DMahalko
09-10-2008, 03:56 PM
This isn't something I am interested in pursuing, but I am just putting this out on the table for anyone who might think it would be worthwhile.
With most threshing machines you are left with the vision of a big steel box with pulleys and levers swinging all over the place, and bundles of wheat/oats going in, and seed streaming out with chaff spraying out the back.
But what happens inside? Pretty much all the really interesting mechanical action is hidden away behind sheet steel, and is invisible to the observer.
.
I am wondering how it would work to rebuild a thresher with transparent Plexiglas sheeting to replace all the sheet steel sidewalls, and replacing as much sheet steel as possible, including on the grain conveyor, the blowers, the shaker pans, and so forth.
This would be done on a model which is fairly common so that there isn't any loss of a particularly special or rare model of machine, and it would be done with the primary intent not for restoration to the thresher's original condition, but rather to serve as a tool for public education of how a thresher actually works when in use.
.
There are four big problems to deal with if this were to be done:
1. Scratching. I really have no idea how Plexiglas would hold up to the abuse of the grain and straw constantly rubbing across the plastic surface. If the plastic is soft then the grain will scratch the plastic which will slowly fog it. Tougher plastic like lexan may be needed, though the tougher stuff also tends to be more brittle.
Probably the first step before doing anything would be to make experimental transparent troughs out of different kinds of plastic, and set up a small auger to continuously dump grain over each one, to see how well each type holds up to abuse. The type which scratches the least would be the choice for the project.
2. Material thickness. The plastic sheeting would probably have to be much thicker than the galvanized sheet steel it is replacing. But the machines were designed for very thin steel walls, so some tolerances might have to be adjusted to make room for the plastic.
Typically there is a steel skeleton around the outside. Directly installing plastic inside this skeleton means the interior spaces are slightly smaller. A row of teeth on the extreme edges of the separator cylinder may need to be removed, and the shaker pans might need to be trimmed slightly to make toom.
The other direction is to leave the interior tolerances the same and instead expand slightly outward. This means slightly enlarging the outer steel skeleton that supports the enclosing body, and may require replacing much of the skeleton frame in order to add the necessary extra quarter inch or so on each side.
3. Weakness around mounting holes. It probably would need a metal reinforcing straps or huge flat washers on the inside, to better support the plastic around the mounting holes and to prevent cracking.
4. Reinforcement for places to walk. Threshers are designed to be climbed and workers may walk around on the roof. It may be necessary to leave the roof as metal sheeting, or to use much thicker plastic to support the weight of a person standing on the roof.
.
It seems like a "visible thresher" would be a fun and interesting public education tool, but this is not a project I would want to take on. Maybe there is a scale-thresher modeler (now or in the future) who would have an interest.
I'm not really expecting any replies to this post. I am just putting this out, to wait for the right person to find it.
- Dale
With most threshing machines you are left with the vision of a big steel box with pulleys and levers swinging all over the place, and bundles of wheat/oats going in, and seed streaming out with chaff spraying out the back.
But what happens inside? Pretty much all the really interesting mechanical action is hidden away behind sheet steel, and is invisible to the observer.
.
I am wondering how it would work to rebuild a thresher with transparent Plexiglas sheeting to replace all the sheet steel sidewalls, and replacing as much sheet steel as possible, including on the grain conveyor, the blowers, the shaker pans, and so forth.
This would be done on a model which is fairly common so that there isn't any loss of a particularly special or rare model of machine, and it would be done with the primary intent not for restoration to the thresher's original condition, but rather to serve as a tool for public education of how a thresher actually works when in use.
.
There are four big problems to deal with if this were to be done:
1. Scratching. I really have no idea how Plexiglas would hold up to the abuse of the grain and straw constantly rubbing across the plastic surface. If the plastic is soft then the grain will scratch the plastic which will slowly fog it. Tougher plastic like lexan may be needed, though the tougher stuff also tends to be more brittle.
Probably the first step before doing anything would be to make experimental transparent troughs out of different kinds of plastic, and set up a small auger to continuously dump grain over each one, to see how well each type holds up to abuse. The type which scratches the least would be the choice for the project.
2. Material thickness. The plastic sheeting would probably have to be much thicker than the galvanized sheet steel it is replacing. But the machines were designed for very thin steel walls, so some tolerances might have to be adjusted to make room for the plastic.
Typically there is a steel skeleton around the outside. Directly installing plastic inside this skeleton means the interior spaces are slightly smaller. A row of teeth on the extreme edges of the separator cylinder may need to be removed, and the shaker pans might need to be trimmed slightly to make toom.
The other direction is to leave the interior tolerances the same and instead expand slightly outward. This means slightly enlarging the outer steel skeleton that supports the enclosing body, and may require replacing much of the skeleton frame in order to add the necessary extra quarter inch or so on each side.
3. Weakness around mounting holes. It probably would need a metal reinforcing straps or huge flat washers on the inside, to better support the plastic around the mounting holes and to prevent cracking.
4. Reinforcement for places to walk. Threshers are designed to be climbed and workers may walk around on the roof. It may be necessary to leave the roof as metal sheeting, or to use much thicker plastic to support the weight of a person standing on the roof.
.
It seems like a "visible thresher" would be a fun and interesting public education tool, but this is not a project I would want to take on. Maybe there is a scale-thresher modeler (now or in the future) who would have an interest.
I'm not really expecting any replies to this post. I am just putting this out, to wait for the right person to find it.
- Dale