Compressing Blocks of Snow

This is quite a bizarre question, but this group seems like the best place for it. For a number of years, I've had a hobby of building large snowforts.
The structures are built primarily from blocks of snow, and with the help of friends, some of these have reached heights of over 15 feet. I've devoted a website to these creations, and I recommend checking it out to get a better idea of what I'm talking about: www.geocities.com/snowfortzone.html (some pages aren't complete yet but all the fort pictures/specs are there)
The blocks are made by packing the snow, by hand, into 20-liter (5 gallon) buckets and allowing them to harden. This simple but labourous method has been used right from the beginning, but it has some inherent problems. The first problem is that there's no way to maintain consistency between blocks. One might weigh 15 pounds, the next 30, the next 25, and so on. Variations in the density of the blocks can have a MAJOR effect on the finished structure. As the structure is built higher, the added weight tends to further compress the blocks on the bottom. If for example, the blocks near the bottom on one side are made from lighter snow, they will sag much faster and cause the entire structure to lean in that direction. This problem has plagued many of our projects, and the cause of poor blocks is usually shoddy workmanship, not poor snow. The other problem is the labor involved. If the snow is damp and packy, a block can be assembled in less than a minute. If the snow is dry and hard to pack, it can take up to 2 minutes to make the block, plus 30+ minutes for it to become stable enough to handle. This isn't a problem if there are plenty of helpers, to keep up a steady stream of blocks. But good help is becoming harder and harder to find, and as this winter rapidly approaches, it appears that I'll have only one helper to assist me with these projects. Which brings me to the point of my post: What appears to be needed is some kind of contraption to speed up the production of these blocks, and to produce better consistency. My basic idea is a tall steel frame, with some kind of ramming/compressing device that will pack the snow VERY FIRMLY into the pails. I need something that could assemble a block in about 1 minute, and pack each one to a density of about 35-40 lbs (currently, we can pack by hand to a density of 15-30 lbs). The idea would be to fill the bucket with snow, operate the "ram", top off the bucket again, compress, and repeat until the block is fully assembled. This is as far as I've come with the idea. I'm told that compressed air would be the best way to do this, and this sounds feasible as I have a 200 PSI, twin-cylinder compressor that could be used for this. If anyone could come up with some ideas, I'd appreciate it. If I can manage to construct such a device within the next couple of months, this cherished winter tradition might just be saved for another year or two......
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Actually, that gave me a 404 - Not found. The link below may give better results:     <http://www.geocities.com/snowfortzone/
Mike
--
Mike Beaty, Professional Engineer snipped-for-privacy@nyx.net
Boulder, CO
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
My mistake, that should have been:
www.geocities.com/snowfortzone/index.html
Sorry about that!

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Chris F. wrote:

Fun stuff.... I would construct it this way (with just a couple minutes thought after scanning your website)...
Get a piece of sonotube that is the same inside diameter as your buckets. (sonotube is the plasticized cardboard tubes that they use as moulds to make concrete pillars). Set up the sonotube (verticaly?) so that there is just enough room to slide a bucket under the end. Figure out (your experience will come in handy here) how much length above the bucket you will need to get your desired density using the driest snow... Cut a big hole out of the side of the tube at this point...
I'd just use levers (shovel handle) and a "ladder" arrangement with a disk of plywood on the bottom as a press... but if you want to spend bigtime on a long-travel ram.. fill your boots... (perhaps a log spitter that isn't being used?) Maybe horizontal or 45deg tilt on the rig would be easier?
In use, I'd figure out how much snow to put in the rig to get the right density of block on a given day.. The plywood disk press sitting just above your big hole in the side of the tube.... fill snow to your line... then press it down till it's all in the bucket.
Glad I don't live where you do.... =)
Al...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
If you have to leave them in the buckets for any length of time, you may want to consider pouring cold water into the buckets, or having a ready made pool of "slush" to freeze into solid blocks of ice. Your consistency would be better, and you could cover the structure afterwards with snow to give it that feel of being only snow.

