Structure 1 : first structure in the universe built using EMT and straps

Brought to you by Lows Inovation Lab.

This is bunny's portable bathing tub. He uses the whole of our bath tub so he doesn't make everywhere wet. We still put this tub in our tub but water use is a lot less. There are plastic EMT caps at the legs to protect the tub.

You can probably stand on the quad-strap cross joints without slipping. Very strong.

You can combine 2-hole straps with 1-hole straps for tee joints, and hardware straps for rotation and sliding. You can use 2 1-hole straps for fixing conduits when it's not load bearing.

1-hole straps are quite neat when snapping onto conduits. Here I use it for holding aluminum wires for the cage.

This is totally built without measuring tools, other than that the EMT's are cut to size. The quad strap joints have a tendency to be perpendicular, but not exactly. I suggest to using #10 nuts and bolts so there is less wobbling of the straps and the joints will tend to be more perpendicular.

World exclusive: Crius Quad stripes for low cost custom furniture, building and construction

From the Real Lows Innovation Lab

Previously, you can build furniture using PVC pipes or rigid conduits. This is because the pipes can be joined by coupling and tees that fit together. Not so much for emt conduits.

It's a shame that emt is only about two dimes per ft. There are fittings but not designed to couple pipes together rigidly. Also, an elbow cost a few dollars. I am not aware of any tees.

One day I screw 4 EMT stripes together and put them around two EMT conduits at a cross. The rest is history. Contrary to intuition, the cross joint is as rigid as you get, even though the stripes are a little flexible. It is difficult to put the pipes in position even before the screws are tightened.

There is no movement in any direction. You can't even twist the pipes. I don't know how much load it can carry before slipping gradually over a long time. But I think you can support body weight with ease. And you can design around this possibility of slipping by using load distributing for example. And the load can be born by the length of the pipes instead of the joints, such as legs of a table.

The cost of each quad is about 5 dimes. Not too bad that is about twice of a PVC tee.

Imagine the possibilities! You can build anything from a small stool to a swing sofa in the yard. The joints are not as neat but it is much easier to design and build without the need for tees. It's much stronger too.

If you just need to fix two pipes in position without much load, you just need two one hole stripes instead of 4 two hole stripes.

I'm pretty surprised when I found out that my hardware store has an innovation lab online! I don't know how long they have it. But my impression is that they are trying to move away from hardware as soon as they can. The all important section is the appliances. Then anything connected to expensive remodeling.

A sq ft of flooring cost a few dollars. A can of paint can be over a hundred. They are just not interested to stock pipe fittings and emt fittings. Last year or the year before they ran out of EMT pipes around xmas, causing their competitor to mock them with the sign "always in stock" by the pipes. And for a long time the 25 pack of emt stripes are not restocked.

Once I was in the middle of a project in the midst of thanks giving. I ran into the store on black friday morning and caused a sensation. The guy in the pipe fitting section was very unhappy as if I jinxed their black friday. They had high hopes when I came in but I can hear him murmuring "stupid fittings".

I bet very few staff knows they have an innovation lab online.

Another great tip: you can sand the zinc coating with a sanding block (or paper) to give a brushed stainless steel finish! There's very little effort and the coating remains stainless. I bet it will take paint well too.

I discovered craft acrylic paint. They come in small bottles so you don't need to waste money or storage for a small job. They have all the colors, from pink to metallic copper. The brushes are truly washable with water. All are non-toxic with little or no voc. They are tough and some claim to be dishwasher safe ?! Some even use it outdoors and let it weather. You can also protect the color with some clear outer seal.

Successful Green Pea litter system for bunnies may be cats and other small animals

I gave up on the Green Pea system because it was difficult to clean thoroughly. But it was much worse when I went back to disposable litter. The pellets are gone from the pet store shelves. The remaining have some have sticky residues and made a mess with bunny's tail. I ended up on the top quality paper litter. It's expensive and still I have to change often to keep bunny dry and clean. Over $10 a week just isn't right.

