4mm The Harboro Stone Co.

[Dave]

The camera idea is on the back burner and a problem there, apart from the cost, is that they aren't designed to focus as close as I would need. It would have to be inside the building and so at the most the camera would be only a couple of inches away from the chute. It's something that I didn't think about yesterday.

The Archimedes screw would certainly work but the loading would still need to be observed.

The magazine idea is interesting and I may have a go if my own idea doesn't work.

I would definitely work on the “measured amount” approach, were I trying to develop a motorised loader. The question is then one of how to fill the measure, which can be done to excess, as the extra will then fall back in the tray.

If you do it manually, that might be a simple solution

The idea that I described cannot be done to excess. Perhaps this poor sketch on the back of an envelope may help explain it.

The inner tube is designed to hold the same volume of material as the wagons that are to be loaded. It is a tight enough fit in the outer tube to prevent load material from getting between the tubes but loose enough to be rotated and has a single slot cut in it.
The inner tube is connected to a motor/gearbox and the outer tube is fixed to the hopper.
The outer tube has a slot at the top that matches the slot in the inner tube.
With the inner tube's slot facing upwards the tube is filled with the load material.
As the tube revolves through 90 degrees the hopper inlet port is cut off from the tube and so nothing more can pass from the hopper.
By revolving the tube further, the exit port in the outer tube is revealed and the load drops into the wagon.
As the tube is made to hold the same volume as the wagon it will not be necessary to observe the loading as the wagon is guaranteed to be full and cannot be overfilled as material cannot continue to flow from the hopper.

The addition of microswitches and cams ought to allow a single button to be pressed to set it in motion and it then stop once the tube is refilled and ready for the next wagon to be positioned.

That's the theory but what actually happens to the material when the tube comes round to close the inlet port is another thing. It could jam. It could bend the edge of the tube. I guess I will just have to build it and see.

 

[Osgood]

Sorry but I don't hold out much hope for the tube being jam free.
Whilst miniaturisation often throws out surprises, and much depends on the type of material employed, in this case I reckon the aggregate is likely to behave much like the real thing - and I for one would be really annoyed if you do get away with what can't be done in the 1/1 world

Here's a bitsa I knocked up earlier:

 

[simond]

Dave, I was thinking something like that but without the “funnel“ either side, so the excess material would simply fall back into the tray below from whence it could be recycled, perhaps multiple times, before any given stone would get into the drum and be delivered to the wagon.

but Tony’s “revolver” idea has much merit, you could have a group of more-or-less vertical tubes rotating around an axis. You’d need a funnel at the top to guide the stones into all but the one lined up with the barrel, which would be the chute to the wagon(s), and there would be little chance of a jam, as the “gate” only opens, it never tries to close where there might be a stone. One increment of rotation would deliver a wagonload of gravel. You could arrange a conveyor to bring the stones up to the top to fill the magazine.

 

[Dave]

Sorry but I don't hold out much hope for the tube being jam free.
Whilst miniaturisation often throws out surprises, and much depends on the type of material employed, in this case I reckon the aggregate is likely to behave much like the real thing

Sadly, it would appear that you are correct.

I made the revolving tube and then made a small mock-up hopper in styrene. As the edge of the tube neared the edge of the hopper it would jam. I was using a very coarse material and decided to try with some fine N gauge ballast but that was a complete disaster!

The stuff was so fine that it leaked past the tube and into the gearbox. Fortunately I had only lubricated the gearbox with powdered graphite and was able to (eventually!) clear the grit out of the gearbox and restore it to working order. I found some Woodland Scenics ballast, which is the material that I will use as wagon loads. It didn't leak but the thing fared no better than the first attempt.

The opening in the brass tube was made by filing a flat on it until it opened up sufficiently and has left flats on either side of the opening. I am wondering if filing these flats to a curve will allow the ballast to be pushed out of the way, rather than being trapped between the flat of the tube and the flat end of the hopper wall. That may or may not work and I can't decide if it's worth pursuing it or not.

 

[steve50]

Just found this layout and I'll be following it with much interest. Looks superb so far, I love the plan and the gradients involved, all great stuff

 

[Dave]

Going back to the camera idea, does anyone know if these things can focus down to just a couple of inches? That's how close it would be inside the building and would it broadcast directly to a mobile phone? Mini Spy Camera Hidden WiFi Wireless Small Video Cam Full HD 1080P Night Vision | eBay

 

[Dave]

Keep it simple.

Hopper, motor/gearbox, push button, microswitch.

The hopper holds enough to fill 11 wagons and two such hoppers will be installed in the building. A gearmotor operates a sliding valve through a crank and con rod. A microswitch registers the closed position of the door and cuts the power. A press of a button bypasses the microswitch to set it in motion and gives one rotation.

I need to tinker with the stroke, cam timing and voltage (speed) as the gearmotor doesn't use a worm and tends to run on after the microswitch cuts the power. The con rod will be replaced by one made from brass wire, with an omega loop, to allow some give. As it stands, some pieces of stone can get trapped toward the end of the closing stroke and jam the door, necessitating reversal of the motor. A bit of give in the con rod ought to eliminate this. If I replace the gearmotor with a more powerful motor and a gearbox that includes a worm, and if it can run slow enough, it may be possible to set it up to deliver a complete wagon load with one press of a button.

 

[Dave]

I've left the working part of the loader for now and am working on the cosmetic shell instead. It is made mostly from card but with Evergreen H column sections with individual corrugated aluminium sheets glued on.

It isn't looking too good at the moment and I keep altering and adding bits but once it's all clad in corrugated, and some paint has been thrown on, it should be acceptable.

