Making crittall bins self emptying

Jack Russell · Apr 12, 2015

we want make a few of our crittall grain bins self empty. I was planning on removing a couple of panels at the back of the bin and fill it with 40mm down chalk to get the slope. Then concrete it, but how would you get it concreted so it doesn't slump and get a good polished finish?

Do you put a rough layer of cement in and then skim it with a final layer?

Pan mixer · Apr 12, 2015

Jack Russell said:
we want make a few of our crittall grain bins self empty. I was planning on removing a couple of panels at the back of the bin and fill it with 40mm down chalk to get the slope. Then concrete it, but how would you get it concreted so it doesn't slump and get a good polished finish?

Do you put a rough layer of cement in and then skim it with a final layer?

That is more or less what I did in an 8 by 10 bin, it took a lot of slope though, the polish never lasts that long, I would have painted it with floor paint but I reckon that I could never go in there again to clean it out/spay it etc as it would be too slippery.

Lay the concrete like a plasterer would, leave a rough surface then do a thin screed of dryish material, perhaps some lime in the top layer would help, I am not an expert though and I did mine with 3:1 sharp sand and troweled it smooth, no danger of slumping with a thin layer, just a slight difficulty in getting out after.

With your idea, beware getting the panels back in again, I did mine when I was putting the bin up and had the benefit of a 'sky hook' (Matbro) to bring in materials and the hang a ladder off for the final little bit of smoothing.

The worst bit to do is round the auger, best to do that a couple of days later but that involves working on the tummy facedown and is not for the less mobile amongst us.

Flat 10 · May 2, 2015

Use PVA glue mixed in with the final screed..........

KennyO · May 2, 2015

Place I worked as a student bought a big sucker blower for emptying bins (sweep augers were knackered). They said it was good however I never got the pleasure of working it.

Might be easier- or hire a concrete pump??

organicguy · May 2, 2015

We have 12 self emptying crittals. They are built on top of a 6ft tunnel and cones dug out to let them run to a conveyor. father RIP built them by hand in the 50s. Just laid fairly dry concrete on the slope, tamped it hard and worked a smooth finish. Brilliant system but only runs at 5 tons an hour.
We built an above ground one for emptying a drier into. Took out two panels and put a plywood floor sloping away from the open side.We can empty the drier and move the grain away at our leisure. I am sure it is written up in farmideas.

Pennine Ploughing · May 2, 2015

i was at a farm the other day, they were putting a wood pellet boiler in,
now the store for the pellets had a flat floor in it, and it was a square shed, in the middle was a rotor that went round when the it stopped flowing to the augar
wish i had taken a pic of it, but it had 2 spring steel blades on it, and how it work i was told is,
each blade is a bit like a rotorspreader chain, it wraped around the center drum when the bin was full, when it got low, the rotor turned and the blades moved the pellets to the augar, as the bin got less and less in it the blades sprung out as far as the pellets and emptied the shed even the corners and only moved at a slow speed by a geared down motor
hope you see what i mean as not good at explaining it

i know it not what your looking for but i thought a would say about it anyway

Flat 10 · May 3, 2015

You need to find out the angle of repose for the crops you wish to store. I think wheat is about 34deg.............

bravheart · May 3, 2015

Flat 10 said:
You need to find out the angle of repose for the crops you wish to store. I think wheat is about 34deg.............

Sloped wet bin at 45degrees so uses up half the space in bottom of bin, 3 outlets.
Sloped one at 30degrees for dry grain with one corner outlet. The angles are way out on this one,it should have been at least 34 deg. as flat10 suggested on the diagonal from the outlet to the far corner.
Just gave the concrete a cement wash with a steel float, works fine and the grain movement keeps it polished

Foxcover · Mar 14, 2021

Did hot ever get sorted with this @Jack Russell?
I’ve got an idea if not!

tullah · Mar 14, 2021

Drop a tethered half dead rat attached to baler twine over the side of bin onto top of grain heap.
Put Jack Russel into bin via the hatch. An hour later when you return bins been shovelled out.

Jack Russell · Mar 14, 2021

We have done so many but more to do. What’s your solution?

