The mechanical toothpaste squeezer is an invention that I created mostly to see if I could, but also to make a more convenient and effective method for extracting excess toothpaste from nearly empty toothpaste tubes. Sure, there are manual toothpaste squeezer clips, but I'd much rather use gears and a lever to squeeze my toothpaste. Wouldn't you?
Step 1: Pick Your Favorite 3D Modeling Program
You can use whatever you're comfortable with, but I prefer to use Autodesk Inventor 2016. Whatever you use, you'll need to make sure you can make all kinds of shapes, including complex shapes like gears. Heck, you can do it manually without computer assistance if you want to, but I wouldn't recommend it.
Step 2: Make Your Cylinders
You'll need to 3D model a two cylinders like the one seen in this picture (most likely you'll only need to model it once because both cylinders are identical). Use whatever diameter you feel necessary because different sizes can alter the effectiveness. I decided to make the cylinders .5in in diameter. The hole in the center should have a diameter of less than 50% of that of the full circle. Mine is about .1360in because that is that size of the screws I initially planned on using. Instead, using screws is an alternate method that I have not yet looked into. Take note of the keyhole (the little grove in the center hole). You'll need to model one into your cylinders and remember the dimensions for a future step.
Step 3: Make Your Axles
Now, you need to model your two axles that are to go into the holes of your cylinders (again, you probably only need to model one). These axles needs to be cylindrical as to fit properly inside the cylinders, and going along with that, they need to have the same dimensions (only width, not length) as the hole minus just a hundredth or two in diameter. This reduction is so that they can actually fit inside of the cylinders without smashing them with a hammer. A very important part is that you need to make the other half of the key on the side of the axles. This is why you had to remember the dimensions of the keyhole you made in the cylinders. You need to make this key the same dimensions as that keyhole (maybe slightly smaller as it'll fit). The final detail you need to know about these axles is that they should be the same length as the cylinders plus 4 times the thickness of your gears (add the thickness of two gears to each side). Note that the key should match the length of the keyhole plus 2 times the thickness of your gears (add the thickness of just one gear to both sides of the key), but the cylinder should still extend by the said length. You'll have to plan ahead a bit and determine what you want the thickness of your gears to be, but it's not super important as long as they're sturdy. My gears are .1in in thickness, so I added .2in to both sides of my axles and .1in to both sides of my keys.
Step 4: Make Your Supports
Your gears and cylinders aren't going to just hover in mid air. You'll need to model some sort of support like the one shown in the picture. You can be creative and make a better support, but the one I designed and recommend is the simple design above which is made with 2 holes and 2 extrudes. The thickness of the material is .1in and therefore the holes are too. This is because, if you remember, the gears are .1in in diameter. The extra length that we added on both ends of the axles was designed to fit perfectly in these holes without sticking through. The holes should be, like the holes in the cylinders, .1360in in diameter. The extrudes are far the 2 stray gears that aren't connected directly to a cylinder. These should extrude, you guessed it, .1in and should be .136in in diameter minus a hundredth or two, much like the axles. The hardest part of this step is spacing the holes and extrudes so that they line up so that the gears interact properly and the holes lineup with the axles so that the correct spacing between the cylinders is achieved. I will make a new step for this process.
Step 5: Make Your Supports Cont.
First, we want to get the proper spacing between the two cylinders so that they can squeeze the toothpaste tubes. After measuring a toothpaste tube, I've determines that .025in is the optimal space distance for getting the most toothpaste out of the tube. What that means is that we need to take the diameter of the two cylinders and add .025in to it. Since my cylinders are .5in in diameter, my support is 1.025in long. The height is just 1in because it just needs to be tall enough to have room for the two extrudes, but other than that the height is not very important. To get the correct spacing, find the middle of one of the edges of your support and draw a line towards the center of the plane that is the same distance as the radius of your cylinders (do this on the opposite side as well). For me, that is .25in because my cylinders are .5in in diameter. Go to the end of that line and make a circle (hole) that is .1360in in diameter. This will allow you to put the axles into those holes and will leave a perfect .025in between the cylinders. Next, you need to draw the extrudes in a way that makes them equidistant from each other and each one's respective hole so that the gears interact correctly. To do this, you need to first measure the diameter of the inner part of your gears (valley to opposite valley). This distance will be approximately the distance between each gear (and therefore each hole and extrude). Mess around with it a bit to find the best distance and then get ready to do some drawing to get that perfect distance.
Spacing: First, find the middle of the top edge of the plate that you've made for the support. Draw a line in each direction from the middle, each being half the length of the distance that you determined the spacing to be. Then, draw a line straight down from the end of each of this lines, all the way down the plate. Next, take the line tool and draw a line from the center point of one of the holes and move the other end across the vertical lines you drew until the line you are drawing is the correct distance for your spacing. The picture above may help you understand what I'm trying to describe.
Step 6: Make Your Gears
The gear you model doesn't need to be perfect. The only necessities for your gear to work well are as follows:
1. The diameter of the gear from peak to peak must be less than the diameter of the cylinders.
2. There needs to be room in the middle of the gear for a hole the same size as the holes in the cylinders.
3. There needs to be room for a keyhole identical to that of the cylinder.
4. The peaks and valleys need to interact correctly. Good luck.
5. The thickness of the gear needs to correspond to all of the holes and extrudes you made.
Other than these circumstances, the size doesn't matter too much. The worst you'll have to do is change the height of the support plate.
How you make your gear is completely up to you because there are many methods to do so. The method I used and recommend is the 'Spur Gear' function in Autodesk Inventor 2016. You'll need to be in assembly mode, then go to the 'Design' tab and all of the gears will be under the 'Power Transmission' section of the ribbon. Now, deciphering all of the gear gibberish that follows clicking on the 'Spur Gear' button is up to you. I basically just messed with the settings until I got what I needed. Either way, if it works, then you did it right.
Step 7: Assemble and Finalize
Now that you have everything made and made the right size, it's time to put it all together, whether that be in the program you're using or in real life. First, get two axles and two cylinders and put the axles into the cylinders so that the keys and keyholes are lined with approximately the thickness of your gears on both sides which would be .1in in this case (if using Autodesk Inventor 2016, use the constraints tool). Next, slide the gears into their locations, 2 on the axles and 2 on the extrudes on the support. After that, all you need to do is push the extra length of the axles into the holes in the support. You may need to mess with the gears a bit, but this should link them up nicely. If you did this in real life, move on to finalize. If you did it in a program, print it, do it in real life, then move on to finalize.
Get creative and figure out how this gadget is going to be dropped into your world (how Bob Ross of me). You can design a mount, you can create screw holes in the corner to screw it into the wall, or you can just set it on it's side. It's up to you. I would personally try making screw holes because that sounds pretty cool. Other than that, all you need is a way to work the thing. I would make a lever this is shaped kind of like this:
(Instructables messed up my symbol picture so it's uploaded as a picture up top)
Step 8: Go Brush Your Teeth
You've finally fabricated the means to continue good oral health. Probably. Take this gadget and go collect all of that toothpaste that, in that past, you so often wasted. Enjoy.
www.carolinasdentist.com if you care about toothpaste pictures.