Kit review Full Metal Beam Engine Steam Engine (RETROL) - EngineDIY

[James H]

Full Metal Beam Engine Steam Engine (RETROL)
EngineDIY
Catalogue # 33ED3487709
Available from EngineDIY for USD $299.99

 

 

A beam engine is a type of steam engine where a pivoted overhead beam is used to apply the force from a vertical piston to a vertical connecting rod. This configuration, with the engine directly driving a pump, was first used by Thomas Newcomen around 1705 to remove water from mines in Cornwall. The efficiency of the engines was improved by engineers including James Watt, who added a separate condenser; Jonathan Hornblower and Arthur Woolf, who compounded the cylinders; and William McNaught, who devised a method of compounding an existing engine. Beam engines were first used to pump water out of mines or into canals but could be used to pump water to supplement the flow for a waterwheel powering a mill. They also could be used to power steam ships.

 

The first steam-powered ships used variants of the rotative beam engine. These marine steam engines – known as side-lever, grasshopper, crosshead, or 'walking beam', among others – all varied from the original land-based machines by locating the beam or beams in different positions to take up less room on board ship.

 

The kit

This steam engine kit comes in quite an anonymous and thick gauge cardboard box with absolutely no label! The box itself is reasonably heavy too, weighing in at just under 2kg. Lifting that lid off immediately shows the colour printed instruction sheets which are sat on a sheet of foam which protects the two trays of parts underneath.

This kit contains 84 parts, inclusive of screws etc. All parts are sat in foam cutouts which provide excellent protection for the assemblies and parts. I say assemblies, because I see this as more of a semi-kit in that a number of elements are pre-built, and the idea is to assemble these to the individual parts, which are all then mounted on a metal base.

A number of the parts are in plastic sleeves. These are the ones made from stainless steel, and are for building the boiler's mounting chassis,  and also the fuel/igniter tray. 

Work starts on mounting a number of parts to a metal stand-off frame which will eventually mount to the main plinth. This includes the piston mount/condensation block, and the column for the cross beam. Hex keys are provided for the bolts, as well as a spanner with various sized jaws for various nuts etc.

This assembly can now be mounted to the main plinth. This is done via a series of brass stand-offs. I'll also now fit the two fly wheel mounts.

All screws are tightened up except for those holding the brackets. I decided to make sure I align the drive shaft through them before properly tightening up.

This is the cross beam, and one of the number of pre-built assemblies in this model. This is composted of cast and turned brass, plus stainless steel. You can see the piston plunger on the right of the image.

This is now fitted to the column using a small grub screw to secure. I ddi apply a little lubricating oil into the piston chamber first and then made sure the beam would move freely, pulling the piston up and down. A separate sheet of instructions gives tips on how to achieve this. If not done correctly, this is about the only area which will cause enough friction to stop the engine from running freely. I found I needed to do a little adjustment of the base of the beam. That's why you can see an adjustment hole underneath this, in the main plinth. The idea is that once the piston is raised, it will drop into the piston cylinder due to gravity.

This drive arm is now lubricated and slid into the base of the piston block, and the two bearings are interred into the outside of each of the brackets. Notice the larger end isn't yet engaged into anything and is sat on the bracket simply for the photo opportunity!

You could say this is one of the main events...the fly wheel. This beautifully machines piece of aluminium will now be fitted between the two bearings, via that drive shaft. Flats are machined onto this so the grub screws have a proper surface to fasten to. 

The opposite side of the drive arm is now engaged into the drive shaft and a grub screw used to tighten up to the machined flat on the shaft. 

The drive wheel can now also be secured to the drive shaft via a grub screw. A small collar is used to help space the components.

This is the beam link which will connect the beam to the flywheel drive shaft. The brass fastener has a reverse screw thread which secures into the drive arm.

This beautiful little assembly is the centrifugal regulator. The lowest bolt needs to be removed from the unit and reattached from the underside of the plinth, along with the smaller bolt you can see here. Pushing the small brass linkage downwards will force the two balanced wheels outwards. This is what will happen when pressure is pushed through the brass block that you can see midway down the assembly.

A small length of silicone tube is used to link the centrifugal regulator to the condensate box/piston chamber.

Lastly, for this section, a silicone drive belt is applied between the centrifugal regulator and the fly wheel.

The boiler sits atop a stainless housing which doubles as the heat box for the boiler. The first side is fitted, via two brass shafts which also help reinforce the assembly, as well as create mounting points for the boiler securing straps.

The box is now complete, with the scalloped side towards the top, and the square cutout as shown. The latter is to accommodate the fuel tray.

