Grain Silos

I used "For Sale" signs from the hardware store to make the flat tops on my grain silos and used plastic fence post or rain gutters for the building on top of the silos.

Great way to recycle!  Very interesting use of materials.

Thanks Keith.  Great idea on how to expand what I have as a kit.

Actually I was thinking of the ones you see on a farm in silver metal.  They are about 25' in diameter and 50' tall.

John, 16 years ago I lived in the Texas Panhandle and farms had your type of silos.  The silos would have enclosed bucket system taller then the tops of the grain silos. with tubes from the top of the enclosed bucket system to the tops of each silo so grain can be picked up at ground level and moved to the top of enclosed bucket system and dumped into the different tubes to the different silos. 

This picture shows two bucket systems on the side of cement silos in southeast Kansas. these are a newer type of bucket system. The older ones had the buckets enclosed in a rectangle box and not two tubes.  You can make the rectangle box out of a 1/2 by 3/4 inch wood lumber that is taller than your silos and curved like these in the picture at the top and use wooden dow rods to the tops of each of the silos.

Find another picture. I think this picture is from southwest Oklahoma.

Also on the smaller type silos like in your picture the farmers have an auger system that was on wheels that they would move to each silo top, And auger the grain from the farm trucks to the top of the silo.

Here's a few other pictures of tops of grain elevators.

Check Walthers or Hobbyinc or Imex and Rix HO metal grain silo kits.  There is one that is 5.5" in diameter.  You can stack them.

https://rixproducts.com/product/grain-bin-30-ho/

https://www.imex-model.com/pro...HO-SCALE.html?cid=95

Jan

John - you would have to cut a cone - usually 20 mil plastic then scribe lines in it. Alan Graz has many photos of this technique for his tank builds on this forum. Basically you cut a circle, cut a wedge into it then fold the circle into a cone. The height and circumference of the cone will depend on the diam of the circle and the width of the wedge cut.

see method 3 - https://www.wikihow.com/Make-a-Cone

I went through a similar search for cones, in my case for a silo bottom discharge, rather than the top.  There are in fact lots of options out there if you look outside of the typical modeling sources.  The problem is most of the commonly offered items are less than ideal for various reasons.  

The foremost issue is material.  There are lots of cones available for funnels, or sports field markers, or "dock piling caps".  However, they are almost always made of a slippery plastic like polyethylene or polypropylene, which resist adhesion with most common glues or solvents.

The second issue is the angle of the cone.  It can be difficult to find "flatter" cones, or those with a larger degree included angle, or at least in the materials we normally use for modeling.

The last issue is diameter.  At ~25' diameter for your prototype, you could use a 6" diameter cone.  But at larger diameters, anything in between the whole inch increments, and often anything in odd inch increments, are not available.  I am modeling a specific prototype, and needed a 7.5" diameter cone, which was impossible to find while meeting the criteria already listed above.

No matter what solution you find for the cone shape, you will need to add the vertical standing seams between panels.  But for the cones themselves, I'll list off some of the things I considered.

1.  Best option for material - Plastruct ABS cones - up to 6" diameter, but 90° included angle, so steeper than what you typically see on these silos.  These were too small for me to use on my silo.

2.  Dock piling caps - usually listed as PVC or polyethylene, they come in a variety of diameters, but are also usually fairly steep cones.  You will need to cut off the base of the cone, and also possibly part of the cone itself, to get the proper diameter to match the cylinder below.

3.  Sport or soccer cones - these come in a variety of sizes.  They are usually flatter cones, which would be ideal for your project.  However, they are also usually made of polyethylene or polypropylene, so have the same issues as the piling caps.

4.  Acrylic cones - these can be plain clear acrylic, or another interesting source is light fixture sconces and shades.  They often are available in flatter cones.

The polyethylene is very hard to glue to anything, although contact cement may be effective (I didn't try, making my own cone instead).  The PVC could theoretically be solvent welded to a PVC pipe for the main part of the silo.  Or it could probably be glued using contact cement as well.  Acrylic is generally pretty easy to work with.  The thing you need to remember with any of these materials, is that the real trick will be attaching the details to the base structure, since they will almost certainly be dissimilar types of plastic, or possibly even other materials.  Contact cement is going to be the only option for some of these bonds.

I originally started with one of the PVC dock cap cones, and a length of 8" PVC pipe, plus sheet PVC for the silo top and PVC rod for the legs.  I had presumed that because both PVC and styrene were solvent-weldable plastics, that they could therefor be welded to each other.  That is not the case unfortunately, as the structures of the plastics aren't similar enough.  So I was faced with the issue of how to attach all of the details with any degree of confidence, including bracing, fittings, conduits, work platforms, and stairs.  I think if you want to use any of the "poly" type plastic cones, you will need to test to make sure that contact cement will adhere to it.

I ultimately decided to fabricate my own cone (and whole silo structure) from styrene.  It was the only way to get a cone of the proper angle, diameter, and material to match the prototype I was modeling.  If I was doing a silo of 24' diameter or less, I would have used the Plastruct ABS.

I created a frame of formers from cnc routed .125" styrene sheet, and then wrapped that with two layers of .020" styrene sheet.  I used an online sheet metal reducer calculator to create a pattern for the the cone skin.  It was tricky getting the cone wrapped, as it was difficult to hold the styrene wrap in place while gluing, because there's nothing to clamp to, and rubber bands tend to slide up the cone and loosen.  I was finally able to use tape to hold the wrapper closed in place while I applied solvent.  Ultimately, it turned out well, but was a tedious and sometimes frustrating experience to get there.  It didn't help when I knocked the bottle of solvent over and welded a bunch of miscellaneous parts together!

I still need to wrap the drum part of the silo, although that will hopefully be a bit simpler than dealing with the cone.  I laminated three discs of .125" styrene together to form the top of the silo, and a friend is currently turning a flat dished dome on his lathe.  The styrene tube running up the center is intended to keep the cone, drum, and cap concentric.  It will be cut to length.

Currently working on the left hand of the two silos.  When I'm done, I get to do it all over again for the other silo.

One method I forgot to mention earlier is if you have a wood lathe, or know somebody that does, you could turn the cones out of wood.  In retrospect, I actually think this is a good approach.  I don't have a lathe myself, but I probably could have gotten somebody else to turn the parts for me.  But I was also kind of hung up on doing everything out of stryrene or abs, for ease of assembly. 

I hope this gives you some ideas on how to proceed.  If you can find existing parts that will work for your project, and if you can get everything to attach together successfully, I would definitely recommend that route.  But starting from scratch isn't impossible either.  Maybe the method depends on how many silos you need.  

Good luck,
Jim

I do use the Plastruct VC-96 6 inch cone I cut down to diameter for my cone top water tanks. The inside is serrated at regular intervals so it is easy to cut through the 40 mil cone and not wander off line. Just note these cones are expensive.

There is a hole as you will notice in the top - however the cone comes in two pieces with a top piece you simply glue on. See below.

I'd make a cone of aluminum or steel flashing. Metal makes a nice cone.

A tab on both sides of the wedge, fold, connect by screws/rivet/etc leaves one seam to cover up (or not?)

Back side, each silo was cut (1/2) for the module display. (Grey) 

Fort Pitt Highrailer, Matt Irwin's modules.  I'm not sure where Matt got them.  Forum member, East coast.     Recent Pittsburgh Home and Garden show, much of what is picture, needs a lot of re-assembly, upgrade.  Nothing mobile, last for ever.   IMO,  Mike CT.