 

[Dave]

Another idea for the working loader has been suggested to me. I've thought of a few little touches myself and I am going to carry out some experiments as this one sounds like a winner.

A container, such as a coffee tin, mounted about 10 degrees off horizontal, and with a hole in one end, sits on three rollers. A wheel with a rubber tyre to give sufficient friction to drive the container replaces the fourth roller and is powered by a motor and gearbox.

As the container rotates the contents spill into a chute that directs it into the wagon. As it rotates more the loading ceases. A microswitch stops the container with the hole at the top.

There are no working parts as such and so the stone cannot jam against anything. With the friction drive the container can be lifted away for refilling and so there is no risk of spillage on the layout itself and more loaded containers can be kept ready.

I thought my own first idea would work and look how that turned out, so what do you chaps think about this?

 

[Rob R]

The theory sounds sound (if you seee what I mean..)
Two thoughts:-
How free flowing is the stuff you are trying to load?
If you have 10 wagons worth in the tin will it flow out of the hole or bunch up and jam?
Conversley, when you only have one wagon worth left in the tin will it all flow out before the opening rotates back up again?
I suspect a bit of experimentation will be in order for the above, both with hole size/shape and rotational speed.

Second thought, you may need a pair (or two) of rollers on top of the tin to stop it lifting/slipping. A simple weighted setup that hinges out of the way for exchanging tins would do.
Have fun.
Rob

 

[Dave]

The theory sounds sound (if you seee what I mean..)
Two thoughts:-
How free flowing is the stuff you are trying to load?
If you have 10 wagons worth in the tin will it flow out of the hole or bunch up and jam?
Conversley, when you only have one wagon worth left in the tin will it all flow out before the opening rotates back up again?
I suspect a bit of experimentation will be in order for the above, both with hole size/shape and rotational speed.

Second thought, you may need a pair (or two) of rollers on top of the tin to stop it lifting/slipping. A simple weighted setup that hinges out of the way for exchanging tins would do.
Have fun.
Rob

I have been experimenting. The tin can be completely packed full and the stone will still flow, as long as the hole is large enough. As it becomes more empty it takes more rotations to fill a wagon. I didn't have anything to hand to make a friction drive so used gears instead but the tin can still be lifted free of the chassis for replacement and refilling. It needs some alteration from how it is in the photos as the frame sides are too close to the tin. With a full tin the load starts to spill out at around 90 degrees from top and continues all the way to around 270 degrees and that last spillage was getting stuck between the tin and frame. The entire thing is bodged up using card and superglue. It's one of those things where there's no point in making a proper job of it until you prove that it works and then if it works there's no point in making a proper job of it because it works and no one's going to see it anyway.

 

[Dave]

It seemed like a good idea but I can't get it to work reliably. I don't mean the construction itself, although that could be better. It's the physics of the way the stone flows and the fact that it begins to flow after a relatively short duration and continues to through roughly 180 degrees when the tin is full, or mostly full. Once it's flowing there's no control over it until the hole has rotated 180 degrees and the flow stops again. Added to the lack of control over the flow, the speed of flow increases as the hole gets nearer the bottom and decreases as it comes back up, which makes it unpredictable. The more the tin becomes empty the less stone flows per rotation and so on. The bottom line is that it's virtually impossible to load a wagon without it overflowing, let alone get a load of realistic appearance.

 

[Paul Tomlinson]

Dave, there might be some merit in your reading Phil Hindley's thread "Moving Coal" over on RMWeb, though many of the images are now lost. From page 13, here's a fascinating video of his coal loader in operation - it might offer some inspiration.

 

[Osgood]

Makes you wonder if a load sensor light beam running across the top of the wagon from side to side would form the basis of a flow control system.
As soon as beam is cut the flow stops - can be used for 2 or 3 x dose loading as above or just the one dose.

Just need to adjust beam height if wagons vary significantly, but that could be schemed to happen automatically - one wagon height sensor beam raises the load sensor beam until it detects wagon top, thus putting the load sensor at correct height.
Oh hang on, its getting complicated again

 

[Dave]

Makes you wonder if a load sensor light beam running across the top of the wagon from side to side would form the basis of a flow control system.
As soon as beam is cut the flow stops - can be used for 2 or 3 x dose loading as above or just the one dose.

Just need to adjust beam height if wagons vary significantly, but that could be schemed to happen automatically - one wagon height sensor beam raises the load sensor beam until it detects wagon top, thus putting the load sensor at correct height.
Oh hang on, its getting complicated again

I've decided the whole load dosing and camera ideas are going. I'll use the Mk1 human eyeball to monitor the loading. I'll go back to the hopper and reinstate the rigid bar from the crank to the door, ditch the microswitch and push button and replace them with a DPDT sprung centre-off toggle switch. Toggle one way to open and the other to close the door. Job done.

The thing with the hopper is that the stone flows at the same rate from full to empty and the flow can be started and stopped in an instant. If that doesn't work then I'll build an oil depot instead. Tank wagons look exactly the same whether full or empty.

 

[Rob R]

If that doesn't work then I'll build an oil depot instead. Tank wagons look exactly the same whether full or empty.

Or a powdered/bagged stone product that uses Vans/Sheeted Opens/Covered Hoppers/Presflows/Prestwins and keeps the Peak District feel of the layout?

R

 

[Dave]

The building has progressed significantly. It needs gutters and drainpipes yet but is almost finished. I may have overdone the rustiness but it will tone down somewhat with extra weathering to appear as a layer of stone dust.

 

[2996 Victor]

I reckon that looks blooming good!

 

[michael mott]

Hi Dave how are you making your corrugated iron? The building looks great.

Michael

 

[Osgood]

There looks to be a neat mechanical arm type of hopper re-loading device here ( ):