From avoiding pollution during engine oil change, I got the idea of revolving cleanliness. Say you use the same used oil tray every time and you don't ever need to wash it clean with detergent. Say after cleaning some spills, the floor is cleaner than before and you don't normally go there, that's clean enough, until next time.

For my modified Green Pea system, you just need 3 trays that can stack close together, and some sort of screen as in screen doors. And the main ingredient is aquarium gravel. And you also need some duct tape.

The bottom tray is unmodified to hold liquid.

You drill a lot of small holes on the middle tray such that gravels rarely get through. These holes are to drain water after rinsing. The number isn't important but affects the speed of drainage. But the holes should be placed such that water do not pool on the corners, the sides or the middle. A little pooling also not important. Then you put 1 to 2 inch of aquarium gravel on this tray. They support the weight of the bunny and allow liquid to drain to the bottom.

For the top tray you cut off 1 to 2 inch off the bottom, a height approx equal to the thickness of the gravel. Replace the bottom with a screen. I use those for solar screen door. Tough, flexible and soft. I duct tape it to the outside of the tray. I tried to super glue it but not successful yet.

That's it. You need two to three sets for rotation.

For extra credit, if the stacked height is too high for baby or old bunnies, you can put off parts of the wall in all three layers to let them in and out easily. A shallow tray will do, one to two inches. But usually trays are deeper than that.

So, the bunny do it's business on top of the screen. It's weight is supported by the gravel. Any solid or pill will stay on top without going into the gravels making them difficult to clean. If some solid sticks to the screen, you can sprinkle some paper litter to keep clean. You can just lift the top tray off with the screen to empty it as often as you like. Liquid will go into the bottom of the gravel layer.

Bunnies like gravel. He likes to dig a shallow depression and rest in it. Pea gravel from hardware store will do but smaller ones should be more comfortable. I suggest white angular gravels from aquariums but not too fine. You can easily see how dirty the white gravels are. Angular ones stack as in paving well while round ones slip around the feet. Indeed he sleeps on the gravels a lot of times, more so with the soft clean screen on top.

To clean, solids are simply emptied from the top tray as often as you like. Each day you need to soak the screen tray on top of the bottom tray a bit. Then it's easy to rinse it clean of sticky solid with or without a moderate pressurized nozzle.

The gravels just need to be rinsed. You can pour out the top water and let the water drain from the bottom holes.

It's not easy to dry the gravels thoroughly. The sun dries fast but only the top that it sees. I tried to bake it in the oven. It would work but you need a big oven ware. The gravels also have to be relatively clean, free of pills, so that the smell reminds you of cooking rather than the bunny.

This setup is designed to dry the gravel in place. With or without the sun, the gravels at the top will dry fast. So three sets of gravels are enough for a rotation. After enough drying, you just put the gravel tray onto the bottom tray and put back to use. The gravels may not be completely dry, but the top layer is dry, drier and cleaner than the last batch that the bunny did his business the day before. In comparison, if the gravels are not completely dry in the oven, you will feel the wetness when you pour them around into the litter tray.

In my last version, my two problems are that too much water with dirt goes into the outdoor laundry sink. If I use it to irrigate, the pills are fly magnets.

This time I just use a small patch of gravel pit outdoors to clean and drain. Since the pills are separated and the gravels have relatively little dirt in it, I just pour the dirty water down the pit for irrigation. The gravels will help to trap the tiny dirt down there better than bare soil. Everybody and the plants are happy. The liquid waste I pour as far away from plants as possible. And with a lot of water to dilute, I hope the plants are OK with it.

The running cost is the very few gravels that are lost everyday, and water. The water consumption I would say is about a flush of the toilet. I think I can use a lot less water if I try. It's revolvingly clean as long as the gravels don't smell. The top gravels will be relatively clean.

For cats, you can't have the screen layer. The gravel lost will be greater when you scoop out the solids, but you can use cheaper hardware store gravels.