place
snowforts.
of
a
better
all
tends
a
to
it
plenty
becoming
appears
idea
about
two......
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The best snow for winter shelters in the arctic has the consistency of styrofoam,. I believe created by the wind driving snow into itself. ( I assumed the surface bonds from kinetic energy meling the bond area while the core of the "snowflake" remains free-air crystaline.)
However, if you don't want to use a directed fan and a venturi pick-up tube to layer and pack the columns -
blue sky time -
---- I would get a beam and hang two weights, e.g., large buckets/barrels of water/ice on either end, arranged in size and distance from a pivot so they balance on the beam.
Now you can pivot the entire weight assembly by only having to overcome friction.
Now, do you want to tamp or do you want to pack?
Tamping, you can put a bucket of snow under each end and teeter-totter the beam so the weights hit the snow-filled buckets alternately - tamping two at once using the energy you put into in the moving weights.
Alternatively, I would put the bucket to be packed under one of the weighted barrels. I would put a lever to the ground/table/etc.on the other end at the other barrel, so I could lift the weight off the back end of the beam, putting all the weight on the barrel over the bucket to be packed
By arranging the pivot of the beam and the size of the weights accordingly, I can drop the tamping end a lot or a little, and get just gravity load or gravity plus a lot of kinetic energy, (e.g., if I had a long arm dropping and a very short arm counterweighting, I could arrange my lever to lift the counterweight off the beam-hook faster than gravity dropping the long arm on the other side of the pivot moved that beam-hook )
Note that you can cut off a man's fingers or hand at the edge of the packing tube by dropping a close-fitting weight into a bucket If i were dropping the weight, I would either use a long sonatube or the like and not let the tamping weight come out on the upstroke, or I would make a box that fit over the bucket to be packed, to allow me to add snow, to guide the tamping weight, and to protect fingers and hands.
Or you can get a vertical logsplitter and replace the wedge with a flat ended solid cylinder that fits into your really strong pipe, arranged so that you can strip the pipe off as the ram retracts and then lift the cylinder (the inside diameter which is the size of your bucket) :-) Sizing that so you don't kill someone if it explodes when you get a rock in the snow pushing on the wall is a whole 'nother problem
hope it helps
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ok, there's a blue sky gaffe - leetle problem with one. (- which is why when the idea is for pay, you bake it and come back to check it out after it cooks by itself a while) -
there was a detail I didn't mention

When you take off the rear weight and the front end falls down to pack snow, you don't have the system balanced in order to bring it back easily - you need to set up the geometry so that the removal lever is then lowered a little bit to let the weight go back onto the beam point, which is now up from where you removed the rear weight to let the front fall
or you could step up on a stirrup to lift it back up, and then re-attach the weight.
enough on snow blocks - time for cognac and pack - gotta fly out tomorrow (airplane)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Chris F. wrote:

I would go with a simple lever setup, where the lever is overhead, hinged on a fixed post of some sort (see below). The lever would have a beam with a circular piece of plywood hanging of it. the helper puts snow in the bucket and makes sure the plunger (which is free to swing) makes it into the bucket. Then you're own weight pulling on the handle will compact the snow. should require little effort on your part.
x----------x---------------<|||> <--Handle ^ | | | pivot | | | --- <--Plunger
| | | | Bucket | | -----
-Matt
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Have you considered a trash compactor? Do you have electricity available at your site or a generator? You can build a box with removable sides to fit where the bag goes and get decent blocks of snow.
Richard
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
If the the blocks can be rectangular instead of cylyndrical (Change is good. It keep thing fresh.), then you might want to consider an ordinary, store-bought trash compactor. The last one I owned was a Sears model that cost a couple hundred bucks, and seems like it could have been ideal for your needs.
If you've never owned one, a typical household compactor has a square, sheet metal box, maybe 12" wide by 15" long by 16 or 18" deep. The box has little slots and clips on it so you can pop it open to insert a new bag, or to remove a full one. In use, the box (which is designed to provide amazing inside-out burst strength, even though it appears pretty flimsy) is lined with a heavy paper/plastic bag that fits in the box well enough so that the box prevents tearing and bursting of the bag.
The working part of the compactor is just a vertical ram, positioned over the bag/box, which is driven by a screw, and by a motor that stops and reverses when the factory preset compression is reached. When you toss some trash in and push the start button, the ram (with a nice big flat plate on its bottom end) pushes down into the bag/box and squishes everything downward with quite a lot of force. It also does this with rather good consistency. When the spec'd pressure is achieved, the motor reverses and the ram retracts. Typical use involves tossing trash into the bag until it's about full, then squishing it, which makes room for more trash to be tossed in. When the bag is full enough, and compacted firmly enough, that the ram can't make any more room, then the bag is removed, and 20 or 25 lbs of squished trash are disposed of.
It seems to me that this would work just about perfectly for snow. Not only would it provide a quick (about 15 seconds is a typical cycle) way to squish the snow consistently; but it would also leave the snow in a neat, rectangular, water-tight, plastic lined, paper container for the final chilling process. After chilling and hardening, I would expect that the finished block would just slide out of the inverted bag, and the bag could be re-used many times.
I wouldn't be surprised if there was some simple way (probably an adjusting screw or adjusting collar on a shaft, presetting the compression of a spring) to tweak the machine's compression force to suit your exact needs. You'd want to think about safety, of course, but all the electrical stuff on compactors I'm familiar with is at the top end of them, and might easily be protected with a little care or thought. And, a couple bits of angle iron, or maybe some old sled runners, would make the thing plenty portable.
A compactor like this is probably something you could find cheap and used, at a garage sale, or maybe on e-bay. If its cheap enough that you don't mind tearing it apart, then it would probably be small work to modify it for your exact demands - like maybe with a small air-motor instead of the electric motor, to make things really safe and simple. Or maybe you could fix the bottom end just a bit so that you could still use your 5 gallon buckets, instead of the rectangular bag and box thingy.
Anyway, it might be worth looking at. Good luck, and have fun.
KG __ I'm sick of spam. The 2 in my address doesn't belong there.
Chris F. wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.