Engineerable » Furniture

FlowCat – Litter Box Exhaust Fan

Daniel Bauen — Sat, 22 May 2010 20:50:35 +0000

CAUTION: Following these simple instructions may lead you to forget that you own a litter box, and therefore neglect to clean it. Please proceed with care.

I despise the smell of litter boxes. Even when cleaned well, the smell of cat litter can be overwhelming. It’s ok if you live in a large house where you can dedicate a utility room, garage, or basement to the litter box. In an apartment, it is often impossible to keep a litter box out of smells reach.

For that reason, I made this simple litter box exhaust, which draws a small amount of air out of a covered litter box, and blows it outside. The computer fan draws just enough air to keep odors from escaping the box. The hot/cold air loss to the exterior seemed to be pretty minimal, because there is no noticeable change in heating/cooling costs. It works so well that people would be surprised that there were cats in the apartment.

The computer fan is rated at 0.13A, so it could easily be run off batteries being charged from a small solar panel outside.

Cats are generally freaked out by noise and weird stuff in the litter box. The fan is so quite, and far enough away from the litter box, that the cats did not care in the least bit. They were actually a little curious as to the dryer hose sticking in the box.

I built this system years ago, but was prompted to put it up after seeing this:http://hackaday.com/2008/09/16/hack-your-littler-box/
The bathroom fan seems like overkill, especially considering the fact that they cannot leave it on all the time.

step 1Materials

1. Computer Fan
2. Plastic dryer hose
3. Sheet of Lexan
4. 2 Plastic cups that fit about 3/4 of the way into the dryer hose
5. Outdoor electrical junction box (which computer fan fits inside of)
6. Screws
7. Glue
8. 12 Volt wall power adapter

step 2Fan Box Construction

The fan housing consists of an electrical utility box.

1. Cut a square hole in the bottom of the box to accommodate the size of the fan.
2. The fan is mounted to the back using screws at the corners of the hole.
3. Since the back of the box will be facing the exterior, a screen is placed across the hole to prevent the entry of bugs.

4. A circle is cut in the cover of the electrical box (fan box) to accommodate one of the plastic cups.
5. Cut the bottom off the plastic cup, and push the cup through the hole of the electrical box cover. Glue in place.

step 3Mount Fan Box in Window

I mounted the fan box in a sliding window. There are many other ways to mount the fan box. If you want it to be permanent, you could just mount it through the wall using standard dryer fixtures. This just gives you an idea of one way to do it.

1. Cut a piece of Lexan to the appropriate size to fit in the window.
2. Cut a square hole in the Lexan. The hole should be the same size as the hole that was cut in the electrical box. I only cut 3 sides of the hole, bending the center piece out to create a mini awning to protect the fan from rain, etc.
3. Screw the electrical box to the Lexan window.
4. Mount the Lexan and fan box assembly in the window. (The pictures below show it with the dryer hose already installed)

step 4Install Dryer Hose on Fan Box

Slide the dryer hose over the plastic cup. It should get tighter as you slide it up further. Apply tape if it is too loose to stay on.

step 5Install Dryer Hose in Litter Box

1. Cut a round hole in the litter box lid. You should be only able to slide the plastic cup 3/4 of the way in. This will allow you to wedge the dryer hose in between the cup and the hole.
2. Pass the end of the dryer hose into the hole in the box.
3. From the inside, push the plastic cup into the dryer hose. Push far enough to wedge it tightly.
4. I covered the top of the cup with a screen to try to keep cat hair out of the fan. You could also use a filter, because the dust still goes through the screen. But the dust never damaged the fan, and computer fans are cheap.

step 6Power it up, and Test it Out

To power the fan, use a 12 Volt power adapter, and connect the leads to the computer fan leads.

Hope this improves your air quality, and leads to a healthier life. Enjoy!