Small creatures like to live in the gravels. So you may want to dry the gravels high up on some stands. There are plenty ways to clean the gravels thoroughly once a while. Many germs die at 60 C for a minute or so. (please check). So pouring boiling water on the gravels and soak them until the water cools will do nicely to kill a lot of things. Bugs will do poorly than germs. You can also use chemicals like hydrogen peroxide, salt, baking soda, vinegar. Bartender's friend is a rather strong acid but organic. Just don't eat it or let it absorb into your skin too much.

Even if the duct tape isn't secure, they don't come off that easily during cleaning, and the whole setup is rather neat when stacked on top of each other. Let me know if you have ideas to get rid of the duct tapes.

Green Pee Litter Box II (for rabbits)

I gave up on the Green Pee system once. I figured out dry is the way to go and you can throw away the trash when and how much you want.

I tried different dry litter and finally back to square one, the high quality plain white paper litter, that expands 3X. I had been running away from it since day one. It's about the most expensive type commonly available. I tried most others. Now my bunny is a bit old to clean himself thoroughly so I have little choice.

The problem is, the litter box is so good that he sleeps in it too. And pee outside the box. And since he can't keep his feet dry outside the box, he pee inside the litter box too.

It's not lack of training or he is hard to train. When he was a baby he just pee on the tiny corner litter box. He kept going when he was a lot bigger, even when the box can barely allow him to sit down.

Now we just want to make it comfortable in every way, and now he lives indoor.

We just can't have his "cage" all covered with expensive litter. And how to clean it? He pees like a facuet.

So we went back to the Green Pee system and see what we can improve. Gravel is less messy if he pees and sleeps in the same place. And we can surely afford to cover the whole cage with gravel.

Now it looks like this. The litter box is two simplest cat litter box stacked together. The top one has some small holes at the bottom for drainage. The bottom hold any liquid passes from the top. The top litter box has inside it a layer of aquirum gravel, or substrate. On top of the gravel is a screen to reduce dirt or pills to get into the gravel. We use solar type screen for patio screen doors, which has a thick plastic coating on the screen wires.

Bunnies like gravel. Given the chance he will dig a shallow depression and hug his body in it. But earth and sand are similar. Just that gravel is easy to clean. Cool too.

My previous mistakes include thinking that the gravel must be completely dry before next use. For this 2nd version, the bottom box is taken away for the gravel to drain through the holes after rinsing. After overnight draining and an hour or two under the sun, the top gravel will be very dry and comfortable. Here we don't worry about humidity.  If the gravel isn't that deep, almost all will be dry except for some on the bottom.

Last time I used pea gravel from gardening stores. They are bigger and less comfortable to sleep on. The sizes of gravels vary a lot. Indeed I use a sieve to collect smaller gravel for the litter box.

Aqurium gravel or substrate are much finer. Some are not a lot bigger than a grain of sand. It's a lot more expensive than pea gravel but you don't need that much. About 10 lb for a litter box.

Some still wet gravel on the bottom doesn't matter, as long as you don't turn over the gravel. In version two, the gravel drains and drys in the litter box. Once done the litter box is put back for use plus the bottom box to hold any liquid. The gravels aren't moved once the top are dry.

Acquarium gravel seems to dry faster. Because it's finer, you don't need that much.

The other mistake is thinking that you need something to absorb the pee. The pee can stay on the bottom of the gravel, and held by the bottom box. So the system is very simple. But you need to clean up everyday, which is rather simple. You can also put something at the bottom to absort the pee, like kitchen towel and baking soda.

I thought cleaning was easy after soaking in some powerful solution overnight. It was the other way round. The more soak, the more is the time wasted for drying. And it is messy.

Now the cleaning is just take away the top screen. Rinse the gravel in the litter box. Pour away the floating dirt. Rinse the bottom box.

It's seems that the gravel are lighter so it's easy to rinse clean. And you don't need that much to be comfortable to sleep on and hold enough pee under.

The screen can be cleaned using thin jet patterns coming out of a garden hose.

I clean everyday and have two litter box system for rotation. I can have 3 if needed, less than $10 each.

