Hi everyone!
I’ve been thinking about the feasibility of producing the machines myself and was wondering how much forces the framework for each machine gets during operation?
Since I’m not much of a welder I’d probably try to make the framework out of wood. Is there a lot of arguments on not doing it that way? Wood is of course more flexible an lighter but that can be solved by using strong joinery in critical areas and adding weights.
What do you think?
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Hey!
Since I never welded before I was thinking about it too, however I cancelled it and asked a friend of mine, who will weld the frame for me next week.
Shredder:
The Frame (at least some parts of it) has to withstand quite some forces. Let’s take the worst-case-scenario:
Let’s say your motor is massively overpowered and “produces” 500Nm of torque. You are shredding and throwing in a piece that is too hard even for your shredder and so it blocks. Now the 500Nm want to turn the whole shredding unit, but since it is mounted to the frame all that force is used to twist your framework. The Question: How hard is it pushing? If your framework is 20cm wide, the distance from the shredding axe is 10cm. Since Nm = F * r , we can fill in the known values: 500Nm = F * 0,1m ==> F = 5000 N =~500kg. So in this worst-case scenario the forces are equal to 500 Kilograms laying on your framework. I would not recommend using wood there.
However, If you enlarge the width of your framework and make it twice as wide, the force gets twice as small. Also if your motor is only half as powerful, the force is also only half as small.
Example: Having a motor producing 250 Nm with a 40 cm wide framework, results in “only” 125kg pressing on the framework, which is doable with a bigger wooden bar I think.
So the “magic” is the lever principle: the more distance you make, the less force you need to get the same amount of torque. Or: the longer the distance to your axe, the less force you get that wants to destroy your framework. I hope that helps.
For the rest of the machines: No idea 
PS: Sorry for my bad English, expecially when explaining physics 
They’re aluminium round bars, 25mm diam. (the motor is huge) screwed with bolts… I think it should be fine, we do it at work (design of industrial machinery). I’ll let you know, as I’m building it right now!
Sounds like a good idea to make it stronger @javierrivera.
But I assume this would need to be welded as well which brings me back to the point of welding as little as possible. 
Or do you reckon this could be done without welding?
Hey guys,
this is what I was meaning. The shredder is mounted directly on the gearbox via a flange plate and standoff cylinders. The motor rests on a main plate. Then that plate can be mounted on a wooden bench, no problem. As long as the wood can hold the weight it will be fine, but the wood won’t take any torque loads. @flo-2 @siemenc @jerzeek
Yep, keep your timbers/wood well separated from your heat source:
Reaction – Temperature (Celsius)
Wood slowly chars* – 120°-150°
Decayed wood ignites – 150°
Ignition temp of various woods – 190°-260°
I think is doable, you gave me an idea to try…
For the shredder:
To avoid those strong forces mentioned in case the shredder gets stuck or fails to shred, if you mount the motor firmly attached to the shredder, something like this (https://static.rcgroups.net/forums/attachments/3/2/4/1/5/a3839128-196-Homemade%20motor%20mount.jpg?d=1299105153) with stand off round bar and plate (all in metal) then the frame wouldn’t need to be made of steel. In case of failure, the forces wouldn’t be transfered to the frame, I think.
If the motor is firmly attached to the frame, shaft coupled and the shredder is attached to the frame, then if it fails yes, the motor would try to twist and the frame would be resisting that twist. But if the motor and the shredder are firmly bolted together, it should be fine
Hope I explained myself properly
Cool to see your working on this 
I would say that yes, most part of the frames can be made from wood.
there are a couple of things to take into account:
Shredder:
Use enough strong woods, i guess this is just trial and error, make sure the connection between the metal parts and the wood is solid
Extrusion:
force produces by the screw pushing the material forward, i would say make the connection between the tube of the extrusion and the motor from steel, the rest can be wood.
Injection:
I think here the only problem is heat. So the connection between the barrel and the wood needs some thinking. i would suggest making the plunger bar still from metal.
compression:
Same as injection, think about the heat radiating from the oven.
Good Luck!
