Its all well and good to have a working reprap, but with out the skills to design new parts I would be limited to what ever already exists on thingiverse.com and other such sites. Since my own Mendel wont be finished for months I thought it would be best to use the time to pick up the skill required to make my own opjects.
As such I spent a few hours watching the fantastic tutorials for google sketchup, as I hear it can now be imported into another free 3d design program called blender. From there it can be exported to an STL format which can then be understood and converted to gcode for the a reprap.
Blender, although undoubtedly more powerful, looked far too intimidating for a first time user such as my self. So I settled on sketch up. The only other 3D design I have done before this was with bryce 5 many years ago. That program was only for landscapes but I still managed to make some more interesting images.
After looking at some fantastic mechanical shredders on youtube.com I thought I would have a go at making a reprap printable mini version as a learning task in sketchup.
Here is a video of the shredder in action.
and here is what I came up with.
As far as I can tell each part should be printable in that there are no sharp overhangs or gaps to be spanned. The round parts on the lower left is a representation of a bearing and would not be printed. A square 10x10mm steel rod would be used as the shaft. The top part on the left is flipped upside down and mates with the part on top right to pin the bearings in place.
An electric brushed DC motor or stepper motor would be mounted on the side to drive the large toothed gear at the bottom. A cut off bump switch on both sides would also be advisable just in case it tried to shred your figures..
I’m still amazed at just how easy to use sketchup is. Every thing in the program has been thought of in terms of ease of use for the end user.
Here is a short video of what it would look like if running.
Obviously as there is no collision detection and so only the one model I have selected is moving, but it gives you the general idea.
The original idea was that something like this could be used to shred milk bottles. Unfortunately, after having more time to consider it I doubt this would work very well, if at all. Due to the size of the milk bottle, its shape and the ductility of the plastic its more likely to gum it into submission as opposed to shredding it.
Still it was a fun start to sketchup and I can highly recommend using it. I have an idea for an adapted version of this that uses counter rotating drill bits and a pinch gear well to feed in the milk bottle that I will look into in the future.
If anyone wants to take a further look at the sketchup file you can find it here. Please note that I didnt take into consideration the size of a ‘standard’ baring, a proper way to mount it, a way to couple the too halves together and many, many other important things.
Edit: You are also able to export straight to an STL using a small plugin for sketchup. A quick explanation on how to use it can be found here.
Thanks Bob for pointing this out.