The problem of washing is that rabbit poop is top fertilizer but attracts flies. So unless you have some sort of draining pit outdoor that flies cannot get to, you need to deal with the waste water. I have a big outdoor laundry tub and I can wash things in it.

Fault tolerant vacation automatic pet feeder

Finally, I made it. I went on vacation for a full week and my bunny survived. Though I have a pan and tilt cam watching if anything went wrong.

Those on the market are too expensive. And even if I get one I don't trust them. First, they have a single motor. Auger / screw types can jam. If the motor fails, all meals will fail.

I actually built a multiple meal automatic feeder for my dog. It was complete with a hacked digital timer, and low level logic chips like NAND gates. I did that because I always have about a week to design and build it. And it have to work. The problem is, the motors are too expensive, or I couldn't reliably mount them to "open doors". So I only tested it for a weekend or two before he rested in peace.

At the time I hardly know what is a servo. And after I came across it, I just didn't have time to learn the hardware and software of a controller to drive them. And how much 7 servos cost? I used the cheapest motors and they work fine. The problem is that it's hard to glue some latches to the bare motor axle without gears.

This time around it's different. Tiny servos like sg90 cost next to nothing. Arduino kits are cheap and you can do a lot of other things with it. You order it from Amazon and they came quick enough before I setoff for vacation. I hope it's plug-and-play as they claimed. But I saved some money by ordering from other sources. So it's not plug-and-play but I figured it out how to program it.

I'm sort of a hardware and software professional so the rest is easy. The software is supposed to be simple, just wake up everyday at the same time and turn on different motors. That's why I actually built one with discrete logic that could be more reliable, and worked first time. But I don't trust a cheap controller working outdoors. One power outage or interruption the controller can be trapped into non-operational states.

I was prepared to write and test complicated software so if power is stopped for an hour, the operation behaves as if time has been lost for an hour or two, not whole days and not skipping meals.

After more thinking than coding, I realized it's best to drive the Arduino with a digital or mechanical timer. When the Arduino has stable power, it only need to use one location to remember which motor to turn on. The software is real simple. I was preparing to work overnight to make something work reliably. With this simplicity, I just needed trivial modifications to the sample code. There's only a few "critical" lines so I can tested them thoroughly in no time and went to sleep before leaving early the next morning. So to fail the timer has to fail and the board hardware has to fail. They seldom do.

My designs has been for the servos to open something like a trap door under food, and so all the food fall down to a tray. And I have no time to make the custom containers.

What I did was building a see-saw with fat lolipop sticks, with a cup of food on one end and a servo arm on the other end. When the servo turns the cup will drop. Everything is made of fat lolipop sticks that you can find in craft shops, and school glue. They are a surprisingly fast and secure combinations. To guard against earthquick, bigger animals and an angry bunny shaking the pet house, there are little slip guards also made of strips from wooden sticks and the cups are stabilized by cup cake paper liners. The craft isn't too bad but I have to build ad-hoc guards and defences to defend against bigger wild animals and the weather.

Wooden sticks was a surprisingly good choice because you can stack them up with glue to your desired height, or stick them to square dowels, also from craft stores and also hardware stores.

All the wires from the servo, 21 of them, are not soldered, but using the wires from the kit that plug directly into the Arduino board, and also use the tiny development board for the 5V and GND distribution. It doesn't matter if the wires fail to contact. Only one servo will be affected by one circuit failure.

And to ensure a good drop, the first thing was to custom built a big tray and inclined walls for the pet house. I had sewing threads glued to the cups and sticks to ensure they fall as expected but not into the tray to confuse the bunny.

The see-saw isn't the best design but I picked it because I had no time for other things. A long see-saw can balance out a heavy cup if the servo is weak.

As seen in the picture, one of the cup didn't drop. But there's only treats in the cups. There are plenty of other pellet food and hay that the bunny doesn't eat that much unless he has to. The problem was that the little vertical slip guard wasn't vertical enough. So the see-saw stick was trapped. This was a known problem in one or two of the unique handmade mechanisms. I forced the little glued sticks sections apart until it was smoother for the see-saw stick to drop. But one of them revert to the bad position eventually.