This really is a very nice piece of engineering, mostly from machined brass. I remember the boilers from the Mamod steam engines, and I can vouch that there are flimsier than this, and that had soldered joints. This is a far superior unit. 

The boiler is now fitted and secured. The protruding outlet pipe is connected to the centrifugal regulator via a length of silicone tubing.

The steam engine itself is now complete.

These parts assemble to create the fuel tray. This contains a tray into which the fuel (methylated spirits, IDA etc) will be poured. The 'wick' units which create a chamber from where the fuel vapours emit, are then plugged into the tray and then the cap is fitted. This creates a shield which closes off the fuel chamber from the outside world. 

The underside of the piston block has that condensation pipe. This little tray will sit underneath that whilst in operation. 

Instructions

These are quite sparse in text, with quite a lot of Chinese present, but the illustrations themselves are enough to easily build this steam engine. 

 

With the engine complete, we can now give it a test. First, the safety valve needs to be unscrewed and then water added. I do this with a syringe. First you need to open the valve at the front of the boiler, or the water will just leak from the injection point, as you add it. I found that about 60ml of water was enough for this. I also added about 10ml to 12ml of methylated spirits to the fuel tray and then lit the burner. The boiler took just a few minutes to come to pressure. The flywheel began to rotate slowly, so I gave it a gentle push and off it went!

 

 

 

 

 

 

Conclusion

Firstly, I have to say that this is a delightful little steam engine that is both easy to understand and build. This took me a little over 90 minutes to build, inclusive of taking the unedited photos. The quality of parts really is excellent, which is what you need when you are dabbling with a miniature boiler unit and the pressures within. The overall feel of the kit and the finished model is one of quality. All I would suggest is adding a little lube in areas such as the piston and gearing in the centrifugal regulator etc. When you compare the beautiful finished model here, compared with the current Mamod models which are pre-built and cost over a £100 more than this, then I consider this to be excellent value for money. It will also make a wonderful cabinet display piece too, which is exactly where mine will be heading. 

 

My sincere thanks to EngineDIY for sending out this kit for review on Model Ship World. To buy direct, click the link in the header of this topic.

 

 

 

[BrochBoating]

Excellent review, thanks. Are Mamod really that much now! Awful when they were cheapish!

[James H]

1 minute ago, BrochBoating said:

Excellent review, thanks. Are Mamod really that much now! Awful when they were cheapish!

They sure are. 

 

Was a big surprise to me as the last two I bought for the school I work, were between £150 and £200, possibly. Certainly nowhere near £400. And let's be honest, they aren't great technical creations with their soldered joints and thin boiler jacket, faux chimney and rickety construction. This new one feels incredibly robust and 'sure' in its operation. 

 

If anyone wants a nice discount on this or any other model engine from EngineDIY, just use the voucher code: JAMESHATCH

[Roger Pellett]

This looks like a really nice little engine and a great value. Eye candy for steam engine junkies like me.  
 

Not a criticism but a question.  Most steam engines are double acting; steam is alternatively admitted and exhausted  from each end of the cylinder.   In other words steam pressure alternatively acts on each end of the piston.  This is a single acting engine. Steam pressure acts only on one end of the piston, the bottom.  It is also non condensing.  The condenser block is just a tray that collects water.  When the piston reaches the top of its stroke pressure across the piston is balanced and the only downward force acting on it is gravity.  Once the engine is running momentum from the flywheel is sufficient to allow gravity to overcome friction and to return the piston to the bottom of its stroke.

 

The question:  If you’ve fired up the engine will it operate from a standing start or is it necessary to first spin the flywheel?
 

Roger

[James H]

15 minutes ago, Roger Pellett said:

This looks like a really nice little engine and a great value. Eye candy for steam engine junkies like me.  
 

Not a criticism but a question.  Most steam engines are double acting; steam is alternatively admitted and exhausted  from each end of the cylinder.   In other words steam pressure alternatively acts on each end of the piston.  This is a single acting engine. Steam pressure acts only on one end of the piston, the bottom.  It is also non condensing.  The condenser block is just a tray that collects water.  When the piston reaches the top of its stroke pressure across the piston is balanced and the only downward force acting on it is gravity.  Once the engine is running momentum from the flywheel is sufficient to allow gravity to overcome friction and to return the piston to the bottom of its stroke.

 

The question:  If you’ve fired up the engine will it operate from a standing start or is it necessary to first spin the flywheel?
 

Roger

 

For me, it did start to move, but not not enough to start its cycle. I needed to push the flywheel to get momentum. I presume the initial movement was because the cylinder was at the start of its travel (at bottom of stroke), and needed external momentum to begin that cycle.