
Replacement main-bearing installation

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.

January 14, 2018
Fitting the External Bearing

Here's the complete assembly in place prior to fitting the final bolts. The trusty jack is pressed into service once more so we can lift the temporary bearings out from under the shaft and leave the new bearing doing it's job.

January 13, 2018
External Main-bearing repaired

Here is the transformation to the external main-bearing with a stainless steel sleeve glued in place ready to receive the roller bearing assembly.

January 12, 2018
Restoring the External Main-bearing

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.

December 21, 2017
Three bolts holding the plate onto the pit wheel
The complete drive flange and shaft bolted to the pit wheel

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.

December 14, 2017
Drilling holes in the pit wheel
Drilling holes in the pit wheel

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.

December 5, 2017
A circular steel plate held on to the pit-wheel with clamps
Gearbox drive flange clamped in place

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.

December 4, 2017
Collecting the flange

The drive flange for the gearbox was collected in the back of our trusty old Golf it's a two-man lift. Getting it in was relatively easy - moving it to the mill was hard.

December 4, 2017
Collecting the drive-shaft

Andy Soos at CNC Bedford made the drive system components for us. They were spot on.

This picture shows the drive shaft ready for collection. It too is a two-man lift. The Golf had a hard time with both the drive-plate and the shaft on board.

December 1, 2017
The Old Main Bearing

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.

November 15, 2017
Fitting the new sluice gate

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.

November 14, 2017
Testing out the new sluice tray

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.

November 8, 2017
New sluice tray

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.

November 3, 2017
Hands on Deck

All hands on deck or under the deck in this case. Here's Sarah clearing out the first and second layers of silt and stuff from under the waterwheel. 

October 4, 2017
Trial bucket bolts

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.

August 1, 2017
Don preparing the pit wheel
Preparing the pit wheel

Don prepares the end of the main shaft. This is simply a tidying up of the end of the shaft enabling the drive flange to locate on a spigot.  The flange will couple the gearbox to the pit-wheel converting 10rpm to the 1500rpm necessary to match grid electrical frequency.

May 16, 2017
Temporary bearing

The outer plain bearing of the waterwheel needs to be replaced.

This little temporary stand supports the shaft with roller element bearings mounted on a steel and wooden plinth. We can rotate the wheel with the use of a winch. 

July 28, 2016
Buckets 2

The trial of the buckets continues. It was important because we discovered that the bolt spacing is different from one side to the other. This necessitated separate drawings.

July 27, 2016
Trial buckets 1

Here we are trialling prototype buckets on the water wheel they fit one above the other.

August 3, 2013
Removing the buckets

About a third of the buckets have been removed. We freed a log trapped down the side which has made the wheel a little easier to turn but there's plenty more debris to remove before it will rotate without a great deal of force.

August 2, 2013
Scaffolding for the wheel

The scaffoling has been put up alongside the waterwheel ready for renovation to start.

July 2, 2013
Stopping the flow

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.

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