I almost built a automatic flush toilet too using the Arduino with servos. But it's too risky first time so the flush was driven by the lawn sprinkler controller for now.

Homemade custom non-slip microfiber car mat / rug / carpet

This driver side mat is customized from a a pure polyester microfiber bath mat. It is non-slip, thick with "deep pile". Less than $10.

Both the top and bottom side are stitched in squares. So it's easy to cut off the excess parts with a scissor, between the squares.

That's it. Completed in 3 minutes. But the cut sides will probably fray (come off) after repeated machine wash. I'll think about that when the time comes. But you can always stitch it by hand. Or I just found out that you can seal the sides with a flame. I'll try it with the excess parts first.

Update: Heat gun! The craft type. It's so easy to control. You can just melt the frayed threads to heal themselves, melt the edge, or melt the whole pile. There's not even smoke unless you heat the mat more than necessary.

It's more tricky on the driver side with all the controls. At the passenger side, I don't even need to cut anything. Because it's totally non-slip on every inch, it hugs the curves on the car floor. It also hugs the side walls all the way up the glove box. There are only little folds that you can hardly see and hardly touches. So, cutting is hardly necessary.

Why? It's cozy. Imagine a thick bath mat. It's highly absorbent for rainy days. And the deep pile can trap a lot of dirt.

Being purely polyester without the need for a non-slip backing, you can wash it often without worrying that the backing disintegrating. My OEM mats have integrated tough rubber backing at the back. You cannot put it in the washing machine. And after 20 years, the rubber mostly disintegrated but still shredding black residue to this date.

Microfiber don't absorb oil. So it's easier to keep clean and I used it in the kitchen. It even doesn't slip on vinyl when I run fast over it at a sharp angle. The only downside is that without a hard backing, it doesn't keep it's shape. It's still very rectangular but the straight lines are not visually perfect. It's a problem if you have to maintain the look of a formal kitchen. But in a car it's hardly a problem. There are curves everywhere. And you can hardly see the edge of the mats.

I don't remember any microfiber giving me troubles, like disintegrating. This will protect the carpet under it unless the mat becomes very thin. It may be less fluffy as time goes on. But it's thick. And it's not a bathroom where you bare foot all the time.

Restart your heater furnance with sand paper and how to upgrade spark igniter

A bit of history. My Trane central heating system from the previous owner must now be over 20 years old. Now Trane isn't in the same sort of furnace business any more. The relay is the 1st to go only a couple of years back. This year the transformer block went South just because one of the plastic socket melted. Part numbers (and replacement part numbers) are no longer applicable but I found one replacement that looked exactly the same on eBay. The wiring and spec are compatible.

Then the furnace is completely dead. I have an electronic (intermittent) spark ignition furnace, the sort that you can hear tick, tick, tick. After avoiding the engine wiring harness diagram for my car for many years, suddenly it made sense to me. After staring at the furnace diagram for so many years, it suddenly make sense to me. I'm sort of professional but I don't know what a pilot relit looks like and what it means. Suddenly I can relate the blocks in the wiring diagram to the boxes in the furnace. The rest is simple.

I checked that the pilot relit has 24V to it when heating is demanded. Basically it's a low to high voltage transformer to create the spark. I immediately ordered one replacement because it is cheap.

Then I thought of lighting it manually until the replacement arrive from the wrong coast. You should NOT attempt this unless someone is in danger of dying from cold and the sort. There is little difference between ignition by a spark and by a BBQ lighter. BUT, the ignition happens inside a room with a door closed. With a lighter you have to open the door and get to within 1 feet of the burner. And also, the furnace cover is open. If anything happens, there's a huge difference. So make sure there's no gas accumulation. Follow manufacturer's procedure to shut down completely, including the gas line, let possible gas leak dissipate, set thermostat to minimum and follow procedure to restart. Set thermostat to above room temperature. Finally put the BBQ lighter tip to where the pilot is and ignite.