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Trail Mix and Other Goodies Dispenser

Daniel Bauen — Sat, 22 May 2010 14:05:52 +0000

Sticking our grubby hands into the bowl of trail mix has probably increased our immunity, but I finally had a chance to make something better with a scoop. Unsatisfied with the dispenser offerings at the store, I resorted to making my own, as usual. An airtight container is key to keeping the trail mix fresh. I was tempted by the hopper type dispensers that had a twist knob which dispensed measured amounts every time the knob was turned. However, the inexpensive ones ($50) looked cheap, and didn’t seam to have a good airtight seal. Nor did I believe that they would be able to handle some larger items in the trail mix. These Clik-Clak containers provide a nice airtight seal, but still have a quickly removable lid. To test out my idea about how the plywood stand would work, I first made a cardboard template, used it to adjust the dimensions, and then as a template for the plywood.

Update: We’ve been using this at the office for a few months. It’s been a hit. Everyone feels better about scooping out the trail mix, and our built up immunities are slowly deteriorating. The only change I had to make is add a weight (steel bar), which is screwed in under the front edge. It is not visible, but prevents the container from tipping back.

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iPad Leather Case

Daniel Bauen — Sat, 17 Apr 2010 05:43:30 +0000

This is my first attempt at making a leather case for the iPad. It’s also the first time I’ve worked with leather, so it’s kind of rough and unfinished, but that’s how I like it. Thanks to John Sanders from www.joxasa.com for helping me pick out the leather and excellent design advice.

I started out with a full frame around the edges, but due to the flexibility of the leather, the center parts of the frame tended to lift up, so it didn’t look or work very well. I cut the center of each edge away at angles from the corners, so that the iPad is only held in by it’s corners. This retains the iPad very well, but I can’t easily slide it in and out of the case like I had originally planned. Once the iPad is in case, it’s not coming out anytime soon. The edges are left wide and unfinished for a rough appearance, and added drop protection… Hopefully.

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Electric Violin Wall Case

Daniel Bauen — Mon, 15 Mar 2010 05:41:31 +0000

The NS Designs Violin is practically a work of art by itself. Unfortunately, the case it comes with is not so practical. As with any violin, the shoulder rest must be removed when the violin is stored in the case. Installation/removal of the custom shoulder rest requires tightening/loosening two thumbscrews, sliding the shoulder rest post out of the violin’s body, and folding the post flat with the shoulder rest. That’s not difficult in itself, the problem is that every time the shoulder rest is reinstalled, it has to be repositioned the same way, which is not easy with 3 degrees of freedom. Etching some markings would make it a little easier.

The violin is used at home the large majority of the time, so the solution was to make a storage case which did not require me to remove or reposition the shoulder rest.Due to their solid wood body design, electrical violins like this one are less susceptible to changes in humidity and temperature. Thus storing it outside the case is not a problem. Still have to be cautious, especially if the bow is stored outside the case.

I had an old violin case that was in terrible condition. I think it’s the case from my first violin. The interior fabric was pealing off, as was the vinyl on the exterior. I was afraid to see what kind or crappy wood the case was made off. Surprisingly it was reasonably good looking plywood. But the adhesive used to attach the fabric took a lot of sanding to remove. Using a small random orbit sander and lots of hand sanding, I managed to remove most of the glue residue.

In order to accomodate the shoulder rest, a cutout in the back of the violin case had to be made. I also built a box which is glued to the back, and lifts the bottom of the case away from the wall.

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Towel Rack

Daniel Bauen — Wed, 03 Mar 2010 13:53:21 +0000

I needed a towel rack to fit on the back of the door, and allow the towel to be slipped off the end. This makes it easy to grab the towel or hang it up just by sliding it off or on the end. I had scrap dowel like pieces of nice outdoor wood from a broken patio umbrella. That would be useful for the bar from which the towel would hang. The support for the bar was made from other scrap wood ends.

These are the individual components. I used some scraps of wood for the mounting block, and the long stick came from the frame of a broken outdoor patio umbrella.

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