Mining, especially mining of Gold and Silver Ores, is a popular topic for Model Railroaders, and even N-scalers are not immune from a desire to model the industry.
One of our membership has recently asked for information about how to build these all-important items, and a rather long reply from me was the result.
As it seems a shame to limit the post to only a 'General' forum, I have taken the liberty of creating a separate posting under the 'Scratchbuilding and Kitbashing' Forum, and so make it more readily available to our membership in the future.
It is written on the assumption that the ore within the bin is going to be loaded from the front (The deepest part of the bin), into a railway wagon sitting directly in front and below the bin discharge chute.
NB: 'Centre-loading' bins, where wagons run-in under the bin 'body' are not covered in this article.
The post is substantially that which I wrote in reply to the original enquiry, with a small amount of editing being undertaken to make it more suitable for general use.
General Research
If the topic 'Mine Ore Bins' is 'Googled' the result will get quite a few responses - some good, some not so good.
I would suggest that particular attention is paid to the sites named On30 Mine and Silver Bell Mine, the first to give the reader an idea about location for these structures, the second to give an idea about how they were constructed.
Ore Bin Construction
I have always use Picture-Framing Cardboard for my structures - it is far more flexible than styrene and IMHO easier to work with - it also tends to be free!!
This article is written on the basis that cardboard will be used in construction of this bin, though no doubt the construction methods can be modified to suit the styrene medium
The Essential Ore Bin:
The principle of a 'Bin, is that, by using gravity, whatever is put into it at the top, or back, will slip-down to the front, from which point it can be removed by opening either a trapdoor, raising a slide, or lowering a chute. Consequently, the front of these bins is always deeper than the back! At its most basic, an Ore Bin essentially consists of five pieces - a Front, two Sides, and a Back, with an insert placed inside, to keep all these pieces together Based on the 'slip-down principle I mentioned before, therefore, the front is deeper than the back, As a rough guide, on the assumption that your bin is on the side of a hill, the rear wall will be about 1/2 the vertical depth of the front wall (the one facing the tracks)
Drawing-up the 'Bin plan
Because the bin will be on the side of a hill, the two sides of the bin will taper from the rear to the front so that they are in fact narrowest at the point where they connect with the back wall of the bin (that point that is farthest away from the front of the bin). (still with me?). If you are, and understand what I'm saying, draw-up a plan of the bin that you want to make, using the basic criteria that I have just given, BUT for the sides just draw-in a rectangle that is the same vertical depth as the front wall of the bin, and as long as you want the bin to be as it 'backs in' to the hill.
Scribing
A suggestion: BEFORE you, as the builder, cut out the 5 pieces of the bin, you may care to scribe-in the boards which comprise the sides of the structure. If you are not familiar with the essentials of scribing, I have covered the topic in detail in an article on Cardboard-construction titled 'Scratchbuilding Structures from Cardboard' 'in the 'Scratchbuilding and Kitbashing' Forum on this site.
If you ARE aware of what scribing is, I would suggest that this is done before any cutting-out is done, It is not usually necessary to scribe the back wall of the bins - it is almost never seen.
Scribing the Front of the Bin
(I am assuming that the bin will be raised above the ground on wooden supports, and am writing accordingly)
(On the assumption that you have scribed the bin components as you wish, and have then cut them out):
With the rectangle that comprises the front of the bin lying on the table in front of you, measure a point two 'scale' feet up from the bottom of the rectangle, and draw-in a line parallel with the bottom of the bin.
Draw-in another line three 'scale' feet above this, and above that line draw-in another 2 foot-scale line.
At a point half-way along the rectangle, draw-in a vertical line from bottom to top of the rectangle.
Place your Scale Ruler at right-angles to this line and draw-in a point 1 foot wide to left and right of the vertical line.
Draw-in a vertical line that is 1 foot wide, and running from bottom to top of the rectangle, so that you should have a vertical line that is, in total, two feet wide.
At each end of the rectangle, measure-in a point 2 feet-in from reach outer edge.
Draw-in a vertical line, from Bottom to top, that matches this point, so that you should have a vertical line 2 scale feet in from each end of the rectangle, running from the bottom to the top of the rectangle
You have now drawn-in the locations of the bracing-timbers for the front of the bin, and can fill the two-foot wide sections with balsa, card, Plastruct or whatever you choose to use to represent these.
The three-scale foot rectangle that is left between the two two-foot wide sets of parallel lines running across the blower section of the rectangle, should now be divided in two by a two-foot wide vertical.
These two spaces are the 'exit-points' for the bin's ore and can be can be either painted-in (my preference) or cut out to create two actual gaps.
A Discharge-chute of your choice can be either fabricated (or bought) and attached to the cross-timber below each 'exit', and super-detailed as you wish.
Sides
When you have drawn-up your basic bin plan, on the 'hill' (Left-hand) end of the sides, measure-down from the top to a point that is the same vertical height as the back wall of the bin (that wall that is farthest-away from the tracks).
Draw-in a line from that point to the bottom RH-end of the 'side' rectangle that is to be the front (track-side) of the bin.
You have now got the angle of the bin sides.
From, each end of the sides, measure-in a scale two-feet , and then draw-in a vertical line from the bottom to the top of the side, as you did for the front of the bin.