After that, I discovered a youtube video showing the same thing. I cannot agree more that you cannot leave the furnace alone after starting. You must shut it down also after desired temperature is reached. Otherwise, the relit will try to spark, the pilot gas will come on, and the whole control will be in some sort of cycle. The gas from the pilot should be adequately dissipate from the vent and that the wast of gas will be minimal compared with when the furnace is started.

After some work, I can see that the sparks aren't completely dead. That led me to wonder if the relit is the only possibility of fault. From the web I vaguely read about that the relit isn't probably earthed, and cleaning the igniter with pin, brush, or sand paper. Now I know that they are talking about, or they don't want to talk about too much just like replacing the spark igniter with a BBQ lighter. Here's what I do.

Of course you check if 24V AC reaches the relit terminals and they are not rusty. Check if the earth terminals have 0 ohm with earth, usually the metal chassis and bare metal gas pipes are earthed. Now the high voltage wire aren't soldered into the relit. You can just pull it out. You may want to cut off a little bit wire and push it back in to ensure better contact.

Inside the ignition hole there are three components in the assembly. The pilot is basically a tough gas tube with a funny shaped end to direct the flames. The flame sensor connects to the gas valve via a bare earth wire like connection. The flame sensor itself is like a thicker stiff earth wire.

The igniter is at the end of the high voltage wire, which is itself a piece of stiff wire. It is usually thin and bent to direct the spark. When it was sparking, I observed that the spark goes to either the pilot or the flame sensor. Indeed both of them are earthed. And my igniter is midway between the flame sensor and the pilot.

So the principle is like lightning find it's way to earth. So I think the cause of not sparking is that the high voltage conductor or the earth conductor are not conducting due to oxidation. If you restore them to shiny metal surface, they should spark if everything else are working properly.

Without unmounting anything, you can see all three tips at an angle from above. You can scratch them to expose a little bare metal using a long pointed object. You can use a long narrow file or sand paper rolled into a tube. If it sparks better, you could take out the assembly and restore the metal surfaces so it will last another 20 years.

To take the assembly out, the minimum is to take out the pilot gas connector. Taking out the whole gas line together with the valve controller saves you a lot of grief.

If scratching a little doesn't work. I thought of mounting an earthed metal tip beside the igniter as a quick fix. It could be a narrow piece of steel sheet metal that can bend toward the igniter tip.

Now for the upgrade. Now manufacturers are all using hot surface igniter, and still some direct spark igniter (that starts the main burners). My intermittent spark igniter (that start a pilot first) are long gone. There's really not much good reason other than that you don't like the tick tick tick any more. A spark igniter last 20 years while a hot surface igniter last a few years at most, though the newer materials last a bit longer.

May be you can't find parts any more. May be your igniter is so bad that you need to replace it. And of course the valve. If you can't find a valve with main and pilot control anymore, you have to replace one with only main valve. Then you need hot surface igniter for the main gas line directly.

It's conceptually simpler if you upgrade to a hot surface. You just need to find a HSI that can be mounted onto the metal sheet chassis and place it close to the pilot tube. The newer rounded type are more likely to fit. A longer one is surer.

Most of them use line voltage at 120V. You probably have that control signal in your system. But to make it simple, you can use the relit input voltage at 24V AC to control a 120V relay, that in turn drives the HSI. The whole thing cost may be $20 that is about the price of a relit.

You need a HSI that is fast acting like a spark igniter. The relay should match the output current of the HSI. One caution is that relays have different types. Solid state relays cannot handle even small motors though their current rating are not exceeded.

Anyway, my relit is arriving next week but I probably do not need that.  My furnace is working now after taking out the igniter assembly and sand paper all over.

After sanding off some oxidation, the relit sparks better but not consistence. I put in my new relit and it works perfectly. This is the 2nd time now. The components was new but in a box that may be 20 years old, from the original parts supplier and original parts number - a collectable. That's how I locate the part on eBay with my 20 year old user manual. Did someone got it from an estate sale of a furnace technician? Did someone retired and clear his stuff? Amazing!