This is it. The last of the reverse engineering of the composting toilet series. All that remains are the four knobs on the lower drawer of the humanure maker.

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The exact profile of the knobs is somewhat shady, but with a bit of educated guesswork, they’ll come out great for all intents and purposes. In the image below, you can see that I started by creating a sketch on the lower front face, then placing and centering a point on what I would call the right hand stile of the poo drawer.  The next step is to create a plane 90° to the face using the construction line that was used to center the point horizontally.

The only difference between this plane created on a line and the others in this series is that I selected the line, then instead of one of the Origin planes, I selected the face that the line sits on. The angle was left at the default 90°…   Read the rest of this entry →

Most of the things that remain to be modeled to complete this project have been covered earlier, and are relatively easy – the four knobs on the front are the last challenge.

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I’ll run through some of the procedures that weren’t covered earlier and get the rest of the stuff modeled in this post. If there is time, I’ll move right into the knobs to finish this up, otherwise, there’ll be one more post in this series.

On the side of the unit, there is some sort of hatch that will be represented in this model as a shallow groove in the surface, and a tapped drain hole –both of which are procedures covered earlier in this series, but there are differences that should be shown. To begin, I created a plane on the furthest right horizontal edge of the model (could also have been completely off the model).   Read the rest of this entry →

I’ll begin this post by going all the way back to the first extrusion in this model to fix an error I made way back then. It will go a long way to demonstrate the power of parametric modeling.

The problem was that during the first extrusion, I inadvertently included the profile of the front reinforcing ribs in the selection set, giving the entire lower front an angle that it should not have. To fix this mistake, all I did was double click on the offending extrusion, get the profile selector from the dialog, hold down the shift button on my keyboard, and select the profile I want to remove from the selection set…

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The features that I’ll model in this post are those that comprise the front hatch group. The group consists of a rectangular hatch with wire U-handles on either side, and a round grille in the center.

In reality, the drain on the right hand side would be the only thing that I would need at this point, but I’m committed to making this poo composter pretty(er).  If you had a lot stuff in close proximity to the unit in your digital prototype, you may need some of the handles, etc. to check clearances as well.

To begin the hatch, I created a sketch on the angled front face. I immediately window selected the projected geometry and turned it into construction geometry. In the original drawing, the hatch appeared to extend from fillet to fillet vertically, so I created a rectangle to reflect that. I know the width to be 11” from the tracing, so I added that dimension for the width.  I then used the Offset tool from the Modify panel to step in the rectangle .125”. I centered a circle in the rectangle and sized it to 8”, giving me what you can see below…
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I figured this series would likely turn out to be three or four fairly long posts as it took 3 or 4 hours to create the original model used in the ComPOWTS story.

As it turns out, hours spent modeling have no relation to the page count it takes to describe said modeling. Whoda thunk?  But back to the modeling. I left off in the last article cutting away the artifact geometry on the top platform thingie—which I think houses a fan, a thermostat, and possibly some other controls. The modeling technique for that was very similar to the one before it.

The holes on the other hand, are a bit different. For these I created a sketch  on the same face that the last extrusion was extruded to (the upper platform), and turned on the original sketch with the dimensioned image so that I could access the dimensions.

I then  deleted the geometry that Inventor projected for me (not needed in this case), and projected the lines shown below……..the outermost edges of the unit in that particular corner…

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