Foxcover · Mar 14, 2021

Jack Russell said:
We have done so many but more to do. What’s your solution?

right, 8 wooden triangles from sturdy timber, sit 4 per side with their right angle corners into the left and right side bottoms and then some sheets of smooth mdf on top so what you end up with is a V in bottom of bin with the trench running from back of bin to outlet.
Drill 2 inch hole through bin side at bottom of bin in the V furthest from outlet, start emptying bin through outlet, when no more grain is coming insert long steel pipe attached to a compressor on tick over and push it through grain right to outlet and then slowly draw it back blowing remaining grain to outlet and completely emptying bin.
pros over stone and concrete is that it would be cheaper and easier and removable.
Con is that you might get a bit of dust from air pipe and you’d need someone to pull pipe out but it’ll empty remaining grain in 5 mins or so.
Could even make the triangle cheese wedges from box section or rsj and galvanised steel sheet if you wanted a proper job

grainboy · Mar 14, 2021

Have some in kit form available,
But seriously would go down the timber frame. Plywood route,

Daniel · Mar 14, 2021

Foxcover said:
right, 8 wooden triangles from sturdy timber, sit 4 per side with their right angle corners into the left and right side bottoms and then some sheets of smooth mdf on top so what you end up with is a V in bottom of bin with the trench running from back of bin to outlet.
Drill 2 inch hole through bin side at bottom of bin in the V furthest from outlet, start emptying bin through outlet, when no more grain is coming insert long steel pipe attached to a compressor on tick over and push it through grain right to outlet and then slowly draw it back blowing remaining grain to outlet and completely emptying bin.
pros over stone and concrete is that it would be cheaper and easier and removable.
Con is that you might get a bit of dust from air pipe and you’d need someone to pull pipe out but it’ll empty remaining grain in 5 mins or so.
Could even make the triangle cheese wedges from box section or rsj and galvanised steel sheet if you wanted a proper job

This is a great idea, we have 6 X 33 ton bins and 2 x 27 ton bins that we barely use any more. The emptying conveyor died years ago and we bought a sucker blower, but you still have to shovel them empty.

Will do some maths to see how much volume would be lost.

Foxcover · Mar 14, 2021

Daniel said:
This is a great idea, we have 6 X 33 ton bins and 2 x 27 ton bins that we barely use any more. The emptying conveyor died years ago and we bought a sucker blower, but you still have to shovel them empty.

Will do some maths to see how much volume would be lost.

Rough maths would be square metres of floor area times by height of triangles and then divide the total by 2

Daniel · Mar 14, 2021

Foxcover said:
Rough maths would be square metres of floor area times by height of triangles and then divide the total by 2

I worked it out sloping the 4 sides down to a central point, making the bin hopper bottomed in effect, it would reduce the capacity to 27.9 tons I reckon. The joinery would be a bit more complex, but you could leave a pipe length permanently connected to the base of the 'hopper' for the sucker blower.

Foxcover · Mar 14, 2021

Daniel said:
I worked it out sloping the 4 sides down to a central point, making the bin hopper bottomed in effect, it would reduce the capacity to 27.9 tons I reckon. The joinery would be a bit more complex, but you could leave a pipe length permanently connected to the base of the 'hopper' for the sucker blower.

It’s not hopper bottomed, it would be like an inverted Toblerone so less volume would be lost.
How you gonna use the sucker blower?

Daniel · Mar 14, 2021

Foxcover said:
It’s not hopper bottomed, it would be like an inverted Toblerone so less volume would be lost.
How you gonna use the sucker blower?

We already have holes cut in one side of each bin with a length of twin wall pipe pushed through to the centre of each bin. These pipes are capped off, when you want to empty the bin you push a sucker blower pipe in through the twin wall.

Your method does lose a bit less volume, bin would still hold about 29 tons I think.

Foxcover · Mar 14, 2021

Daniel said:
We already have holes cut in one side of each bin with a length of twin wall pipe pushed through to the centre of each bin. These pipes are capped off, when you want to empty the bin you push a sucker blower pipe in through the twin wall.

Your method does lose a bit less volume, bin would still hold about 29 tons I think.

so you’d empty by sucking it out?

Daniel · Mar 14, 2021

Foxcover said:
so you’d empty by sucking it out?

Yeah, that's how we empty them now.

Making crittall bins self emptying

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