Repeat this process for both the top, and the 'angled bottom', of the sides.
Scribing the Sides
While scribing will follow the usual method, it is essential to remember that for the sides, the 'boards' will follow the angle of the slope, from back to front NOT the horizontal of the top of the side.
Floor
Next, cut out the 'Floor' of the bin - the bit that goes inside the entire structure and keeps it together.
It should be slightly smaller than the outside of the bin, and the bin sides should still meet at the corners with the floor' in place (do a dry-test before gluing anything in place, and trim the 'floor' accordingly).
It is not necessary to scribe the floor, as it is usually not seen, though if you really HAVE to show the boards, it is entirely over to you as a modeller.
Cutting-Out
I use a VERY sharp craft Knife blade, replacing it as the point gets worn, which it does very rapidly, a steel ruler and a cutting mat, and make a series of smooth strokes, holding the ruler parallel with the cut as you make it.
Doing this should result in a smooth clean cut - if it doesn't replace the blade.
NB - DON'T cut yourself!!
Assembly
If everything has gone as it should, you will now have five pieces of 'bin' in front of you - a Front, a Back, a pair of Sides, and a Floor.
I place the floor on a piece of glass mirror, and apply PVA (Elmers) glue to the bottom of the front wall, pressing it up against the front (rail-side) face of the floor.
I then apply a small line of PVA to the edge narrowest edge of the RH side and carefully place it so that the side is against the back of the front wall.
It should fit in behind the wall, and make a nice L-shaped joint.
Work your way around the 'floor - PVA'ing the back of the bin to the RH side, leaving it to dry, then doing the same with the remaining side.
If everything goes well, you should now have a box that looks like an ore bin - with a 'deep' front, tapering sides and a rear wall. The 'box' will also have bracing timbers around its edges.
Fitting in Place
Front:
Because every site is different, I have left this until last.
Your individual bin will need to be so placed that it 'dumps' into whatever wagon you are using to convey the ore to 'points off' and processing.
Having decided the wagon you ill be using, put some sort of support under the bin, and raise it (the bin) until you are happy that is contents could cascade into the wagon concerned.
Carefully measure the distance between the 'ground' (not the track or sleepers (ties)) and the bottom of the 'bin.
I then construct a hollow rectangular frame out of wood (balsa, spruce - your choice - you can even use card) , cut to the same width/depth dimensions as that you have used for the bracing on the bin itself.
The rectangle should be so created that its bracing matches that on the front of the bin - including the centre vertical between the two outlets.
Allow this to dry, then re-check to make sure that it is still at the height you want.
If it is, then use PVA to attach it to the underside of the bracing along the bottom of the bin
Check the height again just to make sure that you are happy, trimming and adding as you need to.
Sides:
With the sides you have two options -:
You can either build another rectangle-like frame, cutting the top pieces of the framework to fit under the angled bracing, while ensuring that the bottom section is still horizontal with the 'dirt' on which the structure will eventually sit.
Or:
You can fit it in place (if you have a spot already built and landscaped), and add only those bits of bracing which you deem necessary, leaving the terrain to act a a support for the structure. The choice is yours.
If you so wish, it is also an option to add a 2-foot wide vertical brace half-way along each side in the same way as you did for the front, remembering to continue it onto the framework that is supporting the bin 'body'
Ideally, you should now have a structure that looks like an ore bin, and that is sitting on its own framework and that is high enough above the wagon to enable any of the bin's contents to (theoretically) fall out of the discharge-ports and into the wagon below.
If you have reached this stage, the rest is up to you - paint it and superdetail it as you wish.
I use acrylic tube colours and weather and 'tinker' with the colour-scheme until I'm happy with the result.
Installing on site:
I place the completed, weathered structure on its chosen site, then when happy with the result, run a line of PVA (Elmer's, White Glue), along the underside of the supporting frame and put it back into place, leaving it to set.
When all is done, and I am still happy, I then add scenery as appropriate.
Filling the 'Bin:
The bin is now essentially complete, and it is now ready to be loaded with your rock of choice, remembering that, in reality, such structures are very rarely filled to the top with whatever ore/rock is being put into them.
Although my own preference is towards using a small-gauge railway to (theoretically) put the load into the bin, road access, and use of tipping-type motor trucks (lorries) is also possible - just build-up the 'road' until it is level with the back of the bin, and place an appropriate truck at the edge.
In both events, loading should be from the back of the bin, as gravity will ensure that the contents will slide forwards towards the front along the sloping floor, and so facilitate removal into the waiting railway wagon.
However, it is equally possible to run a small-gauge (18-inch to two-foot) mining tramway from either side of the bin, and to use either end-dump (over the end of the rails) or side-dump (over the side of the rails) wagons to run the ore into the bin. You would however have to build-in suitable wooden supports for the tracks in this instance, as they simply don't support themselves in mid-air.
Usually this would consist of cross-timbers placed across the bin, rather than trestle-type supports placed within it as these will be too spindly and likely to be snapped by the mass of rock sliding against them.
Trusting that what I have written is of use to all potential miners . .
Komata
"TVR - serving the Northern Taranaki . . . "
Joined: 2005-05-12