Physical Build details

A project log for Captain Underpants Toilet

Arduino controlled Toilet using wiper motors and wave shield, range finder. Eyes made out of ping pong balls with green LEDs

hamblin.joehamblin.joe 08/06/2017 at 00:330 Comments

I am going to break up the project into three parts.  Physical build, Arduino work bench sensors, and lastly integration of all the systems.  For the Physical build I first needed to find a toilet to work with.  I went to eBay, I found several around the $60 - 80 range but they where at least an hour away (probably longer).  I looked on eBay for three days.  Then I saw what I was looking for, one that was only about 15min away, and only cost $20.  I brought that home and did a very good cleaning of it, I took the tank off the back and cleaned that area.  Next I needed to work out how to attach the wiper motors.  One of my design rules was I did not want to drill the toilet.  I did this once on an earlier project and it is not easy drilling into porcelain.  

I had recently purchased a bench grinder.  This came in very handy with this project.  To mount the motors I purchased some 90 degree three whole brackets.  I then had to drill holes to align correctly with the motor.  This was a slow process, I cut off the excess bracket and used the grinder to round the edges.  I used a oscillating belt sander to form the plywood mount for the bowl.  This takes some time I wanted it too fit well all around so it wound not move.    The mount for the bowl can easily be removed if needed.  I later painted the bowl wiper motor and mount white to blend in better.  I made one mistake I cut the bolt that holds the motor mount too short.  I can get the nut started but it a delicate process, if it was an inch longer it would be easier to work with.  

Attaching the wiper motor to the bowl lid was not that hard.  I cut a piece of 1" flat bar about 9" long ( this is too long on purpose).  I then drilled a 1/2 hole into one end.  I went to auto zone and purchased 

Dorman 49447 Windshield Wiper Linkage Bushing Assortment

I had to use an x-acto knife to cut off excess from the bushing, this held the flat steel bracket on very securely.  I then cut 10" of Punched Angle zinc plate.  This was perfect is had holes every inch.  I spent about an hour walking up and down home depot trying to find items that I could use for my project that they where not intended for :D   I attached the Angle bracket to the back side of the bowl lid with short screws making sure they did not go through to the other side.  Then I noticed that the alignment was not correct the wiper motor was correct.  I should have mounted the angle bracket differently than I did.  I was able to put a Z bend in the bracket, I was very happy that I had a vise.  I had to use hammer and care that the bend was where I needed it.  Once this was done, I could test out how long the flat bar needed to be, I would hold the bowl lid up to the highest point.  I then would take small cuts off the flat bar and then test fit again.  Important to make sure the bowl wiper motor arm is up at the highest point while doing this.  I then used the grinder to round and smooth all the edges.  After drilling a 1/2" hole into the other end of the flat bar, I was able to attach the bowl wiper arm.

I also mounted a micro switch in the bowl seat, only the lid would move up and down.  I needed the switch to let me know when the bowl lid was closed.   This meant that I would have four wires that needed to be routed to the tank.  I tried to route them trough the toilet, the passages are very small.  In the end I went for 1 1/2 white heat shrink that I got from MicroCenter.  I cut a notch in the back of the toilet seat for the microswitch.  It took a bit of trail and error to get the switch into the correct position.  Then I realized I can take the toilet seat off the toilet and get to the bottom of it, this made getting the correct location for the microswitch easy.  Here is the bowl section completed and painted

Now on to the tank.  I removed the rubber gasket that connects it to the bottom section, I then put two small 3/8 piece of plywood spacers on either side, and re-attached the tank.  I wanted to have a gap so that I could route wires from the bowl into the tank.  

I epoxied two five inch 2x2 diagonally to the bottom of the tank, on each side.  Its important to leave room on the sides to be able to route the wires from the tank ( you don't want to pinch them).  

The Tank was the most DIFFICULT part of the build.  The motor mounting was the same as for the bowl.  The challenge came with the how to hold the arm and then lift the lid.  The wiper motor had way more movement range than needed for the lid.  It could easily pick up the lid and throw it off.  I tried several methods to control the arm that at first seemed fine, then when testing with the lid on, I saw that their was too much travel.  Cutting the arm shorter solved the range problem but create a problem with being able to control the arm.  I spent several days trying to figure this out, I took a break for a day.  Then I got the idea that if I milled a slot in the middle of the flat iron I could put a screw in there and I would be able to control the bracket.  We recently got a table lathe with a mill attachment, this solution worked out perfectly.  

When I mounted the motor on the plywood for the tank I purposely left an area that would just fit a 12v motor cycle battery laying on its side, then on the other side I would locate the Arduino's motor controllers etc.  In the end I cut two pieces of 3/8 plywood that cut a little larger than an arduino foot print.  I then hot glued these to the back side of the tank.  I used small screws too attach the arduino's to these pieced of wood.  This way I would have easy access to the arduino's.  One frustrating issue was the new arduino's come with a nice clear plastic tray.  I assumed the arduino was securing attached to the tray.  This is not the case, I put a spot of hot glue between the tray and the arduino.  Now the arduino's will stay in the tray, and if need too I can get them out of the tray.

The last build part was the Eyes.  I thought of several different ideas.  I really wanted something that was reliable/solid and easy.  I built some Ping Pong Eye decorations for halloween a couple of years ago.  So I went with that.  One unexpected problem was finding ping pong balls in summer,  I wanted simple white ping pong balls all I could find was glow in the dark.  I tried these out after painting, they did not look good.  In the end I use one set from my halloween set.

I tried out mounting the eyes to the back of the tank lid.  First I mounted the flat on the lid, when I tested this with the Lid up it did not look good.  The eyes where looking up.  I then tilted the eyes down by about 3/8 (used a square  piece of balsa), this worked out very well.  I then hot glued the eyes in place, this is a bit tricky since the eyes are not attached.  I had to redo this a couple of times to get the look I was going for.  FYI, be careful the eyes stick out and later when working on the electronics its easy to knock the eyes loose.  

This is the final build of the tank.  I built a small plywood platform for the speaker. Great care needs to be taken to keep all wires away from the motor linkages.  The motor will happily grab anything and tear it apart.  I learned this the hardware with a earlier set of Eyes.  You can also see the microswitch in this picture for the Lid.  I'm doing dead reckoning with the wiper motors, I use the switches to know when the lids are closed.